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Peripheral Circulation 1
Lecture 6 Exam 2
51
Pharmacology
Graduate
01/31/2012

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Cards

Term
What are the three major types of blood vessels?
Definition
  •  Arteries - distributing systems
  •  Capillaries - diffusion and filtration
  •  Veins - Collecting system
Term
What is the structure and function of arteries?
Definition
Carry blood away from the heart, efferent flow. High pressure vessels with strong vascular walls.
Elastic arteries - conduct, contain an internal elastic layer
Muscular arteries - distribute. Very thick SM tunica media
Term
What is the function of arterioles?
Definition
Controls flow into capillaries. Smooth muscle in the lumen makes it the major site of blood pressure control. RESISTANCE VESSELS. SM present.
Term
What site is the major site of blood pressure control?
Definition
Arterioles
Term
What is the function of capillaries?
Definition
'Leaky' vessels allow for nutrient and gas exchange. Exchange vessels.
Term
Where is pulsation seen?
Definition
Only in larger arteries?
Term
What is the function of the venules?
Definition
Collect blood from capillaries, coalesce into veins. The postcapillary venules are sites of inflammation. Only possess a tunica externa
Term
What is the function of veins?
Definition
Carry blood back to the heart under low pressure. Large lumens that can greatly expand. Capacitance vessels.
Term
What is arborization?
Definition
Branching of big vessels into smaller vessels. All vessels are arranged in series, except for capillaries which are in parallel.
Term
In the 3 different circuits, which circuit has the most blood? In that circuit, which side has the most blood?
Definition
The venous side of the systemic circuit.
Term
What is the fundamental law of blood vessel branching?
Definition
CSA of a vessel decreases as a result of arborization. However, the total CSA of combined daughter vessels will exceed the CSA of the parent vessel. This is why capillaries have the highest total CSA.
Term
Are there more capillaries present in the systemic circulation or in the lungs?
Definition
In the lungs, have the highest total CSA.
Term
How does CSA relate to velocity?
Definition
v = F/CSA. Therefore velocity is inversely proportional to CSA. Blood flow in the aorta is faster than in a capillary, however aggregate flow in all the capillaries is almost equal to the flow of the aorta.
Term
Which vessels are under high pressure?
Definition
Arteries and arterioles only
Term
How do you calculate mean pressure?
Definition
Mean pressure = Diastolic - 1/3(pulse pressure) and pulse pressure = systolic - diastolic)
So MP = diastole - 1/3(Systole - diastole)
Term
Why don't capillaries have a high resistance?
Definition
Even though they have the smallest diameter, they are arranged in parallel. The more vessels in parallel, the smaller the aggregate resistance.
Term
How do the lymphatic vessels work?
Definition
Hydrostatic pressure pushes fluid out of the capillaries. Fluid is taken up by the thoracic duct, connects directly to the left subclavian and then eventually the vena cava.
Term
What are the differences in structure between veins and arteries?
Definition
Veins are flat, have a larger lumen, possess a valve to prevent backup.
Arteries only possess an elastic lamina. Also have thicker SM
Term
What is vasa vasorum?
Definition
Blood vessels ennervate BV walls in BV that are very thick, such as arteries.
Term
In endothelium, what are permeability barriers?
Definition
tight junctions prevent leaks, though capillaries are intentionally leaky. Also cell surface binding proteins.
Term
In endothelium, what promotes anti-thrombotic activity/prevention of clotting?
Definition
- Thrombomodulin - binds thrombin and allows Protein C to bind
- Protein C - Anti-thrombotic and thrombolytic
-TFPI - blocks activity of thrombin and Xa
- tPa - conversion to plasmin, fibrinolytic
Term
In endothelium, what promotes pro-thrombotic activity/clotting?
Definition
vWF - allows platelets to bind to injury
PAI - inhibits tPa
Thromboxane - a prostaglandin that promotes aggregation
Term
In endothelium, what are vascular factors?
Definition
-PgI2 and prostacyclin - prostaglandins that inhibit aggregation.
- NO - a vasodilator, inhibits aggregation
- EDHF - increases K influx, membrane more difficult to depolarize.
Term
In endothelium, What keeps the surface smooth?
Definition
upregulation of adhesion molecules and chemotactic factors
Term
What receptors are present on endothelium?
Definition
LDL receptors, bradykinin, autonomic.
Term
What type of artery is the aorta?
Definition
An elastic artery. Elastic > smooth muscle.
Term
What is the formula for determining flow?
Definition
Flow = change in pressure/resistance
increase in pressure or a decrease in resistance to increase flow.
An increase in pressure shows a nonlinear increase in flow due to elasticity.
Term
What is critical closing pressure?
Definition
As resistance increases, the point at which blood no longer flows. Sympathetic stimulation constricts, increasing pressure. Increases the pressure at which critical closing will occur.
Term
What goes a graph of flow vs resistance and pressure show?
Definition
As you increase pressure, resistance decreases and flow increases. Sympathetic tone increases resistance.
Term
Which vessel has the largest lumen?
Definition
The vena cava
Term
What are properties of elastic arteries?
Definition
Thick walled and near the heart. Low resistance and high velocity. Not much SNS control. Arteriosclerosis - loss of elasticity. Ex: aorta
Term
What are the properties of muscular arteries?
Definition
Distributing vessels, majority SM with some elastic fibers. Can constrict, with some SNS control.
Term
What are properties of arterioles?
Definition
Mostly SM, significant SNS control. The major resistance vessels. Controls blood flow via resistance, reducing pulsation to a steady flow.
Term
What are some properties of capillaries?
Definition
Only posses a tunica intima. Pericytes stabilize wall and control permeability. Mostly tight junctions, some clefts to allow leakage. Astrocytes maintain tight junctions.
Highest regeneration capacity in the capillaries.
Term
What are the different types of capillaries?
Definition
- Continuous - least permeable and most common. Few intracellular clefts
- Fenestrated - larger pores allowing more permeability. Important for filtration in the kidney
- Sinusoidal - Most permeable with large clefts, important in the liver.
Term
How does the capillary bed control local blood flow?
Definition
If no oxygen is needed, sphincters close and blood goes through anastomosis and thoroughfare channel
Term
How does the structure of the venous system differ from arteries?
Definition
Mostly tunica externa. Thin walls with large lumen. Venules are porous with no elasticity. Veins have 3 layers but little elasticity and SM, large amount of collagen. SNS stimulation causes contraction and displacement of blood. Presence of valves prevent backflow.
Term
What are the 3 mechanisms to increase venous return?
Definition
  1. SNS - Contracts vessels to squeeze blood up and valves prevent backflow.
  2.  Muscular pump - contracting skeletal muscle squeezes vein
  3. Respiratory pump - inhale to create pressure in the abdomen drawing blood up.
Term
What is angiogenesis and vasculogenesis? What are treatments involving angiogenesis?
Definition
Growth of new blood vessels. Vasculogenesis is angiogenesis in fetal development. Stimulate angiogenesis when collateral blood flow is needed in ischemia. Prevent in cancer.
Term
What are the steps in angiogenesis?
Definition
1)Injury of a BV releases growth factors 2)GFs bind to receptors on ENDOTHELIUM on prexisting BVs 3)Endothelium is activated, release matrix metallo-proteanases 4) MMPs dissolve holes in surrounding basement membrane 5) Endothelium divides and sprouts into holes
6) Integrins/adhesion molecules serve as grappling hooks
7) MMPs dissolve tissue in front of new BV 8) Endothelium forms BV tube, connect to form loops, and are stabilized by SM and pericytes.
 
Term
What are 4 important components in angiogenesis?
Definition
Vascular endothelial growth factor (VEGF) - stimulates angiogenesis by signaling endothelium to reproduce and migrate
Fibroblast Growth Factor - growth of endothelium, fibroblasts, and smooth muscle
Angiopoietins - form mature blood vessels and stabilize them
MMPs - form holes in basement membrane and allow sprouting.
Term
What are the components of the axial skeleton?
Definition
The skull, the ribs and sternum, the spine, and the sacrum.
Term
What are the bones of the appendicular skeleton?
Definition
  • Arms - Clavicle and scapula, humerus, Radius and ulna (Ulna towards pinkie), carpals/metacarpals/phalanges.
  • Legs - Pelvic bones and girdle, femur, patella, tibia (large) and fibula, tarsals/metatarsals/phalanges
Term

Where is blood pressure measured?

What are the other major arteries of the arm?

Definition

At the brachial artery

Axillary -->Brachial --> Radial and Ulnar (ulnar towards pinkie) --> palmar arches and digital arteries

Term
What is the nomenclature for abdominal arteries?
Definition

Above the diaphragm -- thoracic aorta

Below the diaphragm -- abdominal aorta

Into the legs: Common Iliacs

Branches off of abdominal aorta:

Celiac trunk - splits off into gastric, splenic, and hepatic arteries
Renal artery
Superior and inferior mesentary - Small and large intestine respectively.

Term

What is the nomenclature of the arteries of the legs/feet?

What branch can be palpated for a pulse in the feet?

Definition

Common iliac --> Internal and external iliac --> Femoral artery --> Popliteal artery --> Anterior/posterior tibial artery and fibular artery --> Plantar artery --> Dorsal pedis and plantar arch.

 

The dorsal pedis can be palpated for blood flow.

Term

What are the veins of the head?

 

Which vein is a sign of heart problems?

Definition
The brachiocephalic vein branches into the subclavian and the large internal jugular. The external jugular runs just below the surface of the neck. Visible distension is a sign of heart problems.
Term

What are the veins of the arm?

 

Which veins are superficial/can you draw blood from?

Definition

Subclavian --> Axillary --> Brachial --> Radial and ulnar veins, palmar venous arches and digital veins

 

Superficial veins: Cephalic vein, Median antebrachial vein, Basilic vein. Blood may also be drawn from the median cubital vein.

Term
What is the nomenclature of veins in the abdomen?
Definition

The common iliac leads into the inferior vena cava.

 

The mesenteric and celiac veins empty into capillary beds in the liver called the hepatic portal system/sinusoids, then empty out the hepatic vein. Capillary --> Vein --> Capillary --> Vein

 

Term
What is the nomenclature of the veins in the leg/feet?
Definition

Iliac --> Femoral --> Popliteal --> Tibial and fibular --> Dorsal pedis vein and arch

 

Saphenous veins are superficial, responsible for varicose veins.

Term
What arteries are most commonly palpated for blood flow?
Definition
  • Posterior tibial artery
  • Right Common Carotid
  • Brachial artery
  • Radial artery
  • Femoral artery
  • Dorsal Pedis
  • Popiteal artery
  • Facial and temporal artery
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