Blood Flashcards
What are the 5 types of vessels?
Arteries, capillaries, veins, arterioles, venules
Artery function
Takes high pressure blood away from the heart to the other body regions.
Artery size
Less than 18mm (aorta)
Artery layers inside to out and other structural features
Tunica interna (endothelial cells) - smooth endothelium to to minimise friction Tunica media (smooth muscle) - lots of elastic tissue to accommodate surges in blood flow from ventricles by stretching and recoiling -> helps maintain high pressure Tunica externa (elastin and collagen) - thick walls to resist high pressure -> collagen helps specifically with this Narrow lumen
Features of arterioles
Same as artery but can also adjust diameter to adjust blood supply by contracting (vasoconstriction -> reducing blood flow to capillary) or relaxing (vasodilation -> increasing blood flow to capillary)
Capillary structure
There are small gaps between the cell so solutes can leak out. Capillaries link small arteries with small veins and allow exchange of materials with tissues. Large number in the body so a high surface area. The walls are only one cell thick and there is no elastic tissue. There is a small diameter of the lumen with friction which slowers the flow but enhances the ability to exchange materials by diffusion.
Vein layers inside to out and other structural features
Tunica interna (endothelial cells)
Tunica media (smooth muscle) - little elastic here -> much thinner than in arteries
Tunica externa (elastin and collagen) - much thinner than in arteries - outer layer of collagen to help resist stretching.
Valves in veins - prevent backflow
Wider lumen allowing a decreased resistance to mass flow of low pressure blood.
Vein size
Less than 30mm (vena cava)
Vein function
Returns low pressure blood to the heart from the lungs in the body
How does skeletal muscle assist veins?
It contacts around the vein to create pressure to return blood to the heart.
Describe and explain the relationship between total cross-sectional area and velocity of flow
As the total cross-sectional area increases, the velocity of flow decreases. the pressure is spread out over a larger area and so volume as there are progressively more blood vessels from an artery to a capillary bed. There will also be increasingly more friction with the walls of the blood vessel which will reduce flow and pressure.
Red blood cell structure
Biconcave shape, no nucleus when mature. 2.5micrometres height, 7.5micrometres diameter
Plasma
A water based constituent of the blood that allows hormones, nutrients, antibodies, amino acids and more to be suspended in.
Plasma location
Capillaries
Plasma constituents
hormones, dissolved nutrients e.g. glucose, antibodies, amino acids, large plasma proteins (help maintain waterpotential of blood), RBCs and WBCs (but sometimes not classed as constituents of plasma), mineral ions, CO2, fatty acids, glycerol, urea
Tissue fluid location
Around cells in tissue
Lymph fluid location
Lymph vessel
Tissue fluid constituents, compared to plasma
No RBCs, fewer WBCs, no large plasma proteins but all the dissolved nutrients e.g. glucose
Role of blood
Transport medium through the plasma.
Distributes heat (+ chemical) energy
Suspension for cells (RBCs and WBCs)
Percentage composition of blood
Plasma 55%
White blood cells and platelets <1%
Red blood cells 45%
White blood cells (WBCs)
Used for defense (immune system)
Red blood cells (RBCs)
Carry oxygen and carbon dioxide
Kwashiorkor
Lack of protein in the diet means that plasma proteins are not produced in the body. this means that the water potential of the blood is not low enough compared to the tissue fluid and therefore the fluid is lost from the arteriole of the capillary bed but it is not returned at the venule’s end. The lymphatic system cannot draw off all the excess and so an Oedema forms.
Tissue fluid function
To deliver nutrients to the tissues from the capillary
What does the oxyhaemoglobin dissociation curve show?
The relationship between levels of oxygen in the tissue fluid and saturation of haemoglobin with oxygen in the blood.
How many haemoglobin molecules are there per red blood cell?
270 million
Associate definition and dissociate definition
Loading oxygen onto Hb and unloading of oxygen of Hb when delivering to body cells
What does Hb mean?
Haemoglobin
Affinity
Attraction between molecules
Structure of haemoglobin
4 polypeptide chains - two alpha and two beta.
3D globular shape
Metabolic role
Prosthetic group is haem - Fe2+
Function haemoglobin
Carriage of oxygen and carbon dioxide
What shape the oxygen dissociation curve?
S-shaped, sigmoid
Prosthetic group
Thing added to protein that is not a protein, at golgi body
Why why doesn’t percentage saturation of haemoglobin with oxygen reach 100%?
It is difficult for the last oxygen molecules to associate with the 4th haem group. Max is 98% roughly
Reason for steep rise in saturation in the middle of oxygen dissociation curve
Change in shape of Hb molecules makes it easy for more oxygen to associate
Why doesn’t haemoglobin take oxygen up easily at low partial pressure oxygen?
The haem groups are hidden.
How do humans adapt to high altitude?
They get more red blood cells
