Coordination Of NS And Endocrine System

Question 1

What is fight or flight?

Answer 1

• dangerous situation detected -> body AUTOMATICALLY triggers response -> aid survival.

Question 2

What detects the stressor?

Answer 2

Hypothalamus.

Question 3

Two components of hypothalamus linked to fight or flight.

Answer 3

• Sympathetic nervous system and CRF.

Question 4

How does the sympathetic nervous system work?

Answer 4

• adrenal medulla secretes stress hormone -> adrenaline and noradrenaline.
• SNS uses nerve impulses io initiate response by effectors.
• Fight or flight response.

Question 5

How does CRF work?

Answer 5

• Pituitary gland releases “acth” adrenocorticotropic hormone
• which stimulates adrenal cortex secretes stress hormones -> cortisols.
• Stress hormones travel in blood stream to target organ.
• Fight or flight response.

Question 6

Cortical regulate carbohydrate metabolism and promote glucose release from glycogen. What are the uses for this?

Answer 6

• Increase cell glucose conc = which inc cell resp rate = more ATP made per sec = more energy for muscle contraction to run away/ face danger.

Question 7

What survival value do these physiological changes have?
- Pupils value
- incr HR and BP
- arterioles to digestive system constricted, vasodilation to muscles + liver
- Increased blood glucose levels

Answer 7

• more light enters eye -> see better -> retina inc sensitive
• increase rate of blood flow -> increase O2 + glucose to muscles and CO2 and toxins taken away
• blood flow away from digestive system and to muscles
• increase energy via ATP for muscles

Question 8

How does adrenaline work?

Answer 8

• requires second messenger system
• protein hormone -> cannot diffuse across cell membrane
• attaches to external receptor = triggers 2nd messenger response inside - triggers activation of adenylyl cyclase :
  Converts ATP -> cAMP -> activates other enzymes to convert glycogen -> glucose.

Question 9

What is the cascade effect?

Answer 9

1 adrenaline molecules can cause many cAMP molecules to form.

Question 10

What is the HR controlled by?

Answer 10

Controlled by cardiovascular centre in medulla oblongata.

Question 11

What happens when HR increases?

Answer 11

• sends more frequent NI along sympathetic nerve to SAN in heart = this increases frequency of waves of electrical excitation across atrial walls.

Question 12

Decrease in HR.

Answer 12

Sends more frequent NI along parasympathetic nerve to SAN in heart = decreases frequency of waves of electrical excitation across across atrial walls.

Question 13

What do chemoreceptors do and where are they located?

Answer 13

• detect changes in chemical levels in blood, e.g. CO2
• located in aorta and carotid arteries and medulla.

Question 14

How does this work?

Answer 14

1- sensitive to blood pH changes.
2- increased activity = increases cell resp rate = which increases CO2 release.
3- CO2 dissolves in plasma (H20) to make H2CO3, which releases H+, decreases blood pH.
4- Chemoreceptors detect change -> send NI to medulla oblongata.
5- Which sends more frequent NI along sympathetic nerve to SAN in heart.
6- Which sends more frequent electrical impulses across atria.
7- Increases HR.

Question 15

What does baroreceptors do and where is it located?

Answer 15

• Detect changes in BP.
• In aorta, vena cava, carotid arteries

Question 16

How does it work?

Answer 16

1- If increase BP detected.
2- N.I sent to medulla oblongata.
3- Which sends more frequent NI along parasympathetic nerve to SAN.
4- Which sends out less frequent impulses across atrial walls.
5- decrease HR and BP = back to normal.

Question 17

What hormone regulates HR?

Answer 17

Stress= adrenal medulla releases noradrenaline into blood = directly affects heart cells in SAN = increases electrical excitations per sec = increases HR.