Chapter 40: Basic Principles of
Animal Form & Function
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Cell size limited by
surface area :volume
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Cells must be in aqueous solution for nutrient &
waste exchange
tissues
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Groups of cells with common structure & function
Types:
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Epithelial
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Cover body, line organs, & body cavities
Tightly packed; held together by tight junctions
Barrier against microbes, fluid loss, or mechanical injury
Categorized by numbers of layers & shape
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Shape
 Cuboidal- dice-like
 Columnar- brick-like
 Squamous- floor tile-like
Types:
Simple epithelium
 Single layer
 “leaky”- allows for diffusion
 Ex. Alveoli, capillaries
Stratified epithelium
 Multiple tiers of cells
Glandular epithelia
 Absorb or secrete solutions
 Ciliated- lining of respiratory system
 Mucus membrane- oral cavity, nasal passages; moisten &
lubricate
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Connective tissue
Bind to & support other tissues
 Sparse number of cells scattered through an
extra-cellular matrix
 Consist of 3 protein fibers
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Collagen: non-elastic; strength; resists stretching
Elastin: rubbery; retain shape
Reticular: branched to connect adjacent tissues
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Types of connective tissue
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Loose connective
 Fibroblasts- secrete proteins of extracellular fibers
 Macrophages- immune response
Adipose
 Storage of fat
 For energy & insulation
Fibrous connective
 Tendons- attach muscle to bone
 Ligaments- attach bone to bone
Cartilage
 Part of all of skeleton in vertebrates
Bone
 Mineralized connective tissue
Blood
 Plasma- liquid matrix of water, salts, & proteins
 Leukocytes- white blood cells
 Erythrocytes- red blood cells
 Platelets- blood clotting
 Form in red bone marrow at ends of long bone
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Nervous tissue
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Sense stimuli & transmit signals within the animal
Neuron=nerve cell specialized to conduct impulses
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dendrites= extensions that conduct impulses to the cell
body
Axons= extensions that transmit impulses away from
the cell body
Muscle tissue
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Capable of contraction when stimulated
Consists of contractile proteins actin & myosin
Types:
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Skeletal muscle
 Attached to bone by tendons
 Voluntary
 Striated pattern
Cardiac muscle
 Contractile walls of heart
 Striated pattern
Smooth muscle
 Lines walls of internal organs
 Involuntary
 Tapered, non-striated appearance
Organ systems
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Are inter-dependant; organs with separate
functions act in coordinated manner
Tissues organized into organs except in
simple organisms
Some organs are layered (ex. Vertebrate
stomach)
Mesentery=sheets of connective tissue in
which organs are suspended
Bioenergetics
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Flow of energy through an organism
Limits animal’s behavior, growth, &
reproduction
Determines food requirements
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Animals are heterotrophs
Energy Input
(ingested food)
Digestion
(enzymatic hydrolysis of food)
Absorption
(small energy molecules by body cells)
Catabolism
(cellular respiration & fermentation harvest chemical energy
from food molecules)
some Energy Stored in ATP
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some Energy Lost as heat is to
surroundings
Energy Used - chemical energy of ATP powers cellular work.
After the needs of staying alive are met, leftover chemical
energy and carbon skeletons from food molecules can be
used in biosynthesis.
Energy Lost - cellular work generates heat, which is lost to
surroundings or used to maintain body temperature (endotherms)
Metabolic rate
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Total amount of energy an animal uses to stay alive
Measured in Calories (kilocalories)
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Calculated by measuring:
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oxygen used
Amount of heat loss per unit of time
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Heat loss is by-product of cellular work
Heat loss is measured with calorimeter
Range of metabolic rates
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Minimal rate for life support (breathing, sleeping….)
Maximal rates occur during peak activity (all out exercise)
Vary depending on:
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Age, sex, size
Body and environmental temperature
Food quality & quantity
Amount of available oxygen
Hormonal balance
Time of day & activity level
Endotherms
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Animals that generate their own body heat
metabolically
Includes birds, mammals
Many endotherms are homeothermic
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Maintain temperature within narrow limits
Basal metabolic rate
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Endothermic animal’s metabolic rate
measured under resting, fasting, & stress-free
conditions
Average BMR for humans:
Males….1600-1800 kcal/day
 Females….1300-1500 kcal/day
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Ectotherms
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Animals that acquire most of their body
heat from the environment
Includes fish, amphibian, reptiles, &
invertebrates
Minimal metabolic rate must be
determined at a specific temperature
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Standard metabolic rate (SMR)
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Ectotherm’s minimal metabolic rate measured
under controlled temperature as well as resting,
fasting, & stress-free conditions
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Metabolic rate/gram is inversely related to
body size among similar animals
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Smaller animals consume more calories/gram
than larger animals
Correlated to higher metabolic rate & need for
faster oxygen delivery to tissues
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Small animals have a higher
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Breathing rate
Blood volume
Heart rate
Inverse relationship holds true for both
endotherms & ectotherms
Body plans & the external
environment
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single celled organisms
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Multi-cellular animals body plan
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must have sufficient surface area of plasma membrane
to service the entire volume of cytoplasm
two-layered sac ... e.g. coelenterates / cnideria
flat-shaped body ... max. surface area exposed to water
(e.g. the flat worms)
most complex animals have a small SA : volume
and lack adequate exchange area on the outer
surface but…..
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Highly folded, moist, internal surfaces for material
exchange.
Circulatory system shuttles materials between the inner
& outer surfaces
Regulating the internal
environment
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Mechanisms
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interstitial fluid
Regulators:
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Internal controls used to maintain homeostasis if
external environment changes
Conformers:
internal conditions vary with external environmental
changes
**animal may be regulate according to 1 variable &
conform to another
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Homeostasis depends on feedback circuits (i.e.
nervous system)
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receptors - detects internal change
control center - processes information from receptors
& directs the effectors to respond
effector provides a response
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feedback (common method of regulation in
animals)
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positive feedback
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enhancement of a response
Rare
Ex. Blood clotting, childbirth contractions
negative feedback
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reduced response
examples: insulin regulation in mammal, body temp.
regulation
 hypothalamus ... detects high blood temperature
impulse to sweat gland sweat gland increases
output evaporative cooling normal temperature
obtained stops sending impulse
Thermo-regulators
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Animal maintains internal temperature within a
tolerable range
Can be ectotherm or endotherm
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Poikilotherm
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Homeotherm
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Internal temps vary widely
Relatively stable internal temps
Modes of heat exchange between organism &
the environment:
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Conduction
Convection
Radiation
Evaporation
Adaptations for thermo-regulation
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Insulation
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Hair, feathers, & fat layers
Reduce flow of heat between organism & the
environment
Circulatory adaptations
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Vaso-dilation
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Vasoconstriction
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Increase diameter of surface blood vessels
Warms skin & transfers heat to environment by radiation,
convection, & conduction
Decreases diameter of surface blood cells
Reduces blood flow to the surface
Retain heat
Countercurrent heat exchange
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Arrangement of blood vessels to help trap heat in body core
Reduces heat loss
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Cooling by evaporative heat loss
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Sweating
Breathing
Panting
Increase mucus production
Spread of saliva on body surface
Behavioral responses
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Move between shaded & sunny locales
Huddling
Shivering
Torpor
Hibernation- long term (cold)
 Estivation/summer torpor- slow in summer to
survive high temps & low water levels
 Daily torpor- based on feeding times
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Acclimatization
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Physiological response occurring over days or
weeks to environmental temperature change
Occurs by:
Increasing or decreasing insulation (fur or fat)
 Changing functional enzymes
 Changing proportions of unsaturated fats &
cholesterol in the cell membrane
 Rapid adjustments to temperature change involve
stress-induced proteins
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i.e. heat shock proteins- protect other proteins from
denaturization at high temperatures