BASIC PRINCIPLES OF ANIMAL FORM & FUNCTION

Campbell & Reece Chapter 40

Definitions

Anatomy: structure of an organism Physiology: processes & functions of

an organism

Evolution of Animal Size & Shape Physical laws influence animal body

plans with regard to maximum size. As body sizes increase: thicker

skeletons required to maintain adequate support affects animals with exoskeletons as

well as endoskeletons also affects amt body mass that must be

allocated to muscle @ some pt. locomotion becomes impossible

Body Plans

Physical requirements constrain what natural selection can “invent”

the mythical winged dragon could not possibly exist (anything that large could not generate enough lift to take off & fly)

Body Plans: Aquatic Animals Laws of hydrodynamics constrain the

shapes possible for aquatic organisms that swim very fast

All animals that swim fast have same fusiform shape minimizes drag convergent evolution occurs because

natural selection shapes similar adaptations when diverse organisms face the same environmental challenges (resistance of water to fast travel)

Convergent Evolution

Exchange with the Environment Animals must exchange materials

with their environments which also imposes limitations on their body plans

rates of exchange for nutrients, wastes, & gases is proportional to membrane surface area

amt material necessary to sustain life is proportional to cell vol.

Exchange in Multicellular Animals

works only if every cell has access to a suitable aqueous environment (either in or out of animal’s body)

Aqueous Environment Required exchange with environment occurs

as dissolved substances diffuse or are transported across plasma membranes

ex: unicellular protists living in water has sufficient surface area to serve its entire volume: surface area/vol ratio important physical constraint on size of unicellular organisms

Exchange with the Environment Interstitial Fluid: fluid that fills

space between cells in multicellular organisms; allows all cells to have contact with aqueous environment

complex body systems can filter & adjust composition of interstitial fluid

Interstitial Fluid

Exchange with the Environment Animals of diverse evolutionary

histories & varying complexity must solve how to obtain energy, oxygen, how to get rid of wastes & manage movement

All animals must obtain food for nrg, generate body heat, & regulate internal temperature, sense & respond to external stimuli

Hawk Moth

Its probiscus extends as a straw thru which moth sucks nectar from deep w/in tube-shaped flowers

Bioenergetics

how organisms obtain, process, & use nrg resources: a connecting theme in the comparative study of animals

Organization of Body Plans

Definitions Cells: basic unit of structure &

function in living things; cells form a functional animal body thru their emergent properties

Tissues: groups of cells with similar appearance & a common function

Organs: different types of tissues grouped together into functional units

Organ Systems: groups of organs that work together with a common function

Organization of Body Plans

simplest animals lack true tissues & organs

Organ Systems in Mammals

Organ Systems in Mammals

Organ System Main Components Main FunctionDigestive Mouth, pharynx,

esophagus, stomach, intestines, liver, pancreas, anus

Food processing (ingestion, digestion, absorption, elimination)

Circulatory Heart, blood vessels, blood

Internal distribution of materials

Respiratory Lungs, trachea, other breathing tubes

Gas exchange

Immune & Lymphatic

Bone marrow, lymph nodes, thymus, spleen, lymph vessels, WBCs

Body defense (fighting infection & cancer)

Organ Systems in MammalsOrgan System Main Components Main Functions

Excretory Kidneys, ureters, urinary bladder, urethra

Disposal of metabolic wastes; regulation of osmotic balance of blood

Endocrine Pituitary, thyroid, pancreas, adrenal, & other hormone-secreting glands

Coordination of body activities

Reproductive Ovaries or testes & ass’c organs

Reproduction

Muscular Skeletal, Smooth & Cardiac muscle

movement & locomotion

Organ Systems in MammalsOrgan System Main Components Main FunctionNervous brain, spinal cord,

nerves, sensory organs

coordination of body activities, detection of stimuli & formulation of responses to them

Integumentary skin & its derivatives (nails, hair/fur claws, skin glands)

protection against mechanical injury, infection, dehydration; thermoregulation

Skeletal bones, tendons, ligaments, cartilage

body support, protection of internal organs, movement

Organ Systems in Animals

built from a limited set of cell & tissue types

4 tissue types:1. Epithelial2. Connective3. Muscle4. Nerve

Epithelial Tissue

Epithelium (singular); Epithelia (plural)

sheets of cells cover outside of body or line organs

& cavities w/in body closely packed cells often w/ tight

jcts: so can function as protection vs.. mechanical injury, infection, fluid loss

5 cell types

1. Cuboidal Epithelial Cells

cubes, dice specialized for secretion found:

renal tubules glands

2. Simple Columnar Epithelium large brick-shaped functions: secretion, absorption found: lines intestines

3. Simple Squamous Epithelium plate-like cells functions: diffusion found: lining blood vessels, air sacs

in lungs (alveoli)

4. Pseudostratified Columnar Epithelium single layer that appears to be >1

layer cells are of different hts +/- ciliated form mucous membranes (lines

cavities that open to exterior of body)

found: lining respiratory tract where beating cilia move film of mucus with any trapped material away from lungs

Pseudostratified Columnar Epithelium

5. Stratified Squamous Epithelium multiple layers of cells; top layer

squamous regenerates rapidly/ new cells

formed on basement membrane…upper cells sloughed off

function: protection found: on surfaces subject to

abrasion

Stratified Squamous Epithelium

Keratinized Nonkeratinized

Connective Tissues tissue type with sparsest density of

cells main cell: fibroblast: secrete fiber

proteins like collagen also macrophages (phagocytes)

cells in extracellular matrix made up of web of fibers embedded in

liquid, jelly-like, or solid foundation functions: holds tissues together & in place

3 Connective Tissue Fibers

1. Collagenous provide strength & flexibility

2. Reticular join CT to adjacent tissues

3. Elastic make tissues elastic

Loose CT

vertebrates:most widespread of 3 types

binds epithelia to underlying tissues

holds organs in place

has all 3 fiber types

higher % matrix than others

Fibrous CT

dense w/collagen fibers

found in tendons (attach muscle to bone) & ligaments (attach bone to bone)

Bone

mineralized CT Osteoblasts: bone-

forming cells lay down matrix of collagen then Ca++, Mg++, & PO4-- combine into hard mineral

Osteons: repeating microscopic units that make up bone

Blood CT with liquid

matrix called plasma water , salts,

dissolved proteins cells suspended in

plasma RBCs: O2 WBCs: fight infection Platelets: cell

fragments used for clotting

Adipose Tissue

specialized loose CT that stores fat in adipose cells

Function: 1. pads & insulates2. stores fuel

Cartilage collagen in rubbery

protein-carbohydrate complex called chondroitin sulfate secreted by cells called chondrocytes

makes cartilage strong but flexible

many vertebrate skeletons start as cartilage replaced by bone

Muscle Tissue responsible for nearly all types of

body movement made of filaments with actin &

myosin (contractile proteins) cells called muscle fibers 3 types:1. Skeletal2. Smooth3. cardiac

Skeletal Muscle attached to bones

by tendons striated voluntary muscle fibers form

by fusion of several cells so appear multinucleated

sarcomere: contractile units (actin/myosin)

Smooth Muscle

nonstriated involuntary spindle-shaped

cells in walls of organs

Esophagus/Stomach

Intestines Bladder Arteries & Veins

Cardiac Muscle

striated involuntary found only in heart intercalated disc:

connections between cardiac fibers which relay signals from cell to cell synchronizes heart contractions

Nervous Tissue

receives , processes, & transmits information

cells: neurons: transmit action potentials

supportive cells: glial cells many animals have a concentration

of nervous tissue = a brain (information processing center)

Neurons basic unit of nervous

system receive nerve

impulses (action potentials) from other neurons or sensory organs via dendrites or cell body impulse to next neuron (muscle fiber, gland) via axon

nerve: bundle of axons

Glia

various types: all help nourish, insulate, & replenish neurons

some modulate neuron function

Coordination & Control The endocrine & nervous systems

are the 2 means of communication between different locations in body.

Endocrine system releases signaling molecules called hormones via blood target cells (have the correct receptors)

Nervous system uses cellular circuits involving electrical & chemical signals to send information to specific locations

Feedback Loops

Homeostatic Mechanisms

usually based on negative feedback in which the response reduces the stimulus

Homeostatic Mechanisms

positive feedback: involves amplification of a stimulus by the response & often brings about a change in state

Alterations in Homeostasis Circadian Rhythm: physiologic cycle

of ~24 hrs that persists even in the absence of external cues

Acclimatization 1 way normal range of homeostasis can

change gradual process by which animal adjusts to

changes in its external environment Example: moving from Charleston, SC to

Denver CO: physiological changes over several days will facilitate living at higher altitude: lower O2 in air will stimulate increase in rate & depth of respirations raises blood pH by exhaling more CO2 kidneys release more erythropoietin which stimulates RBC formation in bone marrow

Thermoregulation process by which animals maintain

an internal temperature w/in a tolerable range

most biochemical & physiological processes are very sensitive to changes in temperature

for every 10°C drop most enzyme-mediated reactions decrease 2 – 3 fold

increasing temps speed up reactions but only to a pt…. proteins denature (unfold)

fluidity of membranes changes (+/-) with temp changes

Endothermy

animals that are warmed mostly by heat generated by metabolism are endothermic also a few nonavian reptiles, some

fishes, & many insects

Exothermic

animals that gain heat from their external environment

reptiles, amphibians, many fishes

Thermoregulation

endothermy requires greater expenditure of nrg able to maintain stable body temp even

when there’s a large fluctuation in environmental temp

able to increase temp when its very cold & have adaptations for staying cooler than environment when it is hot

extremes usually intolerable to most ectotherms

Ectotherms

because they do not have to generate heat by metabolism to stay warm they usually get by on far fewer calories than endotherms of similar size

many adjust body temps by behavioral means: basking in sun for warmth; digging burrow to stay cool in heat

Variation in Body Temp

animals can have either constant or variable body temp

Poikilotherm: body temp varies with its environment largemouth bass

Homeotherm: body temp remains relatively constant river otter

Variation in Body Temp

there is no fixed relationship between source of heat & stability of body temp not all poikilotherm are ectotherms &

not all homotherms are endotherms ex: some fish live in waters of very

stable temps so their body temps do not really vary

bats & hummingbirds can enter an inactive state where they maintain a very low body temp

Remember! Terms cold-blooded & warm-blooded

are misleading & are avoided in scientific communication.

Which 1 is a poikilotherm? Which is a homotherm?

Balancing Heat Loss & Gain Thermoregulation depends on

animal’s ability to control the exchange of heat with their environment.

Heat exchange occurs in 4 ways (same as inanimate objects)

1. Radiation2. Evaporation3. Convection4. Conduction

Heat Exchange

Thermoregulation

animals must maintain rates of heat gain that = rates of heat loss

have adaptations that either reduce heat exchange overall or favor heat exchange in 1 direction

mammals utilize integumentary system

Integumentary System1. Insulation

reduces heat loss from animal environment

hair, feathers, layer of subcutaneous adipose (esp. important for marine mammals)

2. Circulatory alterations major role in heat exchange from

internal to external body nerve signals relax/constrict smooth

muscle in blood vessels depending on need to loose or retain body heat

Countercurrent Exchange

transfer of heat (or solutes) between fluids that are flowing in opposite directions

Countercurrent Exchange

used by birds, mammals, certain sharks, fish, & insects

Great white sharks, bluefin tuna & swordfish all use it to keep main swimming muscles several degrees warmer than tissues near animal’s surface

bumblebees, honeybees, & some moths use it to maintain higher temps in their thorax (flight muscles located there)

Cooling by Evaporative Heat Loss if environment’s temp > animal’s

body temp they will gain heat from their surroundings + metabolism: evaporation is only way to keep body temp from rising

terrestrial animals lose water by evaporation from their skin & respiratory surfaces

Cooling by Evaporation

water absorbs considerable heat when it evaporates: removing heat from body in process

some animals have adaptations that greatly augment this cooling effect: panting important for many mammals

& birds some birds have pouch rich in blood

vessels in mouth…fluttering the pouch increases evaporation

Behavioral Responses

used by both endotherms : & ectotherms: change position to increase or decrease amt radiation from sun

Behavioral Responses

Honeybees: response depends on social behavior: cold weather: huddle, bees move from

outer edge of huddle to inside to keep everyone warm enough, use honey as nrg source

in heat: bring water in hive & fan over it with wings promoting evaporation & convection

Adjusting Metabolic Heat Production endotherms can vary thermogenesis to

match changing rates of heat loss increase thermogenesis: (as much as 5-

10x) shivering

chickadees use it to maintain 40°C even if-40°C

mammals: some can switch mitochondria from making

ATP heat others use brown fat (specialized for rapid

heat production)

Adjusting Heat Loss

increasing thermogenesis: Burmese pythons become endothermic

when incubating eggs (were some dinosaurs endothermic?)

smallest endotherms are bees & moths use flight muscles, shivering, to generate heat

Acclimatization in Thermoregulation often involves changes in amts of

insulation in endotherms (thicker coat in winter/ shed in warmer weather)

ectotherms: make adjustments on the cellular level: make variants of enzymes that have

same function but different optimal temps

sat./unsat lipids in membranes changes produce antifreeze cpds

Hypothalamus (Mammals)

contains sensors that function as a thermostat when sense body temp outside normal

range responses that activate mechanisms that promote heat loss or gain

Energy Requirements

Animals obtain chemical nrg from food, storing it for short time in ATP

Total amt of nrg used in a unit of time defines an animal’s metabolic rate

Generally, metabolic rates higher for endotherms than ectotherms

Basal Metabolic Rate

BMR: the metabolic rate of a resting, fasting, & nonstressed endotherm at a comfortable temperature.

BMR for endotherms substantially higher than the Standard Metabolic Rate (SMR) of ectotherms (the metabolic rate of a resting, fasting, and nonstressed ectotherm at a particular temperature

BMRs in Humans

BMR

minimum metabolic rate/g is inversely related to body size among similar animals

animals allocate nrg for basal (or standard) metabolism, activity, homeostasis, growth, & reproduction

Torpor

a state of decreased activity & metabolism, conserves nrg during environmental extremes

animals may enter torpor during sleep periods (daily torpor), in winter (hibernation) or in summer (estivation)

Hibernation most hibernating animals are small metabolic rates drop 20x so nrg

savings huge