blood vessels

Question 1

1. Describe the pressure and volume relationships of the vessels as blood moves in its passage from the heart to the capillaries and back.

Answer 1

Blood vessels form aclosed systemof tubes that carry blood away from the heart, transport it to thetissuesof the body, and thenreturnit to the heart.

Question 2

Elastic arteries or conducting arteries
– Pressure reservoirs
– Recoil of elastic fibers propels the blood
. • Muscular or distributing arteries
– Constrict or dilate to adjust blood flow

Answer 2

arteries

Question 3

• Small arteries (10-300mm) that deliver blood to capillaries. • Regulates blood flow • Regulates blood pressure

Answer 3

arterioles,

Question 4

are the site of substanceexchangebetween the blood and body tissues.

Answer 4

capillaries,

Question 5

connectcapillariesto larger veins.

Answer 5

venules

Question 6

convey blood from the tissues back to the heart.

Answer 6

Veins

Question 7

Identify and discuss the factors that contribute to systemic vascular resistance.

Answer 7

Peripheral vascular resistance(systemic vascular resistance, SVR) is theresistancein the circulatory system that is used to create blood pressure, the flow of blood and is also a component of cardiac function. When blood vessels constrict (vasoconstriction) this leads to an increase in SVR.

Although SVR is primarily determined by changes in blood vessel diameters, changes in blood viscosity also affect SVR. SVR can be calculated if cardiac output (CO), meanarterialpressure (MAP), and central venous pressure (CVP) are known.

Question 8

What is blood viscosity? What does it depend on?

Answer 8

Blood viscosity:depends on the ratio of RBC to plasma. Higher viscosity = higher resistance.

Question 9

What is the most important factor in forcing blood flow through the veins?

Answer 9

The variables affecting blood flow and blood pressure in the systemic circulation are cardiac output, compliance, blood volume, blood viscosity, and the length and diameter of the blood vessels.

Question 10

What is the direction of the diffusion of gases at capillaries near systemic cells?

Answer 10

oxygen out of the blood, carbon dioxide into blood

Question 11

What part of the brain regulates the heart rate?

Answer 11

Medulla – The primary role of the medulla isregulatingour involuntary life sustaining functions such as breathing, swallowing andheart rate. Aspart of the brainstem, it also helps transfer neural messages to and from thebrainand spinal cord. It is located at the junction of the spinal cord andbrain.

Question 12

Stimulation of what nerve reduces heart rate?

Answer 12

vagus nerve
Parasympathetic innervation of the heart is partially controlled by thevagus nerveand is shared by the thoracic ganglia.Vagaland spinal ganglionic nerves mediate the lowering of the heart rate.

Question 13

How would you define blood pressure?

Answer 13

Blood pressure isa measure of thepressureor force ofbloodagainst the walls of yourbloodvessels (known as arteries). Yourblood pressurereadingisbased on two measures calledsystolicanddiastolic

Question 14

10. Define intracellular and interstitial fluid?

Answer 14

Intracellular fluidis the place where most of thefluidin the body is contained. Thisfluidis located within the cell membrane and contains water, electrolytes and proteins. Potassium, magnesium, and phosphate are the three most common electrolytes in the ICF

Interstitial fluidconsists of a water solvent containing sugars, salts, fatty acids, amino acids, coenzymes, hormones, neurotransmitters, white blood cells and cell waste-products. … The composition ofinterstitial fluiddepends upon the exchanges between the cells in the biological tissue and the blood.

Question 15

What is the major difference between plasma, lymph and other interstitial fluids?

Answer 15

Onedifferenceis a matter of definition. Bloodplasmais the liquid part of blood, always contained in blood vessels.Lymphis the fluid contained inlymphaticvessels.Lymphis similar to bloodplasmain composition, except for being much lower in protein.

Blood plasmais 91% water, 7% protein, 2% other solutes, and 1% electrolytes.Interstitial fluidis likeblood plasmabutcanvary with the metabolism of the surrounding tissue. Mostlymphis derived from liver and has a higher protein concentration thaninterstitial fluid.

Question 16

What is the immediate blood vessel after an arteriole

Answer 16

Eventually, the smallest arteries,vesselscalledarterioles, further branch into tiny capillaries, where nutrients and wastes are exchanged, and then combine with othervesselsthat exit capillaries to form venules, smallblood vesselsthat carrybloodto avein, a largerblood vesselthat returnsbloodto the heart.

Question 17

What are the walls of a blood vessel? Which artery wall is responsible for anchoring the artery to the adjacent tissues?

Answer 17

The largestblood vesselsare arteries and veins, which have a thick, toughwallof connective tissue and and many layers of smooth muscle cells (Figure 22-22). Thewallis lined by an exceedingly thin single sheet of endothelial cells, the endothelium, separated from the surrounding outer layers by a basal lamina.

The tunica adventitia is composed of connectivetissue, mainly collagen and elastin. Intissues, thisarterial walllayer isresponsible for anchoringthe bloodvesseltoadjacent tissue. The tunica adventitia is normally nearly as thick as the tunica media layer.

Question 18

Which of the following options is in charge of the vasoconstriction of the arteries in our limbs?

Answer 18

• Some of the arteries, especially in the limbs, are accompanying by anastomic veins. the superficial veins are within the subcutaneous layer (superficial fascia) and they are mostly used for intravenous injections. They communicate with deep veins via small connections (anastomoses). They are much larger than the deep veins in upper limbs and serve the major pathway of venous blood backflow.

Question 19

What vessels function as pressure reservoirs?

Answer 19

Arteries are low resistancevessels that serve as pressure reservoirsto maintain blood flow during diastole. All arteries have muscular walls. In response topressure, to paracrines, and to nervous activity, the smooth muscle of the artery can either constrict or relax and thereby change the diameter of thevessel.

Question 20

What vessels function as blood reservoirs?

Answer 20

Veinsare considered blood reservoirs as they contain more than half the volume of blood in the entire body at any given time. The system ofveinsin the human body is often called a low pressure or capacitance system due to its primary function as blood reservoirs.

Question 21

What is the main role of capillaries?

Answer 21

The primary function of capillaries is topermit the exchange of nutrients and wastes between the blood and tissue cells through interstitial fluid.

Question 22

What is the most capillary exchange method?

Answer 22

Diffusion, the most widely-used mechanism, allows the flow of small molecules across capillaries such asglucoseand oxygen from the blood into the tissues and carbon dioxide from the tissue into the blood.

Question 23

What controls blood flow through a capillary bed?

Answer 23

Thebloodentering somecapillary bedsis controlled by small muscles called precapillary sphincters. … Precapillary sphincters: (a) Precapillary sphincters are rings of smooth muscle thatregulatetheflowofblood through capillaries; they helpcontroltheblood flow towhere it is needed.

Question 24

Give examples of tissues with continuous capillaries.

Answer 24

Continuous capillariesare a continuous tube of endothelial cells with intercellular clefts for diffusion to the tissues.Found in skeletal and smooth muscle, connective tissue, lungs.

Question 25

Blood flow depends on what two parameters?

Answer 25

The rate of meanblood flow dependson bothbloodpressure and the resistance toflowpresented by thebloodvessels. Meanbloodpressure decreases as the circulatingbloodmoves away from the heart through arteries and capillaries due to viscous losses of energy.

Question 26

Which layer of the arterial wall is responsible for vasoconstriction?

Answer 26

This is the middle layer. It is made ofsmooth muscleandelastic fibers. It is responsible for vasodialation and vasoconstriction of theblood vessels. It is also the target tissue for Vasopressin (ADH) Hormone and plays into blood pressure.

Question 27

Which layer of the arterial wall is primarily composed of elastic and collagen fibers?

Answer 27

All arteries have an outer tunica externa (mostly elastic and collagen fibers), an inner tunica media (mostlysmooth muscleand elastic fibers) and a lining called the tunica interna (endothelial tissue).

Question 28

When an artery or arteriole is damaged, its smooth muscle layer contracts producing

Answer 28

A vascular spasm

Question 29

In resting individuals, which vessels serve as a large blood reservoir from which blood can be quickly diverted to other vessels as needed?

Answer 29

Veins and venules

Question 30

What is the largest driving force for pulling fluid from the interstitial spaces back into the capillaries is?

Answer 30

blood colloid osmotic pressure.

Question 31

What is the pressure-driven movement of fluids and solutes from blood into interstitial fluid is called?

Answer 31

filtration.

Question 32

What is Cardiac output and what does it depend on?

Answer 32

heart rate and stroke volume.

Question 33

When chemoreceptors in blood vessels detect high levels of carbon dioxide in the blood, they stimulate what events?

Answer 33

1. increased vasoconstriction of arterioles.
2. increased blood pressure.
3. increased sympathetic stimulation of arterioles and veins.
   increased vasoconstriction of veins.

Question 34

The pulmonary trunk divides into what branches?

Answer 34

right and left pulmonary arteries.

As thepulmonary trunkreaches the superior surface of the heart, it curves posteriorly and rapidly bifurcates (divides)intotwobranches, aleftand aright pulmonary artery

Question 35

Which of the following vessels is a pulse point found at the wrist?

Answer 35

radial artery
Theradial arterysupplies the arm and hand with oxygenated blood from the lungs. Due to the size of theradial artery, and its proximity to the surface of the arm, this is the most common artery used to measure a patient’s pulse. The pulse is checked at the wrist, where theradial arteryis closest to the surface.

Question 36

Which of the following vessels drains blood from the lower leg?

Answer 36

The femoral vein merges with thegreat saphenous veinin the groin to form the external iliac vein. (a) Veins of the lower extremities and (b) Veins of the lower extremities: Thegreat saphenous veinand its tributaries, shown in blue, drain blood from the lower limbs.

Question 37

Which of the following vessels drains blood from the head and neck?

Answer 37

Jugular vein. Jugular vein, any of several veins of the neck that drain blood from the brain, face, and neck, returning it to the heart via thesuperior vena cava

Question 38

• Blood is carried away from the heart in arteries. All arteries have an outer tunica externa (mostly elastic and collagen fibers), an inner tunica media (mostly smooth muscle and elastic fibers) and a lining called the tunica interna (endothelial tissue). Large diameter arteries have more elastic fibers than smooth muscle in their walls and conduct blood to regions of the body, e.g. the subclavian artery carries blood toward the upper extremity.

Answer 38

As arteries enter a body region, they branch and their diameters decrease. Their walls have proportionately more smooth muscle than elastic tissue. These arteries are called muscular or distributing arteries, e.g. the radial artery. Branching of the blood vessels continues until the vessels are nearly microscopic arterioles. Arterioles have little elastic tissue, but can change diameter quickly because of the smooth muscle in their wall. Thus, they are the major sites of regulation of blood pressure and distribution. Arterioles feed into capillary beds. Capillaries are the sites of exchange between the tissues and the blood. Venules drain the capillaries and begin the path back to the heart. Venules merge to form veins (and ultimately, vena cava) that carry the blood to the heart. Veins have much less smooth muscle than arteries. Vein also have valves that help prevent backflow of blood.

Question 39

• Blood viscosity is dependent on the ratio of formed elements and proteins to plasma.

Answer 39

In general, increased viscosity, via increased formed elements or decreasing plasma volume, increases resistance. 2) Total blood vessel length is directly proportional to resistance; thus, increasing length of circuit (by adding new blood vessels to serve added tissue) increases resistance. 3) Diameter/radius of blood vessels, which is primarily controlled by ANS, has a major effect on resistance. Increased vessel diameter decreases resistance, thus increasing flow. In general, changes in the diameter of small vessels (e.g. arterioles) have greater effect because more surface area is in contact with blood.