PHTY142 Heart

Question 1

shape, position, size of the heart

Answer 1

Size of the closed fist

Heart rests on the diaphragm

In the mediastinum and 2 thirds lies to left of midline

Shaped like an inverted cone

Question 2

What is the mediastinum

Answer 2

an anatomical region that extends from the sternum to the vertebral column.

From the first rib to the diaphragm.

Between the lungs

Question 3

base of the heart

Answer 3

Formed by the atria, mostly the left atrium

Question 4

Apex of the heart

Answer 4

tip of the left ventricle and rests on the diaphragm

Question 5

Describe the right atrium

Answer 5

receives blood from superior and inferior Vena Cava, Coronary Sinus

2-3mm in thickness

Tricuspid Valve

Question 6

Describe the right ventricle

Answer 6

4-5mm thickness

cusps of tricuspid valve are connected to Chordae Tendineae

Pulmonary semilunar valve into pulmonary trunk

Question 7

What separates the Right and Left Atrium

Answer 7

interatrial septum

Question 8

What separates’ the Right and Left Ventricles

Answer 8

Interventricular Septum

Question 9

Describe the Left Atrium

Answer 9

2-3 mm thick

Forms most of the base of the heart

Blood from pulmonary veins

Bicuspid valve

Question 10

What is the bicuspid valve also known as

Answer 10

Mitral valve

Question 11

Describe the left ventricle

Answer 11

thickest chamber of the heart

chordae tendineae to papillary muscles

aortic semilunar valve into aorta

Question 12

Pathway of blood from the left ventricle

Answer 12

Through aortic valve
into aorta

Some to coronary arteries which branch from ascending aorta

The rest goes to arch of aorta and descending aorta to be carried to rest of the body

Question 13

What is the pericardium

Answer 13

Membrane that surrounds and protects the heart.

It consists of 2 main parts the Fibrous Pericardium and the serous pericardium

Question 14

What is the role of the pericardium

Answer 14

Confines the heart in the mediastinum

Allows for movement for vigorous, rapid contraction

Question 15

The Fibrous Pericardium

Answer 15

Tough, inelastic, dense, irregular connective tissue

Rests and attaches to diaphragm

Prevents overstretching of the heart

Anchors heart to mediastinum

movement of diaphragm facilitates movement of the heart

Question 16

Serous Pericardium

Answer 16

Deeper layer

thinner, more delicate that forms a double layer
around the heart

Outer parietal layer - fused to fibrous pericardium

Inner visceral layer - has pericardial cavity with lubricating serous fluid which reduces friction between the layers as the heart moves

Question 17

name 3 layers of the heart

Answer 17

epicardium
Myocardium
endocardium

Question 18

Endocardium

Answer 18

Thin layer of endothelium

Provides smooth lining for chambers

minimises surface friction as blood passes through the heart

Question 19

Epicardium

Answer 19

outer layer is the Visceral layer of the serous pericardium

Beneath mesothelium is a variable layer of delicate fibroelastic tissue and adipose tissue

Contains blood vessels and lymphatics that supply the heart

Question 20

Myocardium

Answer 20

Pumping action of the heart

Cardiac muscle tissue. Muscle fibres are wrapped and bundles with connective tissue sheaths

Fibres organised in swirls moving diagonally

Question 21

What is the fibrous skeleton of the heart

Answer 21

4 dense connective tissue rings that surround the valves of the heart and merge with interventricular septum

Prevents overstretching of the valves

A point of insertion for bundles of cardiac muscle

Acts as electrical insulator between atria and ventricles

Question 22

Atrioventricular valves

Answer 22

When they open the ends of cusps project into ventricles

When ventricles are relaxed the paillary muscles are relaxed and chordae tendineae are slack

When ventricles contract pressure drives cusps upwards and close the valve. Papillary muscles contract and chordae tendineae tighten preventing evertion

Question 23

Semilunar Valves

Answer 23

3 crescent moon shaped cusps each attaching to a arterial wall

When ventricles contract pressure increases higher than in valves so valves open

As ventricles relax blood starts to flow back tot he heart and fill cusps acusing them to contract and close the opening

Question 24

How are the AV valves and SL valves similar

Answer 24

Both prevent backflow

both facilitate unidirectional blood flow

open and close at the right time

Question 25

Differences between AV valves and SL valves

Answer 25

Different locations Names different Av Valves allow blood flow from atria to ventricles and prevent backflow during systole SL valves pump blood outward and prevent backflow from form arteries to ventricles

Question 26

Function of coronary arteries

Answer 26

supply blood to myocardium Left and right deliver to heart Aortic sinuses are found in aorta. when the heart is relaxed backflow fills the valve pockets allowing blood to enter coronary arteries

Question 27

Right coronary artery

Answer 27

Supplies right atrium and right ventricle

Question 28

Right marginal artery

Answer 28

right ventricle and apex

Question 29

posterior interventricular artery

Answer 29

right and left ventricles Interventricular septum

Question 30

Left circumflex artery

Answer 30

left atrium and left ventricle

Question 31

left marginal artery

Answer 31

left ventricle

Question 32

left anterior descending artery

Answer 32

right ventricle left ventricle and interventricular septum

Question 33

what are Autorhythmic fibres

Answer 33

Cardiac muscle fibres Self excitable repeatedly generate action potentials

Question 34

Conducting system of heart

Answer 34

SAN - right atrium wall Right and left atria contract at the same time AVN passes information to bundle of His but there is a slight delay Bundle of His splits into purkinje fibres so left and right ventricles simultaneously contract

Question 35

What does ECG stand for

Answer 35

Electrocardiogram A recording of action potentials at the heart

Question 36

Describe an ECG

Answer 36

P wave - upward deflection representing atrial depolarisation form SA node QRS complex - upright triangular wave representing rapid ventricular depolarisation T Wave - Dome shaped and upwards representing ventricular repolarisation occurring just as ventricles start to relax

Question 37

Systole

Answer 37

period of contraction where blood is pumped into circulation

Question 38

diastole

Answer 38

Period of relaxation when chambers fill with blood

Question 38

Outline cardiac cycle

Answer 38

Passive filling - both relaxed but AV open Atrial systole Ventricular isovolumetric contraction Ventricular systole relaxation period

Question 39

Atrial Systole

Answer 39

atria contract, ventricles relaxed Depolarisation at SA Node so pressure increases as blood volume increases AV valves open and blood forced into ventricles ventricles contain 130 ml of blood at end diastolic volume

Question 40

Ventricular systole

Answer 40

Ventricles contract and pressure against AV valves For about 0.5 seconds both AV and SL valves are closed - isovolumetric period - isometric contraction When ventricular pressure is higher than aortic pressure SL valve opens and ejection begins

Question 41

Relaxation in cardiac cycle

Answer 41

Both atria and ventricles are relaxed Ventricular repolarisation causes ventricular diastole As pressure decreases blood starts to move back and enters cusps so SL valves close There is a brief period where all 4 valves are closed Blood enters atria, so by end of relaxation period ventricles are 3/4 full - passive filling

Question 42

Cardiac output

Answer 42

Volume of blood ejected from the left ventricle into the aorta each minute CO= SV X HR In adults 5.25 litres/minute = 75 X 70