Blood And The Heart

Question 1

Superior vena cava

Answer 1

Deoxygenated blood enters the heart from the body through the veins cava leading towards the right atrium
Atria are lined with thin muscular walls

Question 2

Explain for blood plasma leaves the capillaries

Answer 2

At the atrial end pressure is higher
The hydrostatic pressure is higher than oncotic pressure
Capillary walls have holes therefore plasma dissolved stubstances are forced out
Red blood cells and plasma proteins are too big to get out

Question 3

Explain why tissue fluid drains pack into the capillaries

Answer 3

Pressure is lower at the Venus end
The oncotic pressure is how higher than the hydrostatic pressure so the tissue fluid.
Oncotic pressure is created by the water potential in the capillaries being lower than in the surrounding tissue

Question 4

What is hydrostatic pressure

Answer 4

The pressure created due to the volume of liquid in an area

Question 5

what structures are in veins and arteries

Answer 5

Tunica intima-endothelium, Squamous epithelial cells
tunica media - smooth muscle and elastic fibres
tunica external- Collagen
Valves
Wide lumen

Question 6

In the tunica media what structure is touching the collagen and the squamous epithelium

Answer 6

Smooth muscle

Question 7

What is a ectopic heartbeat

Answer 7

heartbeats that are out of the normal rhythm. Most people have at least one of these a day. However they can be linked to serious conditions

Question 8

What is atrial fibrillation

Answer 8

an example of arrhythmia.
Rapid electrical impulses are generated in the atria. They contract very fact ( fibrillate) up to 400 times a minute. However they don’t contract properly an only some of the impulses are passed on to the ventricles, which contract much less often. As a result the heart does not pump blood very effectively

Question 9

What is arrhythmia

Answer 9

means an abnormal rhythm of the heart

Question 10

What is Tachycardia

Answer 10

heart beat is very rapid, over 100bmp. This happens very frequently when you exercise or are frightened. May be cussed by problems in the electrical control of the heart which is abnormal and needs treating

Question 11

What is Bradycardia

Answer 11

when the heart rate slows down to below 60bpm. Many people have bradycardia because they are fit. Serve bradycardia can be serious and an artificial pacemaker is needed to keep the heart beating steadily

Question 12

Diastole

Answer 12

Diastole- heart relaxes. Atria and ventricles fill with blood. Pressure of blood in the heart builds as the heart fills, pressure in arteries is a minimum

Question 13

Systole

Answer 13

• atria contract followed by the ventricles
• the pressure inside the heart increases dramatically and blood is forced out of the right side of the heart to the lungs and from the left side to the main body.
  Pressure in arteries is at maximum

Question 14

Rhythm of the heart - SAN

Answer 14

Wave of electrical excitation begins in the pacemaker area Called the Sino-atrial node, causing atria to contract initiating the heartbeat
Layer of non conducting tissue prevents excitation passing directly to ventricles

Question 15

How AVN stiumlates a contraction

Answer 15

Electrical activity from the SAN is picked up by the atrioventricular node.
AVN imposes a slight delay before stimulating the bundle of his, a bundle of conducting tissue made up of purkyne fibres which penetrate through the septum between the ventricles
Bundle of his splits into 2 branches and conducts the wave of excitation to the apex
At the apex the purkyne fibres spread of through the walls of the ventricles triggering a contraction

Question 16

Reason for AVN delay

Answer 16

To make sure the atria have stopped contracting/contracted fully
To make sure ventricles do not contract early

Question 17

Examples of substances found in tissue fluid

Answer 17

Oxygen , sugar , amino acids, white blood cells, water

Question 18

veins and the lymph vessels have in common

Answer 18

Both rely on muscle contraction to help transport fluids and both contain valves to prevent backflow of fluid

Question 19

Why does electrical excitation move to the apex

Answer 19

So contraction stems from below the ventricle forcing the blood upwards

Question 20

Type of muscle found in walls of the heart

Answer 20

Cardiac

Question 21

why the hydrostatic pressure of the blood drops as blood moves away from the heart

Answer 21

More vessels such as capillaries and arterioles, increases total lumen volume
Loss of plasma/fluid

Question 22

Role of haemoglobin transporting o2 round the body

Answer 22

Hb contains fe2+ which has a high affinity for oxygen
Oxygen binds to haemoglobin in the lungs to form oxyhemoglobin
When partial pressures of o2 decreases o2 dissociates from hb

Question 23

Where are the valves located in the heart

Answer 23

Tricuspid valve. Located between the right atrium and the right ventricle.
Semilunar valve. Located between the right ventricle and the pulmonary artery.
Bicuspid valve. Located between the left atrium and the left ventricle.
Aortic valve

Question 24

Reason for AVN delay

Answer 24

To allow atria to contract fully

And to ensure the atria are empty