BIO 2 Animal physiology

Homeostasis

• maintaining stable conditions inside the body even while conditions outside are changing

• Different species regulate aspects of physiology to various degrees.

regulate

• For some physiological variables, an organism maintains the
  variable within a consistent range

conform

For other variables, an organism has no set point and the
variable fluctuates with changes in the environment

negative feedback (type of regulation)

• system resists change to stabilize internal conditions

• systems OPPOSE change and RETURN a system to set point

1. ex. thermoregulation

positive feedback (types of regulation)

• system encourages/amplifies change to rapidly push

• intensifies process and moves conditions away from set point; destabilizes

• Results in destabilizing a system by causing responses that grow stronger and stronger

• Examples: Childbirth, urination, clotting, sexual responses

set point (feedback system part)

target value for a physiological variable

sensors (feedback system part)

measure current value of a variable

control centers (feedback system part)

compare variable to set point and send directions to effectors responses

effectors (feedback system part)

body part used to respond (e.g., sweat glands)

thermal energy

• (heat) moves. (Cold doesn’t. It’s absence of heat.)

• Heat flows down a thermal gradient from warm objects to

  cooler objects.

endotherms

can generate body heat

ectotherms

are unable to generate body heat

homeotherms

can maintain stable body temperature when environmental temp
changes

heterotherms

Body temperature of these matches the environment

physical (control of heat flow)

insulation with fat, hair, or feathers; increase or reduce surface area

behavioral (control of heat flow)

sunning or shading; activity during specific times of day

physiological (control of heat flow)

sweating, shivering, changes in blood flow to skin

moves around the body because of the circulatory system

1. gas: O2 and CO2

2. nutrients

3. waste

4. hormones

5. heat

6. immune cells

• diffusion is rapid over short distances but insufficient to move materials around the bodies of larger organisms.

hemoglobin

• carries O₂ in many animals

• Iron atoms are able to reversibly bind O₂

• O₂ binds when O₂ concentration is high

• Releases O₂ when O₂ concentration is low

Carbon monoxide is poisonous because…

• Carbon monoxide sticks to hemoglobin much more strongly than O2

• Oxygen is unable to compete for the “seats” on hemoglobin

arteries (vessel in circulatory system)

carry blood AWAY from heart

veins (vessel in circulatory system)

carry blood TOWARD heart

capillaries (vessel in circulatory system)

very thin, narrow vessels where gas/nutrient/waste exchange

occurs; typically form dense “beds”

sphincter

• “rubber-band”-like muscles change flow through capillary beds

• muscle in vessel walls can affect blood flow by changing diameter of vessels

closed circulatory systems

blood FULLY contained within vessels; vertebrates, annelids, cephalopod (molluscs)

open circulatory systems

marinating; blood partially contained in vessels; blood mixes with extracellular fluid; arthropods and most molluscs

benefits of closed circulatory systems relative to open systems

1. more rapid transport (oxygen, wastes, etc.)

2. better control of blood flow to specific areas of the body

3. Specialized blood cells and molecules can be retained inside vessels

pulmonary (circuit in circulatory system)

blood movement to/from lungs or gills

systemic (circuit in circulatory system)

blood flow to remainder of the body

trend in evolution

more and more separation of the “lung/gill” and “rest of body” circuits

which of the following is true?

none of the above

Why does speed of blood flow and pressure drop as blood moves away from the heart?

Friction with sides of the blood vessel.

(most) fish circulatory system

1 circuit; 1 ventricle, 1 atrium

• capillaries have the lowest pressure so blood flow is the slowest

• right after the heart (arteries leaving the ventricle) the pressure is the highest so blood flow is higher

• Low systemic pressure slows delivery of O2 to tissues

Amphibians and most reptiles circulatory system

• 2 circuits

1. ventricle

2. atria

Some mixing of blood occurs in the single ventricle. A septum

helps partially separate blood flow in the ventricle.

Mammals and birds circulatory system

• 2 circuits

1. 2 ventricles

2. 2 atria

Complete separation of ventricles eliminates mixing seen in 1 ventricle systems

relaxation and contraction of the heart

1) Atria and ventricles RELAX and fill with blood (diastole)

2) Atria CONTRACT, forcing blood into ventricles (systole)

3) Ventricles CONTRACT, pushing blood into aorta and pulmonary

arteries (systole)

• Heart contraction needs lots of oxygen and nutrients

coronary arteries

deliver oxygen and nutrients to cardiac muscle

• Cholesterol, plaque, and calcium deposits build up and block flow through these, causing heart attacks

comma

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period