Anatomy 2: Blood Vessels

When comparing 2 blood vessels, which one will have less resistance? A or B? Which vessel is experiencing vasoconstriction?

'A' will have less resistance. Vasoconstriction is decreases the radius of a vessel, so A is experiencing Vasoconstriction.

Define systolic pressure, diastolic pressure, and pulse pressure.

*Systolic pressure*: pressure exerted in aorta during the ventricle *CONTRACTING* *Diastolic pressure*: lowest level of aortic pressure when heart is at *REST* Pulse pressure: throbbing of arteries

How are veins different from arteries in their structure and function?

*Veins*(blue) carry {deoxygenated} blood *TOWARD* the heart and are generally larger, but their walls are thinner with large lumens *Arteries*(red) carry {oxygenated} blood *AWAY* from the heart and are smaller with thicker walls w small lumens

It is the pumping action of the ___________ (be specific here, not heart) that generates blood flow. Pressure results when flow is opposed by ______________.

;resistance

Where is systemic blood pressure highest in the body?

Aorta

Which is the most important factor for blood flow in local tissue areas, blood pressure, or resistance? And how is that factor altered for local blood flow to tissues?

Blood resistance is more important in influencing local blood flow because it is easily changed by altering blood vessel diameter

Which artery is most often used to auscultate the sounds of Korotkoff?

Brachial

The structure of a capillary wall differs from that of a vein or an artery because a) it has two tunics instead of three b) there is less smooth muscle c) it has a single tunic- only tunica intima d) none of the above

C

Which of the following can lead to decreased venous return of blood to the heart? a) an increase in blood volume b) an increase in venous pressure c) damage to the venous valves d) increased muscular activity

C

How are capillaries different from arteries and veins in regard to these layers?

Capallaries only have thin tunica intima, but arteries and veins have all three layers.

How could you explain the size of capillaries to a layperson(someone w no knowledge of the subject)?

Capillaries are so small that only red blood cells can travel through them in a single line.

Which statement does not accurately describe veins? a) have less elastic tissue and smooth muscle than arteries b) contain more fibrous tissue than arteries c) most veins in the extremities have valves d) always carry deoxygenated blood

D

Why is the arterial blood pressure in arteries near the heart so pulsatile in nature?

Due to the heart beating

Arterial blood pressure increases in response to a) increasing stroke volume b) increasing heart rate c) atherosclerosis d) rising blood volume e) all of the above

E

What is the venous sinus?

Flattened veins composed of only endothelium in the sinus of the heart or dural sinuses in brain.

What is the function of capillaries and which tissues do not have capillaries?

Function of capillaries: Exchange gases, nutrients, wastes, & hormones between blood and interstitial fluid. Tissues that don't have capillaries: cartilage, epithelia, cornea and lens of the eye.

Why is it important that the blood flow is the slowest of all vessels in the capillaries?

It allows time for exchange of gases and nutrients

Define peripheral resistance.

Measurement of amount of friction blood encounters with vessel walls.

What is atherosclerosis and why does it lead to unwanted problems in the body? How does it lead to high blood pressure?

Plaque build up in an artery. It dramatically increases resistance.

In which location/ vessel is the pulse most often taken?

Radial, Carotid, Brachial

Define "endothelium."

Simple squamous epithelium that lines lumen of all blood vessels. ~Slick surface reduces friction

What type of tissue/ cells does the layer in #6 consist of?

Smooth muscle

Which branch of the autonomic nervous system innervates blood vessels?

Sympathetic nervous system

Interstitial fluid

fluid that bathes the cells in the space within cells.

How does the pressure in capillaries compare to the pressure in arteries? Why is this important in the scheme of things?

The BP is much higher in arteries because blood is coming from the heart, where its under higher pressure. The blood from the arteries eventually makes its way to the capillaries

Why are veins called blood reservoirs?

The large lumen & thin walls make veins good storage vessels for blood.

How do the veins help in returning blood back to the heart?

The venous valves push blood up in one direction from the body, working against gravity.

How does the pressure in the aorta compare to the vena cava?

They are completely opposite; aorta has the most BP

Explain the terms: Vasoconstriction and Vasodilation.

Vasoconstriction: decreased lumen diameter Vaso*dilation*: increased lumen diameter *dilation= pupils get bigger, lumen diameter gets bigger*

Are veins high or low-pressure vessels, and why?

Veins are low-pressure vessels because they have lost considerable pressure traveling through arteries and capillaries

Where is systemic blood pressure lowest in the body?

Vena Cava

If blood pressure decreases, blood flow _____

decreases

If peripheral resistance increases, blood flow _____

decreases

If peripheral resistance increases, blood pressure _____. This is how people with atherosclerosis end up with hypertension.

decreases

Just as in the heart, blood always moves in the direction from _______ to _________ pressure.

higher;lower

If blood pressure increases, blood flow ___

increases

Which type of blood vessel is most important for determining peripheral resistance and why?

Arterioles, because they control flow via vasoconstriction and vasodilation. The changing diameters change resistance to blood flow.

List the 3 structural types of capillaries, and describe each one's permeability and locations.

1. *Continuous capillaries*: -*LEAST* permeable. - Location: Abundant in skin, lungs, muscles & CNS 2. *Fenestrated capillary*: -Have large fenestrations(pores) that increase permeability, which allows more to be filtered in & out. *2nd most permeable* -Location: Found in areas involved in filtration( kidneys), absorption (intestines), or endocrine secretion. 3. *Sinusoidal capillaries*: *MOST permeable.* Location: Found only in the liver, bone marrow, spleen and adrenal medulla.

Name and describe the characteristics of the 3 types of arteries, and where each type of arteries, and where each type is located.

1. *Elastic arteries*: thick-walled w large, low-resistance lumen. Location: Aorta & its major branches 2. *Muscular arteries*: Elastic arteries give rise to these. Also called distributing arteries b/c they DELIVER BLOOD to body organs. ~have thickets tunica media. 3. *Arterioles*: smallest of all arteries. Control flow into capillary beds; slows blood down. ~leads to capillary beds~

Name the 3 different types of blood vessels and give a description or function of each one.

1. Arteries: carry blood AWAY from the heart; they are red b/c they are oxygenated 2. Capillaries: Microscopic vessels; so small that only RBC's can pass. Function: exchange gases, nutrients, wastes, & hormones between blood & interstitial fluid (fluid that bathes the cell). 3. Veins: carry blood TOWARD heart; blue b/c they are deoxygenated.

Remember the permeability of capilaries in order.

1. Continuous 2. Fenestrated 3. Sinusoidal C--> least permeable F--> 2nd most permeable S--> most permeable

Describe the 3 distinct layers of the most blood vessels.

1. Tunica intima: innermost layer that is in "intimate" contact with blood. 2. Tunica media: middle layer composed mostly of smooth muscle and sheets of elastin. -The bulkiest layer responsible for maintaining blood flow and blood pressure. 3. Tunica externa: outermost layer of blood vessel wall. -Composed mostly of collagen fibers that protect wall and anchor it to surrounding structures.

List 3 factors that determine resistance in a vessel. Which of these 3 factors is most physiologically important?

1. blood viscocity-thickness 2. total blood vessel length 3. blood vessel diameter ~The most important is blood vessel diameter b/c it has the most influence on resistance. always changing

Where does the biggest drop in BP occur in the systemic circuit?

Arterioles

Smooth muscle in the blood vessel wall a) is found primarily in the tunica intima b) is mostly circularly arranged c) is most abundant in veins d) is usually innervated by the parasympathetic nervous system

B

The myocardium receives its blood supply directly from the a) aorta b) coronary arteries c) coronary sinus d) pulmonary arteries

B

Define "Blood Pressure" and give the units of measurement

Blood Pressure (BP): force per unit area exerted on wall of blood vessel by blood. Expressed in mm Hg (Mercury)

Define "Blood Flow" and give the units of measurement

Blood flow: volume of blood through vessel, organ, or entire circulation in a given period. Measured in Cardiac Output (CO)

How is the anatomy of capillaries and capillary beds well suited to their function?

Capillaries walls are very fine to allow the diffusion of nutrients/wastes across the membrane, allowing tissues to receive and remove nutrients/wastes

Which layer of the blood vessel wall do these nerves innervate?

Tunica Media

If peripheral resistance decreases, blood flow _____

increases

Name the instrument used to measure blood pressure.

sphygmomanometer