What are your arterioles and why are they important?
Smallest arteries that regulate blood flow into capillary beds.
Easy Question You should know by now: Systole is what?
When the heart contracts duh.
Easy Question You should know by now: Diastole is what?
when the heart relaxes
The recoil of a distended elastic artery is called what?
What is a dissecting aorta?
when you aorta can't take the pressure from expansion and as a results rips through the inner t. intima layer and can even rip the t. media. You get a seperation of the layers, and blood flowing through the other layers.
Rips all the way? Du bist schnell tot. Rips partially? Blood ends up in the t. media which needs to be fixed.
What is characteristic of the larger muscular arteries?
They have less elastic fibers in the middle of the t.mediaAlso have Inner/external elastic lamina that seperates external media from adventitia
True or False? The largest muscular artery will have both an Internal/External elastic lamina?
TRUE: the largest muscular arteries have both layers--
As the artery gets smaller you lose the external elastic lamina first and the internal elastic lamina last.
How do you recognize a muscular artery?
The INTERNAL ELASTIC LAMINA!Seperates the tunica intima from the tunica media.
Capillaries don't have any _______?
If it has muscle around the vessel it is called a metarteriole not a capillary.
An arteriole has what in its tunica media?
2-3 layers of SMOOTH MUSCLE cells.
A muscular (medium caliber) artery has what in its tunica media?
up to 40 LAYERS of SMOOTH MUSCLE
Veins have a smaller _______ than arteries of the same size?
*instead veins can have more smooth muscle in the adventitia, to help blood move along
Veins have _______ present in the tunica adventitia that is a major feature to distinguish them from arteries.
Smooth muscle bundles are present in the tunica adventitia which contract and cause parastaltic motion that moves the blood along
What have more vasa vasorum, large arteries or large veins?
because veins carry deoxy blood, to compensate, the larger veins typically contain more vasa vasorum to provide metabolites to the thick t. adventitia
How do you differentiate between an artery and vein?
LOOK at the size of the WALL
Veins have thinner walls than arteries
Lumen of vein is much larger relative to the size of the tunics
Veins have _____ arteries do not.
Valves!Used to regulate blood flow, prevent backflow of blood
The valves of veins are made from what layer? and composed of what fibers?
tunica intima jutting out into the lumen
Reinforced with collagen and elastic fibers
Purpose: PREVENT BACKFLOW :(
What are varicose veins?
If the one-way valves in your veins fail to close, blood will pool in the vein
Over time, the pooling will force the vein walls outward resulting in enlargement and ugly bulging of the vein, making to look rope-like.
MORE COMMON IN WOMEN--less developed skeletal muscle, being overweight can also contribute to this as well.
Capillaries serve what purpose?
Junction between arteries and veins
Major place for exchange of gases and nutrients btw. bloodstream and extravesicular tissue
***THIS is WHY we need a circulatory system.
The heart is just a pump, A/Vs are just transporters, the capillaries are where the action is
Capillary blood flow can be controlled with precapillary sphincters, but what is the name of the channels that always alows blood to flow from the artery to the vein?
Called Thoroughfare channels
What are the three types of capillaries
Continuous (least leaky)
Discontinuous (most leaky)
Each capillary is composed of a _______layer of endothelium attached to a basal lamina
What are pericytes?
Associated closely with capillaries and post-capillary venules, they have contractile function (contain actin & myosin, tropomyosin
WHY? because remember capillaries lack a tunica media and muscle and pericytes take the place of the muscle in the tunica media.
Allows blood to continuously flow though capillaries
_________ capillaries contain lots of pinocytotic vesicles responsible for transport of large macromolecules in both directions across the endocytotic cytoplasm
Continuous (or somatic) capillaries
Why does skeletal muscle have lots of capillaries?
Capillaries provide the oxygen & nutrients to the muscles in order to contract!
Where do you find a lot of fenestrated capillaries?
Tissues where rapid interchange of substances occus between the tissues and the blood
KidneyIntestine (for nutrients)
Fenestrated capillaries are different from continuous capillaries how?
Have PORES or "windows" bridged by an ultrathin diaphragm! (allows movement of substances across capillaries)
WHAT IS THIS?
A fenestrated capillary of the glomerulus of the kidney.
NAME the STRUCTURE the ARROWs pointing to
Each arrow is a Fenestration with a diaphragm, picture is then of a fenestrated capillary.
What are the leakiest capillaries?
Sinusoidal (discontinuous) capillaries
Have HUGE gaps btw endothelial cells
Incomplete basal lamina
What organs do you find Sinusoidal (discontinuous) capillaries?
Hematopoietic organs (megakaryocytes send their projections through these holes)
***Whole CELLS will pass through these large holes
Cavelolae are very numerous in endothelial cells, they function to ______ ?
Shuttle material across the endothelial wall!!
Adluminal refers to what?
The side of a vessel facing the lumen
Abluminal refers to what?
The side of a vessel directed away from the lumen
b for beyond!!!!
Blood brain barrier (BBB) has what?
A special type of capillary which lets essential metabolites (O2, glucose) pass from blood to brain and CNS but blocks molecules bigger than 500 daltons.
The BBB has extensive _____________ that resemble the ___________ of epithelial cells
Tight tight tight tight tight junctions.
What is one part of the brain NOT "behind" the BBB?
the PINEAL GLAND which secretes hormone melatonin directly into the systemic circulation.
Must Know: What are the four types of microcirculation?
1.) Normal: Arteriole --> metarteriole-->capillary-->venule and vein
2.) Arteriovenous anastomosis (direct communic. btw arterioles and venules, no capillaries --> ie, penis clitoris
4.)Venous portal system: present in liver (venule-->capillary-->venule
Sequence of an arterial portal system?
ie KIDNEY glomerulus
Example of an arteriovenous anastomosis?
Penis & Clitoris (normally closed off with a sphincter!
Sequence of a venous portal system?
What are the three layers of the heart? Which is the thickest?
Endocardium: continuous with tunica intima of blood vessels entering heart
Myocardium (middle and thickest layer)
Epicardium: the outer most layer of the heart, called the visceral layer of the pericardium
Be familar with the three layers of your heart (endocardium, myocardium and epicardium
What type of tissue is this?
Cardiac muscle tissue, dark red is myocardium
Endocardium is above it and is stained purple
Pale fibers are the PURKINJE FIBERS in the endocardium
What are these structures with the nuclei and light area around them?
These are purkinje cells
The light area around the nuclei of the conducting cells is caused by local accumulation of glycogen
______________ is the chronic disease characterized by abnormal thickening and hardening of the arterial walls with resulting loss of elasticity.
______________ is an arteriosclerosis characterized by the deposition of fatty substances in and fibrosis of the inner layer of the arteries.
Athrosclerosis involves changes to what layer of the arteries?
the tunica intima
What is an Atheroma? What is a characteristic of?
lipid deposits in the tunica intima of arteries, porducing a yellow swelling on the endothelial surface.
Characteristic of artherosclerosis!
What triggers atheroclerosis?
any damage to the cells lining the arteries
a result of high BP
Atheroclerotic plaques develop how?
1.) Monocyte migrate through endothelial wall and into the intima, where they differentiate into macrophages
2.)Macrophages take up excess LDL (lipid) forming FOAM cells. These foam cells release GF (growth factors, cytokines that act on smooth muscle, so smooth muscle cells migrate secrete collagen and fibrous tissue to heal damage and form a fibrous cap.
What are FOAM cells?
When macrophages that have migrated to a atherosclerotic plaque forming area, and take up lots of LDL (lipid) and take on a different "Foamy" appearance
What is a fibrous cap?
It is a bunch of lipid (fat) that has forms UNDER the endothelial cells, that will become calcified, brittle and could crack and expose collagen, jumpstarting the clotting cascade that can cause a heart attack.