UNIT 5 BIOLOGY B1 (CARDIOVASCULAR SYSTEM)

The human cardiovascular system is a ?. This means that for every complete circulation in the body, the blood passes through the heart ?

The human cardiovascular system is a DOUBLE CIRCULATORY SYSTEM. This means that for every complete circulation in the body, the blood passes through the heart TWICE.

What are the features of the blood vessel known as an Artery?

• Thick walls containing lots of thick smooth muscles & elastin fibres to withstand high blood pressure from LEFT VENTRICLE

• Elastin allows recoil after pulsation of blood as pressure changes

• Small (narrower than vein) Lumen

What are the features of the blood vessel known as a Vein?

• Thin walls as blood has low pressure & thin muscle and elastic layer

• Largest lumen to reduce friction to blood flow

• Semi-lunar valves present to prevent backflow of blood

What are the features of the blood vessel known as a Capillary?

• Links arteries and veins through tissues

• Site of gas exchange of materials (o2 & co2) between the blood and tissues by diffusion

• Walls are one endothelial cell thick, giving a short diffusion pathway

Why is it important that the capillary walls are very thin?

• short diffusion pathway

What is the role of the elastic tissue in arteries?

• Allows arteries to stetch so it can withstand blood pressure

• Recoils to return to their original size

Why are older people more likely to get high blood pressure?

• Their arteries are less stretchy due to the loss of elastin

• So blood pressure rises

What is the role of the smooth muscle tissue?

• Allows vasoconstriction and vasodilation

• This allows blood to be directed to specific tissues

What antigens are present on the surface of the red blood cells for the following groups:

1. A

2. B

3. AB

4. O

1. A antigens

2. B antigens

3. AB antigens

4. No antigens

What antibodies are present on the surface of the red blood cells, who can they donate to & receive from? for the following groups:

1. A

2. B

3. AB

4. O

1. Anti-B antibodies, can donate to A,AB, can receive from A,O

2. Anti-A antibodies, can donate to B,AB, can receive from B,O

3. NO antibodies, can donate to AB, can receive from A,O,AB,B

4. Anti-B & Anti-A antibodies, can donate to A,AB,B,O can receive from O

1. If a person is rhesus positive, who can they send and receive blood from?

2. If a person is rhesus negative, who can they send and receive blood from?

1. rhesus positive- they can send to Rh+ and receive from Rh- & Rh+

2. rhesus negative- they can send to Rh+ & Rh- and receive from Rh-

Combining the ABO and the Rh systems gives 8 possible blood groups- what are they?

• A⁺

• A⁻

• B⁺

• B⁻

• AB⁺

• AB⁻

• O⁺

• O⁻

Who can the 8 blood groups receive blood from?

1. O⁻

2. O⁺

3. A⁻

4. A⁺

5. B⁻

6. B⁺

7. AB⁻

8. AB⁺

1. O⁻= O⁻

2. O⁺= O⁻, O⁺

3. A⁻= O⁻, A⁻

4. A⁺= O⁻, O⁺, A⁻, A⁺

5. B⁻= O⁻, B⁻

6. B⁺= O⁻, O⁺, B⁻,B⁺

7. AB⁻ = O⁻, A⁻, B⁻,AB⁻

8. AB⁺ = O⁻, O⁺, A⁻, A⁺, B⁻, B⁺, AB⁻, AB⁺

1. Which blood group is the universal donor and why?

2. Which blood group is the universal receiver and why?

1. Blood group O⁻ because there are no antigens on the surface

2. Blood group AB⁺ because it has A, B and Rh antigens on its red blood cells.

Explain the following:

1. Why AB⁺ cannot give blood to A⁺?

2. Why AB⁺ cannot give blood to AB⁻ ?

3. Why B⁻ cannot give blood to A⁻ ?

4. Why B⁺ cannot give blood to AB⁻ ?

1. The A⁺ would start producing anti-B antibodies

2. The AB⁻ would produce anti-D antigens

3. The A⁻ would produce anti-B antibodies

4. The AB⁻ would produce anti-D antibodies

1. What is the myogenic muscle?

2. What is the septum?

1. Muscles that are made to contract due to signals from the heart itself, NOT from the brain

2. The dividing wall between the left and right side

What is the role of the coronary artery?

• Delivers blood containing oxygen & glucose to the heart muscle

• This is needed for aerobic respiration where it produces ATP for the heart to contract

Why is the muscle of the left hand side thicker than the right hand side?

• The blood on the left side of heart travels to tissues, so during contraction a high force must be generating

• However, blood from the right side of heart is only going to the lungs so the force generated does not need to be as high

1. What is the function of the Vena cava?

2. What is the function of the pulmonary artery?

1. Carries de-oxygenated blood from tissues of head and body to the right atria.

2. Carries de-oxygenated blood from right ventricle to lungs, to become oxygenated

1. What is the function of the pulmonary vein?

2. What is the function of the aorta?

1. Carries oxygenated blood from the lungs to the left atrium of the heart

2. Carries oxygenated blood from the left ventricle to the tissues of the head and body

1. What happens when there is a high pressure behind a valve?

2. What happens when there is a high pressure in front of a valve?

1. Causes it to open

2. Causes it to close

1. Where is the Bicuspid valve located?

2. When will it open?

3. When will it close?

1. Between the left ventricle and left atrium

2. When pressure is high in left atrium & low in left ventricle

3. When pressure is lower in left atrium & higher in left ventricle

1. Where is the Tricuspid valve located?

2. When will it open?

3. When will it close?

1. Between the right ventricle and right atrium

2. When pressure is high in right atrium & low in right ventricle

3. When pressure is lower in right atrium & higher in right ventricle

1. Where is the Semi Lunar valve located?

2. When will it open?

3. When will it close?

1. Between the ventricles & blood vessels (aorta and pulmonary artery)

2. When pressure is high in ventricles & low in blood vessels

3. When pressure is lower in ventricles & higher in blood vessels

What is the function of the bicuspid valve?

• Allows blood to flow from the left atrium into the left ventricle when the valve is open.

• Prevents backflow of blood from the left ventricle into the left atrium when the left ventricle contracts.

What is the function of the tricuspid valve?

• Allows blood to flow from the right atrium into the right ventricle when the valve is open.

• Prevents backflow of blood from the right ventricle into the right atrium when the right ventricle contracts.

What is the function of the aortic valve?

• Allows blood to flow from the left ventricle into the aorta when the valve is open.

• Prevents backflow of blood from the aorta into the left ventricle when the left ventricle relaxes.

What is the function of the pulmonary valve?

• Allows blood to flow from the right ventricle into the pulmonary artery when the valve is open.

• Prevents backflow of blood from the pulmonary artery into the right ventricle when the right ventricle relaxes.

What happens in the diastole of a cardiac cycle?

(All chambers are relaxed)

• Atria & ventricles relax, so pressure is higher in arteries than ventricles

• This closes the SL valves in artery as blood pushes valves, so atria fills with blood from vein

• This causes AV valves to open

What happens in the Atrial systole of the cardiac cycle?

(All chambers contract)

• Ventricles relax, atria contracts

• increases pressure in atria, this forces blood through the AV valves & into ventricles

What happens in the Ventricular systole of the cardiac cycle?

(All chambers contract)

• Atria relaxes, ventricles contract

• Increasing the pressure in the ventricles above the atria and arteries

• This closes the AV valves and opens the SL valves, allowing blood to be pumped into arteries

What is the equation for cardiac output?

CO (L/min or dm3/min) = SV (ml/beat) X HR (beats/min)

Describe the Sino-Atrial Node

• Found in the wall of the right atrium

• Has a pacemaker which initiates heartbeat & sets heart rate at 70-80 beats/min

• Generates electrical impulse that moves across both atria walls, causing them to contract at the same time

Describe the Atrio-Ventricular Node

• Electrical impulse from SAN is picked up by the AVN in the septum

• AVN imposes a slight delay in sending the wave of excitation to ventricles

• Allowing atria to finish contracting & to fully empty of blood before ventricles contract

• AVN passes signal to the Bundle of His which is also found in septum

Describe the Bundle of His & Purkyne fibres

• Bundle of His conduct electrical impulse down the septum down the apex

• The purkyne fibres then spread up to the ventricle walls, transmitting the electrical impulse & causes contraction of ventricles from apex upwards.

• This pushes the blood up + out of heart

What does the P wave do?

• Shows when atrial systole is happening, so shows the start of atrial contraction in Atrial systole

What does the QRS complex do?

• Shows when ventricular systole is happening so shows the start of ventricular contraction in ventricular systole

• At the same time, atrial diastole is happening but is hidden by QRS complex

What does the T wave do?

• shows when ventricular repolarisation is happening, so shows when the heart is relaxing in cardiac diastole

What is Tachycardia showing?

• Increased heart rate

• Peaks of QRS complex are regular but closer together

• Typically over 100bpm

What is Bradycardia showing?

• Decreased heart rate

• Peaks of QRS complex are regular but further apart

• Slower than 60bpm

What is Ventricular Fibrillation showing?

• No PQRST visible

• Contraction is not controlled

• Can lead to cardiac arrest

What does Sinus Arrythmia show?

• Irregular heart rate

• Peaks of QRS complex are not regularly spaced

• Linked with breathing- faster when breathing in, slower when breathing out

What does Asystole/Flat Line show?

• No PQRST visible as no electrical activity in the heart

• Heart not beating

Increasing a patients stroke volume increases their cellular respiration enabling them to be more active.

Explain why.

• More blood to carry more oxygen & glucose

• More aerobic respiration, so more ATP produced

• So muscles contract more

What are some examples of Cardiovascular diseases?

• Heart attack

• Hypertension

• Stroke

Transplantation is a type of treatment for CVD, describe what it is, the benefits & risks

What is it?

• Used if a person has coronary heart disease/heart failure

Benefits?

• Can prolong life

• Can be effective if tissue match is found & has long lasting effect

Risks?

• Can cause infection from bacteria

• Failure to pump

• Must take immunosuppressants for rest of life

• Must find a donor & a match

Antihypertensives are a type of treatment for CVD, describe what it is, the benefits & risks

What is it?

• Ace inhibitors (relaxes blood vessels)

• Diuretics (removes excess water from body)

• Calcium channel inhibitors (prevents calcium entering heart)

Benefits?

• Lowes BP

• Reduces risk of CVD

Risks?

• Have to keep taking them for life

• Causes excess fluid loss & impotence

• Raises sodium/blood sugar levels

Statins are a type of treatment for CVD, describe what it is, the benefits & risks

What is it?

• Lowers LDL levels in blood

• Reduce formation of fatty plaques/blood clots

Benefits?

• Cheap & easy to take

• Prevents heart disease getting worse

Risks?

• Have to keep taking them for life

• Increases risk of diabetes & cannot cure CVD

• Causes side effects such as nose bleeds and sore throat