basic principles of animal form & function
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Campbell & Reece Chapter 40. Basic Principles of animal form & function. 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. - PowerPoint PPT PresentationTRANSCRIPT
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