7 Flashcards
Function of capillaries
Site of exchange between blood and tissue
Function of capillaries requires
- very thin walls (thick wall make it a barrier to exchange processes)
- large CSA of capillary bed
- slow and moved blood flaw
Large total ____ of the _____ _____ (compared to arteries) means much ________ _____ _______
Latte totals area of capillary bed (compared to arterioles) means much slower blood flow
Strucutre of capillary
Capillary is just a cell (endothelial cell) forming a tube (no imina or media)
- blood cells in single file
Electron microscopy in lumen of capillary - CONTINOUS
8-10 micrometers in diameter
- only one blood cell in single file at once
- this means passage of diffusion is short for oxygen
- intercellular junctions - tight junctions - forms a seal - this depends on how leaky the capillary is
Precapillary sphincters function
- can dial up and dial down how much blood gets to capillary bed
- at inflow sites precapillary sphincters wrap around terminal arteriole - these can constrict prevent blood going into side pathways
- this forms a direct pathway through the vascular shunt to the venuole
- can get partially shut off - its a dial system not on/off - fills half capillary bed
What are precapillary sphincters made of
Precapillary sphincters are composed of smooth muscle cell
- involuntary contraction - smooth muscle - involuntary muscle - under autonomic tone
Terminal arteriolr and postcapillary
The strucurte of capillaries varies according to the ________ of _______ needed, and how _____ the ________ must be
The structure of capillaries varies according to the rate of exchange needed, and how controlled the exchange must be
Which cells of the cell wall do you alter to make the capillary more or less leaky?
Endothelium cells
Three types of capillary structure
- Continuous capillaries (most wide spread)
- Fenestrated capillaries (leaky)
- Sinusoid capillaries (very Leaky)
Continuous capillary
- Intercellular Cleft is tightly fused
- found in skeletal and cardiac muscle
- no adventiia or media
- specific size - efficient diffusion - only one red blood cell
Diameter of continuous capillary
8-10 micrometer diameter
Epithelial cell of lumen determines leakyness by how many tight cells it lays down
Yep
Basement membrane
- layer of extracellular matrix - collagen ( not phospholipid )
- layer of tissue that site around cells and is an anchor point
Fenestraded capillary diameter
8-10 micrometers
Structure of fenestrated capillary
- endothelium cells are fenestrated - physical openings
- allows things to go from the lumen to the basal surface of the cell without going inside cell - through pore
Example of location with fenestrated capillary
- to form urine we run blood through fenestrated capillaries so its easier for fluid to leave blood vascular space and into the glomerulus
Fenestrated capillary in small intestestion
Diameter of sinosoidal capillaries
30-40 micrometers
Fenestrated capillary structure
- gap in basement membrane
Sinusoidal capillary structure
- not primarily focused on diffusion as 2 or 4 blood cellls can fit
- big openings are still smaller then cells
- membrane doesn’t form complete seal
Processes
Fenestrated may not even have to pass through membrane
What is the lymph vascular system
- open entry drainage system
Function of lymph vascular system
- drains excess tissue fluid and plasma proteins from tissues and returns them to the blood
- filters foreign material form the lymph
- ‘screens’ lymph for foreign antigens and responds by releasing antibodies and activated immune cells
- absorbed fat form intestine and transports to blood
Lymphatic vessel structure
- commence as large, blind ending capillaries
- form small intestine, a special group of lymphatic vessels called lacteals drain fat-laden lymph into a collecting vessel called the cisterns chyli
- larger (thin wall =, just like veins) collecting vessels have numerous valves to prevent blood flow
Why is lymphatics important
- to prevent swollen tissue
- in lymphatics the endothelium isn’t continuous seal allowing fluid to enter
Concentration of s
Features of the lymph
- lymph vessels are very thin - transparent
- VALVES: leaflets stop back - shows which way blood is following
- No Red blood cells (only white blood cells)
- not part of blood vascular blood system? Are lymphatic
Regions of the bodies drained by lymph nodes
Lymph collecting vessels are…
… all throughout our body
- very very small
Left Upper body all drains into the..
Entrance of thoracic duct into left subclavian vein from the thoracic duct
Right subclaivian vein from the right side
Lacteal
- big capillary in blood vasualar space in amongst the capillary bed
- takes up a lot of fat
- drains into lymphatic until reaching the distal part of thoracic duct called the cisterns chyli
Lypmnode sturucte
- fine strands running through them
Hanging on the strands are immune cells - lymph from periphery comes in through afferent lymphatics
-lymph goes through fibres with immune cells - runs out through efferent lymphatic
- if lymph pocked up forgein antigens immune cells become activated
- drains form breast, through axillary lymph nodes, and joins form right lymphatic duct forming connection with right subclaivian vein
Metastatic cancer
Breast tissue lymphatic drainage can carry cancer cells into the blood vascular system
- if there are tumor cells in armpit lymph nodes it tells you there may be more in the blood vascular network
