Download ch 40: an introduction to animal structure and function

I.
A.
CH 40: AN INTRODUCTION TO ANIMAL STRUCTURE AND FUNCTION
Physical laws and environments determine animal size and shape
A. single celled organisms are in constant contact with their environment and therefore do not have
specialized tissue for survival
B. multicellular organisms have adapted compartmentalization for the overall efficiency and survival of
the organism
Four main categories (epithelial, connective, nervous, muscle)
1.
epithelial tissue
a.
thin tightly packed cells which protect against diseases, injury, fluid loss, and
secrete/absorb chemicals (mucous membranes/digestive nz then absorb nutrients)
b.
line outside of body, and internal organs and cavities
c.
basement membrane attach cells at base (fig40.1) – an extracellular matrix
d.
types depend on number of cell layers and shape of cells p 824
1.
simple epithelium – single layer of cells
2.
stratified epithelium – multiple layers
3.
pseudostratified epithelium – single layer but look multilayered since cells are
various heights
4.
cuboidal (cubed), columnar (columns), and squamous (flat) shapes
5.
Ex. simple squamos epithelial tissue
2.
connective tissue
a.
binds/supports other tissues
b.
consists of sparsely scattered cells within extracellular matrix
c.
three kinds of extracellular matrix
1.
collagenous fibers- made up of protein collagen, nonelastic, do not tear easily
2.
elastic fibers – made up of protein elastin, provide elasticity to collagenous fibers
(complement each other), restores shape
3.
reticular fibers – made up of protein collagen, continuous with collagenous
fibers, joins connective tissues to adjacent tissues
d.
6 major types of connective tissues p825
1.
loose connective tissue – binds epithelial to underlying tissue, holds organs in
place, contains all 3 connective tissue types (collagenous, elastic, reticular),
contains fibroblasts (secrete the protein part in the extracellular matrix) and
macrophages (engulfs bacteria and dead material)
2.
adipose tissue – stores fat in its cells, insulates body, stores fuel, heredity, diet,
and exercise affect amount stored
3.
fibrous connective tissue – dense, lots of parallel-lined collagenous fibers
increase its strength, ex tendons/ligaments
4.
cartilage – consists of collagen and chondroitin sulfate which are secreted by
chondrocytes,
5.
bone – mineralized connective tissue, contain osteoblasts which secrete collagen
(flexibility) and hydroxyapatite (hardness)
6.
blood – no true extracellular matrix, but blood cells are surrounded by plasma
(water, salts, dissolved proteins), two types of blood cells = erythrocytes
(rbcs/carry O2) and leukocytes (wbcs/fight disease) and also platelets (blood cell
fragments/clotting)
3.
nervous tissue- p 826 sensory tissue consisting of a neuron (nerve cell) which consists of a cell
body, axon, and dendrites
4.
muscle tissue p 826- cells capable of contraction due to contractile proteins called actin and
myosin, adults have a fixed number of muscle cells (so weight-lifting does not increase number only
size or length of existing muscles. That is why when you stop body building, you lose the bulk)
a. three main types
1. skeletal (striated) muscle – attach to bones through tendons, give a stripped appearance
under the microscope
2. cardiac muscle – makes up wall of heart, cells are joined to relay contraction impulse,
also looks stripped under microscope
3. smooth muscle – lacks stripped look (smooth-look), slow to contract, but can remain
contracted for relatively long periods of time (ex. digestive tract, bladder arteries)
III.
A.
B.
Organs
suspended by mesenteries (connective tissue)
mammals have a thoracic cavity (houses lungs and heart) and a abdominal cavity (houses digestive
systems) and both are separated by a diaphragm (thin sheet of muscle)
IV.
Bioenergetics of animals (energy obtainment/use)
A.
are heterotrophs which break down food stuffs for energy
B.
metabolic rate of animals
1.
metabolic rate-total amt of energy an animal uses in a unit of time, measured in calories (cal),
can be determined through heat loss per unit of time or the amount of O2 consumed through
respiration
2.
the metabolic rate of endotherm is usually higher than that of ectotherms since the former rely on
energy to maintain their body temperature
3.
basal metabolic rate – (BMR) the metabolic rate of an endotherm at rest on an empty stomach
and not stressed
4.
standard metabolic rate – (SMR) the metabolic rate of an ectotherm at rest on an empty
stomach and not stressed and at a specific temperature (must use a specific temp since their body
temperature and metabolic rate change over time depending on environmental temperature
*any form of activity (ex. writing/turning head) will increase the metabolic rate over the BMR or SMR
C.
metabolic rate per gram is inversely related to the body size of the animal
1.
Ex. a mouse has a higher metabolic rate for each of its grams in weight than an elephant – why?
Hypothesized that the smaller the body (high SA to volume) the faster lose/gain heat so must use more energy
to maintain homeostasis, downfall? – only works with endotherms and has not been shown experimentally – no
answer yet found
V.
Body plans and the external environment
A.
physical support on land depends on body proportion (ex. size of legs to support body) and posture
(location of legs relative to main body)
Body size and shape affect interactions with the environment
1.
single-celled organisms have a large enough surface area to volume ratio to allow for
diffusion of nutrients across its plasma membrane
2.
a multi-celled organisms consists of many cells due to its size, but the same process occurs
3.
a single-celled organism or an organism consisting of 1-layer of cells has the advantage of
having nearly all of it surface area exposed to the environment (internal/external) for nutrient,
O2, etc exchange
4.
a multi-celled organism does not, but does have many foldings of its internal structures
which increases SA for ex. nutrient absorption, gas exchange, wastes exchange etc.
VI. Regulating the internal environment
A.
Homeostasis
1.
interstitial fluid-fluid within the vertebrate animal that fills the spaces between cells and
helps to exchange nutrients and wastes within the blood
2.
interstitial fluid helps maintain efficient blood pH, O2 concentration, body temperature, etc =
homeostasis “steady state”
B.
Regulator- uses internal control mechanisms to moderate internal changes (vertebrates)
C. Conformer- allows the environment to determine its internal conditions (invertebrates)
D. Homeostasis depends on feedback mechanisms = adaptive response = textbook theme
3.
three parts to a feedback mechanism = receptor (detects change), control system (processes
change information), and effector (gives a response)
4.
negative feedback mechanism-acts against any change/most animal systems are this Ex. if
gets too cold in a room, thermostat picks it up, sends info. to control system and effector
turns on heater (tries to counteract any change from what presently is)
5.
positive feedback mechanism-acts with and tries to amplify the change Ex. during
childbirth baby’s head pressure on mom stimulate contractions which push baby harder
against mom which stimulates more pressure, etc = amplifying the change
E. Thermoregulation is a way an organism maintains its internal temperature
1. ectotherms gain their heat from the environment and therefore have to change their behaviors to
adjust to environmental temperature changes. They also have low metabolic rates so the heat they
generate would be too like to regulate their body temperature
2. Endotherms use metabolic heat generated by chemical reactions within their bodies to regulate
their body temperatures. This is a very energy intensive regulation and requires more energy overall
to maintain a regular internal temperature. (Many chemical reactions within endotherms give off
heat as a byproduct of the reaction)
3. Don’t use warm blooded or cold blooded anymore. Some “cold blooded “ organisms like desert
lizards in the sun can actually have warmer body temperatures than “warm blooded” humans.
F. Ways to balance heat gain or heat loss
1. insulation-materials produced by the integumentary system or the outer covering of the body
(hair, fur, feathers, skin and nails) Adipose tissue can also be used as an insulating material
2. Circulatory adaptations- vasodilation can increase blood flow and regulate body temperature
when the blood is sent to the surface of the organism to be cooled off. Vasoconstriction is when
blood vessels constrict to retain heat and prevent heat loss by reducing blood flow to internal organs.
3. Countercurrent heat exchange- many aquatic organisms reduce heat loss by directing blood
vessels to pass by each other. Veins carry cooler blood to the heart while arteries carry warmer blood
away from the heart. The close proximity will help heat the body when swimming or standing in
cooler water. It can also cool off the body by passing blood close to the body surface.
4. Evaporative heat loss- Water or sweat cools in the outside air and blood flow is directed to the
surface of the body to allow the surface blood to cool down before being transported back to the
warmer internal body parts
5. Behavioral responses- moving into the sun to warm up or hiding in the shade to cool down is a
simple way to regulate body temperature. More complex behaviors from insects include dragonflies
that carry their abdomens high in the air to expose more body surface to the sun. Other flying insects
will flap their wings but not fly to “warm” up flight tissue.
6. Adjusting metabolic heat production-nonshivering thermogenesis in mammals can make
mitochondria to produce heat instead of ATP. Shivering will increase heat production by muscle
movement. Brown fat in the neck and between the shoulders is specialized for heat production. (That
is why we often sweat around our necks and upper back)
7. Acclimatization- adjustments to new temperatures- blood thickens in cooler temps and thins in
warmer climates. Other adaptations include growing a thicker coat in winter and losing the coat in
summer. At the cellular level, cells can produce enzymes that can function at different temperatures.
Cell membranes change their fatty acids from saturated to unsaturated in response to cold
(unsaturated fats remain liquid at room temperatures) to prevent solid molecules from freezing. Heat
shock or stress induced proteins are produced when a rapid change in temperature occurs. Many of
these cellular changes however can not remain permanent.
8. Torpor- a physiological state of lowered metabolism and activity in response to extremes in heat
or cold. Estivation is summer torpor and hibernation is winter torpor. Daily torpor can occur as
well when animals feed during cooler temperatures and rest in the heat of the day SIESTA!!!!!