form, function, homeostasis -...
TRANSCRIPT
F O R M ,
F U N C T I O N ,
H O M E O S T A S I S
Who’s in charge here??
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
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.
“All for One, and One for All!”
Animals are complex, multicellular organisms
No ONE organ or ogran system can stand alone!!!
http://www.comp.dit.ie/dgordon/League/OtherLeagues/c17/threemuskeeters2.jpg
LE 40-4
Digestive system
Circulatory system
Excretory system
Interstitial fluid
Cells
Nutrients
Heart
Animal body
Respiratory system
CO2 Food
Mouth
External environment
O2
50
µm
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).
10 µm
Inside a kidney is a mass of microscopic tubules that exchange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM).
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).
Unabsorbed matter (feces)
Metabolic waste products (urine)
Anus
0.5 cm
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:
Tissues are classified into four categories
LE 40-5_2 CONNECTIVE TISSUE
Collagenous fiber
Elastic fiber
120 µm
10
0 µ
m
Chondrocytes
Chondroitin sulfate
Cartilage
15
0 µ
m
Adipose tissue
Fat droplets
Blood
Red blood cells
White blood cell
55 µm
Plasma
Bone Central canal
700 µm
Osteon
30 µm
Fibrous connective tissue
Nuclei
Loose connective tissue
Muscle Nervous
consists of long cells called muscle fibers
contract in response to nerve signals
Types
senses stimuli
transmits signals throughout the animal
Types
Four categories of tissues cont’d
LE 40-5_3 MUSCLE TISSUE
Multiple nuclei
100 µm
Skeletal muscle
Cardiac muscle
Smooth muscle
Neuron
Muscle fiber
Sarcomere
Intercalated disk
Nucleus 50 µm
Nucleus
25 µm
Muscle fibers
Process
Nucleus
50 µm
Cell body
NERVOUS TISSUE
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
LE 40-7
External environment
Organic molecules in food
Animal body Digestion and
absorption
Nutrient molecules in body cells
Carbon skeletons
Cellular respiration
Biosynthesis: growth,
storage, and reproduction
Cellular work
ATP
Heat
Heat
Heat
Energy lost in urine
Heat
Energy lost in feces
“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
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
Bioenergetic strategies
LE 40-9
A = 60-kg alligator
A = 60-kg human
Key
Existing intracellular ATP
ATP from glycolysis
ATP from aerobic respiration
Time interval
1 second
1 minute
1 hour
1 day
1 week
500
100
50
10
5
1
0.5
0.1
Ma
xim
um
me
tab
oli
c r
ate
(k
ca
l/m
in;
log
sc
ale
)
A H
A H
A
H
A
H
A
H
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
Bioenergetic strategies
The term “internal environment” is in reference to the interstitial fluid
LE 40-10
800,000
Endotherms
340,000
Basal (standard) metabolism
Reproduction Temperature regulation
Growth
Activity
60-kg female human from temperate climate
4-kg male Adélie penguin from Antarctica (brooding)
4,000
0.025-kg female deer mouse from temperate North America
4-kg female python from Australia
8,000
Ectotherm
Total annual energy expenditures. The slices of the pie charts indicate energy expenditures for various functions.
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.
438
233
36.5 5.5
Python
Human
Deer mouse Adélie penguin
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?
Mechanisms of homeostasis receptor control center effector
Thermoregulation…..
This guy’s got it easy!
LE 40-13
Radiation Evaporation
Conduction
Convection
…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
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
Back to that “All for One” philosophy
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!
upload.wikimedia.org/wikipedia/commons/thumb/...
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
LE 40-21 Thermostat in hypothalamus activates cooling mechanisms.
Increased body temperature (such as when exercising
or in hot surroundings)
Body temperature decreases; thermostat
shuts off 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.
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.
Skeletal muscles rapidly contract, causing shivering, which generates heat.
Thermostat in hypothalamus activates warming mechanisms.
Homeostasis: Internal body temperature of approximately 36–38°C
Negative feedback and appetite?
Neuronal pathways that control energy balance and their regulation by hormonal signals such as insulin and leptin
http://www.medscape.com/viewarticle/448465
The Stork….or Positive Feedback?
Childbirth is the best example of the positive feedback mechanism at work
Fever is also considered
http://www.sciencedaily.com/images/2007/04/070402215329.jpg