Cardiovascular System

Question 1

1- Describe the anatomical position of the heart

Answer 1

The heart is located within the thoracic cavity
Medically between the lungs and the mediastinum
It is about the size of a fist
It is broader at the top and tapers towards the bottom
About two thirds of the hearts mass is on the left side of the midline

Question 2

1- identify as many structures as you can that make up the heart

Answer 2

Superior vena cava (blue)
Inferior vena cava (blue)
Pulmonary artery (blue)
Pulmonary vein (red)
Aorta (red)
Left atrium
Right atrium
Left ventricle
Right ventricle
Pulmonary valve
Aortic valve
Tricuspid valve

Question 3

1- what are the three types of vessels that make up the circulatory system?

Answer 3

Veins (blue- take deoxygenated blood from the body back to the heart)
Arteries (red- take oxygenated blood to the rest of the body)
Capillaries (delicate vessels that connect and distribute blood flow throughout the body)

Question 4

1- what is a vein?

Answer 4

Carry deoxygenated blood from the body back into the heart
(Blue)

Question 5

1- what is an artery?

Answer 5

Carry oxygenated blood away from the heart to the rest of the body
(Red)

Question 6

1- what is a capillary?

Answer 6

Tiny blood vessels between arteries and veins that distribute oxygen rich blood around the body

Question 7

1- how many layers does heart muscle have? Name them

Answer 7

3 layers

Pericardium
Myocardium
Endocardium

Question 8

2- briefly describe the structure and function of the pericardium layer of the heart

Answer 8

-Outermost layer of heart muscle
-Made up of two sacs:
Outer sac= fibrous tissue. In elastic and prevents over-distension of the heart
Inner sac= serous membrane. Endothelial cells folded over itself to create double layer
-outer layer= parietal pericardium
-inner layer= visceral pericardium
-about 20ml of fluid lies between these two layers to prevent the heart from rubbing when it beats

Question 9

2- briefly describe the structure and function of the myocardium layer of the heart

Answer 9

Middle most layer of heart

-Specialised cardiac muscle (so is only found in the heart)
-each cell has a nucleus
-involuntary control
-rich in mitochondria for energy
-end-to-end continuity of the fibres so each cell doesn’t need its own nerve supply
Impulses spread cell to cell via branches
-striation allows the whole heart to contract in a coordinated way

Question 10

2- briefly describe the structure and function of the endocardium layer of the heart

Answer 10

Innermost layer of the heart

-thin membrane
-lines the valves and chambers in the heart
-single layer of epithelial cells
-smooth to minimise friction when blood flows over it

Question 11

2- what are cardiac myocytes? Explain how they depolarise

Answer 11

Striated muscle cells!
They are like skeletal muscle, however, they don’t need their own nerve supply to contract. They spontaneously depolarise.

Depolarisation:
Spontaneous
Spreads via intercalated discs
Calcium ions enter
Causes contraction
Rapid due to conduction system

Question 12

2- how are capillaries structured to allow for nutrient and gas exchange within the heart?

Answer 12

Single layer of endothelial cells
Thinness allows gases and nutrients to diffuse through easily

Question 13

3- what is meant by the double pump?

Answer 13

Heart is a single organ, but it acts as a double pump
This means that each half pumps blood around a different circulatory system
Right side- veins (blue) pump deoxygenated blood to the lungs to receive oxygen
Left side- arteries (red) pump oxygen rich blood to the rest of the body

This is why the left side is bigger, it needs to exert more energy to reach all parts of the body, not just the lungs

Question 14

3- how does the heart pump blood around the body?

Answer 14

Blood enters the RA
Pumped into the RV
Blood enters the PA
Blood carried to the lungs to pick up oxygen
Returns to heart through the PV
Blood enters the LA
Pumped into the LV
Pumped through AV into the AORTA
Pumped around the body to deliver oxygen
Returns deoxygenated via the IVC and SVC

Blood then enters the RA and the cycle starts again!

Question 15

3- describe how pressure changes as blood progresses from the arteries around the venous (circulatory) system

Answer 15

RIGHT side- BLUE deoxygenated blood- LOW pressure- EASIER job- SMALLER in size
Only travels short distance from heart to the lungs
Lungs filled with air creating low resistance

LEFT side- RED oxygenated blood- HIGH pressure- HARDER job- LARGER in size
Travels a longer distance to reach all bodily extremities
Meets high resistance from muscles and tissues along the way

Blood travels gradually from high pressure to lower pressure around the body
Capillaries in the extremities will have lower blood pressure than central arteries

Question 16

4- how many valves does the heart have? Name them

Answer 16

Four valves
-tricuspid valve
-aortic valve
-pulmonary valve
-mitral/bicuspid valve

Question 17

4- describe how heart valves work

Answer 17

They prevent back flow of blood
They are flaps that open and close on a one way system
Ensure that blood flows in the right direction and at the right time
As they open and close they make two sounds, this is what we hear as a heartbeat!

Question 18

4- describe the role of skeletal muscles in returning blood to the heart via veins

Answer 18

‘Skeletal muscle pump’
Veins are embedded within muscles,
When the muscles contract then the veins are compressed,
Blood pressure increases,
The one way valves within the veins push blood back towards the heart

Question 19

5- can you locate the major arteries within the venous system of the human body?
(Aorta, subclavian, common carotid, internal and external carotid, axillary, brachial, ulnar, radial, femoral, tibial)

Question 20

6- what is cardiac output/cardiac volume?

Answer 20

The volume of blood pumped out of the heart in one minute (Rate of blood flow)

Question 21

6- give the calculation used to generate cardiac output

Answer 21

Cardiac Volume (CV)= Stroke Volume (SV) x Heart Rate (HR)

Cardiac output/volume = volume of blood pumped out of the ventricles in each contraction x number of beats per minute

Question 22

6- describe the cardiac cycle (systole and diastole)

Answer 22

Rhythm of contraction and relaxation!

Systole= contracting of ventricles
Diastole= relaxing of ventricles

Question 23

6- identify the major pulse points

Answer 23

Temporal artery- temple
Facial artery- under jaw
Carotid artery- collarbone
Femoral artery- groin
Radial artery- wrist
Brachial artery- upper arm
Dorsal artery- toes
Popliteal artery- behind knee
Tibial artery- ankle

Question 24

7- describe the position of the heart (in relation to the lungs, major vessels, diaphragm and oesophagus)

Answer 24

Lungs-
The heart lies medial to both lungs (directly in the middle of the right and left lungs)
The left lung is slightly smaller in order to make room for the larger left side of the heart

Major vessels-
Great veins (IVC and SVC) attach to the superficial layer of the heart. SVC is at the top and IVC is at the bottom
Great arteries (Aorta and Pulmonary trunk) attach to the superficial layer of the heart. Aorta begins at LV and extends upwards into the chest, Pulmonary trunk connects to the RV at the front of the heart

Diaphragm-
The heart is located in the thoracic cavity, above the diaphragm

Oesophagus-
The oesophagus is attached to the pericardium by connective tissue. It lies behind the heart in the posterior mediastinum

Question 25

6- what is a normal pulse? What is it called when the pulse is too slow or too fast?

Answer 25

60-100 beats per minute is a normal pulse rate

Bradycardia- slow
Tachycardia- fast

Question 26

8- name the four chambers of the heart and their jobs

Answer 26

RA- receives deoxygenated blood from lungs, lumps it into the rv
RV- receives deoxygenated blood from the ra and lumps it to the lungs
LA- receives oxygen rich blood from the lungs and pumps it into the lv
LV- recieves oxygen rich blood from the la and pumps it around the body

Question 27

8- where is the septum located in the heart?

Answer 27

Tissue/wall that separates the right side from the left side

Question 28

8- where is the apex and the base of the heart?

Answer 28

Apex- the most inferior part of the heart. It resembles the tip of the cone and sits at the bottom
Base- the most posterior surface of the heart. It resembles the base of a cone and sits at the top

Question 29

8- what are the four heart valves?

Answer 29

Tricuspid valve
Bicuspid/mitral valve
Aortic valve
Pulmonary valve

Question 30

8- where is the chordae tendineae?

Answer 30

Also known as the heart strings!
Placed between the papillary muscles and edges of the tricuspid and bicuspid/mitral valves

Connective tissue that prevents swinging in the heart

Question 31

8- what are the vessels called entering and leaving the heart?

Answer 31

Entering-
Pulmonary vein (red blood enters)
SVC (blue blood enters)

Leaving-
Aorta (red blood leaves)
IVC (blue blood leaves)

Question 32

10- describe the blood flow through the heart

Answer 32

RA
RV
Pulmonary Artery (away from heart, oxygenated blood)
Lungs
Pulmonary Vein (towards the heart, de-oxygenated blood)
LA
LV
Aorta
Body
Return via SVC/IVC

Throughout this process, blood travels through 4 valves:
Tricuspid, Pulmonary, Bicuspid, Aortic

Question 33

11- what happens in one cardiac cycle?

Answer 33

Atria and ventricles alternately contract in one cardiac cycle
Split into two phases: systole (contraction) and diastole (relaxation)… each of these is then split further into two: atrial and ventricular components

The four stages:
1- Atrial systole- both atria contract, blood forced into ventricles
2- Ventricular systole- both ventricles contract, blood forced to lungs via pulmonary trunk and body via the aorta
3- Atrial diastole- atria relax and fill with blood from large veins
4- Ventricular diastole- ventricles relax and fill with blood from the atria

Question 34

11- how does the heart act as a pump?

Answer 34

The heart functions as a double pump
It’s main function is to lump blood around the entire circulatory system

Question 35

11- what is arterial blood pressure? What units do we measure it in?

Answer 35

The pressure that is exerted on arterial walls by blood
It fluctuates with each heartbeat
(Blood pressure is dependent on cardiac output and total peripheral resistance)

Expressed as systolic/diastolic pressure. E.g. 120/80mmHg

It is measured in millimetres if mercury (mmHg)

Question 36

11- describe the concept of peripheral resistance

Answer 36

It describes the fact that arteries can alter their diameter with each heartbeat

In artery walls, smooth muscle cells contract, this results in the artery constricting
Resistance to the flow of blood therefore increases as there is less room for it to squeeze through
Makes pressure on the arterial side of the heart higher

Question 37

12- describe how the heart works as an electrical/conduction system

Answer 37

Rather than the brain firing electrical messages, the heart is relied on to do it itself!
The pump of the heart relies on its electrical conduction

SA node cells within the heart depolarise,
It is this depolarisation that sets the rate of contraction,
Depolarisation spreads through the atria,
Signals reach atrioventricular node,
Stimulates ‘bundle of his’,
Purkinje fibres carry the electrical signals throughout the heart muscle