The Heart

Question 1

What is the function of the cardiovascular system?

Answer 1

• Pump and delivery system
• Pumps the blood around the body which:
  1. delivers substances essential to cells for body homeostasis
  2. removes waste products from cells to designated areas
  3. functions as part of the immune system

Question 2

What is the cardiovascular system?

Answer 2

A closed system containing the heart and blood vessels

Question 3

What is the definition of the heart?

Answer 3

A muscular organ that contracts and relaxes

• Contractions push blood around the body
• Relaxation helps the blood return to the heart

Question 4

What is the position of the heart?

Answer 4

• In the thoracic cavity (pericardial cavity)
• Between the lungs- mediastinum
• Size of your fist
• Set obliquely (apex pointed to left hip, broad flat base pointed to right shoulder)

Question 5

What are the three layers of the heart wall ?

Answer 5

Pericardium is the outermost layer
Myocardium is the muscle layer
Endocardium is the smooth innermost lining

Question 6

What is the structure of the pericardium ?

Answer 6

• Double walled sac enclosing the heart
• Fibrous pericardium (outmost layer)
• Serous pericardium (parietal cavity and visceral cavity)

FIBROUS-PARIETAL-PERICARDIAL CAVITY-VISCERAL

Question 7

What is the structure of the myocardium ?

Answer 7

• Specialised muscle found only in the heart
• Contains mitochondria
• Striated and branching
• Ends joined to enable cells to contract as a unit

Question 8

What is the structure of the endocardium ?

Answer 8

• Very smooth inner layer
• Attached to the myocardium
• Lines the heart chambers and valves
• Enables friction free flow

Question 9

What are the 4 chambers of the heart?

Answer 9

Right atrium
Right ventricle
Left atrium
Left ventricle

Question 10

Why is the left side of the heart thicker?

Answer 10

Because it needs more force to pump blood around the entire body

Question 11

What is the structure of the atria?

Answer 11

Receive blood
Thin walled- not much muscle
Blood pumped into ventricles

Question 12

What is the structure of the ventricles?

Answer 12

Discharge blood
Thick walled- more muscle
Right side less muscular than left- blood only to lungs
Left side most muscle- blood to whole body

Question 13

What are the order of the heart valves?

Answer 13

(RIGHT)
Tricuspid
Pulmonary

(LEFT)
Mitral
Aortic

Toilet Paper My Ass

Question 14

What creates the ‘lub’ ‘dub’ sounds?

Answer 14

• ‘Lub’ (tricuspid and mitral valve closing)- atrioventricular
• ‘Dub’ (pulmonary and aortic valve closing)- semilunar

Question 15

What causes valves to open?

Answer 15

An increase in pressure

Question 16

What are the blood vessels to the heart?

Answer 16

Inferior and superior vena cava

4 pulmonary veins

Question 17

Which vessel carries blood away from the heart?

Answer 17

Aorta

Pulmonary artery

Question 18

What is the blood flow through the right side of the heart?

Answer 18

From the body via
Superior Vena Cava and Inferior Vena Cava INTO
Right Atrium THROUGH
Tricuspid Valve INTO
Right Ventricle THROUGH
Pulmonary Valve INTO
Pulmonary Artery to Lungs

Question 19

What is the blood flow through the left side of the heart?

Answer 19

From lungs via
4 Pulmonary Veins INTO
Left Atrium THROUGH
Mitral Valve INTO
Left Ventricle THROUGH
Aortic Valve INTO
Aorta to Body

Question 20

Describe coronary blood flow

Answer 20

Coronary arteries from the aorta carry oxygenated blood. Deoxygenated blood returned via a coronary sinus to the right atrium

Question 21

Outline the heart conduction system

Answer 21

Sinoatrial node sends a wave of excitation across the atria to the AV node, causing them to contract. Upon reaching the AV node, the signal is delayed in order to allow the atria to finish contracting before the ventricles. The atrioventricular node carries the impulse down the bundle of HIS through the left and right bundle branches. When it reaches the apex, it penetrates the purkinji fibres, causing the ventricles to contract from the apex across the walls of both ventricles.

Question 22

Describe what happens in heart conduction (ECG)

Answer 22

P wave- wave of electrical activity (depolarisation) as it passes across the atria from the SA node (‘lub’ sound)
QRS Complex- wave of depolarisation as it passes down the ventricular septum and across the walls of the ventricles (‘dub’ sound)
T Wave- repolarisation of ventricle
ECGs show whether the electrical impulses of the heart are firing correctly

Question 23

Explain the cardiac cycle

Answer 23

Refers to one complete heartbeat
Blood flows into the atria and a response to an electrical stimulus causes the atria to contract. There is then a short pause (PR interval). Blood flows into the ventricles through the AV valves. Response to an electrical stimulus causes ventricles to contract, pushing blood through the aortic and pulmonary valves to the pulmonary and systemic circulation. Heart fully relaxes.
Atrial and ventricular contraction known as systole, relaxation known as diastole.

Question 24

What is blood pressure?

Answer 24

The measurement of systole and diastole

Question 25

Describe what causes heart rate

Answer 25

Sinoatrial node (pacemaker) sets the heart rate (HR)
(HR) is the number of heart beats per minute (bpm)
Each ventricular contraction results in a pulse
A pulse can be felt peripherally at certain point
A pulse tells us the heart rate, strength of the contraction and regularity

Question 26

What is the formula for cardiac output

Answer 26

CO= The amount of blood ejected from each ventricle per minute (SV) multiplied by the heart rate (HR)

Average SV in an adult is 70mls