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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.

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Basic Principles of animal form & function


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definitions
Definitions
  • Anatomy: structure of an organism
  • Physiology: processes & functions of an organism
evolution of animal size shape
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
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
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)
exchange with the environment
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
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
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 environment1
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
exchange with the environment2
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
Hawk Moth
  • Its probiscus extends as a straw thru which moth sucks nectar from deep w/in tube-shaped flowers
bioenergetics
Bioenergetics
  • how organisms obtain, process, & use nrg resources: a connecting theme in the comparative study of animals
definitions1
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 plans1
Organization of Body Plans
  • simplest animals lack true tissues & organs
organ systems in animals
Organ Systems in Animals
  • built from a limited set of cell & tissue types
  • 4 tissue types:
  • Epithelial
  • Connective
  • Muscle
  • Nerve
epithelial tissue
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
1. Cuboidal Epithelial Cells
  • cubes, dice
  • specialized for secretion
  • found:
    • renal tubules
    • glands
2 simple columnar epithelium
2. Simple Columnar Epithelium
  • large brick-shaped
  • functions: secretion, absorption
  • found: lines intestines
3 simple squamous epithelium
3. Simple Squamous Epithelium
  • plate-like cells
  • functions: diffusion
  • found: lining blood vessels, air sacs in lungs (alveoli)
4 pseudostratified columnar epithelium
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
5 stratified squamous 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
Stratified Squamous Epithelium

Keratinized

Nonkeratinized

connective tissues
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
3 Connective Tissue Fibers
  • Collagenous
    • provide strength & flexibility
  • Reticular
    • join CT to adjacent tissues
  • Elastic
    • make tissues elastic
loose ct
Loose CT
  • vertebrates:mostwidespread of 3 types
  • binds epithelia to underlying tissues
  • holds organs in place
  • has all 3 fiber types
  • higher % matrix than others
fibrous ct
Fibrous CT
  • dense w/collagen fibers
  • found in tendons (attach muscle to bone) & ligaments (attach bone to bone)
slide36
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
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
Adipose Tissue
  • specialized loose CT that stores fat in adipose cells
  • Function:
  • pads & insulates
  • stores fuel
cartilage
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
Muscle Tissue
  • responsible for nearly all types of body movement
  • made of filaments with actin & myosin (contractile proteins)
  • cells called muscle fibers
  • 3 types:
  • Skeletal
  • Smooth
  • cardiac
skeletal muscle
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
Smooth Muscle
  • nonstriated
  • involuntary
  • spindle-shaped cells
  • in walls of organs
    • Esophagus/Stomach
    • Intestines
    • Bladder
    • Arteries & Veins
cardiac muscle
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
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
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
slide47
Glia
  • various types: all help nourish, insulate, & replenish neurons
  • some modulate neuron function
coordination control
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
homeostatic mechanisms
Homeostatic Mechanisms
  • usually based on negative feedbackin which the response reduces the stimulus
homeostatic mechanisms1
Homeostatic Mechanisms
  • positive feedback: involves amplification of a stimulus by the response & often brings about a change in state
alterations in homeostasis
Alterations in Homeostasis
  • Circadian Rhythm: physiologic cycle of ~24 hrs that persists even in the absence of external cues
acclimatization
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
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
Endothermy
  • animals that are warmed mostly by heat generated by metabolism are endothermic
    • also a few nonavian reptiles, some fishes, & many insects
exothermic
Exothermic
  • animals that gain heat from their external environment
  • reptiles, amphibians, many fishes
thermoregulation1
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
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
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 temp1
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
slide64

Remember!

  • Terms cold-blooded & warm-blooded are misleading & are avoided in scientific communication.
balancing heat loss gain
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)
  • Radiation
  • Evaporation
  • Convection
  • Conduction
thermoregulation2
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 system
Integumentary System
  • Insulation
    • reduces heat loss from animal  environment
    • hair, feathers, layer of subcutaneous adipose (esp. important for marine mammals)
  • 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
Countercurrent Exchange
  • transfer of heat (or solutes) between fluids that are flowing in opposite directions
countercurrent exchange1
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
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
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
Behavioral Responses
  • used by both endotherms : & ectotherms: change position to increase or decrease amt radiation from sun
behavioral responses1
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
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
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
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
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
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
Basal Metabolic Rate
  • BMR: the metabolic rate of a resting, fasting, & nonstressedendotherm 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 nonstressedectotherm at a particular temperature
slide87
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
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
Hibernation
  • most hibernating animals are small
  • metabolic rates drop 20x so nrg savings huge