Unit 3 - Blood and blood vessels Flashcards
What is plasma?
Liquid component of blood
What is the function of plasma?
Transports dissolved substances e.g glucose, amino acids, mineral ions, hormones, albumin and fibrinogens
Why is albumin important?
It helps to maintain osmotic pressure
Why are fibrinogens important?
Involved in blood clotting
What are platelets?
Small fragments of cells
Which is the function of platelets?
Start the process of blood clotting
What triggers blood clotting?
- a rough surface
- exposure to air
What is the function of erythrocytes?
-carry oxygen and carbon dioxide around the blood
What are the characteristics of granulocytes?
- lobed nucleus
- granular cytoplasm
What are the characteristics of monocytes?
- kidney bean shaped nucleus
- cytoplasm not granular
What are the characteristics of lymphocytes?
- large round nucleus
- cytoplasm not granularr
What is the function of granulocytes?
- some phagocytic
- involved in allergy/inflammation
What is the function of monocytes?
-involved in defence against pathogens
What is the function of lymphocytes?
-produces new antibodies
What are the functions of blood as a whole?
- transport of oxygen and carbon dioxide to and from respiring cells
- transport hormones
- transport nitrogenous waste products from cells to excretory organs
- transporting cells and antibodies involved in the immune response
- helps to maintain steady body temperature
- acts as a buffer to minimise pH changes
What are the 3 layers of arteries called?
Tunica intima
Tunica media
Tunica externa
What makes up the tunica initima?
squamous epithelial
What are the functions of the arteries?
Carry oxygenated blood away from the heart apart from the pulmonary artery
What is bloodflow into arteries like?
- high pressure
- pulsatile
- fast
Why do arteries need to maintain high pressure of the arteries?
So that blood can reach tissues in the body
What makes up the tunica media of the arteries?
Smooth muscle and elastic fibres
What makes up the tunica externa of the arteries?
Collagen
What do the elastic fibres in the tunica media of the arteries do?
Stretch to receive blood and recoil between contractions of the heart which helps to maintain pressure and even out bloodflow
What is the function of collagen in the tunica externa of arteries?
Prevents blood vessels from bursting under high pressure
Why is the tunica initmia of arteries smooth?
So blood flows over it easily
What does contact of blood with artery walls cause?
- friction
- slows blood down
- evens out pulsatile flow
What is the function of laminas?
Separate the inner from middle and the middle from outer
What is the function of basement membranes?
Anchors the endothelium to the connective tissue and supports endothelial cells
What is the function arterioles?
regulate the flow of blood into capillaries
Do arterioles have a higher proportion of smooth muscle than arteries?
Yes
What is the function of the smooth muscle?
It is neuronally stimulated causing vasoconstriction of vasodilation which controls the flow of blood into capillaries e.g during body temperature regulation
Why do arterioles have a lower proportion of elastin in their walls compared to arteries?
The blood flow isn’t very pulsatile
Why is blood slower in the arterioles?
Due to friction with the vessel walls
How does the slightly wider lumen in arterioles affect pressure?
Reduces it slightly
What is the function of capillaries?
To exchange substances between the blood and tissues
What is the advantage of capillaries being one cell thick?
Gives a short diffusion path
What is the advantage of blood flow being slow through capillaries?
Gives a longer time for the exchange of substances
Why is the blood flow low pressure through capillaries?
Prevents them from bursting
Pressure is spread across many vessels
What is blood flow like through capillaries?
Smooth, low pressure, slow
What is the function of venules?
to link capillaries to veins
What are the walls of venules mostly made of?
Collagen
Why do venules have a thin tunica media?
low pressure flow doesn’t require muscle or elastic fibres
Why do veins have a wide lumen?
To accommodate the large volume of blood carried
What is the blood flow through veins like?
Very slow, low pressure, smooth
Why are valves present in veins?
Prevent backflow
What 3 mechanisms aid blood flow back to the heart?
-Movement of skeletal muscles contract/relax and push
blood through veins as they lie near the surface
-Pocket valves prevent backflow
-Breathing mechanism causes negative pressure in the thorax so pulls blood towards the heart
