Homeostasis

Question 1

What is homeostasis

Answer 1

Homeostasis regulates the body systems in order to maintain a state of equilibrium

Question 2

What is the points of a negative feedback loop

Answer 2

Stimulus— receptor—- control centre— effector

Question 3

What is a stimulus

Answer 3

A stimulus indicates that a normal range has exceeded its ‘set point’

E.g too hot or too cold

Question 4

What is a receptor?

Answer 4

Detects changes and forwards it to the control centre

Question 5

What is the control centre

Answer 5

Receives information from the receptor and sends instructions to the effectors

Question 6

What is the effector

Answer 6

Receives instructions and responds by producing a change to bring the body back to a ‘set point’

Question 7

What is thermoregulation?

Answer 7

The process of keeping the body in a balanced state of temperature even when external temperature is different

Question 8

Example of thermoregulation feedback loop

Answer 8

( stimulus) Body goes about 37’C

( receptor) Nerve cells in the skin and body detect change

( control centre )Temperature regulatory centre in the brain send message to sweat glands

( effector) Sweat glands in the body produce sweat to lower body temperature back to its set point

Question 9

What is osmoregulation?

Answer 9

Maintains a stable balance of fluid and electrolytes in the body.

Stops fluid in the body from becoming too diluted or concentrated

Question 10

What are osmoreceptors?

Answer 10

They are found in the hypothalamus and sense the concentration of fluid in the body

They control the release of ADH ( antidiuretic hormone)

Question 11

What is ADH?

Answer 11

Antidiuretic hormone

Retains fluid in the body & reduces urination

Question 12

What is osmolarity?

Answer 12

The concentration of solutes in the body

High osmolarity = low fluid volume in body = creating thirst= increased ADH= less urine production

Low osmolarity= increased fluid volume in body= reduced ADH= more urine production

Question 13

Example of osmoregulation feedback loop

Answer 13

Too much salt consumed 
                  |
Water content in blood low 
                  |
Brain produces ADH
                  | 
High volume of water absorbed by kidney
                  |
Urine output low 
                  |
Water content of blood normal

Question 14

What happens when blood glucose is too high?

Answer 14

Pancreas releases insulin into the body

Question 15

What happens when blood glucose is too low?

Answer 15

Pancreas releases glucagon into the body

Question 16

Homeostasis when blood glucose is low

Answer 16

Low blood sugar 
         |
Detected by Pancreas
        |
Glucagon released by alpha cells in pancreas 
        |
Liver breaks down glucagon & releases glucose into blood stream
       | 
Blood sugar goes back to its set point

Question 17

Homeostasis when blood sugar is too high?

Answer 17

Blood sugar rises above set point
|
Beta cells in pancreas release insulin into blood
|
Liver stores glucagon as glucose & the body cells takes up glucose
|
Blood sugar levels lower back to set point of homeostasis

Question 18

What is a positive feedback loop?

Answer 18

Where the stimulus is increased away from its set point. Requesting more rather than stopping when normal

( e.g- contractions in labour )

Question 19

Example of positive feedback loop in labour

Answer 19

Brain stimulates pituitary glands to secrete oxytocin
|
Oxytocin carried through the blood stream into uterus
|
Oxytocin stimulates uterine contractions and pushes baby towards cervix
|
Head pushes against cervix
|
Neve impulses from the cervix transmitted to brain