Exchange & the lymphatic system Flashcards
what is the starling equation
it is an equation that illustrates the role of hydrostatic and oncotic forces in the movement of fluid across capillary membranes
what are the 3 processes that capillary movement may occur
diffusion
filtration
pinocytosis
describe the lymphatic system
the network of vessel through which lymph drain from the tissues into the blood
describe the blood brain barrier
a semipermeable membrane separating the blood from the cerebrospinal fluid, and constituting a barrier to the passage of cells, particle and large molecules
what is the blood brain barrier
it is a highly selective semi-permeable membrane barrier
what does the blood brain barrier separate
the circulating blood from the brain and extracellular fluid in the central nervous system
describe 3 important functions of the blood brain barrier
- protect the brain from foreign substances in the blood that may injure the brain
- protect the brain from hormones and neurotransmitters in the rest of the body
- maintains a constant environment for the brain
what is the role of capillaries
to carry blood to tissue cells and capillaries are the exchange site of nutrients, gases, wastes etc.
what is the goal of coagulation
fibrin formation
what does activation of the coagulation cascade lead to
the production of thrombin
what does thrombin then convert
fibrinogen to fibrin
what do physiological anticoagulation mechanisms act to reduce
thrombin production or to reduce the effects of thrombin
what are collateral arteries
they are the arteries that come after coronary arteries
what makes up the arteriole wall
smooth muscle
where does the greatest change in blood pressure and velocity of blood flow occur
at the transition of arterioles to capillaries
what are metarterioles
they are short vessels that link arterioles and capillaries
what do metarterioles have instead of continuous tunica media
they have individual smooth muscle cells
what does each individual smooth muscle cell in metarterioles form
a pre-capillary sphincter that encircles the entrance to that capillary bed
what is the arteriovenous bypass also called
the arteriovenous shunt
what is the arteriovenous bypass
the passage of blood directly from arteries to veins, without going through the capillary network
what are pre-capillary sphincters
they are bands of smooth muscle that adjust blood flow into capillaries mainly in the mesenteric microcirculation
where does a smooth muscle fibre encircle the capillary
at the point where each of the capillaries originates from an arteriole
what is a venule
a very small vein, especially one collecting blood from the capillaries
describe the gross structure of capillaries
they are specialised for blood exchange, there are lots of them, they are thin walled and have a small diametere
what is meant by the ultrastructure
it is the fine structure, especially within a cell, can be seen only with high magnification obtainable with an electron microscope
what does clotting involve
formation of a platelet lug and a fibrin clot
what is carrier mediated osmosis
it is the movement of molecules across the cell membrane via special transport proteins that are embedded within the cellular membrane
describe the diffusion of oxygen from the alveoli
oxygen diffuses from the alveoli into the blood in the capillaries
describe the diffusion of carbon dioxide from the blood
carbon dioxide from the blood moves out of the capillaries into the alveoli
describe the diffusion in general of oxygen and carbon dioxide
oxygen and carbon dioxide more from where there is a large concentration to where there is a lower concentration
describe bulk flow
it is the movement of water and solutes together due to a pressure gradient
what is hydrostatic pressure
it is the pressure exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity
hydrostatic pressure increases in proportion to depth measured from the surface because…
of the increasing weight of fluid exerting downward force from above
what is oncotic pressure
it is a form of osmotic pressure exerted by proteins, notably albumin, in a blood vessel’s plasma that usually tends to pull water into the circulatory system
what is oncotic pressure the opposing force to
hydrostatic pressure
describe the lymphatic system
the network of vessels through which lymph drains from the tissues into the blood
describe lymph capillaries
tiny thin walled vessels located in the spaces between cells which serve to drain and process extra-cellular fluid
what is a lymph node
it is a small swelling in the lymphatic system where lymph is filtered and lymphocytes are formed
what are lymphatic vessels
they are thin walled vessels structured like blood vessels, that carry lymph
what are lymphatic vessels complementary to
the cardiovascular system
where do lymphatic vessels drain lymph to
into the right and left subclavian veins respectively
what are lymph valves
any one of the tiny semilunar structures in the vessels and trunks of the lymphatic system
what is the role of lymph valves
they help to regulate the flow of lymph and prevent venous blood from entering the systemic blood capillaries
basically describe lymph valves
these are one-way valves that prevent backward flow of lymph in lymph vessels
what is oedema
it is a condition characterised by an excess of watery fluid collecting in the cavities or tissues of the body
what are signs of oedema
swelling or puffiness of the tissue directly under your skin especially in your legs or arms
stitched or thing skin
skin that retain a dimple, after being pressed for several seconds
increased abdominal size
what intact blood vessels central to
moderating blood’s tendency to form clots
what do the endothelial cells of intact vessels prevent
blood clotting with a heparin-like molecule and thrombomodulin and prevent platelet aggregation with nitric oxide and prostacyclin
what are the functions of the lymphatic system
removal of interstitial fluid from tissues
absorbing and transporting fatty acids and fats as chyle from the digestive system
transporting white blood cells to and from the lymph nodes into bones
what are causes of oedema
often a symptom of an underlying health condition
list conditions and treatments that oedema can occur as a result of
pregnancy kidney disease heart failure chronic lung disease liver disease malnutrition medication - corticosteroids, medicine for hypertension the contraceptive pill immobility standing for long periods blood clots severe varicose veins leg injury leg surgery burns to the skin
