The Heart

Question 1

How does the sympathetic nervous system (fight or flight response) contribute to heart contraction?

Answer 1

It increases rate and strength of contraction

Causing vasoconstriction (high blood pressure)

Question 2

How does the parasympathetic nervous system (rest and digest) contribute to heart contraction?

Answer 2

Decreases rate and strength of contraction (via vagus nerve)

Little influence on blood vessels

Question 3

What influences heart rate and strength?

Answer 3

Hormones (hypothyroidism)
Age
Gender
Body position
Exercise
Stress
Temperature 🤒

Question 4

Name, in order, the components of the hearts conductive system?

Answer 4

1. Sinoatrial node (sa node). Pacemaker of the heart. Responsible for rate and rhythm. Located in right atrial wall. Action potential via intercalated discs
2. Atrioventricular node (av node)
   Relay station. Slower rate. Located bottom right of interatrial septum.
3. Atrioventricular bundle/bundle of his.
   Action potential conduct from atria to ventricles
4. Right and left branches. Towards apex of heart
5. Purkinje fibres. Causes ventricular contraction

Question 5

In an electrocardiography what does the P wave, QRS wave & T wave represent?

Answer 5

P wave - atrial depolarisation (from sa node)

QRS wave - rapid ventricular depolarisation

T wave - ventricular repolarisation

Question 6

What is meant by systole and diastole?

Tachycardia and bradycardia?

Answer 6

Systole = contraction
Diastole = relaxation (when heart fills with blood)

Tachycardia resting heart rate greater than 100 bpm

Bradycardia resting heart rate less than 60 bpm

Question 7

What are the functions of cholesterol?

Answer 7

Needed for cell membrane

Hormones and vitamin D

Question 8

From which two sources do you get cholesterol?

Answer 8

Liver cells (hepatocytes)
Diet

Question 9

What is the difference between low density lipoproteins (LDL) and high density lipoproteins (HDL)?

Answer 9

LDL is bad cholesterol
LDL carries cholesterol from liver to cells of body
Excess can deposit in arteries

HDL is good cholesterol
HDL removed excess cholesterol from body cells and blood and transports it to liver.
Prevents accumulation of cholesterol in blood.