Introduction to Animal Physiology

BIOL 3800.001 with Lisa Welch Spring 2026

Define Homeostasis

Maintenance of a relatively stable internal environment

Which two systems are the main control systems of the

body?

Nervous and endocrine systems

Which organ system(s) exchanges materials between the

internal and external environments?

Digestive and respiratory

Define Pathophysiology

Study of body functions in a disease state

define diabetes mellitus

condition characterized by abnormally high blood glucose

Response loops begin with a ___.

Stimulus

____ modulate the response loop.

Feedback loops

Define Negative Feedback loops

homeostatic and stabilize the variable by reducing change

Define positive feedback loops

non-homeostatic that amplifies change in the system

Define feedforward control

Allows the body to anticipate control

What is an example of positive feedback loop?

Childbirth, blood clotting, or fruit ripening

What is an example of negative feedback?

Temperature regulation, blood pressure, or osmoregulation

How do you shut off positive feedback?

an outside factor

How do you shutoff negative feedback?

The response loop itself will shut it off

Which of the following is not an example of homeostatic responses?

Sweating increases loss of body fluids, and urination

increases the loss of body fluids.

Which is NOT an example of negative feedback?

uterine contractions during childbirth

Nico is waiting at the start line for the race to begin. His

heart rate is starting to increase, and he is breathing a little

faster. This is an example of

feedforward control

Name the 5 parts of the feedback control system

Stimulus; receptor/sensor; control/integrating center; effector/target; action/response.

Bobby severed a large artery in his leg trying to chop up a block of ice with a knife. After Bobby severed the artery in his leg a cascading event arising from the rough edges of the artery and chemicals released by the damaged cells led to the formation of a clot. What is the sensor?

rough edges of the artery

Bobby severed a large artery in his leg trying to chop up a block of ice with a knife. Because of the large amount of blood Bobby has lost his blood pressure drops. This is detected by baroreceptors in the carotid arteries and the information is relayed to the medulla oblongata in turn the heart is stimulated to beat faster to increase the blood pressure. What is the control?

The medulla oblongata

Bobby severed a large artery in his leg trying to chop up a block of ice with a knife. Because of the large amount of blood Bobby has lost his blood pressure drops. This is detected by baroreceptors in the carotid arteries and the information is relayed to the medulla oblongata in turn the heart is stimulated to beat faster to increase the blood pressure. What is the effector?

The heart

You are taking a hike and spot a venomous snake on the ground a few feet away. Your heart rate becomes elevated and your muscles build tension. This is an example of:

feedforward control

High concentrations of sodium and chloride are found in ___.

Extracellular fluid (ECF)

High concentrations of potassium levels are found in ___.

Intracellular Fluid (ICF)

__ molecules of ___ are removed by the sodium-potassium pump.

3 sodium

The sodium potassium ATPase will pump in __ molecules of __.

2 potassium

Organs included in the circulatory system:

Heart, blood, and blood vessels

Organs included in the digestive system:

Stomach, intestine, liver, and pancreas

Organs included in the endocrine system:

thyroid gland and adrenal gland

Organs included in the immune system:

thymus, spleen, and lymph nodes

Organs included in the musculoskeletal system

skeletal muscles and bone

Organs included in the nervous system:

brain and spinal cord

Organs included in the reproductive system:

ovarties, uterus, and testes

Organs included in the respiratory system:

lungs and airways

Organs included in the urinary system

kidneys and bladder

___ mechanisms maintain the disequilibrium of ECF and ICF to ensure stability and function.

Active Transport

Define Local Control:

Designed to handle small, immediate issues and is restricted to a tissue or cell

Define Reflex control

Deals with larger body-wide adjustments by using the endocrine or nervous system

Define Stimulus

something that removes balance from the system

Define Target

The organ or tissue being told to act

Define output signal

Nerves or hormones that are instructing tissues or hormones to act