Cardiovascular system

Question 1

Heart=

Answer 1

• Pumps blood around the body
• Located in the mediastinum, behind the sternum angled slightly to the left.
• Surrounded by the pericardium

Question 1

What does the cardiovascular system include?

Answer 1

Heart & blood vessels

Question 2

Blood vessels=

Answer 2

• Transports blood, which carries nutrients, gases, waste products, hormones and immune cells.

Question 3

What is the pulmonary circuit?

Answer 3

• Carries deoxygenated blood from the heart to the lungs and returns oxygenated blood back to the heart.
  Requires low pressure

Question 4

What is the systemic circuit?

Answer 4

• Circulates oxygenated blood from the heart to the entire body and returns deoxygenated blood to the heart.
  Requires higher pressured

Question 5

What is the pericardium?

Answer 5

• The heart is surrounded by the pericardium
• Consists of parietal (outer) layer and visceral (inner) layer

Question 6

What are the functions of the pericardium?

Answer 6

1. Protect the heart
2. Anchor the heart in position
3. Prevent overfilling of heart with blood
4. Fluid within pericardial cavity provides a ‘friction-free’ environment.

Question 7

What is the pulmonary trunk?

Answer 7

• Major artery that carries deoxygenated blood from right ventricle to the lungs for oxygenation. It is in the pericardial sac

Question 8

What are the three layers of the heart?

Answer 8

1. Epicardium- on outer layer, visceral pericardium, and supports blood vessels and nerves
2. Myocardium- is the middle layer, made of cardiac muscle
3. Endocardium- is the inner layer, made up of squamous epithelium

Question 9

What are the chambers and sets of valves in the heart?

Answer 9

There are four chambers and two sets of valves:
- 2x atria & 2x ventricles
- 2x atrioventricular valves & 2x semilunar valves

Question 10

What is the heart separated by?

Answer 10

• Interventricular septum

Question 11

Explain the right ventricle vs left ventricle

Answer 11

• Right ventricle pumps blood to lungs
• Left ventricle pumps blood to the body

Question 12

What are valves?

Answer 12

• Prevent backflow of blood- ensure unidirectional blood flow.
• They open and close in response to pressure changes.

Question 13

What are atrioventricular valves?

Answer 13

• Involve bicuspid and tricuspid valves.
• Located between atria and ventricles

Question 14

What are semilunar valves?

Answer 14

• Involve pulmonary and aortic semilunar valves
• Located between ventricles and arteries leaving the heart

Question 15

What are the different heart sounds?

Answer 15

• Lub (S1)= closure of AV valves
• Dub (S2)= closure of SL valves

Question 16

What are the two main blood vessels?

Answer 16

• Arteries= carry blood away from heart
• Veins= carry blood towards the heart
• Arteries & veins have three layers (tunica’s) to their wall.

Question 17

Name the different types of tunica’s?

Answer 17

1. Tunica externa= outer layer, connective tissue rich in collagen
2. Tunica media= middle layer, made of smooth muscle and elastic fibres. More tunica media allows blood flow to be controlled.
3. Tunica intima= inner layer, made of simple squamous epithelia

Question 18

What are the different types of arteries?

Answer 18

• Elastic= thick walled (e.g., the aorta and branches), large amounts of elastic tissue, allows for expansion and contraction causing smooth blood flow.
• Muscular= smaller, branch from elastic arteries, distribute blood to parts of the body.
• Arterioles= made of smooth muscle, surrounds endothelium, held together by outer layer of collagen fibres.

Question 19

Describe smooth muscle

Answer 19

• Allows for regulation of blood flow to the capillaries.
• When smooth muscle is contracted, lumen of blood vessel is smaller so less blood can flow= vasoconstriction.
• When smooth muscle is relaxed, lumen of blood vessel is larger so more blood can flow= vasodilation.

Question 20

What are the different types of veins?

Answer 20

• Capillaries= smallest of blood vessels, thin walled often just tunica intima, are sites of exchange, blood flow is much slower to allow exchange to take place, capillaries create a large surface area.
• Venules & veins= venules are formed by capillaries joining together, veins are formed by venules joining together. The blood pressure in veins is much smaller than in arteries, the tunica’s of veins are much thinner.

Question 21

Explain the return of blood flow to the heart

Answer 21

1. Superior vena cava
2. Right atrium
3. Tricuspid valve
4. Right ventricle
5. Pulmonary semi lunar valve
6. Pulmonary artery
7. Lungs for oxygenation
8. Blood returns to heart through pulmonary veins
9. Left atrium
10. Bicuspid valve
11. Left ventricle
12. Aortic valve
13. Aorta
14. Body

Question 22

Pulse=

Answer 22

• The pressure wave felt in an artery that lies close the surface of the body. The pressure wave is a result of the left ventricles contracting.
• You can count the heart rate by counting the pulse rate
• Examples of pulses: superficial temporal artery, radial artery, temporal artery

Question 23

How does the heart get nourishment?

Answer 23

• Through coronary arteries, left coronary artery and right coronary artery, so through coronary circulation. These are located in the epicardium and branch inwards to supply the myocardium.
• The left coronary artery divides into two branches: anterior interventricular and circumflex artery.
  The right coronary artery divides into two branches: right marginal artery, posterior inter ventricular artery.
• Through coronary veins: Venus blood is collected by the cardiac veins, these veins join to form the coronary sinus which empties blood into the right atrium.

Question 24

Blood pressure=

Answer 24

- Pressure exerted by the blood on the wall of a blood vessel, expressed in mmHg - Blood pressure is measures with a sphygmomanometer and is important to maintain normal body function.

Question 25

Systolic pressure=

Answer 25

- The highest pressure and is measured when left ventricle is contracting and expelling blood into the aorta

Question 26

Diastolic pressure=

Answer 26

- The lowest pressure and is measures when left ventricle is relaxing and blood is flowing into peripheral blood vessels.

Question 27

Pulse pressure=

Answer 27

- Difference between systolic and diastolic blood pressure and can be felt at the arteries. e.g., if blood pressure is 120(SBP)/ 80(DBP)mmHg, pulse pressure is= 120-80= 40mmHg

Question 28

Mean arterial pressure=

Answer 28

- Pressure that propels blood through the tissues. it is equivalent to the DBP + one third of PP.

Question 29

What determines blood pressure?

Answer 29

1. Cardiac output 2. Peripheral resistance 3. Blood volume 4. Blood viscosity

Question 30

How is blood pressure controlled?

Answer 30

- By blood pressure receptors called baroreceptors

Question 31

Explain a homeostatic system for low BP=

Answer 31

1. Stimulus= low Bp 2. Receptor= baroreceptors are inhibited 3. Control centre= baroreceptors stimulate cardioacceletory centre 4. Effector= Increased heart rate, increased contractility, increased cardiac output. Vasoconstriction happens. 5. Response= blood flow returns to homeostatic range (same for high Bp but a decrease and vasodilation)

Question 32

What is Marey’s law?

Answer 32

- There is an inverse relationship between Bp and Hr. If Bp is too high, Hr will decrease to compensate.

Question 33

Franks sterling law of the heart=

Answer 33

- The force of ventricular contraction is determined by length of cardiac muscle fibres

Question 34

Stroke volume=

Answer 34

- Amount of blood ejected from ventricle during one contraction. SV= EDV (end diastolic volume) - ESV (end systolic volume)

Question 35

What is preload and afterload?

Answer 35

- Preload is the degree to which ventricular muscle is stretched before contracting. - Afterload is the pressure the ventricles must overcome to push blood through semilunar valves as the ventricles are contracting.

Question 36

What is the Bainbridge reflex?

Answer 36

occurs when the heart rate increases in response to a rise in atrial pressure, e.g., during exercise. This happens to clear the extra blood from the increased atrial filling.

Question 37

Proprioceptors vs Chemoreceptors=

Answer 37

Proprioceptors= detects increased muscle activity. Chemoreceptors= detect increase in acidity, heart transfer and respiratory rate.