anatomy homeostasis

What does “homeo” mean?

similar/like

What does “stasis” mean?

equilibrium

What is homeostatic regulation?

- the adjustment of physiological systems

to improve homeostasis.

What happens during intrinsic regulation?

cell, tissue, organ, or system, automatically

adjusts its own activities in response to

an environment change.

Give an example of intrinsic regulation

Apoptosis - This is "programmed cell death." If a cell gets old, damaged, or isn’t needed anymore, it can trigger its own death in a safe, controlled way. This helps keep tissues healthy by removing cells that might otherwise cause problems.

What is extrinsic regulation?

- nervous or endocrine systems adjust the

activities of other systems.

Give an example of extrinsic regulation in the endocrine system

When you’re stressed, the endocrine system’s adrenal glands release cortisol and adrenaline. These hormones travel in the blood and tell
the heart to beat faster

the liver to release glucose for energy

and decreases immune system activity

Give an example of extrinsic regulation in the nervous system

When you exercise, nerves step in and:

Nerves tell blood vessels in muscles to widen and in the digestive system to narrow → blood goes where it’s needed most.

Nerves increase breathing rate → more oxygen brought in, more carbon dioxide removed.

How quickly does the nervous system respond when stimulated? 

Very quick, in seconds. Uses electrical messengers/impulses

How quickly does the nervous system respond when stimulated? 

Slow/long term, in minutes, weeks, or longer. Uses chemical messengers/hormones

What a receptor?

A sensor that is sensitive to an environmental stimulus (change)

What is a control center?

A cell, organ, or system that receives and processes the information from the receptor and then sends out a command

What is an Effector?

a cell or organ that responds by opposing or enhancing the stimulus. (muscle, organ, or gland)

All regulatory mechanisms have 3 parts. Name all three

Receptor, control center, effector 

There are two methods of homeostatic regulation. What are they?

Negative and Positive feedback loops

what is is a negative feedback loop?

a stimulus produces a response that

opposes (or negates) the original stimulus.

what is the primary method of homeostatic regulation

negative feedback loop

What type of control does a negative feedback loop provide for the body’s internal condition?

Long-term control 

how do negative feedback loops maintain the loop’s affected variable?

maintains a range around a set-point.

for example, body temperature remains around 98.6 Fahrenheit

“the control of body temperature” (rising temperature)

explain the stimulus
explain all parts of this regulatory mechanism
explain what type of feedback loop it is

Natural body temperature is disturbed.

The body temperature rises. This is the stimulus.

This is picked up on by the receptors, the temperature sensors on the skin. 

This information is then sent to the control center (hypothalamus) along the sensory (A-fferent) pathway.

The hypothalamus then analyzes the information and determines the appropriate response, activating the effector, or in this case, the sweat glands and blood vessels.

The sweat glands begin secreting more sweat, and blood vessels dilate to release heat.

The body temperature will then begin to drop, and body will return to normal temperature, or in other words, homeostasis.

This is a negative feedback loop because it negated the original stimulus (rising temperature) by negating it (increasing sweat and dilating blood vessels.)

The receptor senses change in the environment and responds by sending information to the control center along the ________ pathway

Sensory/A-fferent pathway

The control centers analyzes the input from the receptor, determines the appropriate response, and activates the effector by sending information along the ________ pathway

Motor/E-fferent pathway

What is a positive feedback loop? 

a stimulus produces a response that

enhances (or exaggerates) the original

conditions.

What type of response does a positive feedback loop provide for the body?

provides quick response to potentially

dangerous processes.

“childbirth”

explain the stimulus
explain all parts of this regulatory mechanism
explain what type of feedback loop it is

The child’s head presses up against the cervix. This is the stimulus

Sensors on the cervix pick up on this and send this information to the control center (hypothalamus) along the sensory (afferent) pathway 

The control center analyzes the input, and determines the appropriate response (secrete oxytocin) 

Activates effector (pituitary gland) by sending the information about how to respond along the motor (efferent) pathway 

Oxytocin is released by pituitary gland and released into bloodstream, carried to the uterus

Oxytocin stimulates uterine contractions and pushes baby towards cervix

Baby’s head is pushed towards cervix again

Ends when the baby is out, and the head is no longer stimulating the sensors on the cervix

This is a positive feedback loop because the oxytocin released by the pituitary gland amplifies the stimulus (baby’s head pushing toward the cervix) in order to facilitate the baby’s birth 

“bloodclotting”

explain the stimulus
explain all parts of this regulatory mechanism
explain what type of feedback loop it is

Platelets pick up on damage to the blood vessel wall that caused bleeding and collagen exposure (stimulus) 

Platelets release signaling molecules that communicate the damage to other platelets along the sensory (a-ferrent) pathway 

Other platelets and damaged tissue (control center)  amplify this signal by releasing more chemicals to communicate to other platelets along the motor (e-fferent pathway)

Platelets activated by chemicals continue clotting (effector) until bleeding stops and stops stimulating the platelets