52 terms

blood vessels

Name the three layers that make up the walls of veins and arteries from the outermost to the innermost. Describe the type of tissue that is found in each layer.
Tunica intima-Endothelium lines the lumen of all vessels
Tunic media-Smooth muscle and sheets of elastin and Sympathetic vasomotor nerve fibers (fight or flight system) control vasoconstriction and vasodilation of vessels
Tunica externa- Collagen fibers protect and reinforce
The hollow central area in a blood vessel through which blood flows is called the ______________________.
Describe the structure of a basic capillary (no special kind - just a generic capillary).
average length is 1 mm and average lumen diatemeter is 8-10 um. At the outer surface of some capillaries are spider-shaped.
What is the function of the smooth muscle in the tunica media of arteries?
The activity of the smooth muscle is regulated by sympathetic vasomotor nerve fibers
The aorta and its main branches are called _______________________ arteries.
_________________________ arteries and arterioles deliver blood to body organs.
elastic, conducting
Where in the body DON'T you find capillaries?
cartilage, epithelia, cornea and lens of eye
What is the function of capillaries?
exchange of gases, nutrients, wastes, hormones,
Blood enters capillary beds through ___________________________ (type of blood vessel?) and leaves through _______________________________ (type of blood vessel?).
vascular shunt, true capillaries
Blood flow through capillary beds is controlled by these structures: ___________________________________________________________________________________
Precapillary sphincters
What happens to blood when pre-capillary sphincters are closed (see handout on capillaries)?
Blood flows through the shunts and bypasses the tissues cells
Describe venules. What happens in these blood vessels?
Formed when capillary beds unite
Very porous; allow fluids and WBCs into tissues
Compare the structure and function of veins with the structure and function of arteries.
Formed when venules converge
Have thinner walls, larger lumens compared with corresponding arteries
Blood pressure is lower than in arteries
Thin tunica media and a thick tunica externa
Large thick-walled arteries with elastin in all three tunics
Aorta and its major branches
Large lumen offers low-resistance
Act as pressure reservoirs—expand and recoil as blood is ejected from the heart
Why are veins called "blood reservoirs"? Explain
capacitance vessels (blood reservoirs); contain up to 65% of the blood supply
List three sources of resistance to blood flow. Describe how each affects resistance.
1) Blood viscosity- The "stickiness" of the blood due to formed elements and plasma proteins
2) Blood vessel length-The longer the vessel, the greater the resistance encountered
3) vessel diameter- Small-diameter arterioles are the major determinants of peripheral resistance
Abrupt changes in diameter or fatty plaques from atherosclerosis dramatically increase resistance
Which blood vessels play the greatest role in determining resistance to blood flow? _______________
If resistance increases, blood flow ________________________ (increases or decreases?).
The highest blood pressure occurs in the ________________________ (which blood vessel?). Blood pressure in the right atrium = ___________________mm Hg.
aorta, 0
Blood pressure decreases as blood leaves the heart and travels through the body. The greatest drop in pressure occurs in which vessels? _______________________________
Why is it desirable to have low blood pressure in capillaries? Explain.
Most are very permeable, so low pressure forces filtrate into interstitial spaces
Why is venous blood pressure so low? Explain.
Changes little during the cardiac cycle
Low pressure due to cumulative effects of peripheral resistance
Explain how the "respiratory pump" and the "muscular pump" aid venous return of blood to the heart.
1) Respiratory "pump": pressure changes created during breathing move blood toward the heart by squeezing abdominal veins as thoracic veins expand
2)Muscular "pump": contraction of skeletal muscles "milk" blood toward the heart and valves prevent backflow
Name four parts of the body that work together to maintain blood pressure.
heart, blood vessels, kidneys, and brain
List the three main factors that influence blood pressure.
Cardiac output (CO)
Peripheral resistance (PR)
Blood volume
Stress (increases/decreases - choose one) cardiac output (CO).
cardioacceleratory center increases heart rate and stroke volume via sympathetic stimulation
The kidneys provide long term regulation of blood pressure by altering _________________ _________________________.
blood volume
Nervous system and hormonal controls affect blood pressure by altering ________________________ _____________________________ (by ____________________________/_____________________).
peripheral resistance (by vasoconstriction/vasodilation)
Baroreceptors sense _______________________________. They are located in _______________________________________ and ________________________________________.
pressure, Carotid sinuses and Aortic arch
When baroreceptors detect abnormal blood pressure, they send a signal to this part of the brain:
_______________________________ ___________________________________.
vasomotor center
Within the brain, the vasomotor center usually __________________________ (increases/decreases?) blood pressure, while the cardio-inhibitory center ____________________________ (increases/decreases?) blood pressure.
increases, stimulates
What is a "chemoreceptor"? What do chemoreceptors have to do with blood pressure? Explain.
Chemoreceptors (detect chemical changes) respond to rise in CO2, drop in pH or O2
Increase blood pressure via the vasomotor center and the cardioacceleratory center
What effect do the following hormones have on blood pressure, increase bp or decrease bp?
Angiotensin II:______________________________________
Antidiuretic hormone (ADH):____________________________
Atrial natriuretic peptide:______________________________
increase, increase, increases, decreases
Explain how the following words are related: kidney/ blood pressure/ urine/ blood volume
Increased BP or blood volume causes the kidneys to eliminate more urine, thus reducing BP
Decreased BP or blood volume causes the kidneys to conserve water, and BP rises
What is a sphygmomanometer?
Systemic arterial BP- Measured indirectly by the auscultatory method using a
What artery is usually used when measuring blood pressure?
brachial artery
What are "Sounds of Korotkoff"? Explain.
Sounds first occur as blood starts to spurt through the artery. Sounds disappear when the artery is no longer constricted and blood is flowing freely.
Blood pressure is highest at what time of day? _________________________________
Define the following: hypotension:
Systolic pressure below 100 mm Hg and often associated with long life and lack of cardiovascular illness
The doorbell rings and Suzie jumps up from the couch to answer the door. Suddenly, she feels dizzy and falls to the ground. Suzie experienced a condition known as _____________________________________________________________.
Orthostatic hypotension
Hypertension is high blood pressure, defined as an arterial pressure greater than _______________.
140/90 or higher
Prolonged high blood pressure is a major cause of:
heart failure, vascular disease, renal failure, and stroke
List some causes of high blood pressure:
heredity, diet, obesity, age, stress, diabetes mellitus, and smoking
The speed of blood flow is slowest through the capillaries. Why is this a good thing? Explain.
allows adequate time for exchange between blood and tissues
What substance is the major factor that causes dilation of the blood vessels (vasodilation)? Where does that substance come from?
Vasodilation of arterioles and relaxation of precapillary sphincters occur in response to
Declining tissue O2
Substances from metabolically active tissues (H+, K+, adenosine, and prostaglandins) and inflammatory chemicals
What is "angiogenesis"? Give an example.
The number of vessels to a region increases and existing vessels enlarge. Common in the heart when a coronary vessel is occluded, or throughout the body in people in high-altitude areas
What effect does an abnormally high or low MAP (mean arterial pressure) have on the brain? Explain.
The brain is vulnerable under extreme systemic pressure changes . MAP below 60 mm Hg can cause syncope (fainting). MAP above 160 can result in cerebral edema (fluid in brain)
How does blood regulate body temperature? Explain.
Blood flow through the skin
Supplies nutrients to cells
Helps maintain body temperature
Provides a blood reservoir
List and describe three types of circulatory shock.
Hypovolemic shock: results from large-scale blood loss
Vascular shock: results from extreme vasodilation and decreased peripheral resistance
Cardiogenic shock results when an inefficient heart cannot sustain adequate circulation
List three situations in which blood vessel formation occurs.
To support body growth
For wound healing
To rebuild vessels lost during menstrual cycles
ballonlike outpocketing of an rtery wll tht plces the artery t risk for rupture
dignostic technique involving the infusion of radioscope substance into the circultion for X-ray examination of specific blood vessels
a chemical tht promotes urine formation, thus reducing blood volume
a venous incision or puncture made for the purpose of withdrwing blood or bloodletting