lecture 7 Flashcards
what 3 things does the capillary function demand
very thin walls for efficient diffusion
Large total cross sectional area of capillary bed.
slow and smooth blood flow
what allows the slow blood flow in capillaries
despite the quick and somewhat pulsatile flow of the ateries, the CSA of the capillary beds is large which slows the pulsatile nature.
describe the makeup of the capillary
it is a single endothelia cell which is rounded to join to itself via tight junctions. thus the capillary has a thin wall diameter of 1 cell
3 types of capillary
continuous, fenestrated and sinusoidal
describe the continuous capillary
8-10 micron in diameter, continuous basement membrane and no holes in the membrane
describe the fenestrated capillary
8-10 micron in diameter, continuous basement membrane, does have fenestrations in the membrane, these fenestrations allowing movement of water soluble molecules
describe the sinusoidal capillary
30-40 um diameter, the larger capillary type. have discontinuous basement membrane and discontinuous epithelial lining. these are not just for gas exchange, which explains large diffusion distance.
function of sinusoidal capillary
to allow plasma to pass into the surrounding tissues without the RBCs.
where can we find each of the capillary types
continuous- most common type- skeletal and cardiac muscle
fenestrated- kidney and the small intestine
sinusoidal- the liver sinusoids
what happens in the liver sinusoids
where blood is cleaned and detoxified.
what are the 4 types of movement facilitated by the capillaries
water soluble movement through intercellular clefts
lipid soluble diffusion through the plasma membrane
active transport via vesicles- movement of large substances
water soluble movement through fenestrations and sinusoids.
what movement types do the continuous capillaries allow
intercellular clefts, diffusion across membrane and active vesicle transport
what movement types do the sinusoidal and fenestrated capillaries allow
intercellular clefts, diffusion across membrane and active vesicle transport and movement through fenestrations
functions of the lymph vascular system
- Drains excess tissue fluid & plasma proteins from
tissues and returns them the blood. - Filters foreign material from the lymph.
- ‘Screens
’ lymph for foreign antigens & responds by
releasing antibodies & activated immune cells. - Absorbs fat from intestine and transports to blood.
describe the structure of the lymphatics in the periphery
Commence as large, blind ending capillaries. with a wall that is one cell thick, they contain valves but do NOT CONTAIN RBC
what does blind ending capillaries mean
this means there is no specific, constant inflow into the capillary.
what collects lymph from the small intestine
the lacteals
where do the lacteals drain fat laden lymph to and where does this lead to
to the cisterna chyli which then leads to the venous system to be recycled
whats the path of lymph from the right breast
the auxillary lymph nodes, to the right thoracic duct to the right subclavian vein
whats the path for the left breast lymph
the auxillary nodes to the thoracic duct then to the left subclavian vein
why is breast cancer so dangerous
because there are many lymph vessels in the breast, so the cancerous tissue can easily get into lymph and blood system. thus travelling round the body.
