Control Of Heart Rate

Question 1

Sympathetic system
Where does it start? And as what?
What happens when the myelinated axon leaves the spinal cord?
In what and to what does the nonmyelinated axon travel?
What is the first transmitter?
What is the second transmitter?
What is the system described as?

Answer 1

In spinal cord as a synapse with a sensory or intermediate neurone
Synapses with second neurone in sympathetic ganglion just outside spinal cord
Spinal nerve to organ being innervated
Acetylcholine
Neurodrenaline
Adrenergic

Question 2

Parasympathetic 
 Where does it start?
 What's an example of a cranial nerve?
 The synapse travels down this to what?
 What does it then synapse in?
 What does the non-myelinated axon leave to travel to?
 What is the first transmitter?
 What is the second transmitter?
 What is this system described as?

Answer 2

Base of brain
Cranial nerve (vagus nerve) to organ being innervated 
Parasympathetic ganglion
Regions of the effector 
Acetylcholine
Acetylcholine 
Chlonergic

Question 3

Action of autonomic system
What does it mean that the parasympathetic and sympathetic work antagonistically?
What Re the effects of adrenaline?(3)
What is the parasympathetic mainly involved in?(3)

Answer 3

One stimulates the other
Fear,shock,stress
Secreting,gut movement,emptying

Question 4

Control of heart rate
What is typical resting heart rate for adults?
Why is it altered?

Answer 4

70bpm

To meet changing demand of body for O2

Question 5

Medulla oblangata
 What does it control?
 Which nervous system linking centre to SAN
       Increases 
       Decreases 
 heart rate?

Answer 5

Heart rate
Sympathetic nervous system
Parasympathetic nervous system

Question 6

Control by chemoreceptors 
 What are they sensitive to?
 Where are they found? What is this?
 What does increased CO2 do to ph?
 Sequence of control by chemoreceptors (11)

Answer 6

Change in ph
Carotid arteries-main artery that goes to brain
Lowers

CO2 lowers pH
Chemoreceptors in carotid arteries and aorta detect change
Increase frequency of nerve impulses to centre in medulla oblangata
Increases impulses via sns to SAN
Increases heart rate
Increased blood flow means more CO2 removed from blood at lungs
CO2 levels return to normal
pH of the blood rises to normal
Chemoreceptors in wall of carotid arteries and aorta reduce frequency of impulses to medulla oblangata
Medob Reduces frequency of impulses to SAN
Heart rate decreases to normal

Question 7

Control by baroreceptors
Where are they found?
What do they have that makes them sensitive to vol/pressure?
What receptors send impulses along to?
What does this act as?
What does this lead to?
This slows heart rate,what this an example of?
The parasympathetic acts to restrain the heart,what’s this known as?
What happens if pressure falls?

Answer 7

Carotid and aortic bodies
Stretch receptors
Sensory nerve to cardiac centre
Coordinator
Increase in parasympathetic activity in vagus nerve supplying SAN and decrease in sympathetic
Vagus restraint
Cardiac centre increase sympathetic activity

Question 8

Adrenaline 
   What does it increase?
   What is it released by?
   What is it stimulated by?
   What is fight or flight?
   What does adrenaline cause?

Answer 8

Heart rate 
Adrenal gland 
Sympathetic nervous system 
Getting ready for exercise 
Increases strengths and speed of heart contraction

Question 9

Explain how the SAN control heart thingy

Answer 9

Cardiac muscle is myogenic
SAN sends wave of depolarisation across atria
AVN delays impulse allowing ventricles to fill
Relays impulse across ventricles
Impulse travels down bundle of His and up ventricular walls via purkyne fibres causing ventricular systole

Question 10

Autonomic nervous system
What is it concerned with?
What does it act mainly on?
What is it not concerned with?

Answer 10

Homeostasis
Smooth (involuntary) muscle,cardiac muscle, certain glands
Skeletal muscle