cardiovascular anatomy and physiology

Question 1

The cardiovascular system is composed of

Answer 1

blood vessels that transport blood around the body, by the heart

Question 2

the main function of the cardiovascular system is to

Answer 2

transport nutrients such as oxygen, glucose (sugar), fatty acids and water
hormonal control
regulates temperature by controlling heat distribution between core and extremities
acts as a host defence by transporting immune cells all around the body
moves waste cells and waste products from metabolic process such as carbon dioxide, urea, creatine etc

Question 3

The heart

Answer 3

relatively small in size, approximately the size of your fist, sits within the mediastinum, a region in the thoracic cavity that extends from the sternum to the vertebral column and sits between the lungs

2/3 of the heart sits to the left of the body’s midline, it is cone shaped with h pointed apex orientated anteriorly and inferiorly to the left

Question 4

position of the heart

Answer 4

-sits next to the mediastinum within the thorax (chest cavity)
-Surrounded by the lungs
-Apex slightly lower than the base and sits slightly left of the midline
-Superior to the diaphragm

Question 5

The right side of the heart (pulmonary flow)

Answer 5

-Right side of the heart only pumps short distances to the lungs
-The right side of the heart receives deoxygenated blood from the veins and pumps it into the lungs, where the blood picks up oxygen and expels carbon dioxide
-low pressure side of pump
-receives blood returning from the cells of the body and is rich in CO2
-Chronic injury to this side of the heart may rest in fluid build up in the peripheries

Question 6

The left side of the heart (systemic circulation)

Answer 6

-receives oxygenated blood from the lungs
-This side of the heart constitutes the largest amount of heart muscle and pumps blood to the whole body
-Chronic injury to this side of the heart may result in fluid build up in the lungs (can’t lie flat at nighttime)

Question 7

The function of the heart

Answer 7

-to carry blood to and from all the organs of the body and to drive the constant movement of the blood. the arteries bring oxygenated blood to all the cells. the veins retrieve deoxygenated blood so it can be oxygenated once more and waste products can be removed.

-The heart beats approx 30 million times a year, approx. billion times in a lifetime, with each pump approx 75ml of blood fills the heart

Question 8

The pericardium

Answer 8

a fibrous sea that surrounds and protects the heart, keeping it fixed within the mediastinum. But allowing for the vigorous contractions required to move blood around the pulmonary and systemic circulations

Question 9

outer layer of heart is the same as

Answer 9

the inner layer of pericardium

Question 10

heart pumps

Answer 10

4.7 litres of blood per minute

Question 11

layers of heart

Answer 11

1. Epicardium (outer layer), fatty and has a protective membrane, (inner layer of pericardium)
2. Myocardium (middle layer), heart muscle itself, makes up most of the bulk of the heart, responsible for pumping the heart
3. Endocardium (inner layer), smooth layer of inner fat, covers the valves of the heart. continuous, stretchy, elastic, helps blood vessels absorb blood and gaseous exchange,

Question 12

Chambers of the heart

Answer 12

-The heart has 4 chambers
-The superior chambers are called atria and the 2 inferior chambers are called ventricles

1-right atrium 3- left atrium
2 - right ventricle 4- left ventricle

Question 13

The heart weighs approx

Answer 13

300 grams

Question 14

Right atrium

Answer 14

receives deoxygenated blood from the body, via large veins called the superior and inferior vena cava (24mm in diameter) and from the coronary circulation via the coronary sinus

Question 15

Right ventricle

Answer 15

makes up most of the anterior surface of the heart and receives blood from the right atrium vis the tricuspid valve

Question 16

Left atrium

Answer 16

makes up the majority of the base of the heart. Blood enters the atrium from the lungs via 4 pulmonary veins and its through the bicuspid valve

Question 17

Left ventricle

Answer 17

forms the apex of the heart and also contains the chord tendineae and papillary muscle assemble to secure the mitral valve

Question 18

semilunar valves

Answer 18

aortic and pulmonary valves are collectively referred to the semilunar valves

Question 19

The cardiac cycle

Answer 19

during a single cardiac cycle, both the atria and the ventricles take it in turns to contract and relax, forcing blood from an area of high pressure to low pressure due to the contracted muscle

the cycle is short, just 0.8 seconds in a person with an average heart rate of 75 beats per minute

Question 20

0.8 seconds

Answer 20

atrial systole (contraction) 0.1 seconds
ventricular systole (contraction) 0.3 seconds
relaxation period 0.4 seconds

Question 21

4 unique properties of the heart

Answer 21

1. automaticity (each and every cardiac cell has the potential to start its own heart beat)
2. excitability (one one cell gets excited it pushes along to the other ells around it (domino affect))
3. contractibility (atriums and ventricles squeezing together)
4. elasticity (the muscle, organ can stretch to allow for blood flow)

Question 22

Atrial systole (0.1 seconds)

Answer 22

starts with the sinoatrial node (SA node), generating an action potential (electrical impulse), when it depolarises (voltage changes from negative to positive)

this in turn causes the depolarisation of the atrial cardiac muscle cells, which contract (atrial systole). Blood is forced out of the atria through the atrioventricular (AV) valves and into the ventricles topping them up

Question 23

Ventricular systole (0.3 seconds)

Answer 23

during this time the atrial muscle relaxes (atrial diastole). Ventricular depolarisation causes the ventricular muscles to contract and as the pressure inside the ventricles increases, the AV valves close and there is a brief period where all 4 valves of the heart are shut.

Question 24

isovolumetric contraction (0.05 seconds)

Answer 24

a brief period where all 4 valves of the heart are shut

Question 25

relaxation period (0.4 seconds)

Answer 25

Both the atria and the ventricles relax, as the pressure inside the ventricles falls, the semilunar valves close, as with systole there is a brief period when all 4 valves are closed. Th pressure continues to fall, leading to the AV valves reopening and passive filling of the ventricles begins

Question 26

Electrical conduction pathway

Answer 26

A network of specialised autorhythmic (self excitable) muscle cell fibres that trigger co-ordinated muscle contraction

Question 27

Sinoatrial node

Answer 27

the SA node is the main pacemaker of the heart and is typically shown in a small area of tissue at the junction of the superior vena cava with the right atrium

Question 28

The AV node

Answer 28

found in the right atrial wall, close to the opening of the coronary sinus and septal leaflet of the tricuspid valve. It's primary function is to delay the electrical impulse from the SA node long enough for the atria to depolarise, allowing time for atrial muscle contraction to squeeze additional blood into the ventricles

Question 29

The bundle of His

Answer 29

between the AV node and the bundle branches, which originates in the wall of the right atrium and straddles the inter ventricular septum

Question 30

Left bundle branch`

Answer 30

starts at the end of the bundle of His travelling through the interventricular septum, providing fibres that innervate the left ventricle and the left side of the interventricular septum

Question 31

Right bundle branch

Answer 31

originates from the bundle of His and sprouts fibres the innervate the right ventricle and right face of the interventricular septum, stimulating the Purkinje fibres

Question 32

The coronary arteries

Answer 32

the heart requires its own blood supply in order to function properly. There are 2 main arteries that serve the heart, the right and left coronary arteries which originates at the base of the ascending aorta

Question 33

Blood

Answer 33

connective tissue consisting of a liquid (plasma) and cells performing a range of essential functions for the body. Plasma makes up 55% of blood, and carries antibodies and nutrients to the body's tissues and removes waste products The formed elements make up the remaining 45% and consist of red and white blood cells ad platelets

Question 34

Blood groups

Answer 34

A+ or A- B+ or B- O+ or O- AB+ or AB- blood donors give approx 470ml of blood

Question 35

5 main types of blood vessels

Answer 35

Arteries (leave the heart ad subdivide into medium sized muscular arteries which then subdivide further into smaller arteries known as arterioles) Arterioles control the blood flow into the capillaries Capillaries unite to form small veins known as venules, which merge to form Karger and larger veins to return blood to the heart

Question 36

Most blood vessels (except capillaries) consist of 3 layers (tunics)

Answer 36

1. tunica intima (the internal layer), consists of a smooth layer, endothelium, which acts as a basement membrane 2. tunica media (middle layer), made up of smooth muscle and elastic fibres, most prominent in medium sized arteries 3. tunica externa (outer layer), constructed mostly from elastic and collagen fibres but is also home to the main arteries