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Chapters 40 & 41 (Animal Nutrition (Need to Feed (Nutrition (Food…

- - - - Many animals face large gaps between meals so their digestive system doesn't need to be continuously active
        
        Instead it's processing is activated step wise, as the food reaches a new compartment it triggers the secretion of digestive juices for the next stage
        
        Events are regulated by the enteric nervous system, a network of neurons dedicated to the digestive organs
    - - Glucose Homeostasis
        
        Diabetes Mellitus
        
        Type 1
        
        Insulin dependent diabetes, an autoimmune disorder that cause the body's immune system to destroy its own beta cells of the pancreas
        
        Type 2
        
        Non-Insulin-Dependent diabetes, characterized by a failure of target cells to respond normally to insulin
        
        Glucose homeostasis can be disrupted by multiple disorders
        
        Diabetes Mellitus is caused by a deficiency of insulin or a decreased response to insulin
        
        Blood glucose rises, but cells are unable to take up enough glucose to meet metabolic needs
        
        When blood glucose levels rise above normal levels, insulin triggers the uptake of glucose from the blood into body cells
        
        When blood glucose level drops below the normal range, glucagon promotes the release of glucose into the blood stream
      - When an animal takes in more energy-rich molecules than it can use for metabolism and activity, it stores excess energy
        
        Liver and muscle cells act as primary sites of energy storage, excess energy is stored in glycogen
        
        Additional excess energy is stored in fat in adipose cells
      - At times when fewer calories are taken in than are expended, the body expends liver glycogen first and then draws on muscle glycogen and fat
    - - Consuming more calories than the body needs for normal metabolism, overnourishment, can lead to obesity and excessive accumulation of fat
      - A network of neurons relay and integrate information from the digestive system to regulate secretion of hormones that regulate long-term and short-term appetite
  - - - Food enters the oral cavity, teeth breakdown the food into smaller pieces
      - Salivary glands release saliva, a viscous mucus substance made up of water, salts, cells, and glycoproteins
        
        Amylase, enzyme that breaks down starch and glycogen
      - Tongue movements manipulate the mixture of saliva and food, and help it into a ball called a bolus.
      - Bolus is received by the pharynx, which leads to two passages
        
        Trachea; connects to the lungs
        
        Esophagus: connects to the stomach
      - Food is pushed down esophagus by peristalsis, alternating waves of contractions.
    - - Chemical Digestion
        
        First Hydrochloric acid disrupts the extracellular matrix binding cells together
        
        Protease, a protein digesting enzyme (pepsin), breaks down exposed bonds
        
        HCL and pepsin are both formed within the luman of the stomach, not within the cells
        
        Parietal cells use ATP pumps to expel hydrogen ions into the lumen, at the same time chloride ions diffuse into the luman
        
        Chief cells release pepsin into the luman in an inactive form, pepsinogen, which is then activated by HCL or active pepsin but clipping off a small corner of the molecule to expose it's active site,.
        
        HCL and pepsin don't eat through the stomach lining due to mucus the stomach produces to protect itself from self digestion.
      - Stomach Dynamics
        
        Breakdown of food it enhanced by the coordinated series of muscle contractions of the stomach, which mix it's contents.
        
        Stomach contractions also help move material through the alimentary canal.
      - The stomach plays two roles in digestion
        
        Storage of eaten food
        
        Process food into a liquid suspension
      - The stomach secretes digestive fluid, gastric juice, and mixes it into the food. The resulting mixture is called chyme
    - - The small intestine is the alimentary canal's longest component, and is the location of most enzyme hydrolysis
      - The duodenum mixes chyme with digestive juices from the pancreas, liver and gall balder.
        
        Duodenum releases secretin, which triggers the pancreas to secrete bicarbonate; which neutralizes the acid from the stomach.
      - Fats, form large globules that cannot be broken down effectively by enzymes.
        
        Fat digestion is facilitated by bile salts, a major component in bile that is secreted by the liver and gall bladder, which act as emulsifiers
    - - Nutrient absorption occurs across the lining of the jejunum and ileum. Large folds in the lining are studded with finger-like projections, called villi
        
        Each epithelial cell has multiple microscopic projections, called microvilli, which allows for greater surface area.
        
        Transport across the epithelial cells can be passive or active
      - Hepatic Portal Vein
        
        Where capillaries and veins that carry nutrient rich blood from the villi converge
        
        Leads to the liver to allow the liver to do two things
        
        Regulate distribution of nutrients to the rest of the body, by converting some nutrients to different forms for use elsewhere
        
        Remove toxic substances from the blood stream before it can circulate the body
      - Fats take a different path
        
        Fatty acids and monoglyceride are absorbed by epithelial cells, recombined into triglycerides, and the coated with phospholipids, cholesterol, and proteins forming chylomicrons
        
        Chylomicrons enter a lacteal, the vessel at the core of each villus, which connects to the lymphatic system.
        
        Eventually the lymph containing chylomicrons passes into veins leading to the heart
      - The small intestine also absorbs some water and ions
    - - The alimentary canal ends with the large intestine
        
        The colon, leads to the rectum and anus.
        
        The cecum is important for fermenting ingested material, especially plant material
        
        The appendix, a finger shaped extension of the cecum, is thought to be a reservoir for symbiotic microorganisms
      - The colon completes the recovery of water leaving behind solid undigested material, feces, which includes cellulose fiber.
      - Colon bacteria generate methane and hydrogen sulfide gas
      - Rectum
        
        The terminal end of the large intestine, where feces is stored until it is eliminated
        
        Two sphincters between the rectum and anus, inner is involuntary and outer is voluntary
  - - - Essential Amino Acids
        
        Amino acids that an organism requires, but cannot produce itself and must be obtained from the organism's diet.
      - Essential Fatty Acids
        
        Fatty acids that and organism requires, but cannot synthesize itself and must be obtained from the organism's diet.
      - Vitamins
        
        Organic Molecules that are required in small amounts (.01-100 mg)
      - Minerals
        
        Inorganic molecules that are required in small amounts (<1 mg - 2500 mg)
        
        Ingesting too much of some minerals can upset homeostatic balance and cause health problems.
      - Substances that and animal requires, but cannot assemble from organic molecules
    - - Undernourishment
        
        In malnutrition situations the body uses stored carbohydrates and fats.
        
        Then, once the body runs low on energy stores, it will move on to breaking down its own proteins for fuel.
        
        If energy intake remains less than energy expenditure, the body will shut down.
        
        Even if the organism survives, some of the damage may be irreversible
      - Deficiencies in Nutrients
        
        Insufficient intake of essential nutrients; can cause deformities, disease, or death
      - A diet that lacks one or more essential nutrients or constantly supplies less chemical energy than the body requires, results in malnutrition
    - - provide organic building blocks for macromolecules
      - Provide essential nutrients
      - Provide chemical energy fro cellular processes
    - - Animals must obtain it's food:
        
        A source of organic carbon (Carbohydrates)
        
        A source of organic Nitrogen (Proteins)
  - - - An animals assortment of teeth and structural variation reflects it's diet
    - - Large expandable stomach
        
        Some animals may wait extended periods of time between meals, and must eat as much as they can at their next meal
      - Length of digestive system
        
        Herbivores and omnivores have longer alimentary canals relative to their body size than carnivores. As plant mater is harder to digest than meat.
    - - Herbivore Mutualistic Adaptations
        
        Symbiotic microorganisms have enzymes that can digest cellulose to simple sugars and other compounds that the animal can absorb.
        
        Microorganisms also use the sugar from digested cellulose in the production of a variety of essential nutrients, such as vitamins and amino acids
        
        Some animals have mutualistic bacteria in their large intestine, which cannot absorb the by-products of bacterial fermentation.
        
        To recover these nutrients, some animals take to coprophagy, or ingesting their feces
      - Microbiome, the collection of microorganisms living in and on the body along with their genetic material.
        
        Some also regulate the development of the intestinal epithelium, and innate immune system. In turn for a steady supply of nutrients and a stable environment.
        
        Some intestinal bacteria produce vitamins that supplement dietary intake when absorbed into the blood.
  - - - Intracellular Digestion
        
        Food vacuoles are the simplest digestive compartments
        
        Forms after a cell engulfs solid food by phagocytosis or liquid food by pinocytosis. which then fuse with a lysosome to digest the food.
      - Extracellular Digestion
        
        Gastrovascular Cavity
        
        Digestive compartment with a single opening, functions in digestion and the distribution of nutrients
        
        Alimentary Canal
        
        A digestive tube with two openings, mouth and anus, that moves food in a single direction to allow allow for digestion and nutrient absorption in a step-wise fashion
    - - The act of eating or feeding
      - Filter Feeding
        
        Animal strains small organisms or food particles from surrounding medium
      - Bulk Feeding
        
        Animal eats relatively large pieces of food
      - Substrate Feeding
        
        Animal lives in or on their food source
      - Fluid Feeding
        
        Animal sucks up nutrient rich fluid
    - - Food is broken down into molecules small enough for the body to absorb
      - Mechanical Digestion
        
        Chewing or Grinding breaks food into smaller pieces increasing surface area
      - Chemical Digestion
        
        Breaks down large molecules into smaller components
        
        Digestive enzymes catalyze the process of breaking bonds by the addition of water, Enzymatic Hydrolysis
    - - Animal's cells take up small molecules
    - - Undigested material passes out of the digestive system
  - - - Food being taken in, taken apart and taken up
    - - Eat mainly plants and algae
    - - Mainly eat other animals
    - - Regularly consume animals as well as plants or algae
- - - - Physical laws govern strength, diffusion, movement, and heat exchange limit the range of animal form.
      - Physical laws also influence animal body plans with regard to maximum size.
        
        As body dimensions increase, thicker skeletons are required to maintain adequate support.
        
        As bodies increase in size the muscles required for locomotion represent an ever larger fraction of the total body mass.
    - - Animals must exchange nutrients, waste products and gases with their environment.
        
        Exchange occurs as substances moves across the plasma membrane of each cell.
        
        The rate of exchange is proportional to the membrane surface area involved in exchange.
        
        The amount of material that must be exchanged is proportional to the body volume
      - The number of cells decreases the ratio of outer surface area to total volume
        
        Evolutionary adaptations that enable sufficient exchange with the environment are extensively branched or folded
        
        Branching or folding greatly increases surface area.
    - - Tissues
        
        Groups of cells with a similar and common function
        
        Complex organ systems are build from a limited set of cell and tissue types
        
        Types of Tissues
        
        Epithelial
        
        Cuboidal
        
        Dice shaped; specialized for secretion.
        
        Simple Columnar
        
        Large, brick shaped; found where secretion and absorption is important
        
        Simple Squamous
        
        Single layer of plate like cells; functions in exchange of material by diffusion
        
        Pseudostratified
        
        Single layer of cells varying in height and position of nuclei; forms mucous membranes
        
        Stratified Squamous
        
        Multilayered and regenerates rapidly; commonly found on surfaces subject to abrasion
        
        Sheets of cells that cover the outside of the body, or line organs and cavities within the body
        
        Connective
        
        Holds many tissues and organs together and in place. Consists of a web of fibers embedded in a liquid, jelly-like, or solid foundation.
        
        Fibroblasts secrete fiber proteins
        
        Macrophages engulf foreign particles and cell debris by phagocytosis
        
        Kinds of Connective Tissue Fibers
        
        Collagenous: Provide strength and flexibility
        
        Reticular: Join connective tissue to adjacent tissues
        
        Elastic: Make tissues elastic
        
        Loose
        
        Binds epithelia to underlying tissues and holds organs in place
        
        Fibrous
        
        Dense with collagenous fibers; found in tendons, attach muscles to bone, and in ligaments, connects bones at joints
        
        Bone
        
        mineralized connective tissue; osteoblasts deposit matrix of collagen, ions combine into hard mineral within matrix. microscopic structure of bone is made up of osteons.
        
        Adipose tissue
        
        Specialized connective tissue that stores fat; insulates body stores fuel as fat molecules.
        
        Cartilage
        
        Collegenous fibers embedded in a rubbery complex (Chondroitin sulfate), Chondrocytes secrete collegen and Chondroitin sulfate which makes cartilage strong yet flexible.
        
        Blood
        
        Liquid extracellular matrix (plasma); Erythrocytes carry oxygen, leukocytes defend, platelets aid in clotting.
        
        Muscle
        
        Skeletal
        
        Attached to bones, striated muscle responsible for voluntary movements.
        
        Smooth
        
        Lacks striations, spindle shaped; responsible for involuntary body activities
        
        Consist of filaments containing proteins, actin and myosin, which enable muscles to contract
        
        Cardiac
        
        Striated, branched fibers that interconnect, allowing cells to synchronize heart contractions
        
        Nervous
        
        Neurons
        
        Receives nerve impulses via dendrites, transmits impulses via axons. Often bundled together into nerves.
        
        Glia
        
        Nourish, insulate, and replenish neurons
        
        Receives, processes, and transmits information
      - Organs
        
        Different types of tissues are organized into functional units.
      - Organ System
        
        Groups of organs that work together, providing an additional level of organization and coordination
        
        Organ Systems
        
        Circulatory
        
        Internal distribution of materials
        
        Respiratory
        
        Gas exchange
        
        Digestive
        
        Food processing
        
        Immune & Lymphatic
        
        Body defense
        
        Excretory
        
        Disposal of metabolic wastes; regulation of osmotic balance of blood
        
        Endocrine
        
        Coordination of body activities
        
        Reproductive
        
        Gamete production; promotion of fertilization; support of developing embryo
        
        Nervous
        
        Coordination of body activities; detection of stimuli and formation of responses
        
        Integumentary
        
        Protection against mechanical injury, infection, dehydration; thermoregulation
        
        Skeletal
        
        Body support, protection of internal organs, movement
        
        Muscular
        
        Locomotion and other movement
    - - Endocrine System
        
        Uses signaling molecules released into the blood stream and are carried all throughout the body.
        
        Hormones
        
        Only cells with receptors for particular signaling molecules (hormones) respond causing distinct effects.
        
        Well adapted for gradual changes that effect the entire body.
      - Nervous System
        
        Transmits signals along the body, along dedicated routes connecting specific locations of the body
        
        Nerve Impulses
        
        Travel to specific cells; can act on neurons, muscle cells, or cells and glands that cause secretions.
        
        Travel over long distances, as changes in voltage. Often involves very short-range chemical signals.
        
        Well suited for directing rapid responses to the environment.
      - Contribute to maintaining a stable internal environment
  - - - Regulator
        
        Uses internal mechanisms to control internal change in the face of extreme fluctuations
      - Conformer
        
        Allows internal conditions to change in accordance with external changes
      - Some animals may regulate some internal conditions while allowing others to conform
    - - Mechanisms of Homeostasis
        
        Requires a control system
        
        Set point
        
        A particular value of a variable maintained by homeostasis
        
        Stimulus
        
        Fluctuation of a variable above or below its set point
        
        Sensor
        
        Detects stimuli
        
        Responce
        
        A physiological activity that helps return the variable to homeostasis
      - Feedback Control
        
        Negative Feedback
        
        Control mechanism that "damps" its stimuli
        
        Positive Feedback
        
        Control mechanism that amplifies its stimuli
        
        Positive feedback loops do not play a large role in homeostasis, but instead help drive processes to completion
        
        Homeostasis moderates, but does not eliminate changes in the internal environment, fluctuation is greater if the variable has a "normal range", and upper and lower limit, rather than a set point.
      - Alterations in Homeostasis
        
        some regulated changes are cyclic, certain cyclic alterations in metabolism reflect a circadian rhythm
        
        Regulated changes in the internal environment are essential to normal body function
        
        Some occur during a particular stage in life
      - The maintenance of internal balance, a relatively constant internal environment even when the external environment changes significantly
  - - - Endothermic
        
        Animals that are warmed mostly by heat generated by metabolism
        
        Maintain stable body temperatures even when large environmental temperature fluctuations occur
        
        Have cooling mechanisms for hot environments, and heating mechanisms for cold environments
      - Ectothermic
        
        Animals that gain most of their heat from external sources
        
        Most adjust their temperature but behavioral means, and generally need to consume less food than endotherms of equivalent size.
    - - Poikilotherm
        
        Animals whose temperature varies with its' environment, or cannot regulate its body own temperature.
      - Homeotherm
        
        Animals whose temperature stays relatively constant; or can maintain its body temperature at a constant level, usually above that of the environment.
      - There is no fixed relationship between the source of heat and the stability of body temperature
    - - Animals have mechanisms that reduce heat exchange overall or favor heat exchange in one direction, generally involving the integumentary system.
        
        Circulatory Adaptations
        
        Adaptions regulate the extent of blood flow near the body surface, or trap heat with the body core
        
        Vasodilation
        
        Widens surperficial blood vessels to increase transfer of body heat
        
        Vasoconstriction
        
        Reduces blood flow and heat transfer by constricting superficial blood vessels
        
        Countercurrent Exchange
        
        Transfer of heat (or solutes) between fluids that are flowing in opposite directions
        
        Heat is transferred along the entire length of the exchanger, maximizing rate of heat exchange, minimizing heat loss to environment.
        
        Evaporation Heat Loss Cooling
        
        Water absorbs considerable heat when it evaporates
        
        Heat is carried away from the skin and respiratory surfaces as water vapor
        
        Behavioral Responses
        
        When cold, some organisms seek heat sources and orientate themselves towards the heat source
        
        When hot some organisms bathe, move to cool areas, or turn to minimize heat absorption form the sun
        
        Thermogenesis
        
        Variation of metabolic heat production
        
        Insulation
        
        Reduces the flow of heat between an animal's body and environment.
        
        Can be found both at the body surface, fur and feathers, or beneath, layers of fat.
      - Thermoregulation depends on an animal's ability to control the exchange of heat with its environment
        
        Heat is always transferred from an object of higher temperature to one of lower temperature
        
        Radiation
        
        Emission of electromagnetic waves by all objects warmer than absolute zero
        
        Convection
        
        Transfer of heat by the movement of air or liquid past a surface
        
        Conduction
        
        Direct transfer of thermal motion (heat) between molecules of objects in contact with each other
        
        Evaporation
        
        Removal of heat from the surface of a liquid that is losing some of its molecules as gas
    - - An animals physiological adjustment to changes in it's external environment
        
        Temporary change during an animals life time
        
        Such as adjusting insulation layers
    - - Hypothalamus
        
        Concentrated sensors for thermoregulation
        
        Sensors signal the hypothalamic thermostat when the body's blood temperature increases or decreases
        
        When below normal levels the thermostat inhibits heat lost mechanisms, while activating mechanisms that save or generate heat
        
        When above normal levels the thermostat shuts down heat retention mechanisms and promotes cooling the body by dilation of blood vessels, sweating or panting.
      - Fever
        
        Elevated body temperature due to bacterial or viral infection
  - - - Autotrophs
        
        Harness light energy to build energy rich organic molecules and then use them for fuel
      - Heterotrophs
        
        Obtain their energy from the food they eat, which contain organic molecules synthesized by other organisms
      - ATP
        
        Produced by cellular respiration and fermentation, powering cellular work
        
        used for Biosynthesis, Body growth and repair, synthesis of storage material, production of gametes, heat generation
    - - Metabolic Rate
        
        The sum of all the energy used in a given time interval by an animal
        
        Measured by monitoring an animals rate of heat loss
        
        Can also be determined by measuring the amount of oxygen consumed or carbon dioxide produced by and animals cellular respiration
    - - Size
        
        Larger animals have more body mass and thus require more chemical energy
        
        Metabolic rate stays relatively proportional to body mass
        
        Three quarter power (m^3/4)
        
        As body size decreases, each gram of tissue increases energy cost. As body size increases, energy cost per gram or tissue decreases; but an ever larger fraction of body tissue is required for exchange support and locomotion.
      - Activity
        
        Maximum metabolic rate occurs during peak activity
        
        And is inversely related to the duration of the activity
      - Metabolic rate can be effected by many factors; age, six, size, activity, temperature, & nutrition
    - - Basal Metabolic Rate
        
        The minimum metabolic rate of a non growing endotherm at rest, with an empty stomach and is not experiencing stress
      - Standard Metabolic Rate
        
        The minimum metabolic rate of fasting non-stressed ectotherm at rest, at a particular temperature.
    - - A physiological state of decreased activity and metabolism
      - Hibernation
        
        Long term torpor that is an adaption to winter cold and food scarcity
      - Estivation
        
        Summer torpor, that allows animals to survive long periods of high temperatures and scarce water
    - - The overall flow and transformation of energy in an animal
      - Determines nutritional needs and is related to the animal's size, activity and environment