Chap 21 Blood Vessels Flashcards
What is an embolus?
Something that travels through the bloodstream, lodges in a blood vessel and blocks it ( embolism)
Ex: detached blood clot, clump of bacteria, air
How are arteries and veins different?
Arteries are made to withstand pressure, muscular, elastic
Veins have valves to prevent back flow not built for high pressure
What is a cerebrovascular accident?
It’s a stroke… An interruption of the blood supply to any part of the brain
Describe the two kinds of artieries
Elastic: high content of elastic fibers in the aorta and branches. Works like a pressure reservoir
Muscular: smooth muscle tissue. Adjust the rate of blood flow through vasodilation and vasoconstriction
What happens when blood first enters the Aorta?
It stretches when it receives the blood then retracts. The retracting gives an extrA pulse if pressure to push the blood further
What is atherosclerosis?
Fatty material collects along the walls of arteries. This fatty material thickens hardens and may eventually block the arteries.
How does a blood clot form in an artery?
Plaque breaks off of the wall of the artery exposing colleges which calls the platelets which forms a clot
What is an aneurysm?
Abnormal widening or ballooning of a portion of an artery due to weakness in the wall if a blood vessel
Describe capillaries
Smallest blood vessel thinnest
Connect arterial outflow to venous return
Exchange between blood and interstitial fluid which surrounds body tissue
How does blood flow through the capillaries
One blood cell through at a time
More surface area which allows for rapid exchange between rbc and interstitial fluid
Blood slows significantly through capillaries, allows for efficient exchange
Describe the different types of capillaries
Continuous: most capillaries - exchange between o2 and co2
Sinusoids: giant holes… Found in the liver spleen and red bone marrow… Filters out old rbc’s
Fenstrated: found in the kidneys… Lots of holes helps filter a good amount of water
How do the capillaries control movement?
There are sphincter muscles around the capillaries squeezing or relaxing to push the blood through or constrict it
Describe capillary exchange
Movement of substances between blood and interstitial fluid
Diffusion: high to low concentration of o2
Most important, works with o2 and co2
Bulk flow: through the kidneys
Regulate blood volume
Explain the relationship between velocity and area in blood flow
The less area the more velocity
The greater the area the less velocity
Describe veins
Not designed to withstand high pressure
More numerous than arteries ( blood reserves)
Superficial- very susceptible to pressure changes
Deep - completely surrounded and protected by skeletal muscle
Valves prevent backflow
What are varicose veins?
Swollen twisted and sometimes painful veins that have filled with an abnormal collection of blood
Valves no longer work properly so there is backflow
What is phlebitis?
Inflammation of veins
What are hemorrhoids?
Swollen veins in the anal canal
Too much pressure on the veins in the pelvic and rectal area
Where do you find the greatest volume of blood?
Systemic veins and venules
What is blood pressure?
Contraction of ventricles
Systolic bp: highest bp in arteries during contraction
Diastolic: lowest bp during relaxation
How many pulse points are in the body
9
Explain blood pressure (mean arterial pressure)
The average between systolic and diastolic
Map = co x r
R= vascular resistance
What is vascular resistance and what are the 3 aspects of it?
Opposition to blood flow
- Size of lumen ( area where blood passes)
- Blood viscosity ( thickness, rbc/volume
- Total length of blood vessels (area)
Decrease of lumen = increase of vascular resistance
Increase of resistance = increase of cardiac output
Increase of viscosity = increase in resistance = increase in mean arterial pressure
Explain the different kinds of hypertension
Benign: extended period of high bp
Malignant: sudden and rapid development of extremely high bp > than 200/140
Essential: high bp with no known cause
Explain congestive heart failure
Hypertension over a long period of time leads to CHF
Caused by myocardial infarction, mitral insufficiency, CAD (coronary artery disease) hypertension
If left side fails=pulmonary edema
If right side fails = peripheral edema (arms and legs swelling)
In venous return explain the skeletal muscle pump
For the deep veins contraction of the skeletal muscle presses on the veins an forces the blood upward toward the heart. The valves close to prevent back flow. When the muscle relaxes blood enters the vein but only from the arterial side.
In venous return explain the role of the respiratory pump.
Breathing in causes negative pressure in the thorax causing a suction effect… This means the pressure gradient pushing blood towards the right atrium is increased, thus more blood returns to the heart. Therefore inspiration leads to an increase in venous return.
In the cardiovascular center, what nerve impulses are input?
From higher brain centers: cerebral cortex, limbic system, and hypothalamus
From proprioceptors: monitor joint movements
From baroreceptors: monitor blood pressure
From chemoreceptors: monitor blood acidity H+, CO2, and O2
In the cardiovascular center what are the output effectors?
Vagus nerves (parasympathetic)= decreased heart rate
Cardiac accelerator nerves (sympathetic) = increased heart rate and contractility
Vasomotor nerves (sympathetic) = blood vessels vasoconstriction
In neural regulation of blood pressure, what are the three reflexes that affect this?
Baroreceptor reflexes
Carotid sinus reflex (internal carotid)
Aortic sinus reflex
Explain how baroreceptor reflexes work
Baroreceptors are found in the carotid and aortic sinus reflexes
They are pressure sensitive receptors that respond to changes in blood pressure
What is the function of the carotid sinus reflex?
Monitors changes in blood pressure to the brain
What is the function of the aortic sinus reflex?
It monitors pressure changes to the systemic circuit
What are chemoreceptors extremely sensitive too?
Carbon dioxide levels
What happens when you faint and what are the causes?
Decreased blood flow to the brain, results in a temporary loss of consciencness
Causes: dehydration, psychological factors, shock, drugs and alcohol, standing up suddenly
What is shock?
Condition where the tissues in the body don’t receive enough oxygen and nutrients
This ultimately leads to cellular death, progressing to organ failure and finally to whole body failure and death
Four types : hypovolemic, cardiogenic, obstructive, and anaphylactic
How does aging affect the cardiovascular system?
Decrease in compliance of aorta
Decrease cardiac muscle fiber size and strength
Decrease CO and HR
Increase LDL, CAD, congestive heart failure
