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Chapter 40-41, Side note: it is important to know the difference between…

- - - - Essential nutrients include certain amino acids, fatty acids, vitamins and minerals
        
        key function of nutrients is to act as either substrates or co factors for enzymes
        
        animals can obtain all essential nutrients from eating other animals (certain animals can synthesize their own nutrients from other nutrients so their requirements very from animal to animal)
    - - all organisms need 20 amino acids to complete a set of proteins
      - plants and micro organisms can make all 20 them selves
      - Many animals can synthesize about half of the amino acids they need but they still need to eat other animals to get the rest (humans need eight amino acids in their die : isoleucine, leucine, lysine, methionine, and histidine
      - proteins in our animal products are "complete" compared to plants where some of them "incomplete" or deficient in one or more essential amino acids
    - - Fatty acids that an animal cannot sythesize (animals do not have the enzymes required to make double bonds for certain required fatty acids
        
        fatty acids are needed for storage fat, phospholipid, membrane of cells, and signaling molecules
        
        animals can get these essential fatty acids by eating seeds grains and vegetables
    - - vitamins help enzymes work (vitamins are eaten in small amounts
        
        water soluble: no matter how much you eat if you already have enough you will just pee them out (usually help enzymes work)
        
        fat soluble: if you eat too much they can build to dangerous toxic levels in the fat, when you burn fat they can be released back in the blood stream ( fat soluble vitamins are more for regulation, protection, or structural functions)
        
        Vitamin A is fat soluble and can be incorporated in visual pigments of the eye. Vitamin D can be variable because when we are hit with the sun we can synthesize it
    - - Inorganic materials required in small amounts, also activates enzymes (cofactors)
        
        Some are helpful for carrying oxygen (iron) while others like potassium are crucial for nervous system function and osmotic balance between cells and surrounding body fluid
        
        iodine is incorporated into thyroid hormone, which reguates metabolic rate
        
        vertebrates relatively high amounts of calcium and phosphorus for their building and maintenance of bone
    - - despite animals needing similar nutritional needs they all have diverse diets
      - herbivores eat mainly plants or algae
      - carnivores mainly eat other animals
      - omnivores can regularly eat plants and animals
      - these terms are for what animals usually eat , but sometimes if given the opportunity they can eat other things (deer can occasionally eat worms insects and bird eggs)
    - - diet that lacks one or more essential nutrients or doesn't provide enough energy results in malnutrition
        
        insufficient nutrition can cause deformities, disease or death (deer or herbivores can get weak bones if their soil for their grass is not phosphorus rich)
        
        some grazing animals like goats counter missing nutrients by eating concentrated sources of salt or minerals
        
        protein deficiency is the most common deficiency in humans
    - - diet that fails to provide enough chemical energy
        
        the body first uses stored fat and carbs
        
        second it starts breaking down own proteins for fuel, muscles shrink and brain might become protein deficient
        
        Undernourished animals that survive might have irreversable damage
        
        undernourishment in humans is most common with war or drought, things that supply food supply, but some disorders like anorexia can cause it too
    - - used as energy source
      - monosaccharide: can be used for quick energy (tastes sweet)
      - polysaccharide can be used for long term energy because its digested more slowly (found in starchy foods)
    - - determining ideal diet for humans is hard because humans are so genetically diverse, you also cannot examine nutritional need of children in a way that may harm them
        
        many insight on human nutrition come from epidemiology: the study of human health on the population level, for example they found women where having kids with neural tube defects
        
        As a result they suspected this was a result of malnutricion
        
        they found out that vitamin supplementation greatly reduced the chance of these defects to happen
        
        later they got evidence that vitamin B9 was the specific vitamin responsible
        
        they started adding vitamin B9 to bread so chances of the neural tube defect happening could go down
  - - - first stage: act of feeding or eating
      - Filter feeding: strain small animals or food particles out of surorrunding medium, it is a type of suspension feeding removes suspended food particles via trapping or capture mechanisms Ex: humpback whale
      - fluid feeders: suck nutrient rich fluid from a living host, some fluid feeders benefit host like bees, while others like the tsetse are just parasites
      - substrate feeders: they eat what they live on Ex caterpillars
      - Bulk feeders: eat relatively large pieces of food, some of their adaptations include tentacles, pincers, claws, venomous fangs, jaws and teeth to kill prey or tear off pieces of meat Ex: python killing and swallowing gazelle whole
    - - second part of food digesting
        
        mechanical digestion: physically chewing or grinding food into smaller pieces increasing surface area
        
        food is broken down into particles small enough to absorb
        
        chemical digestion: cleave large molecules into smaller ones
        
        chemical digestion is important since it cant directly use nucleic acids, phospholipids fats and most carbohydrates in food, they are too big or the body to absorb
        
        Molecules must be broken into smaller molecules so that animals can use them to build what they need
        
        macromolecules are built with dehydration reactions this process is reversed and broken down into its smaller monomers through hydrolysis,
    - - small intestine absorbs food
      - large intestine absorbs water so we don't dehydrate every time we poop
    - - waste is eliminated
      - in animals without anus it happens through mouth
      - in animals with anus it happens through anus
    - - animals dont digest themselves when digesting material because the processing of food happens within specialized intracellular or extracellular compartments.
      - intracellular digestion: happens in food vacuoles (cellular organelles and simplest digestive compartments) ]
        
        after food particle has been engulfed by phagocytosis or pinocytosis, new food vacuoles bring food into lysosome which is full of hydrolytic enzyme,
        
        then the hydrolytic enzymes enter food vacuole and digest food. sponges digest all food like this.
      - extracellular digestion:
        
        extracellular digestion:
        
        in most animals hydrolysis occurs largely by extracellular digestion
        
        Having one or more extracellular compartments for digestion lets animal to digest larger pieces of food than what can be ingested by phagocytosis.
        
        simple animals like cnidarians use a gastrovascular cavity which is a food pouch with one opening (hydras use tentacles to stuff prey in their mouth and into their gastrovascular cavity)
        
        specialized gland cells that line the cavity secrete digestive juices to break down food
        
        any waste is released back thorugh the mouth
        
        some animals developed a digestive tube with 2 openings, mouth and anus called an alimentary canal, this allowed the animal to ingest more food while old food was still being digested
        
        animals alimentary canals vary between species
        
        most digestion happens in the small intestine
        
        STOMACH DOES NOT DO CHEMICAL DIGESTION (maybe some) but according to luyster IT ONLY LIQUIFIES FOOD
        
        first part of small intestine is the duodenum, Its very important that is where enzymes from pancreas get added to your food to digest it
  - - - food enters through oral cavity
        
        food is chewed and grinded to facilitate swallowing and increase surface area for later chemical digetion
        
        anticipation of food triggers release of saliva from salivary glands
        
        saliva is anti microbial, lubricates food, facilitates smell and taste, has buffers to neutralize acid and prevent tooth deacy, and protects gums from abrasion
        
        the most abundant enzyme in saliva is amylase which breaks down carbohydrates like starches
        
        tongue helps evaluate food it also helps manipulate food and saliva into a ball and swallowing
        
        food reaches pharynx which tries to prevent food from going down trachea and makes it go into the esophagus (muscular tube that connects to stomach)
        
        food reaches esophagus where it continues to be pushed down by alternating wave of smooth muscle into stomach
        
        food reaches a ring like valve of muscle called the spincter which regulates passage of food into the next compartment the stomach
    - - Digestion in stomach
        
        stores food with a very elastic wall it can expand to hold up to 2 liters
        
        liquifies food or suspends it in liquid called gastric juice this mixture of food and and gastric juice is called chyme
      - Chemical digestion in stomach
        
        HCL denatures proteins, kills bacteria and liquifies food
        
        Pepsin, a protease, adapted for acidic environments, breaks down denatured proteins in food into smaller polypeptides, making them easier for other digestive enzymes to act on later.
        
        There 2 types of gastric glands in stomach
        
        parietal cells that pump hydrogen atoms into lumen and diffuse chloride ions into lumen through specific membrane channels of parietal cells, which late combine with hydrogen ions to make HCL in lumen
        
        Chief cells release deactivated pepsin called pepsinogen into lumen which is later activated by the HCL acid when it clips off a portion of the molecule to expose its active site
        
        HCL and pepsin form in the lumen of the stomach
        
        pepsin activates pepsinogen which makes more and more pepsin (Ex; of positve feedback)
        
        mucus lines stomach and prevents stomach from digesting itself with pepsin and HCL, this lining is replaced every 3 days or so before it is eroded by digestive juices
      - Stomach dynamics
        
        stomach churning makes it easier for HCL and pepsin to act on all food
        
        contractions help bring food through alimentary canal
        
        sphincter where stomach meets small intestine helps regulate the amount of chyme that can enter the small intestine. (one squirt of chyme at a time)
        
        sphincter at the top of the stomach that leads to esophagus sometimes lets acid back up the esophagus causing heart burn
      - Digestion in small intestine
        
        Most chemical digestion happens in small intestine although some happens in the stomach or mouth
        
        small intestine is the largest part of the alimentary canal its only small because of diameter
        
        first part (25cm or 10 inches) of small intestine is called the duodenum, this is where chyme receives digestive juices from pancreas, liver, and gall bladder
        
        hormones released by stomach ad duodenum control the digestive secretions into alimentary canal
        
        additional enzymes from epithetilial lining of duodenum and enzymes from pancreatin work together to complete most digestion in small intestine
        
        bile salts are is major component of bile which is excreted by the liver and stored and concentrated in gall bladder
        
        Arrival of chyme in duodenum triggers release of secretin which triggers pancreas to secrete bicarbonate which neutralizes the acid in chyme and acts as buffer for chemical digestion in small intestine
        
        once pancreatin arrives in duodenum enzymes in pancreating activate because trypsin is activated by enteropeptidase located in lining of duo denum which then activates every other enzyme
        
        Fat is harder to digest since it is insoluble in water, in humans and other vertebrates, fat digestion is facilitated by bile salts which break apart fat and lipid globules
        
        bile production is linked to the destruction of re blood cells that are no longer functional, pigments from red blood cell destruction are incorporated into bile pigments which are eliminated through feces. sometimes in some disorders the bile pigments can build up in skin called jaundice
      - absorption in small intestine
        
        once digestion is nearly complete contents of duodenum move on to jejudenum and ileum where nutrient absorption happens through the lining of the intestine
        
        folds in the small intestine called villi have small microscopic projections called micro villi which massively increases surface area increasing absorption efficiency
        
        some things like fructose are absorbed with the concentration gradient and are transported passively while things like small peptides and amino acid etc, need to be pumped against the concentration gradient making them transported actively
        
        active transport allows much more absorption of nutrients than would be possible with passive diffusion alone
        
        nutrient rich blood carried away from villi converge in liver so that liver can regulate nutrient distributions and remove toxins
        
        some nutrients like fat take a different digestion path because they are absorbed by epithelial cells which make them into triglycerides and then they are coated by phospholipids that form globules called chylomicrons too large to enter blood vessels.
        
        to exit small intestine they must first enter a lacteal (a vessel at the core of each villus that has gaps between adjacent cells)
        
        lacteals are part of lymphatic system, which is a network of vessels with clear fluid called lymph
        
        lymph carrying fat globules is passes into larger vessels of lymphatic system and eventually back into large veins that take them back to the heart
        
        small intestine reabsorbs most of the water from food and digestive juices indirectly by pumping out ions that water follows
      - Processing in large intestine
        
        alimentary canal ends with large intestine which includes colon, cecum, and rectum
        
        small intestine is connected to large intestine with a T shaped junction one arm of the T is the colon which leads you to the anus, and the other arm leads you to a pouch called the cecum where fermentation of ingested material occurs for herbivores, for humans the cecum has an appendix hanging off of it where symbiotic micro organisms are stored
        
        what remains is feces, the wastes of the digestive system and undigested things like cellulose which helps food move along the alimentary canal
        
        if lining of colon is irritated with a bacterial or viral infection then less water may be reabsorbed which results in diarrhea
        
        the rectum is where feces is stored before you defecate, 2 sphincters separate rectum and anus, the first on is involuntary and the second one is voluntary
        
        Strong contractions of colon create an urge to defecate
        
        filling of stomach triggers a reflex that increases rate of contractions from the colon. this means often after a meal you want to defecate
        
        colon completes recovery of water that small intestine began
        
        One third of dry weight of poop comes from bacteria dead or alive and when bacteria eat while on your undigested food they make gases, which you expel out your anus
  - - - arrangement and types of teeth are based on diet (Ex; sea otter that uses sharp teeth to tear apart crabs and use rounded mollars to crush their shells)
      - One of the major reasons mammals are so successful
    - - variations in stomach dimensions may differ depending on what the animal eats
      - Predators that may have to wait a long time between meals have to have large expandable stomachs so that when they do catch something they eat as much as they can
      - Herbivores and omnivores have longer alimentary canals relative to their size because plants are harder to digest due to their cell walls
        
        (longer digestive tract= more time to digest and more surface area for nutrient absorption)
        
        Koala has longer digestive tract relative to its size compared to lion because it mainly eats protein-poor eucalyptus leaves
    - - mutualism: 2 species interact in a way that helps both of them ( bacteria in our large produce vitamins and regulate development of intestinal epithelial tissue which helps us while we give them a steady food supply
      - Scientists have expanded their knowledge on the microbiome by Using PCR (polymerase chain reaction) they have found over 400 different bacteria species in our microbiome
      - variation in microbiomes between organisms are heavily contributed to by diet
      - Benefit of microbiome study demonstrates what bacteria cause stomach ulcers (acid-tolerant bacterium Helicobacter pylori)
      - these studies in microbiome have opened therapy opportunities for antibiotic resistant intestinal infections
      - Fecal microbial transplantation (introduction of microbiome of healthy individual into infected individual) has been used for otherwise untreatable diarrhea caused by the bacterium Clostridium difficile (although risk of secondary infection is very real)
      - side note: treatment for antibiotic resistant bacteria also includes introduction of bacteriophages which kill bacteria
      - scientist analyzed how the microbiome was impacted in indiviuals with H pylori infection. It lead to a dramatic drop in percent of other bacteria normally found in stomach
    - - Herbivores do not have the enzymes to break down (hydrolyze) cellulose so they rely on large populations of mutualistic bacteria in fermentation chamber inside their alimentary canals that can break down cellulose into simple sugars and fatty acids the animal can absorb
      - In horses, koalas, and elephants, these fermentation chambers filled with populations of symbiotic bacteria are in the cecum
      - in the hoatzin an herbivorous bird found in South American rain forests, hosts its symbiotic bacteria in a muscular crop (pouch in the esophagus)
      - Some rabbits and rodents ferment food in the cecum and large intestine, but since absorption happens earlier in the small intestine, they eat their own feces to absorb the nutrients produced by fermentation
      - Most elaborate adaptations for a herbivore diet are found in cud chewing animals
      - animals like giant tube worms which have no mouth or anus obtain all their food from symbiotic micro organisms inside them. these bacteria use oxygen, CO2, hydrogen sulfide, and nitrate available at vents where they live to make their produce organic molecules which the worms absorb
      - Symbiotic relationship happen in invertebrates and vertebrates alike
      - Evolution of mutualistic relation ships with symbiotic micro organisms opened a lot of doors when it comes to accessing sources of nutrition they couldn't access before
  - - - animals digestive system does not have to be active because there is long gaps between each meal.
      - the digestive system is activated like stepwise. as food reaches a compartment it activates secretion of digestive juices for the next one while muscular contractions keep it moving dodwn the alimentary canal
      - these events as well of movements through small and large intestines are regulated by the enteric nervous system (networ of neurons dedicated for digestive organs
      - endocrine system play critical role in controlling digestion like hormones released by stomach and duodenum ensure that digestive secretions are only there when needed
      - when food hits the stomach it causes it to expand which secretes a hormone called gastrin that enters the blood stream and comes back to hit the stomach to tell it to start making digestive juices
      - chyme eventually hits the duodenum which responds by releasing digestive hormones cholecystokinin (triggering release of digestive juice from pancreas) and and secretin (triggers release of bicarbonate to neutralize acid in chyme)
      - if there are high levels of fat in chyme then lots of CCK and secretin are released to slow down movement of chyme allowing more time for absorption
    - - when an animal take in more energy rich molecules the it needs that energy is stored as either glycogen. or fat
        
        a polysaccharide made up of many glucoses put together
        
        glycogen stores are limited while fat stores can continue to grow
        
        when food is scarce muscles can release glycogen, and adipose cells can release glucose and fatty acids into blood stream
        
        most healthy humans have enough fat to sustain them for weeks
        
        adipose tissues provide the most space-efficient way for the body to store large amounts of energy
    - - breakdown and sythesis of glycogen is not only important for energy storage but also maintaining glucose homeostasis
      - when blood sugar is too high body secretes insulin which promote glucose uptake
      - if blood sugar is too low secretion of glucagon promotes release of glucose in blood from energy stores like liver glycogen
      - insulin promotes glycogen synthesis which takes sugar out of blood while glucagon promotes the break down of glycogen so that sugar goes back in the blood
      - insulin and glucagon help regulate blood sugar together
      - Insulin also acts on nearly all body cells to stimulate glucose uptake from blood. with the exception of brain cells ( and a couple others) which can always take up glucose whether or not insulin being there so brain always has access to energy
      - glucagon and insulin are both made in pancreas
        
        pancreas has islets which have alpha cells make glucagon and beta cells which then make insulin
        
        insulin and glucagon enter interstitial fluid and then circulatory system
      - only 1 to 2 percent of the pancreas is hormone secreting cells alot of other cells are for production of digestive enzymes and bicarbonate ions used in small intestine
      - Pancreas is part of both digestive and endocrine systems
    - - diabetes is a disease where there is a lack of insulin or a decreased response to insulin in target tissues
      - Cells not getting enough insulin, or cells with a decreased response to insulin, cause blood sugar to rise, and cells do not get enough glucose they need for metabolic needs
      - Because cells are not getting enough glucose for cellular respiration, the cells resort to using fat as the main substrate for cellular respiration
      - Acidic metabolites during fat break down can build up in blood and dangerously lower blood pH. This condition can also lead to the depletion of sodium and potassium ions in the body
      - People with diabetes can posses excess glucose that the kidneys cannot reabsorb, as a result the glucose that remains in kidney filtrate can is excreted. For this reason, one of the tests for diabetes is presence of glucose in urine.
      - Diabetes type 1
        
        type one diabetes is a diabetes that an individual is born with, this type of diabetes destroys the persons ability to produce insulin
        
        treatment often consists of insulin injections often times multiple times a day
      - Diabetes type 2
        
        type 2 diabetes is a diabetes caused by the target cells inability to respond to insulin normally
        
        Insulin is indeed produced but target cells fail to take up glucose from the blood, leading to blood sugar levels becoming elevated
        
        Although heredity can play a role, excess fat and lack of exercise significantly increase the risk of developing this disorder
        
        Type II diabetes generally appears after the age of 40, but even children can get it, particularly if they are overweight and sedentary
        
        Many people who have diabetes have type 2 diabetes, approximately 90% of people who have diabetes have type II
        
        Many people who have type II diabetes regulate their blood sugar with regular exercise and a healthy diet
        
        Type II diabetes is a leading cause of death in the united states and a growing public health concern world wide
        
        Type II diabetes can be caused by a genetic defect that affects the insulin receptor or the insulin response path way in cells
        
        In many cases however events in target cells suppress the activity of an otherwise functional response pathway, one source of this suppression seems to be inflammatory signals generated by innate immune system
    - - Over nourishment can lead to obesity
        
        Obesity can be a major contributor to health problems alot of health problems including but not limited to cardiovascular disease, type II diabetes, strokes and heart attacks
        
        network of neurons ( and other things like the hyothalamus, etc) relays and integrates information from digestive system to regulate long term and short term appetite
        
        hormone like ghrelin (secreted by stomach walls) makes you feel hungry before meals
        
        In contrast Insulin and PYY are released after a meal and suppress feelings of hunger
        
        Leptin (a hormone produced by fat/adipose cells) suppresses feelings of hunger and appears to have a major role in regulating body fat levels
        
        ghrelin makes you hungry
        
        after eating blood sugar levels rise triggering increase in insulin which helps cells take up sugar and signals to the brain to decrease hunger
        
        leptin suppresses appetite but when body fat levels drop leptin levels drop which increases appetite
        
        PYY hormone released by the small intestine after a meal, suppresses appetite, counteracting hunger signals from ghrelin.”
- - - - Many animals have evolved different shpes
      - These different shapes still have to abide by certain rules (strength, diffusion, heat exhange etc)
      - These rules constrict or limit animals forms
      - Physical laws can also limit Size, and speed
        
        The bigger something is the thicker the skeleton needed to support it is *this effects structures like endo skeletons ex skeletons and
        
        The bigger the animal, the higher percentage of muscle it needs to move, at some point the bones become too big for the muscles so they cant carry the extra weight as well (sacrificing mobility)
    - - Animals need to exchange materials with their environment
        
        Nutrients
        
        waste products
        
        Gases
      - Exchanges occur when sustances in an (aq) solution (dissolved in water) move across plasma membrane of each cell.
        
        The more cell membrane surface area touching its environment, the more easy it is for cells to perform exchange, things like amoebas have a relatively easy time performing cell exchange (Alot of their surface areas in contact with environment)
        
        Animals are made up multiple cells, this means that alot of cells cant come in contact directly with their environment, this meaning, they rely on things like respiratory and circulatory system to get the nutrients and materials they need through inerstitial fluid
        
        Rate of exchange is directly proportional to the membrane surface area involved in exchange
        
        amount of material needed is proportional to total volume of the organism
        
        Multicellular organization, only works if each cell has access to suitable (aq) environment. ( ex: pond dwelling hydras have both their inner and outer parts are constantly bathed in pond water, were as flat shapes, one in a tape worm, insures most of your body is iin direct contact with its environment
        
        Organs for digestion, circulation, and and respiration have folds or branching that helps increase surface area (more surface area= more exchange with out side environment, like air from out side, food from out side and nutrients from digestive system in blood going into interstinial fluid
        
        interstitial fluid is fluid that fills spaces between cells
    - - Cells for working animals through emergent properties
        
        emergent properties (properties that appear once multiple things work together
        
        property cannot be predicted just by looking at one part of the system (like you cant predict conciousness from a single neuron)
        
        the individual part did not have this property
      - Hierarchy of structural organization
        
        cells come together to make tissues (with new emergent properties)
        
        tissues come together to make organs (with new emergent properties)
        
        organs come together to make an organ system (with new emergent properties)
        
        Organ systems come together to make organism (with new emergent properties)
        
        Looking at it bottom up lets you see emergent properties while looking at it top down lets you see the multilayers basis of specializaion ( what its made up of)
      - Many organs have more than ne physiological role
        
        Pancreas is part of both endocrine and digestive system (pancreas produces enzymes critical for digestion, and helps regulate blood sugar critical of endocrine system
        
        If roles are different enough they can be part of 2 different organ systems
      - Organ systems are made up of specialized organs and cells
        
        Digestive system each organ has a specidic role
        
        One of the stomachs roles is starting protein break down this requires multiple things made possible by different parts
        
        churning of stomach caused by stomach muscles
        
        digestive juices secreated by stomach lining
        
        production of digestive juices with highly specialized cell types
        
        One cell makes protein-digesting ennzyme, while another produces hydrochloric acid, and another one produces mucus to protect stomach lining (each part like the stomach lining cells and muscles work together to give an organ its emergent property and its specific role.
    - - Epithelial tissue
        
        barrier against mechanical injury, fluid loss, and infection (tightly packed)
        
        stratified squamous epithilium: multi layered regenerates rapidly found on surfaces subject to abrasion (outer skin))
        
        covers outside of the body and lines organs
        
        Different shape/ arrangeement=different function
        
        ciliated Pseudostratified columnarepithilum: secretes and moves mucus down the trachea
        
        Simple squamous epithilium: Exchange of material through diffusion (gas exchange in alveoili)
        
        Simple columnar epithilium: important for secretion and absorption( found in intestines)
        
        Cuboidal epithilium: Specialized for secreation, found in kidneys, thyroid and salivary glands.
      - Connective tissue
        
        Holds many tissues and organs in place can contain fibro blasts and have macrophages to defend again foreign particles
        
        Loose connective tissue: Bind epithelia to underlying tissues and holds organs in place, found everywhere
        
        Fibrous connective tissue: dense with collagen, found in tendons, connects muscle to bone.
        
        Bone: mineralized connective tissue, has osteoblasts (makes bone with collagen calcium, magnesium and phosphate ions) support structure of the animal
        
        Adipose tissue: specialized to store fat, insulates body and stores energy, fat droplet shrinks when body uses fat as fuel
        
        Cartilage: made of collagen and chondroitin sulfate, chondrocytes secrete collagen and chondroitin sulfate, strong yet flexible material can be found between disks vertebrae
        
        Blood connective tissue: liquid extracellular matix called plasma which is made of water salts and dissolved proteins, suspended in plasma are platelets, red (erythrocytes), and white (leukocytes) blood cells, red blood cells carry oxygen white blood cells help with immune defense, platelets help with blood clotting
      - Muscle tissue
        
        Loco motion and other movement
        
        Skeletal muscle: striated, attached to bone by tendons, responsible for voluntary movements, and multi nucleated :
        
        smooth muscle: No striations found in tubes of body (intestines blood vessels, etc) involuntary activity
        
        Cardiac muscle: striated, branching, intercalated disk, involuntary, found in heart
      - Nervous tissue
        
        sends and receives signals
        
        Neurons: basic units of the nervous system, receive signals through dendrites and send signals through dendrites, axons often come together into bundles of nerve
        
        Glia helper cells: help neurons by nourishing them, insulating them, replenishing them and even modulating them sometimes
    - - Digestive system
        
        Emergent property: food processing (digestion ingestion, absorption and elimination)
        
        organs: Mouth, esophagus, stomach, intestines, liver, pancreas, anus
      - Circulatory system
        
        Emergent property: Internal distribution of nutrients/materials
        
        Organs: heart, blood vessels, blood
      - Respiratory system:
        
        Emergent property: efficient gas exchange ( uptake oxygen and disposal of CO2)
        
        Organs: lungs, trachea, other breathing tubes
      - Excretory system:
        
        Emergent property: Disposal of metabolic waste, regulation of osmotic balance in blood
        
        Organs: kidneys, urinary bladder, urethra
      - Endocrine system:
        
        Emergent property: regulation of body processes via hormones
        
        Organs: pituitary, thyroid, pancreas, adrenal, and other hormone secreting glands
      - Reproductive system:
        
        Emergent property: Gamete production, promotion of fertilization, support developing embryos ( reproduction)
        
        Ovaries, testes and associated organs
      - Nervous system:
        
        Emergent property: coordination of body activies, detecting and responding to stimuli
        
        Brain, spinal cord, nerves and sensory organs
      - integumentary system
        
        Protection from injury, infection and dehydration
        
        Skin and derivitaves
      - skeletal system
        
        Support, protection of internal organs, movement
        
        Bones, tendons, ligaments cartiladge
      - Muscular system
        
        Locomotion and other movement
        
        skeletal muscle
      - Immune and lymphatic system:
        
        Emergent property: body's defense system (fighting infections and virally induced cancers)
        
        Bone marrow, lymph nodes, thymus, spleen, lymph vessels
    - - animals tissues and organs must work in unison to be effective
      - 2 major systems for coordinating and reponding to stimuli
      - Endocrine system
        
        Uses hormones released in the blood stream to carry signals throughout the whole body,
        
        Slower than nervous system because molecule (hormones) need to wait to get circulated
        
        Limited to cells that have receptors for the specific signal/ hormone
        
        effects are long lasting, hormones can remain in blood stream for minutes and even hours
        
        Depending on which cells have the receptor for the specific hormone, effects can be throughout body or more localized
        
        Good for gradual changes that effect the whole body.
      - Nervous sytem
        
        Uses signals (electricity) transported along dedicated routes to specific locations in body
        
        Much faster than endocrine system
        
        Limited to cells that connect via specialized junctions
        
        Nerve impulses last only a fraction of a second
        
        nerve impulses can act on other neurons, muscles or cells that secrete
        
        Convey information only by the path way the signal takes
        
        More than one type of signal, sometimes over long distances, changes in voltage, and chemical signals between neurons
        
        Good for immediate rapid response to environment Ex: reflexes and other rapid movement.
  - - - Conformer lets environment dictate its internal environment for that variable (if its cold outside its cold inside)
      - Regulator causes internal change despite external conditions (if its cold outside the animal will try to stay cold inside
      - Some animals conform to certain variables but regulate others (Bass conforms to temperature in water but regulates solute concentration in blood)
      - Conformer doesnt necessarily mean change in variable in the bottom of the ocean conditions are stable so they can conform without changing alot due to environmetn
    - - Negative feedback
        
        reduces stimulus (determines by upper and lower bound of setpoint) that triggered the response (heater in house activate by thermostat)
        
        Plays major role in homeostasis ( if your hot your nervous system detects it then you sweat to get cooler)
        
        homeostasis is Dynamic equilibrium (is balance between external factors that may change internal environment, and internal factors to oppose changes that might be caused by external factors)
        
        Positive feedback
        
        Amplifies the stimulus
        
        Doesn,t play major role in homeostasis
        
        Helps drive process to completion (orgasm: it feels good so you want more stimulation that eventually makes you cum completing the process of reproduction/pleasure)
        
        note: sometimes it doesnt feel good like contractions before child birth but it still drives towards towards something like the child being born
    - - Maintenance of internal balance at a set point
      - Obtain a steady state where internal environment is steady despite outside conditions
      - Many things show a homeostasis for a range (body temperature in humans (97f-99f)
      - Alterations in homeostasis set point and alterations in homeostasis
        
        certain changes in set point that happen in cycles reflect a circadian rhythm (set of changes that happen roughly every 24 hours)
        
        Changes in temperature (caused by moved set point) greater than .6 C happen roughly once a day and are kept track of with a biological clock mainly regulated by dark and light levels in environment
        
        Jetlag can happen when your internal biological clock is mismatched with time zone
        
        homeostasis alterations can sometimes happen due to acclimatization (animals adapt different external environment) elk moves up mountain with less oxygen so it has to pee more acidic to maintain blood ph
        
        set point may move or change (Ex: fever or during a time of life where body may want regulated change like puberty)
        
        Changes in homeostasis that need to be controlled
        
        Changes in homeostasis set point: body intentionally moves target (controlled change)
    - - Control system: maintains a variable around a certain set point(like thermostat in a home maintains certain temperature)
        
        a change in the upper or lower bunds of a set point serves as a stimulus for a sensor to pick up
        
        Sensor sends signal to the control center triggering a response
        
        response/physiological activity helps return variable back to the set point
  - - - energy allocation and use
        
        animals that need food are hetero trophs
        
        animals that make their own food with light energy are autotrophs
        
        animals use enegy from food for metabolism and activity
        
        food is digested through enzymatic hydrolysis and nutrients are absorbed by body cells
        
        ATP made through cellular respiration keeps animals alive by powering cellular work required in organs and organ systems
        
        ATP enables biosynthesis for body growth, repair, storage for material storage like in fat, and gamete production
        
        Production and use of ATP produces heat which the organism releases into their environment
      - quantification of Enegy use
        
        Physiologist calculate how much energy animals or humas need by measuring rate at which animal uses chemical energy and how rate changes
        
        Sum of all energy a animal uses is called its metabolic rate measured in joules, calories or kcals. kilo calorie has 1000 calories ( the big C on nutrition labels)
        
        Metabolic rate can be determined by measuring an animals rate of heat loss, this is done with a calorimeter, this is a closed insulated chanber with device that measures amount of heat animal gives off to its environment
        
        metabolism can also be measured by seeing how much O2 is consumed or how much CO2 is produced for or from cellular respiration
      - MInimum metabolic rate and thermoregulation
        
        animals need a minimum metabolic rate to continue functioning
        
        For a non growing, non-stressed endotherm on an empty stomach in a comfortable temperature range the minimum metabolic rate is called BMR (basal metabolic rate)
        
        Ectotherm metabolic rate of an unstressed, fasting, ectotherm at a specific temperature is called SMR (standard metabolic rate). It is dependent on temperature
        
        Measuring different minimum metabolic rates lets you see energy cost of endothermy vs ectothermy
        
        The standard metabolic rate (SMR) of an American alligator is approximately 1/20th the amount of calories needed of a human male of equivalent body size.
        
        Ectothermy is much more energy efficient because ectotherms do not rely on metabolic processes to regulate their body temperature.
      - Size influence on metabolism
        
        the higher te body mass the more overall chemical energy the animal needs
        
        Smaller animals require more energy per gram compared to larger ones. as a result they need faster heart rate breathing rate and blood volume relative to size
      - Activity influence on metabolic rate
        
        animals metabolic rate greatly depends on activity level
        
        the harder the activity the shorter it lasts
        
        the longer the activity the lower metabolic rate needs to be to sustain it
      - Torpor and energy conservation
        
        Sometimes environmental conditions are to hard to maintain homeostasis (too hot or too cold)
        
        When temperature is too low or there is little food some animals go into torpor to conserve energy (most animals that experience it are relatively small)
        
        metabolic rate can be 20 times less than if the animal tried to maintain its normal temperature
        
        Hibernation is long term torpor when food and temp,temratures are low for a whole winter, body temperature drastically drops because their body thermostat is turned down
        
        Estivation is another short term period of decreased metabolic rate, but it is for when temperatures are too high and water is scarce
        
        some evidence suggests that circadian clock stops working when in hibernation
  - - - endotherms produce own heat
      - ectotherms get heat from environment
    - - stable body temperature is homeotherm
      - body temperature varies with environment is poikilotherm
      - not all ecto therms are poikilotherms some fish live in the bottom of the ocean where temperature is stable
      - No fixed relationship between where animals get heat and stability of body temperature
    - - radiation: animal gets heat from electro magnetic waves that are emitted from objects above absolute zero
      - evaporation: water absorbs heat on surface of animal and it evaporates away making heat go down
      - Convection: heat is gained or reduced by movement of air and or liquid past surface (lizard is hit with breeze that contributes to heat loss)
    - - reduces flow of heat between animal and environment
      - insulation found in body surfaces like hair feathers and fur
      - some animals have oils that repel water to maintain their insulation like birds
      - most mammals and birds can raise their fur or feathers to increase insulation
      - insulation for marine animals is very important
        
        in the water heat exchange happens 50-100times faster than in air this makes it hard for marine mammals to keep heat
        
        evolutionary adaptation makes called blubber (very thick fat under skin) made it easier for them to keep heat
    - - circulatory systems are major route for heat exchange
      - many animals can alter how much blood is flowing between their body core and skin
      - vasodilation: blood vessels widen making more blood (therefore heat ) comes in contact with its environment (usually increase transfer of body heat to environment )
      - vasoconstriction: blood vessels constrict so less blood goes into contact with environment which makes less heat of the animal go into the environment
      - ectotherms can also regulate heat exchange through blood flow
      - Countercurrent exchange
        
        many birds and mammals rely on countercurrent exchange for reducing heat loss ( can also transfer solutes)
        
        because liquid (in this case blood) move in opposite directions exchange is very efficient
        
        hot artery blood move to extremities and transfers heat to adjacent veins along the entire exchanger
        
        as arterial reaches the end of the extremity it is much cooler than the temperature in the animals core, even so it can still transfer heat to the even colder adjacent veins on their way back to the core ( blood in veins is colder because it has come in contact with cold environment and is on its way back to core causing it to lose even more heat on top of the heat it already transferred to the veins on the way to the extremity when it was in the artery)
        
        once the blood makes its way back to the core it gains heat by running back adjacent to the blood coming from the core in the arteries, this blood gets reheated the closer it gets to the core because the closer the adjacent artery is to the core the hotter it is
        
        is this accurate sharks have counter current exchange systems despite being conformers because the muscles need to be a certain temperature to function best, when the muscles are contracting they produce heat and that heat is preserved by counter current exchange system, this makes them regional endotherms in core muscles
    - - if environmental temperature is above body temperature only evaporation can keep body temperature from rising
      - water absorbs alot of heat when it evaporates (because heat is getting carried away with water vapor
      - some things like horses and humans have dedicated sweat glands for evaporative cooling
    - - adjust metabolic heat production
        
        endotherms maintain body temperature higher than environment, so they have to counter act heat loss
        
        endotherms can vary heat production to counter act heat loss (shivering helps chikadees keep near constant temperature)
        
        Insects can also vary heat production contract muscles rapidly before flight to make warm "flight motors" enabling flight even in cold temperatures
        
        In mammals hormones from endocrine system tell cells to speed up metabolic activity when its cold producing heat instead of atp (non shivering thermogenesis)
        
        some mammals have brown fat specialized for rapid heat production ( more mitochondria makes fat brown). some have been found with human adults
        
        some endothermy has been seen in large non avian reptiles under certain circumstances like a Burmese python incubating eggs
    - - ectotherms and sometimes endotherms regulate temperature with behavioral responses
      - when cold they seek warm exposing as much as they can to the heat source when they are warm they seek col areas, bathe or turn in a direction that minimizes exposure to sun
      - dragon flies go into obelisk position because they want to reduce body surface exposed to sun, which reduces heating
      - despite being simple these behaviors enable many ectotherms to maintain nearly constant temperaure
      - social behaviors also contribute to temperature regulation like when bees huddle together to retain heat and change place between outer shell and inner portion
    - - in mammals and humans sensors for thermoregulation are concentrated in hypothalamus (also controls circadian clock)
      - group of nerves cells in hypothalamus function as thermostats
      - Respond to body temperatures outside normal range (set point) and activate mechanisms that promote heat loss or gain
      - if above normal range thermostat tells body to cool down with sweat, dilation, or panting (depends on animal)
      - if below normal temperature range thermostat (hypothalamus) decreases heat loss mechanisms and activates systems that save heat like contricting vessels at skin or generating heat such as shivering
      - Fevers are from an increase (to move higher up) of normal range (set point) that the body of the human or animal wants to keep
      - certain ectotherms increase body temperature compared to when not infected, upon infection they want to keep a higher temperature than normal this is called behavioral fever (example dessert iguana wants to heat up and stay in temperature range elevated by 2- 4 degrees C