Animal form, function, & nutrition

Animal form & function:

Animal Nutrition:

Animal form and function are correlated at all levels of organization

Exchange with the environment:

animals must exchange nutrients, waste products, and gases w/ their environment

exchange occurs as substances dissolved in an aqueous solution move across the plasma membrane of each cell

a single celled organism has a sufficient membrane surface area in contact with its environment to carry our all necessary exchange

a multicellular organization therefore only works if every cell has access to a suitable aqueous environment, either inside or outside the animal's body

many animals w/ a simple internal organization have body plans that enable direct exchange between almost all their cells & the external environment

ex: pond dwelling hydra, their gastrovascular cavity opens to the external environment

increasing the number of cells decreases the ratio of outer surface area to total volume

ex: the ratio of outer surface area to volume for a whale is hundreds of thousands of times smaller than a water flea

every cell in the whale must be bathed in fluid and have access to oxygen, nutrients, and other resources

the respiratory, circulatory, digestive, and excretory system help with the internal exchange in complex animals

interstitial fluid: the spaces between cells are filled w/ this fluid

Hierarchical organization and body plans:

tissues: groups of cells w/ a similar appearance and a common function

organs: different types of tissues is further organized into functional units (organs)

Organ System:

Digestive: for food processing (ingestion, digestion, absorption, elimination)

main organs: mouth, pharynx, esophagus, stomach, intestines, liver, pancreas, anus

Circulatory: internal distribution of material

main organs: heart, blood vessels, blood

Respiratory: Gas exchange (uptake of oxygen; disposal of carbon dioxide)

main organs: lungs, trachea, other breathing tubes

Immune and lymphatic: body defense (fighting infections and virally induced cancers)

main organs: bone marrow, lymph nodes, thymus, spleen, lymph vessels

Excretory: disposal of metabolic wastes, regulation of osmotic balance of blood

main organs: kidneys, ureters, urinary bladder, urethra

Endocrine: coordination of body activities (such as digestion and metabolism)

main organs: pituitary, thyroid, pancreas, adrenal, and other hormone- secreting glands

Reproductive: gamete production; promotion of fertilization; support of developing embryo

main organs: ovaries or testes and associated organs

Nervous: coordination of body activities; detection of stimuli and formulation of responses to them

main organs: brain, spinal cord, nerves, sensory organs

Integumentary: protection against mechanical injury, infection, dehydration; thermoregulation

main organs: skin and its derivatives

skeletal: body support, protection, of internal organs, movement

main organs: skeleton (bones, tendons, ligaments, cartilage)

Muscular: locomotion and other movement

main organs: skeletal muscles

Animal tissue type:

Epithelial tissue: cover the outside of the body and line organs and cavities w/in the body

stratified squamous epithelium: new cells formed by division near the basal surface push outward, replacing cells that are sloughed off

located on the outer skin and the linings of the mouth, anus, and vagina

Pseudostratified columnar epithelium: forms a mucous membrane that lines portions of the respiratory tract

simple squamous epithelium: the exchange of material by diffusion; lines blood vessels and the air sacs of the lungs

simple columnar epithelium: found where secretion or active absorption is important

cuboidal epithelium: specialized for secretion, makes up the epithelium of kidney tubules, and many glands, including the thyroid gland & salivary glands

Connective tissue: consisting of a sparse population of cells scattered through an extracellular matrix, holds many tissues and organs together in place

Fibroblast: numerous cells w/in the matrix, which secrete fiber proteins and macrophages

loose connective tissue: binds epithelia to underlying tissues and holds organs in place

furious connective tissue: dance w/ collagenous fiber found in tendons

bone: a mineralized connective tissue

blood: has a liquid extracellular matrix called plasma which consist of red blood cells or white blood cells

cartilage: strong flexible support material. Located in the disks that act as cushions between vertebrae

Adipose tissue: a specialized loose connective tissue that stores fat in adipose cells distributed throughout its matrix; insulates the body and stores fuel as fat molecules

Muscle tissue: tissue responsible for nearly all types of body movement

skeletal muscle: responsible for voluntary movements; attached to bones by tendons; contains muscle fiber

smooth muscle: found in the walls of the digestive tract, urinary bladder, arteries, and other internal organs

cardiac muscle: forms the contractile wall of the heart

Nervous tissue: functions in the receipt, processing, and transmission of information

neurons: receives nerve impulses from other neurons via its cell body dendrites

glia: help nourish, insulate, and replenish neurons

Coordination and control

animals have 2 major systems for coordinating and controlling responses

Endocrine system: signaling molecules released into the bloodstream by endocrine cells are carried to all locations in the body

nervous system: neutrons transmit signals along dedicated routes connecting specific locations in the body

Hormones: the signaling molecules that are broadcasted throughout the body

different hormones cause distinct effects, and only cells that have receptors for a particular hormone respond

nerve impulses travel to specific target cells along communication lines consisting mainly of axons

well adapted for coordinating gradual changes that affect the entire body, such as growth, development, reproduction

well suited for directing immediate and rapid responses to the environment such as reflexes

Feedback control maintains the internal environment in many animals

Regulator: an animal is a regulator for an environmental variable if it uses internal mechanisms to control internal change in the face of external fluctuation

conformer: an animal is a conformer if it allows its internal condition to change in accordance with external changes in the particular variable

Homeostasis: the maintenance of internal balance

requires a control system

maintaining a variable, such as a set point

ex: body temp is a set point

a fluctuation in the variable above or below the set point serves as the stimulus detected by a sensor

a control center generates the output that triggers the response

negative feedback: a control mechanism that "damps" its stimulus

ex: when you exercise, you start to sweat to cool your body and return to regular body temp

Positive feedback: a control mechanism that amplifies the stimulus

ex: labor, the contractions result in greater pressure against the opening of the uterus, until the baby is born

homeostasis is sometimes altered by acclimatization (an animal's physiological adjustment to changes in its external environment

Homeostatic processes for thermoregulation involve form, function, and behavior

Thermoregulation: the process by which animals maintain their body temperature w/in a normal range

endothermic: warmed mostly by heat generated by metabolism

ex: some fishes and insect species

ectothermic: they gain most of their heat from external sources

Ex: a bird will warm itself when the sun is out

in hot environments, they have mechanisms for cooling their bodies

generates enough heat to keep its body warmer than its surroundings

adjust their body temperature by behavioral means, like seeking out shade

Balancing heat loss and gain:

controlling the exchange of heat w/ its environment consist of 4 processes

radiation: such as when a lizard absorbs heat radiating from the distant sun

evaporation: like evaporation of water from a lizards moist surfaces that are exposed to the environment has a strong cooling effect

convection: a breeze passing the lizard's dry skin

conduction: the direct transfer of heat between molecules of objects in contact w/ each other

integumentary system: the outer covering of the body, consisting of the skin, hair, and nails

Insulation: reduces the flow of heat between an animal's body and it's environment

found at the body surface, such as hair and feathers, and beneath layers of fat formed by adipose tissue

often animals can adjust their insulating layers to further regulate body temperature

most mammals react to cold by raising their fur, which traps a thicker layer of air, thereby increasing insulation

can vary heat production to match changing rates of heat loss

Hypothalamus: the brain region that also controls the circadian clock; activates mechanisms that promote heat loss or gain

Energy requirements are related to animal size, activity, and enviornment

most animals obtain their chemical energy from food, which contains organic molecules synthesized by other organisms

Metabolic rate: the sum of all the energy an animal uses in a given time interval

energy is measured in joules or calories, and kilocalories

Nutritional Differences:

Herbivores: eat mainly on plants or algae

Ex: cattle, sea slugs, caterpillars

Carnivores: mostly eat other animals

ex: sea otters, hawks, and spiders

Omnivores: eat both animals and plants or algae

ex: humans, crows

most animals are opportunistic feeders, eating foods outside their standard diet when their usual foods aren't available

An animal's diet must supply chemical energy, organic building blocks, and essential nutrients

an adequate diet must satisfy 3 nutritional needs:

chemical energy for cellular processes

organic building blocks for macromolecules

essential nutrients: it's the substances that an animal requires but can't assemble from simple organic molecules

essential amino acids: all organisms require a standards set of 20 amino acids to make a complete set of proteins

the proteins in animal products, such as meat, eggs, and cheese are complete

essential fatty acids: animals typically obtain it from seeds, grains and veggies

vitamins: are organic molecules that are required in the diet in very small amount

there are 13 vitamins required by humans

ex: Biotin, ascorbic acid, thiamine, retinol

Minerals: inorganic nutrients that are usually required in small amounts

ex: calcium, potassium, chlorine, iron

Malnutrition: failure to obtain adequate nutrition

found in salt, dairy products, dark green veggies, meats, tea, and many more

can be found in pork, dairy products, green veggies, egg yolk, nuts, tea, and many more

Food processing involves ingestion, digestion, absorption, and elimination

Ingestion: the act of eating or feeding

filter feeders: strain small organisms or food particles from surrounding medium

substrate feeding: animals that live in or on their food source

fluid feeding: fluid feeders suck nutrient- rich fluid from a living host

bulk feeding: when eating large pieces of food

ex: humans are bulk feeders

digestion: food is broken down into molecules small enough for the body to absorb

Mechanical digestion, such as chewing or grinding, breaks food into smaller pieces

chemical digestion cleaves large molecules into smaller components

Absorption: the animal's cells take up small molecules

ex: amino acids and simple sugars

Elimination: undigested material passes out of the digestive system, completes the process!

food vacuoles, cellular organelles in which hydrolytic enzymes break down food

intracellular digestion: the hydrolysis of food inside vacuoles

extracellular digestion: the breakdown of food in compartments that are continuous w/ the outside of the animal's body

gastrovascular cavity: functions in digestion as well as in the distribution of nutrients throughout the body

Human digestive tract:

Oral cavity/ mouth: where food processing begins

teeth with specialized cut, mash and grind, breaking the food into smaller pieces

Salivary glands: releases saliva; the food in the oral cavity triggers it

Mucus: lubricates food for easier swallowing, protects the gums against Branson, and facilitates taste and smell

Anylase: an enzyme that breaks down starch

the tongue aids digestive processes by evaluating ingested material, distinguishing which food should be processed further

pharynx: throat region which leads to the esophagus and trachea

esophagus: a muscular tube that connects to the stomach

trachea: a windpipe that leads to the lungs

within the esophagus food is pushed along by peristalsis, alternating waves of smooth muscle contraction and relaxation

sphincter: a ringlike valve of muscle acting like a drawstring, regulating passage of the ingested food into the next compartment, the stomach

Stomach: functions as storage and to process food into liquid suspension

gastric juice: mixes it w/ the food through a churning action

protease: protein digested enzyme

small intestine: most enzymatic hydrolysis of macromolecules from food occurs in the small intestine

duodenum: the first 25 cm in the small intestine

pancreas: secretes bicarbonate, which neutralizes the acidity of chyme and acts as a buffer for chemical digestion in the small intestine

liver: where bile is made and needed to make fats soluble (in order to be digested)

gallbladder: where the bile is concentrated

Heptic portal vein: a blood vessel that leads directly to the liver, from the liver blood travels to the heart and then to other tissues and organs

Chylomicrons: the fat globs

Nutrient digestion

Digestive Hormones:

Carbohydrates:

Oral cavity, pharynx, esophagus: polsaccarides (starch) gets broken down to smaller polysaccharides with the help of salivary amylase

then in the small intestine, pancreatic amylases breaks it down to disaccharides

after that, its broken down to monosaccharides

Protein:

In the stomach, pepsin breaks proteins down to small polypeptides

in small intestine, proteases breaks it down to even smaller polypeptides. pancreatic carboxypeptidase breaks it down to small peptides

then broken down to amino acids

Nucleic acid:

IN small intestine, DNA and RNA are broken down to nucleotides by pancreatic nucleases

the enzymes from intestinal epithelium, nucleotidases, breaks it down to nucleosides

nucleosides and phosphates break nucleosides into nitrogenous bases, sugars, and phosphates

Fat:

In small intestine, fat is broken down to glycerol, fatty acids, by pancreatic lipase

Gastrin: circulates via the bloodstream back to the stomach, where it stimulates production of gastric juices

as food arrives at the stomach, it stretches the stomach walls triggering release of gastrin

Hormones Cholecystokinin and secretin

chyme passes from the stomach to the duodenum, which responds by releasing cholecystokinin and secretin

cholecystokinin stimulates the release of digestive enzymes from the pancreas and of bile from the gallbladder

secretin stimulates the pancreas to release bicarbonate which neutralizes chyme