Lifestyle: cardiovascular disease

Question 1

In lifestyle and health, what do CVD and CHD stand for?

Answer 1

Cardio Vascular Disease

Coronary Heart Disease

Question 2

Define diffusion

Answer 2

the movement of molecules or ions from a region of high concentration to a region of low concentration

In unicellular creatures, diffusion is fast enough to meet requirements, but not for larger animals which rely on mass transport systems (cardio-vascular system…)

Question 3

How does blood circulate in insects?

Answer 3

Blood circulates in large open spaces

A simple heart pumps blood into the cavities around an insect’s organs

When the heart relaxes, blood is drawn back into the heart through small valved openings along the creature’s length.

Question 4

What is a closed circulatory system compared to an open circulatory system?

Answer 4

The blood is enclosed in a system of blood vessels, so is under higher pressure and can deliver nutrients efficiently

An open system pumps blood into cavities around the (insect’s) organs and when it relaxes, the blood flows back into the heart.

Question 5

How does a closed circulatory system work?

Answer 5

A closed system has greater pressure, so the blood travels faster in the system and so can deliver nutrients effciently

Heart creates the pressure - blood flows along arteries, arterioles, then capillaries, returning along the venules and then veins back to the heart.

Valves ensure the blood only flows in one direction

Question 6

What is the difference between single and double circulation systems?

Answer 6

Fish, for instance, have a single system

• heart pumps deoxy blood to gills
• gaseous exchange at gills (CO₂ out, O₂ in)
• blood leaves gills, circulates and returns to the heart.

Double circulation (mammals, birds) = blood goes through heart organ twice

• right ventricle pumps deoxy blood to lungs for gaseous exchange (CO₂ out, O₂ in)
• oxy blood returns to heart to be pumped a SECOND time by left ventricle to circulate around the body

A double circulatory system has a higher metabolic rate as O₂ and nutrients can be delivered to cells more rapidly.

Question 7

How does a three chambered heart work and in which animals is it found?

Answer 7

Question 8

Describe how a circulatory system works. What is it also known as?

Answer 8

1) A liquid and its particles are transported in one direction due to a difference in pressure.
2) This process is known as mass flow.

EXTRA: animals - the liquid is called blood which is comprised of

• water,
• digested food molecules (glucose)
• CO2,
• O2

Question 9

What are the properties of water that make it useful for transporting around the circulatory system?

Answer 9

1. Liquid at room temperature
2. H₂O is a polar molecule ; it is a dipole (slight electrical charge: H⁺ and O^- ); its polarity enables hydrogen bonding
3. Solvent properties: many chemicals dissolve in water and then can be easily hooked up to water molecules due to mutual polarity

eg NaCl dissolves into Na⁺ Cl^-, which attracts the dipolar water molecules)

eg -OH sugar groups and NH₂ amines easily dissolve as well; such polar substances are hydrophillic, water loving.

4. Thermal properties - water warms up and cools very slowly due to its specific heat capacity characteristics, which makes it very useful as a stable environment for transported molecules

Question 10

What do hydrophillic and hydrophobic mean?

Answer 10

Water loving (eg -OH and NH₂ groups)

Water hating such as lipids.

Question 11

How do lipids get transported in blood?

Answer 11

They are hydrophilic so can’t work with water, so they combine with proteins to form lipoproteins

Question 12

What kind of pump is the heart?

Answer 12

It is a double pump

Question 13

What is cardiac muscle?

Answer 13

The muscle the heart is made of

Question 14

Explain what the right side of the heart does

Answer 14

It receives deoxy blood and pumps it to the lungs

Question 15

Explain what the left side of the heart does

Answer 15

It receives oxy blood and pumps it around the body

Question 16

What is the name of the main tube bringing deoxy blood to the heart?

Answer 16

(superior) vena cava

Question 17

What is the name of the main tube taking oxy blood to the body

Answer 17

aorta

Question 18

What is collagen?

Answer 18

Tough fibrous protein sheathing that has some elasticity, for instance, as found in arteries and veins.

Question 19

Describe what arteries possess

Answer 19

narrow lumen

thicker walls

more collagen than veins, smooth muscle and elastic fibres

arteries do not have valves

Question 20

Describe veins

Answer 20

wide lumen

thinner walls than arteries

less collagen, smooth muscle, and few elastic fibres than arteries

Veins have valves

Question 21

What is systole

Answer 21

When the heart contracts

Question 22

What is diastole

Answer 22

relaxation of the heart

Question 23

What happens to blood flow in capillaries?

Answer 23

Blood flow slows down due to friction as capillaries have narrow lumen

The slower, steadier flow allows exchanges between the blood and the cells through the one cell thick capillary walls

Capillaries lie close to every cell enabling rapid diffusion

Question 24

What assists venous blood to return to the heart?

Answer 24

The heart’s pumping action has little effect, so venous blood movement is dependent on movement when skeletal muscles contract and when we breathe lowered pressure in the thorax (chest cavity) draws blood up.

The image shows deterioration of the venous system, causing pooling of blood in the lower limbs as gravity is keeping the blood from getting to the heart due to inactivity or venous system issues.

Question 25

What supplies the heart muscles with blood?

Answer 25

Coronary arterties -> capillaries -> coronary veins back out

Question 26

Summarise a cardiac cycle in three concepts:

Answer 26

atrial systole

ventricular systole

diastole

Question 27

Phase 1 of the cardiac cycle is called atrial systole - what happens?

Answer 27

Atrial systole…systole is contraction, so the atria in the two sides of the heart contract

1) blood has been flowing into the atria (left and right) causing an increase in pressure;
2) the pressure causes the atrioventricular valves to open allowing blood to pass into the ventricles
3) this prompts the contraction of the atria to force more blood into the ventricles

Question 28

In phase 2 of the cardiac cycle, the ventricular systole, what happens?

Answer 28

Ventricular systole: systole is contraction so here we’re expecting the ventricles to contract:

Following atrial systole, the ventricles then contract from the base of the ventricles upwarsds, pushing the collect

Question 29

In phase 3 of the cardiac cycle, called the cardia dystole, what happens?

Answer 29

Diastole = relaxing

1. Atria and ventricles relax; the elastic muscle tissues of the heart walls relaxes lowering pressure in atria and ventricles
2. The relatively higher pressure of the blood on the other side of the semilunar valves in the aorta and pulmonary arteries forces the semilunar valves to shut, stopping backflow
3. Lower pressure in the atria draws blood in from the veins and back to phase 1
4. (coronary arteries feeding the heart muscles also fill during this phase)

Question 30

What two things control blood flow in the cardiac cycle?

Answer 30

1. Changes in pressure
2. Valves

Question 31

What is artherosclerosis?

Answer 31

Fatty deposits blocking an artery or increasing chances of a blood clot (thrombosis)

Question 32

What are the effects of artherosclerosis?

Answer 32

Fatty deposits causing a blood clot begin to damage nearby cells;

1. If this happens in the coronary arteries, supplying blood to heart muscle, this results in a myocardial infarction (heart attack)
2. If this happens in the arteries supplying the brain’s cells, this causes a stroke causing brain cell deaths (cerebral aneuryism)
3. If this happens in the legs, narrowing of the arteries can cause tissue death and gangrene (eg poplietal aneuryism)
4. If this happens in the aorta, it is called an “aortic aneurysim” which is associated with smoking, high BP

Question 33

What is the process involved in the formation of artherosclerosis?

Answer 33

Endothelium cells become damaged (eg from high BP or toxins)

When endothelium layer is breached, there is an inflammatory repsonse;

White blood cells leave blood stream and enter the artery wall;

These cells now accumulate cholesterol and a fatty deposity (atheroma) builds up

Gradually calcium salts and fibrous tissue build up causing plaque to form - the artery is now hardening (sclerosis = hardening)

Plaques narrow the artery, causing BP to rise;

dangerous positive feedback now occurs as high BP can cause more plaques to form

Sooner or later, symptoms will start to show.

Question 34

Why is it that arteries are susceptible to artherosclerosis, not veins?

Answer 34

Because arteries are under high pressure and fast flow, hence higher chance of more damage being done

Question 35

How does blood clot?

Answer 35

Immediate:

1. when a blood vessel is damaged, platelets, flowing in blood, hit the damage and alter their shape from flattened discs to spheres with long projections;
2. their surfaces change too causing them to stick to the collagen that is forming on the open vessel wall;
3. they stick to each other to form a plug and release other chemical messengers to bring in more platelets

Longer response:

1. Blood contacting with collagen also triggers a chemical pathway -
2. Platelets and damaged tissue release thromboplastin
3. Thromboplastin activates an enzyme that catalyses the conversion of prothrombin into an enzyme called thrombin
4. Thrombin catalyses the conversion of soluble fibrinogen into insoluble protein fibrin
5. Fribrin creates a mesh that traps platelets and RBCs to form clot to stem blood loss

Question 36

What are the consequences of coronary heart disease?

Answer 36

1. narrowing of coronary arteries limits blood flow to heart muscle -> angina

(lack of O₂ means the heart is working anaerobically, a trigger for the pain)

2. If a fatty plaque causes a coronary artery rupture, collagen is exposed causing a clot to rapidly form -> blood supply to the heart muscles is stopped (“ischaemic” = no blood), which can cause permanent damage - this is called a heart attack or myocardial infarction (and can be fatal)

Question 37

What is a stroke?

Answer 37

When the supply of blood to the brain is stopped.

1. If this is brief, a mini-stroke can occur -> can have full recovery
2. When a full block of an artery occurs, a full stroke results usually leading to permanent damage and even death.