Heart Flashcards
What is the use of blood ? (2)
- to deliver oxygen and glucose for respiration
- and remove carbon dioxide from respiration
What causes heart attack ?
- blockage of arteries lead to damage or death of heart muscle cells causes myocardial infarction
What is diastole
- when heart muscles relax their pressure decreases
- ventricular muscles relax = pressure decreases = closes aortic valve = atria fills with blood again from veins = atrial pressure increase = mitral valve open when AP higher than VP, blood force into relaxed ventricles = VP increase
What is ventricular systole
- full ventricle contract = causes pressure to increase = causes bicuspid valve to close = aortic valve open = forced blood out of the heart through aorta or arteries
What is the use of pocket valve ?
- found in veins to prevent back-flow of blood at low pressure when going into the heart
Calculate cardiac output
- heart rate x stroke volume
What substances are found in tissue fluids ?
- glucose, aas, fatty acids, salts and O2
- CO2, urea, waste products that need to be removed from the cell
What is the role of tissue fluid ?
- a thin layer around organs
- allow exchange of substances between blood and cells
The role of heart in the formation of tissue fluid (2)
- contraction of ventricles causes high hydrostatic pressure
- forces water to drawn out of the capillaries to form tissue fluid
How does tissue fluid form?
- when high hydrostatic pressure of blood flows from arterioles into capillary bed, capillary has permeable membranes and gaps that enable substances to diffuse through
- at atrial end, a higher hydrostatic pressure than osmotic pressure= forces substances from plasma into the areas around tissue cells by ultrafiltration
- causes a layer of fluid to form for gas exchange for tissue cells
How is substances reabsorbed from the tissue fluid ?
- large molecules of proteins, RBC and platelets cannot diffuse through capillary walls so remain
- at venous end, there is a higher osmotic pressure in tissue fluid than hydrostatic pressure in plasma due to loss of fluid
= causes water to be drawn back into plasma by osmosis - rest of the fluid is reabsorbed by lymphatic vessels and drain back into bloodstream near the heart back to circulatory system
Why is lack of protein in blood cause a build up of tissue fluid ?(3)
- water potential is higher ( not as low ) than normal
- reduce concentration gradient between tissue fluid and blood
- osmosis unable to occur, water cannot diffuse back into capillary, leads to excess water build up
Structure of arteries link to functions
- have thicker muscular walls = enable withstand high pressure blood flowing
- have elastic fibres to stretch and recoil = maintain high pressure
- folded endothelium = allow it to stretch and provides rigidity
- no valves = allow more blood flowing with availability of large Volume
Functions of arterioles
- allow blood to direct to specific areas for demand
- muscle fibres contract = constriction = decrease volume of vessel, increase pressure = reduce blood flow
Structure to function of veins
- have wider lumen = enable low pressure blood flow smoothly
- less elastic fibres
- have valves = prevent blood back flowing
- muscles surround veins that contract = cause blood flow despite low pressure
Structure to functions of capillaries
- only have one cell endothelial wall = provide short diffusion pathway for faster exchange of substance
- locate very near to cells in gas exchange surface = short diffusion pathway
- lots of them= capillary beds = increase total surface area
Explain how high blood pressure leads to an accumulation of tissue fluid ? (3)
1) high hydrostatic pressure on atrial end
2) causes increase in outward pressure from atrial end to venous end of capillary
3) causes more fluid to force out into tissue fluid, less can be reabsorbed
Explain why water potential of plasma is more negative at venule end than at ateriole end of capillary? (3)
1) soluble fluids have been drawn out of capillary
2) proteins will remain in cap as too large to diffuse through
3) causes an increase in blood protein conc so a lower water potential
Explain 4 ways in which the structure of aorta is related to its function (4)
1) smooth endothelium SO reduce friction = allow blood flow smoothly and faster
2) have aortic valves SO prevent back flow of blood = ensure enough O2 blood supply for demand
3) thicker walls = allow to withstand high pressure blood from ventricles
4) elastic fibres = allow to recoil when ventricles relax = maintain high pressure to allow blood flow smoothly
Suggest why the rise and fall in blood pressure in aorta is greater than in small arteries (3)
1) aorta is closely linked to the ventricles so pressure is high
2) but aorta has elastic fibres
3) so will recoil when contraction
Describe the role of haemoglobin in supplying oxygen to tissues of body (2)
1) oxyhemoglobin formed when associate with oxygen in high O2 pp area like lungs
2) oxygen is then released from oxyhemoglobin in area of low O2 pp like capillaries to supply cells for respiration
Explain the role of heart in formation of tissue fluid (2)
1) contraction of Ventricles
2) causes high hydrostatic pressure so allow fluid to be drawn out into forming tissue fluid
