Blood vessels Flashcards
What are the three main vessel types?
Veins, Arteries, Capillaries
Veins carry deoxygenated blood to the heart, arteries carry oxygenated blood away from the heart, and capillaries facilitate gas exchange.
What are the three layers of artery and vein structure and what is the structure of each?
Tunica Interna, Tunica Media, Tunica Externa
Tunica Interna: lines inside blood vessels & repels WBC and RBC from sticking; Tunica Media: middle layer with muscle for contraction; Tunica Externa: outer layer anchoring the vessel.
What is a key structural difference between arteries and veins?
Arteries are diverging and have a thicker tunica media; veins are converging, contain valves, and have larger lumens.
What are the three types of capillaries?
- Fenestrated Capillary
- Continuous Capillaries
- Sinusoids
Fenestrated capillaries have filtration pores, found in kidneys, small intestine, absorption and filtration. continuous capillaries have tight junctions, least permeable. Sinusoids are the most permeable allow albumin and new blood cells
How is blood flow regulated to the capillaries?
Capillary beds have precapillary sphincters that open/close to regulate blood flow to tissue. And vasomotion of arterioles.
What distinguishes pulmonary arteries from other arteries?
They carry deoxygenated blood.
What distinguishes pulmonary veins from other veins?
They carry oxygenated blood.
What is the function of venous valves? What can happen if these fail?
They move blood in one direction and prevent backflow/pooling.
Failure = Varicose veins
What type of vessel contains most of your circulating blood?
Veins.
Which vessel type would remain open without blood flowing in it?
Artery.
What is blood flow?
Amount of blood through an organ, tissue, or vessel.
What is blood pressure and what three factors influence it?
Force of blood on a vessel; influenced by cardiac output, blood volume, and resistance.
What is resistance in the context of blood flow?
Resistance of flow due to friction; sources include blood viscosity, vessel length, and vessel radius.
What happens to resistance as vessel length increases?
Resistance increases.
How does blood pressure change from arteries to capillaries to veins?
Blood pressure decreases with increased distance from the heart.
What are the determinants of velocity in the three vessel types?
Distance traveled, radii, number of vessels in cross-section.
Why do arteries pulse?
Increased blood flow during systole causes artery walls to expand.
What is systolic pressure?
Pressure during ventricular contraction.
What is diastolic pressure?
Pressure during ventricular relaxation.
How is blood pressure controlled locally?
- Metabolic
- Myogenic
- Vasoactive chemicals
Includes factors like vasodilators such as histamine.
What is reactive hyperemia?
Decreased blood flow followed by increased blood flow when a body part falls asleep.
What is angiogenesis?
Creating new blood vessels.
What is a normal blood pressure reading?
120/80.
What defines hypotension?
Low resting blood pressure without a specific number.
What defines hypertension?
Blood pressure greater than 130/80 at rest.
What are the mechanisms of substance exchange in capillaries?
- Diffusion
- Transcytosis
- Filtration & Reabsorption
Diffusion includes lipid-soluble substances; transcytosis involves transport of large molecules.
What are three causes of edema?
- Increased capillary filtration
- Decreased capillary reabsorption
- Obstructed lymphatic drainage.
What are the five mechanisms that aid venous return?
- Pressure gradient
- Gravity/Vasomotion
- Skeletal muscle pump
- Thoracic (respiratory) pump
- Cardiac suction.
How does exercise alter venous return?
Increases heart rate, blood flow, skeletal muscle pump, and thoracic pump.
What is circulatory shock?
Cardiac output insufficient for body needs.
What is a TIA?
Brief episodes of cerebral ischemia, warning of impending stroke.
What is a stroke (CVA)?
Sudden death of brain tissue due to ischemia.
Why is an air embolism dangerous?
Bubbles can block vessels.
What is ascites?
Abnormal distension due to serous fluid buildup in the peritoneal cavity.
What are the different types of veins?
- Post capillary venules
- Muscular venules
- Medium venules
- Large veins.
What are the types of circulatory shock?
- Hypovolemic shock
- Obstructed venous return shock
- Venous pooling shock
- Neurogenic shock.
What is the physiological purpose of vasoreflexes
To raise/lower blood pressure throughout the body and selectively, modify perfusion by rerouting blood from one region to another
Why does exercise increase Venus return?
Heartbeat, faster and harder, increasing cardiac output, and pressure
How is increased muscle perfusion during exercise accomplished?
Arterial dilate from EPI/ NOR
Blood diverted from kidneys and digestive track to working muscles.
What is the order through which blood would pass beginning with blood entering the systemic system after exiting the heart?
Conducting arteries, distributing arteries, resistance arteries, arterioles, capillaries, post capillary venules, muscular venules, medium veins, Venous sinuses, large veins
