Blood vessels

Created by

Maddie Clayton

Cards (14)

Systemic system
high pressure from the left ventricle to the capillary bed due to contraction
Pressure drop at capillary bed
low pressure from the capillary bed to right atrium
high pressure = High velocity of flow
Low pressure = low velocity of flow
From the ventricle to the capillary bed the total cross sectional area is increasing
Low pressure at the capillary bed due to a huge total cross sectional area
From the capillary bed to the right atrium there is a decrease in total cross sectional area
Capillaries
Exchange surface between blood and body cells
Large surface area - lots of them, large total cross sectional are
Thin for short diffusion pathway - endothelial cells = 1 cell thick
Moist - capillaries are surrounded by tissue fluid and can exchange materials with it
Permeable - the walls have gaps/fenestrations which allows exchange of fluid
Maintain a concentration gradient - good blood supply
Oxygen, glucose and amino acids diffuse into tissue fluid then into the body cell down a diffusion/concentration gradient.
Maintaining a concentration gradient - oxygen and glucose are used in aerobic respiration - amino acids are used in protein synthesis
Heat may leave body fluid
Reducing velocity of flow
= more time for the exchange of molecules
red blood cells have a larger diameter than the lumen of the capillary = increased friction = increased resistance to blood flow
decreased pressure due to increased total cross sectional area
Blood
Plasma:
water
oxygen
glucose
amino acids
hormones
mineral salts (ions)
heat
carbon dioxide
urea
large plasma protein
Cells:
Erythrocytes - red blood cells
White blood cells
Platlets
Large plasma proteins are too large to leave fit out of fenestrations in the capillary wall - they are retained in the capillary - and maintain the low water potential of the blood
At the arteriole end of the capillaries the hydrostatic pressure is high.
At the venule end of the capillaries the hydrostatic pressure is low
Fluid exits the capillaries due to the high hydrostatic pressure.
Fluid goes in due to low hydrostatic pressure and higher osmotic pressure
pressure is maintained in the aorta by elastic recoil of the elastic fibres
Artery structure:
Out to in
A) Tunica externa (collagen fibres)
B) Tunica Media (smooth muscle and elastic fibres)
C) Tunica Interna (smooth endothelium)
D) basement membrane
Artery structure and function:
Thick wall to resist and sustain high pressure
Smooth endothelium - one cell thick - smooth lining to reduce friction and minimise resistance to flow
Thick layer of elastic fibres and smooth muscle to accommodate changes in blood flow and pressure as the blood is pumped out of the heart - stretch and recoil
Outer layer of connective tissue (collagen fibres) resist over-stretching
Narrow lumen to maintain high pressure
Arterioles use smooth muscle to adjust diameter - vasoconstriction/vasodilation
contains high pressure blood flowing away from the heart
Capillary structure and function:
Connects small arteries with small veins and allows exchange of materials with tissues across the capillary wall which is:
thin for a short diffusion pathway - 1 cell thick
narrow diameter = slow moving blood which allows time for exchange
pores/fenestrations leak to allow exchange pf materials e.g. small solute materials and ions through the endothelial cells
Vein structure and function:
thinner wall (especially muscle layer) as the pressure in the blood is now reduced
smooth endothelium - 1 cell thick - smooth lining to reduce friction and minimise resistance to flow
Outer layer of collagen to resist stretching
Has a wider lumen than arteries
Valves along their length to ensure flow of blood in one direction under low pressure - called pocket valves
Low pressure blood flowing towards the heart
Vein structure:
out to in
A) Tunica externa (collagen fibres)
B) Tunica Media (smooth muscle and elastic fibres)
C) Tunica Interna (smooth endothelium)
D) basement membrane