Lifestyle, Health and Risk Flashcards
What is CVD?
Diseases of the heart and circulation
Main forms are:
Conorary heart disease
Stroke
Open circulatory systems
Occurs in insects and other animal groups
Blood circulates in a large
open space
Heart pumps blood into cavities surrounding organs
Substances diffuse between blood and cells
When heart relaxes, blood is drawn back from the cavities through small, valved, opening into the heart
Closed circulatory systems
Occurs in all vertebrates
Blood enclosed in blood vessels
High pressure as blood is forced along narrow tubes
Blood travels faster, so more efficient at delivering substances
Blood leaves heart through arteries, into arterioles, then through capillaries.
Then back to the heart through venules to the veins
What is mass flow?
The movement of a fluid in one direction due to a difference in pressure, usually through a system of tube-like vessels.
What is the transport medium in animals?
Blood
Why is water a polar molecule?
It has an unevenly distributed electrical charge
The hydrogen end is slightly positive, as the 2 hydrogens are pushed towards each other
The oxygen end is slightly negative, as the electrons are more concentrated
Why is water dipole?
It has both negative and positive charges
Explain hydrogen bonding in water molecules.
Slightly positively charged ends are attracted to slightly negative ends of other water molecules.
Holds holds the water molecules together
It is liquid at room temperature
Why do many chemicals dissolve easily in water?
Water is dipole
Differences in the structure of arteries and veins
Arteries | Veins
Narrow lumen | Wide lumen
Thick walls | Thin walls
More collagen, smooth muscle and elastic fibres | Less collagen, smooth muscle and elastic fibres
No valves | Valves
What is it called when the heart contracts?
Systole
What is it called when the heart relaxes?
Diastole
Why does blood slow down in capillaries?
Narrow lumens cause more friction
What assists the flow of blood through veins?
Contraction of skeletal muscles during movement of limbs and breathing
Explain the cardiac cycle
Atrial systole
- Blood returns to heart due to skeletal muscle as you move and breathe
- Blood under low pressure flows through the pulmonary vein and vena cava into the left and right atria.
- As atria fill the AV valves open as pressure against them increases
- Blood flows into ventricles
Ventricular diastole
- Ventricles contract from base upwards –> increases pressure
- Pressure forces open semilunar valves
- Blood goes out through pulmonary arteries and aorta.
- Pressure of blood against AV valves closes them
Cardiac diastole
- Atria and ventricles contract
- Elastic recoil of relaxing walls lowers the pressure
- Blood under high pressure in the arteries is drawn back towards the ventricles closing the semilunar valves
- Coronary arteries fill
- Low pressure in atria draws blood into heart
What is atherosclerosis?
Fatty deposits either block an artery or increase the chance of thrombosis.
Leads to coronary heart disease and strokes
What happens if atherosclerosis occurs in the coronary arteries?
Results in heart attack (myocardial infarction)
What happens if atherosclerosis occurs in the arteries supplying the brain?
Results in a stroke
What are platelets?
A type of blood cell without a nucleus
What is the process of atherosclerosis?
- Damaged endothelium
can be a result of high blood pressure or toxins from cigarette smoke - Causes an inflammatory response
- White blood cells leave blood vessel and move to artery wall
- Cholesterol +
fatty deposit builds up atheroma forms - Calcium salts and fibrous tissue build up
results a plaque - Artery wall loses some elasticity, it hardens
- Plaque narrows the lumen so it’s more difficult to pump blood
- Increases blood pressure (positive feedback - increasing pressure increases risk of more plaques forming
What is the process of blood clotting?
- Platelets stick to damaged wall and to each other, forming a platelet plug
- Thromboplastin released from damaged tissue and platelets catalyses the enzyme that changes the soluble prothrombin into thrombin
- Ca2+ and vitamin K from the plasma also present
- Triggers clotting cascade
- Thrombin catalyses soluble fibrinogen into insoluble fibrin –> creates a mesh
- Fibrin mesh traps RBC forming a clot
How does blood clotting occur?
Usually the arteries are too smooth and substances repel platelets so platelets don’t stick to the endothelium.
However, if there is atherosclerosis, the endothelium is damaged and platelets contact with the damaged tissue and exposed collagen. Clotting cascade is triggered
What is angina?
Chest pain
Could be a result of narrowing coronary arteries
Usually occurs when cardiac muscle is working hard so needs to respire more.
Explain how atherosclerosis and CHD are linked
Narrow coronary arteries limits oxygen-rich blood supply to heart
Results in angina
Heart is forced to respire anaerobically –> lactic acid produced causes pain
If fatty plaque in coronary arteries ruptures, collagen is exposed
Leads to rapid clot formation
Blood supply may be completely blocked
Heart muscle doesn’t receive blood so is ischaemic (without blood)
If this happens for long, muscle cells will be permanently damaged –> heart attack
Explain how atherosclerosis and stroke are linked
If supply of blood to brain is briefly interrupted then a mini-stroke will occur
If a blood clot blocks an artery leading to the brain a full stroke will occur
If brain cells are oxygen deprived for more than a few minutes, damage will be permanent
What is an aneurysm?
If an artery narrows and becomes less flexible, blood can build behind
Artery then bulges as it fills with blood
Define risk
The probability of occurrence of some unwanted event or outcome
Why will people overestimate risks?
If the risk is :
involuntary (out of their control) not natural unfamiliar dreaded unfair very small
What is a Cohort study?
A study that follows a large group of people over time to see who develops the disease.
Prospective - none of the participants have the disease at start
Used to identify risk factors
Can be very expensive
What is hypertension?
Elevated blood pressure
What is blood pressure?
A measure of hydrostatic force of blood against walls of a blood vessel
When is pressure in the arteries highest?
When the ventricles have contracted, This is systolic pressure
When is pressure in the arteries the lowest?
When the ventricles are relaxed, This is the diastolic pressure
What are the SI units for pressure?
Kilopascals (KPa)
What is peripheral resistance?
The contact between the blood and walls of the blood vessel causes friction.