Homeostasis

Question 1

What is homeostasis?

Answer 1

The maintenance of a stable internal environment even when the external environment is changing

Question 2

Temperature?

Answer 2

If body temperature is too high, enzymes may become denatured
Ionic bonds are broken that hold the 3D shape- the active sites shape is changed and no longer works as a catalyst
Lower temperatures- collisions are less frequent- less ESC’S formed- less kinetic energy

Question 3

PH?

Answer 3

Too high or too low- enzymes become denatured
Hydrogen bonds that hold them in their 3D shape are broken so the shape of the active sites has changed- no longer works as a catalyst

Question 4

Glucose?

Answer 4

Too high = water potential of blood decreases- water diffuses out of the cell by osmosis
Causes cells to shrivel up and die
Too low- water potential increases- water may move into the cell by osmosis- burst
A lack of glucose may slow respiration- lack of ATP- less active transport etc

Question 5

What do homeostatic systems involve?

Answer 5

Receptors, a communication system and effectors

Question 6

What do receptors do?

Answer 6

Detect when a level is too low/high
Monitor any changes in internal (normal) conditions

Question 7

What do the effectors do?

Answer 7

Respond to counteract the change
Bringing the level back to normal

Question 8

What is negative feedback?

Answer 8

Restoring the level to normal by using a corrective mechanism

Question 9

What level does negative feedback keep around?

Answer 9

Keeps things around the normal level

Question 10

How does negative feedback work?

Answer 10

only works within certain limits though- if the change is too big, the effectors may not be able to counteract it

Question 11

Multiple negative feedback systems?

Answer 11

Having more than one mechanism gives more control over changes
Can actively increase or decrease a level so it returns to normal
Only one negative feedback mechanism means a slower response and less control

Question 12

Positive feedback?

Answer 12

Positive feedback mechanism = amplifies the change
The effectors respond to further increase the level away from the normal level
Useful to rapidly activate something
E.g. a blood clot after an injury
Platelets become activated and release a chemical
Platelets very quickly form a blood clot at the injury site
The process ends with negative feedback- the body detects the blood clot has been formed

Question 13

Why is positive feedback not involved in homeostasis?

Answer 13

It does not keep your internal environment constant

Question 14

Definition of negative feedback?

Answer 14

Any change away from the normal level is detected by receptors and a response is initiated to reverse the change

Question 15

Definition of positive feedback?

Answer 15

A mechanism that amplifies the change, moving the system further away from the set point

Question 16

How does the endocrine system function to bring responses in the body?

Answer 16

Release of hormones from endocrine glands
Transport of hormones in the blood
Binding of hormones to complementary/specific receptors on target organs