Blood vessels Flashcards
Which of the following describe structure of BV
Tunica interna is a layer the lines the blood vessel and is exposed to blood.
E all the above
Describe endothelium
barrier to platelets and erythrocytes, allow substrates to pass, produce chemicals that control artery tone
Describe layers of tunica and structure
Provide structure and rigidity to blood vessel.
Describe major blood vessels
Arteries are sometimes called resistance vessels. Expand during systole and recoil during diastole.
Which describe medium sized arteries
Provide blood to major organs. 3/4 smooth muscle
Describe small aterioles
Control blood flow to major organs/tissues. Have thicker tunica media and little tunica externa
Aneurysm is a process by which the arterial wall thins forming a bluging sac that can burst with each heartbeat
TRUE
Which describes the pathology of aneurysm
blood accumulates between tunica layers separates them. tend to form in adomal aorta, renal arteries, ruptures cause hemorrage, caused by syphallis
Common cause of aneuysm
atherosclerosis & Hypertesion
What is true of arteries?
Arterial receptors transmit outputs to the brainstem to regulate heart rate, vasomotion and respirtation. Carotids contain baroreceptors.
Which following describes cartid bodies and aortic bodies
chemoreceptors monitor O CO2 ph . small round bodies near arties.
Capillaries is where nearly all fluids, nutrients wastes are exchanged.
True.
Capillaries are composed by
Basal lamina, endothelial cells
What are capillary structures?
Fenestrated, sinusoids, continuous
Describe continuous capillaries.
Lined with pericytes that can contract to regulate blood flow, endothelial cells forming a tube with intercellular clefts, allow passage of substrates like glucose
Fenestrated capillaries
Endothelial cells riddled with holes or filtration pores. locted where filtration is necessary or maximum
Synusoids
includes bone marrow, liver and spleen. Allow proteins to cross capillary bed, allow for secretion of new cells into bblood stream. irregular blood filled tissues.
True regarding capillaries.
3/4 capillaries shut down to blood flow. Metarterioles supply blood to capilary beds. Meta arterioles surpass closed caps and directly supply blood to venules
What opens an closes capillary sphincters
Muscle at rest closes capillary sphincters. fulls tomach opens capillary sphincters
Veins
decreased capacity for blood containment than arteries. merge to form larger veins.
Post capillary venules
. No muscle fibers with some fibroblasts and tunica interna.
Muscular venules
up to 1mM in diameter. Have one or 2 layers of smooth muscle in tunica media. have thin tunica externa
Medium veins
failure of venous valves results in vericose veins. up to 10mM in dia. skeletal muscle pump propels blood
Describe structure of blood vessel.
Walls of arteries and veins, composed of 3 layers called TUNICS. Tunica interna, tunica media, tunica externa.
Describe different types of arteries.
Arteries: Efferent vessels of cardo system. Carry blood AWAY from heart. Resistance vessels. resists high blood pressure. More muscular than veins.
1) Conducting (large/elastic): biggest arteries. Internal elastic lamina, border bwtn interna and media. Media 40-70 elastic sheets perforated like swiss cheese. External elastic lamina. Stiffen by athersclerosis can’t expand or recoil as freely.
2) Distributing (muscular/medium): distribute blood to specific organs. Internal and external elastic laminae, thick and conspicuous.
3) Resistance (small): Thicker tunica media in proportion to lumen. Smallest arteries called arterioles. very little tunica externa.
Describe different types of Capillaries.
1) Continuous capillaries: Occur in most tissues, skeletal muscle. Basal lamina surrounds epithelium. Endothelial cell separated by intercellular clefts (small solutes can pass, but big molecules, proteins, etc. are held back). Some have cells called pericytes.
2) Fenestrated: endothelial cells with holes. Allow for rapid passage of small molecules. Kidneys, endocrine glands, small intestine, choroid plexus of the brain.
3) Sinusoids: Irregular blood-filled spaces in the liver, bone marrow, spleen and other organs. Separated by wide gaps, no basal lamina, large fenestrations.
Describe different types of Veins.
Thin walled and flaccid, expand easily to accommodate an increase volume of blood.
1) Postcaillary venules: smallest of veins. More porous than capillaries. Venules exchange fluid with surrounding tissues.
2) Muscular venules: Receive blood from postcapillary venules. Have a tunica media of one or two layers of smooth muscle, and a thin tunica externa.
3) Medium veins: Most veins with individual names are in this category. Most form venous valves directed toward heart. Varicose veins result with failure of valves.
4) Venous sinuses: very thin walls, large lumens, and no smooth muscle. Coronary sinus of heart, and dural sinuses of brain. Not capable of vasomotion.
5) Large veins: diameters greater 10mm. Smooth muscle in all 3 tunics. Thin media, moderate amount of smooth muscle. externa thickest, longitudinal bundles of SM. Venae cavae, pulmonary veins, internal jugular veins, renal veins.
Trace the general route usually taken by the blood from the heart and back again.
Heart -> arteries -> capillaries -> veins -> heart.
Portal system: Blood flows through two consecutive capillary networks before returning to heart. Occur in kidneys, connecting hypothalamus and anterior pituitary, intestines to liver.
Anastomisis
Point where two blood vessels merge.
Arteriovenous anastomosis (shunt)
Blood flows from an artery directly into a vein and bypass the capillaries. Occur in fingers, palms, toes, and ears, reduce heat loss in cold weather by allowing warm blood to bypass these exposed surfaces.
Venous anastomoses
one vein empties directly into another. Provide several alternative routes of drainage from an organ, so blockage of a vein is rarely as life-threatening as blockage of an artery.
Arterial Anastomosis
Two arteries merge provide alternative routes of blood supply to a tissue.
Describe 3 layers of tunics
1) Tunica Interna: Lines inside of vessel and is exposed to blood. Simple squamous epithelium called endothelium. Secretes chemicals that stimulate dilation or constriction. Repels blood cells and platelets so they don’t stick. If damaged, form blood clot.
2) Tunica media: middle layer and usually the thickest. Consists of smooth muslce, collagen, and sometimes elastic tissue. Strengthens vessels and prevents blood pressure from rupturing them. Provides vasomotion.
3) Tunica externa: Outermost layer. Consists of loose connective tissue that merges with neighboring blood vessels, nerves, other organs. Vasa vasorum small vessels that supply blood to outer half of wall or larger vessel.
How is the Tunica Media different in a conducting artery, arteriole and venule.
Conducting artery: Consists of 40-70 layers of elastic sheets, perforated like swiss, alternating with thin layers of smooth muscles, collagen, and elastic fibers. Dominated by elastic tissue. Media is LARGER than externa.
Arterioles: Thicker tunica media, very little tunica externa.
Venule: Muscular have tunica media of 1 or 2 layers of smooth muslce, and thin tunica externa.
What is the difference between a medium vein and a medium (muscular) artery? What is the functional reasons for these differences?
Medium veins: Tunica media is thinner than in medium arteries. Exhibits bundles of smooth muscles, but no continuous smooth muscle layer. Thick tunica externa. Thin internal elastic lamina.
Medium (muscular) artery: Have up to 40 layers of smooth muscle that takes up 3/4 of wall thickness. Both internal and external elastic lamina are thick and conspicuous. Distribute blood to specific organs.
Anastomosis/portal system -vs- typical pathway for blood flow
Anastomosis/portal systems have to flow through 2 or more capillary beds before going through to the heart. Portals systems goes through 2 capillary beds. Anastomosis blood flows from an artery directy into vein bypassing capillary bed (poss. frostbite) venous most common. arterial two arteries merge routes of blood supply to tissue.
Typical pathway heart ->arteries->capillaries -> veins -> Heart
Anastomosis/portal system -vs- typical pathway for blood flow
Anastomosis
Anastomosis/portal system -vs- typical pathway for blood flow
Anastomosis/portal systems have to flow through 2 or more capillary beds before going through to the heart. Portals systems goes through 2 capillary beds. Anastomosis blood flows from an artery directy into vein bypassing capillary bed (poss. frostbite) venous most common. arterial two arteries merge routes of blood supply to tissue.
What is the relationship between blood pressure, resistance and flow.
My impression is that arterial blood pressure when within normal levels, flows without difficulties into the blood stream. When this normal level raises to a higher one, there is a narrowing in the blood vessels, making the blood circulation more slow and consequently overcharge the heart work, causing fatigue to that person and easing the formation of atheromas. Conclusively a normal blood pressure makes the blood circulation becomes more efficient, thus nourishing cells better.