6a. Heart and blood vessels

Question 1

What is the jounrney of blood through the heart

Answer 1

Vena Cava - Right atrium - AV Valve - Right ventricle - SL Valve - Pulmonary artery - Pulmonary vein - Left atrium - AV Valve - Left ventricle - SL Valve - Aorta

Question 2

What are the different types of circulation in a mammal

Answer 2

-Pulmonary circulation - deoxygenated blood from body to the lungs
-Systematic circulation - oxygenated blood to rest of the body

Question 3

Why is it an advanatge to have two seperate pumps

Answer 3

RHS generates pressure to send blood through the lungs where pressure drops
LHS generates more pressure so the blood can travel around body at a fast enough rate

Question 4

what is the function of the atrioventricular and semilunar valves

Answer 4

Prevent backflow of blood
AV Valves prevent backflow from V to A
SL Valves prevent backflow from arteries to ventricles

Question 5

What is a cardiac cycle

Answer 5

One complete sequence of contraction and relaxation

Question 6

What is atrial systole

Answer 6

The contraction of the atria

Question 7

What is ventricular systole

Answer 7

Contraction of the ventricular muscles

Question 8

What is diastole

Answer 8

Relaxation of the heart muscle

Question 9

How does blood flow

Answer 9

From regions of high to regions of low pressure

Question 10

What happens during diastole

Answer 10

Heart relaxes
Artia fill with blood from the vena cava and pulmonary veins
SL Valves are closed
AV valves close until pressure in atria is too high and forces the valves open

Question 11

What happens during atrial systole

Answer 11

Blood fills atria from vena cava and pulmonary veins
Artial muscle contracts, increases pressure in atria over the ventricals
AV Valves forced open and blood flows into the ventricles

Question 12

What happens during ventricular systole

Answer 12

Ventricular muscles contract
Volume of ventricles increases, decreases pressure
AV Valves close
Blood pushed upwards, towards arteries
SL Valves open, blood flows into aorta and pulmonary artery

Question 13

How does the heart muscle contract

Answer 13

Cardiac muscle is myogenic
Contractions arise from within the cardiac muscle
Sinoatrial node (SAN) is a group of cell within the wall of the right atrium
SAN originates the initial stimulus for contraction

Question 14

What is the sequence of events that controls the cardiac cycle

Answer 14

SA Node sends an impulse spreading across both atria causing them to contract
Impluses then reach the AV Node where it is delayed
Delay allows the atria to fully empty and the ventricles to fill with blood
Impulses then sent down to the ventricles by the bundle of His - contains specialised conducting tissue - Purkyne fibres
Impulse spread up the ventricle wall from the base via Purkyne fibres causing ventricles to contract from the base up
Blood forced up into the arteries

Question 15

What is the stroke volume

Answer 15

The volume of blood pumped out from one ventricle during each contraction.

Question 16

What is the cardiac output

Answer 16

the total volume pumped out from one ventricle per minute

Question 17

How do you calculate cardiac output

Answer 17

CO (dm3min-1) = Stroke volume (cm3) x Heart rate (bpm)

Question 18

What happens to the cardiac output with the effect of excerise

Answer 18

During exercise heart rate, stroke volume and cardiac output increase from the resting values
An athlete’s heart will get bigger over time so resting stroke volume will be bigger.
This means their resting pulse rate will drop.
This gives them more capacity to increase their cardiac output during exercise

Question 19

How does cardiac ouput relate to the muscles

Answer 19

more glucose and oxygen to be delivered to the working muscles.

Question 20

What is mass flow

Answer 20

The bulk movment of substances from one area to another due to differences in pressure

Question 21

Why are the types of blood vessels in mammals

Answer 21

-Arteries - carry blood away from heart, Branch into arterioles
- Capillaries - Branch from arterioles
-Veins - carry blood towards the heart

Question 22

What are arteries and veins an example of

Answer 22

Organs as they are a collection of different tissures working together to achieve a particular function

Question 23

What are some characteristics of arteries

Answer 23

Carry blood at high pressure
Thick walls to withstand the high pressure
Lumen is relatively small
Walls have an inner coat of a single endothelium layer
Walls have lots of elastic tissues
During diastole, elastic recoils when pressure falls to keep the blood under pressure and pushes it along
Smooth walls to stop pressure fluctuations

Question 24

What are characteristics of aterioles

Answer 24

Control blood flow to the capillaries
Walls have lots of muscle tissue
Walls are thinner then arteries
Walls have a single layer endothelium coat
Muscles can contract to narrow lumen and reduce blood flow (Vasoconstriction)
Muscles can relax to widen lumen and increase blood flow (Vasodilation)
During exercise - vasodiliation to muscles. Vasoconstriction to the gut.

Question 25

What are characteristics of the veins

Answer 25

Fewer elastic tissues as low blood pressure
Walls are very thin
Walls have SL valves
Many veins run close to leg muscles which temporarily raises the pressure when muscles contract

Question 26

What are characteristics of the capillaries

Answer 26

Rate of blood flow is reduced- allows more times for diffusion
Walls made form a single squamous endothelial cell - short diffusion pathway
Small pores in wall - Highly permeable - Many substances can be forced out forming tissue fluid
Small size but large quantity provides a large SA:vol

Question 27

What happens in CHD

Answer 27

• Layers of fatty material (atheroma) build up inside coronary arteries
  -This narrows and reduced blood flow resulting in lack of oxygen for the heart muscles
  -It will build over time and can lead to thrombosis (blood clot)
• Clot can block coronary artery causing a myocardial infarction, some heart tissues could be damaged and may die

Question 28

What is a risk factor

Answer 28

Any factor that increases the probability of developing a disease. They are in correlation with disease but may not be causation

Question 29

What are unavoidable risk factors for CHD

Answer 29

-Inheritance / genetics - history og heart disease, high BP , or high cholesterol can lead to an early CHD
-Gender - Males are more likley to suffer from heart attacks. Oestogen protects females
-Increasing age - Blood vessels tend to lose their elasticity and become narrower

Question 30

What are the avoidable risk factors of CHD

Answer 30

-Smoking
-Diet
-High BP

Question 31

How can smoking lead to CHD

Answer 31

Nicotine increases heart rate and acts as a vasoconstrictor, increasing BP
Can lead to atheroma and thrombosis

Question 32

How can diet lead to CHD

Answer 32

-High blood cholesterol. Eating lots of saturated fats or cholesterol leads to elevated levels of LDL Cholesterol in the blood and can lead to atheroma
Eating less can reduce LDL levels and increase LDH levels
- Statins. Keep open narrow arteries .Reduce blood cholesterol which slows down rate of fatty deposits
-High levels of salt. Raise BP

Question 33

How does high blood pressure lead to CHD

Answer 33

Prolonged stress, certain diets and lack of excerices leads to high BP
The higher the BP the greater risk of damage to the artery
Starting atheroma formation
High BP increase risk of thrombosis