1.1- what is cardiovascular disease ? Flashcards
1
Q
what is a cardiovascular disease (CVDs) ?
A
a disease of the heart and circulation and are the main cause of death in the UK
2
Q
what is an open circulatory system
A
- when blood circulates in a large open system, normally in insects
- the heart pumps blood into cavities surrounding the animals organs
- substances can then diffuse between the blood and the cell
- when the heart relaxes blood is drawn back into the cavities through valved openings along its length
3
Q
what is a closed circulatory system
A
- the blood is enclosed in blood vessels, in many animals and all vertebrates
- generates higher blood pressures as blood is forced along the the blood vessels
- means blood travels faster and so the blood system is more efficient
- animals with closed circulatory systems are normally bigger and more active
4
Q
The general path of blood by a closed system
A
- blood leaves heart under pressure and flows along arteries and then arterioles to capillaries
- there are lots of capillaries which come into close contact with most of the cells in the body where substances are exchanged
- then blood returns to the heart by venules and then veins
- valves make sure the blood flows in only one direction
5
Q
path of blood in a single circulatory system
A
- fish used as an example
- heart pumps blood to the gills
- gaseous exchange takes place; there is diffusion of CO2 from the blood into the water that surrounds the gills and then diffusion of oxygen from water to the gills
- the blood leaves the gills and then flows around the rest of the body before returning to the heart
- they have one ventricle and one atrium
6
Q
what is a double circulatory system
A
- birds and mammals have one
- the right ventricle pumps de-oxygenated blood to the lungs where it receives oxygen
- oxygenated blood then returns to the heart to be pumped a second time by the left ventricle out to the rest of the body
- the blood gets an extra boost that reduces time taken for blood to circulate to the rest of the body
- therefore birds and mammals have a high metabolic rate
7
Q
why do many animals need a circulatory system
A
- in multicellular organisms they are too large for substances to diffuse and move around their body quick enough unlike uni-cellular organisms that are small enough for diffusion to be adequate
- they have to rely on a mass transport system to move substances efficiently by mass flow- a circulatory system
8
Q
what is mass flow
A
The transport medium in animals is blood, mass flow means that blood is transported in one direction due to a difference in pressure
9
Q
what does it mean when water is described as having a dipole nature
A
- has an unevenly distributed electrical charge
- hydrogen end is slightly positive and oxygen end slightly negative
- the slightly positive end is attracted to the slightly negative end of other water molecules
- hydrogen bonding holds water molecules together
10
Q
what are the properties of water that make it an ideal transport medium
A
Solvent-
- many chemicals dissolve easily in water
- allows vital biochemical reactions to occur as the chemicals are free to move around in the aqueous environment
- dissolved substances can be transported around organisms
- ionic and polar substances can dissolve easily as they get surrounded by water due to its dipole nature
Thermal properties-
- specific heat capacity of water very high
- large amount of energy required to break hydrogen bonds
- water warms up and cools down slowly
- helps organisms to avoid rapid changes in internal temp
11
Q
Basic heart structure
A
- made of carciac muscle
- right side receives deoxygenated from body and pumps to lungs
- left side receives oxygenated from lungs and pumps to body
12
Q
what are the similarities between arteries and veins
A
- walls of both vessels contain collagen to make them strong and durable
- contain elastic fibres to allow stretch and recoil
- smooth muscle cells in walls allows to constrict and dialate
13
Q
differences between veins and arteries
A
- arteries narrow lumen- veins wide lumen
- arteries thicker walls- veins thinner walls
- arteries more collagen,smooth muscle and elastic fibres- veins less
- arteries have no valves- veins do
14
Q
how does blood move through the vessels
A
- during systole blood is forced into arteries and walls stretch to accommodate
- during diastole elasticity of artery walls causes them to recoil behind blood, pushing blood forward and smoothing blood flow
- when blood reaches capillaries blood flow is steady
- blood flows slower in capillaries as smaller lumen and friction from walls
- allows for exchange
- blood flows steady through veins- no pulses
- assisted by contraction of nearby muscles
- backflow prevented in veins due to semi lunar
15
Q
what happens during atrial systole
A
- blood returns to heart due to action of skeletal muscles and breathing
- blood under low pressure into left and right atria from pulmonary veins and vena cava
- as they fill increased pressure forces tricuspid and bicuspid valve open and leaks into ventricles
- atria then contract to push blood into ventricles
16
Q
what happens during ventricular systole
A
- they contract forcing open semilunar valves
- pushes blood through pulmonary arteries an aorta
- pressure against atrio ventricular valves keeps them closed
17
Q
what happens during cardiac diastole
A
- atria and ventricles relax
- elastic recoil reduces heart pressure
- blood under high pressure in aorta an pulmonary arteries is drawn back towards ventricles closing the semi lunar valves
- coronary arteries fill during diastole
- low pressure helps draw blood from pulmonary veins
18
Q
what is atherosclerosis (AT)
A
- disease process that leads to coronary heart disease and strokes
- fatty deposits can either block artery directly or make it more likely to be blocked by thrombosis
- if coronary arteries complete block causes heart attack or in brain causes stroke
19
Q
what is the endothelium in an artery
A
- endothelium is delicate layer of cells that lines inside of artery and separates blood flow from muscular wall
20
Q
what happens in AT
A
- endothelium is damaged or becomes dysfunctional
- then an inflammatory response
- white blood cells leave blood vessel and move to artery wall
- these cells accumulate chemicals from blood, mainly cholesterol which is deposited, called an atheroma
- calcium salts and fibrous tissue also build up, resulting in hard swelling called a plaque on inner wall of artery
- build up means artery loses some elasticity
- plaque narrows artery lumen so more difficult for blood to flow and can lead to rise in blood pressure- positive feedback as the increase makes more plaques more common and cycle continues
21
Q
why does blood clot in arteries
A
- vital when blood vessel damaged to seal the break- limits blood loss and prevents entry of pathogens
22
Q
what happens during the clotting cascade
A
- platelets and damaged tissue release protein thromboplastin
- that activates an enzyme that catalyses conversion of prothrombin to enzyme called thrombin
- thrombin catalyses conversion of soluble protein fibrinogen to insoluble fibrin
- mesh of fibrin forms that traps more platelets and red blood cells to form clot
