1. FORM, FUNCTION, HOMEOSTASIS
Who’s in charge here??
FORM,
FUNCTION,
HOMEOSTASIS

2. More than just a common ancestor
All organisms require chemical energy for growth, repair, physiological processes, regulation, and reproduction
characteristics of life anyone?
The comparative study of animals reveals that form and function are closely correlated
The study of bioenergetics
tells us much about an animal’s adaptations

3. The link between form and funciton
Size and shape affect
how organism interacts with it’s environment
how the animal exchanges energy and materials with its surroundings.
Convergence occurs because natural selection shapes similar adaptations when diverse organisms face the same environmental challenge, such as the resistance of water to fast travel.

4. Evolution is NOT perfection! Evolution IS compromise.
Warning!!!!!
Evolution is NOT perfection!
Evolution IS compromise.

5. “All for One, and One for All!”
Animals are complex, multicellular organisms
No ONE organ or ogran system can stand alone!!!

6. LE 40-4 External environment CO2 Food O2 Mouth Animal body Respiratory
system
Blood
50 µm
0.5 cm
A microscopic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment (SEM).
Cells
Heart
Nutrients
Circulatory
system
10 µm
Digestive
system
Interstitial
fluid
Excretory
system
The lining of the small intestine, a digestive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption (cross-section, SEM).
Anus
Inside a kidney is a mass of microscopic tubules that exchange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM).
Unabsorbed
matter (feces)
Metabolic waste
products (urine)

7. Tissues are classified into four categories
Epitheleal
Connective
Covers the outside of the body
Lines organs and cavities
Cells are closely joined together
Types:
Binds and supports other tissues
sparsely packed cells scattered throughout an extracellular matrix
Types:

8. LE 40-5_2 Chondrocytes Collagenous fiber Loose connective tissue
120 µm
Chondrocytes
Collagenous
fiber
Loose
connective
tissue
Chondroitin
sulfate
Elastic
fiber
100 µm
Cartilage
Fibrous
connective tissue
Adipose tissue
Fat droplets
Nuclei
150 µm
30 µm
Blood
Central
canal
Red blood cells
Bone
White blood cell
Osteon
Plasma
700 µm
55 µm

9. Four categories of tissues cont’d
Muscle
Nervous
consists of long cells called muscle fibers
contract in response to nerve signals
Types
senses stimuli
transmits signals throughout the animal
Types

10. LE 40-5_3 Multiple nuclei Skeletal muscle Muscle fiber Sarcomere
MUSCLE TISSUE
100 µm
Multiple
nuclei
Skeletal muscle
Muscle fiber
Sarcomere
Cardiac muscle
Nucleus
Intercalated
disk
50 µm
Nucleus
Smooth muscle
Muscle
fibers
25 µm
NERVOUS TISSUE
Neuron
Process
Cell body
Nucleus
50 µm

11. How is homeostasis maintained?
Bioenergetics, the flow of energy through an animal, limits behavior, growth, and reproduction
Energy-containing molecules from food are used to make ATP to power cellular work
After the needs of staying alive are met, remaining food molecules can be used in biosynthesis

12. LE 40-7 Organic molecules in food External environment Animal body
Digestion and
absorption
Heat
Energy
lost in
feces
Nutrient molecules
in body cells
Energy
lost in
urine
Carbon
skeletons
Cellular
respiration
Heat
ATP
Biosynthesis:
growth,
storage, and
reproduction
Cellular
work
Heat
Heat

13. “I’m not fat, I just have a slow metabolism”
An animal’s metabolic rate is closely related to its bioenergetic strategy
Basal Metabolic Rate:
Metabolic rate is affected by size and activity of the organism
maximum metabolic rate is inversely related to the duration of the activity

14. Bioenergetic strategies
Endothermic organisms
Ectothermic organisms
Example: Birds and mammals
Bodies are warmed by mostly by heat generated by metabolism
Typically have higher metabolic rates
more energetically expensive
Example: Amphibians , fish, and reptiles
Gain heat from their external environment
Have lower metabolic rates
tolerate greater variation in internal temperature

15. Maximum metabolic rate
LE 40-9
500
A = 60-kg alligator A H
100 H A
A = 60-kg human 50 H
Maximum metabolic rate
(kcal/min; log scale) 10 H 5 H A 1 A
0.5 A
0.1 1
second 1
minute 1
hour 1
day 1
week
Time interval
Key
Existing intracellular ATP
ATP from glycolysis
ATP from aerobic respiration

16. Bioenergetic strategies
Regulators
Conformers
uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation
allows its internal condition to vary with certain external changes
The term “internal environment” is in reference to the interstitial fluid

17. LE 40-10 Endotherms Ectotherm 800,000 340,000 8,000 4,000 438 Human
Reproduction
Basal
(standard)
metabolism
Temperature
regulation
Growth
Activity
Annual energy expenditure (kcal/yr)
340,000
8,000
4,000
60-kg female human
from temperate climate
4-kg male Adélie penguin
from Antarctica (brooding)
0.025-kg female deer mouse
from temperate
North America
4-kg female python
from Australia
Total annual energy expenditures. The slices of the pie charts indicate energy
expenditures for various functions.
438
Human
Energy expenditure per unit mass
(kcal/kg•day)
233
Python
Deer mouse
Adélie penguin
36.5
5.5
Energy expenditures per unit mass (kcal/kg•day). Comparing the daily energy expenditures per kg of body weight for the four animals reinforces two important concepts of bioenergetics. First, a small animal, such as a mouse, has a much greater energy demand per kg than does a large animal of the same taxonomic class, such as a human (both mammals). Second, note again that an ectotherm, such as a python, requires much less energy per kg than does an endotherm of equivalent size, such as a penguin.

18. Mechanisms of homeostasis receptor control center effector
Negative Feedback
Positive Feedback
buildup of the end product shuts the system off
Allows certain internal environmental conditions to be maintained within a range
For Example?
change in a variable triggers mechanisms that amplify rather than reverse the change
Pushes a system further until the stimulus is removed
For Example?

19. This guy’s got it easy! Thermoregulation….. Radiation Evaporation
LE 40-13
Radiation
Evaporation
Convection
Conduction
Thermoregulation…..
This guy’s got it easy!

20. …a delicate balance between heat loss and heat gain
Five general adaptations help animals thermoregulate:
Insulation
Circulatory adaptations
Cooling by evaporative heat loss
Behavioral responses
Adjusting metabolic heat production

21. Back to that “All for One” philosophy
Insulation
Circulatory adaptations
Integumentary system
reduces heat flow between an animal and its environment
Structures of the skin
Circulatory system
alter the amount of blood flowing between the body core and the skin
Vasodilation
Vasoconstriction
*Countercurrent heat exchanger

22. Back to that “All for One” philosophy
Cooling by evaporative heat loss
lose heat through evaporation of water in sweat
Bathing moistens the skin
Aaaahhhhh….muuuuuch better!

23. upload.wikimedia.org/wikipedia/commons/thumb/...

24. Back to that “All for One” philosophy
Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat Some animals can regulate body temperature by adjusting their rate of metabolic heat production

25. Internal body temperature
LE 40-21
Thermostat in
hypothalamus
activates cooling
mechanisms.
Sweat glands secrete
sweat that evaporates,
cooling the body.
Blood vessels
in skin dilate:
capillaries fill
with warm blood;
heat radiates from
skin surface.
Increased body
temperature (such
as when exercising
or in hot
surroundings)
Body temperature
decreases;
thermostat
shuts off cooling
mechanisms.
From simple to complex
Homeostasis:
Internal body temperature
of approximately 36–38°C
Body temperature
increases;
thermostat
shuts off warming
mechanisms.
Decreased body
temperature
(such as when
in cold
surroundings)
Blood vessels in skin
constrict, diverting blood
from skin to deeper tissues
and reducing heat loss
from skin surface.
Thermostat in
hypothalamus
activates
warming
mechanisms.
Skeletal muscles rapidly
contract, causing shivering,
which generates heat.

26. Negative feedback and appetite?
Neuronal pathways that control energy balance and their regulation by hormonal signals such as insulin and leptin
Negative feedback and appetite?

27. The Stork….or Positive Feedback?
Childbirth is the best example of the positive feedback mechanism at work
Fever is also considered