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Essentials Of Anatomy and Physiology > Chapter 13 - The Vascular System > Flashcards

Chapter 13 - The Vascular System Flashcards

1
Q

What is the vascular system comprised of?

A

1) Arteries
2) Capillaries
3) Veins
All of which the heart pumps blood throughout.

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2
Q

What is the role of arteries?

A

Carry blood from the heart to capillaries (smaller arteries are arterioles)

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3
Q

What is the first layer of the arteries (of 3)

A

Tunica intima (innermost layer)

  • Only part in contact with blood.
  • Made of endoethelium (simple squamous epithelium, same type of tissues that forms the endocardium)
  • Extra smoothness, prevents abnml blood clotting. Also produces chemicals that affect blood pressure (Nitric oxide - a vasodilater - stimulates relaxation of the smooth muscle of the middle lawyer of a vessel.
  • Endoethelin (peptide) stimulates contraction of this smooth muscle. Nml blood pressure depends on this balance.
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4
Q

What is the second layer of the arteries (of 3)

A

Tunica Media (middle lawyer)

  • made of smooth muscle and connective tissue
  • maintanence of nml BP (especially distolic)
  • Affected by chemicals produced in endothelium.
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5
Q

What is the third layer of the arteries (of 3)

A

Tunica externa

  • Fibrous connective tissues, very strong
  • Important to prevent rupture or burst of larger arteries that carry blood under high pressure.
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6
Q

What is the role of veins?

A

carry blood from ccapillaries back to the heart (smaller veins called venules)

  • Same 3 tissue layers in veins as arteries
  • Inner lawyer is smooth endothelium, but at intervals is folded to form valves.
  • Middle layer is thin layer of smooth muscle (does not regulate BP or flow). Can constrict extensively (important during hemorrhage)
  • Outer layer also thin, less fibrous connective tissue than in arteries (d/t no BP regulation)
  • Greater capacity than arteries (total volume is greater) - 63-65% of blood is flowing through systemic veins (12-15% in arteries)
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7
Q

What is the role of valves (in veins)?

A

Prevent back flow of blood

-most numerous in the legs

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8
Q

What are anstomosis?

A

A connection of vessels (artery to artery or vein to veing)

-Purpose - to provide alternate pathways for the flow of blood if one vessel becomes obstructed

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9
Q

What is arterial anstomosis?

A

Helps ensure blood will get to cthe capillaries of an organ to deliver oxygen, nutrients and reomve waste.

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10
Q

What are venous anstomosis?

A

Helps ensure blood will be able to return to the heart to be pumped again ()most numerous in veins of legs)

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11
Q

What is Arterioscleroris?

A

“Hardening of the arteries”: - arteries lose their elasticity, walls become weakened (part of aging process)

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12
Q

What is an Aneurysm?

A

Weak portion of an atrterial wall, which may bulge out, forming a sac or bubble called an aneurysm.
-Arteriosclerosis is a possible cause, some are congenital
-May be present for years, no sx, usually found incidentally.
0Most common in cerebral arteries and aorta
-Rupture of a cerebral aneurysm is a possible cause of CVA. Life threatening

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13
Q

What is Phlebitis

A

Inflammation of the vein - most common in legs.

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14
Q

What are varicose veins?

A

swollen and distended veins (usually in superficial veins of legs) - blood pools in leg veins stretching their walls. If overly stretched,m their valves can no longer close properly.

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15
Q

What are hemorrhoids?

A

Varicose veins of the anal canal, can be result of pregnancy or chronic constipation and straining to defecate.

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16
Q

What is the role of capillaries

A

To carry blood from arterioles to venules.

  • Sites of exchanges of materials between the blood and the tissue fluid surrounding cells.
  • Walls are only one cell thick
  • An extension of the endothelium of arteries and veins
  • Epidermis, cartilage and lens and cornea of eye do not have capillaries.
  • Volume of capillary networks in an organ reflects the metabolic activity of the organ.
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17
Q

What are precapillary sphincters?

A

They regulate blood flow into capillary networks

  • Smooth muscle cells (found at the beginning of each network)
  • Constrict or dilate depending on the needs of the tissues (not regulated by the nervous system)
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18
Q

What are Sinusoids?

A

Type of capillary that is larger and more permeable than others.

  • Permits large substance (proteins and blood cells) to enter or leave the blood.
  • Found in red bone marrow and the spleen, also in the liver and pituitary gland.
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19
Q

What is diffusion (in capillaries)?

A

The exchange of gas within capillaries from their area of greater concentration to their area of lesser concentration
-i.e. O2 diffuses from the blood in systemic capillaries to the tissues fluid –>CO2 diffuses from tissue fluid to the blood to be brought to the lungs.

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20
Q

What is filtration (in capillaries)?

A

Process which forces plasma and dissolved nutrients out of capillaries into tissue fluid (how nutrients are brought to cells)
-BP in capillaries is 30-35 mmHg, surrounding tissue fluid is 2 mmHG - making up the force of this process.

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21
Q

What is colloid osmotic pressure of blood

A

An attracting pressure (pulling) rather than “pushing pressure.

  • Occurs as blood reaches the venous end of capillaries.
  • albumin contributes to this, its presence puill tissue fluid into the capillaries, which also brings into the blood waste products.
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22
Q

What are the 2 major pathways of circulation?

A

1) Pulmonary circulation

2) Systemic circulation

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23
Q

Describe the process of pulmonary circulation

A
  • Begins at right ventricle. Right ventricle pumps blood into the pulmonary artery (trunk) –> divides into the right and left pulmonary arteries (1 for each lung)–> In lungs, artery branches extensively into smaller arteries and arterioles, then to capillaries.–>pulmonary capillaries surround the alveoli of the lungs, where O2 and CO2 exchange take place –> capilliarries unite to form venules–>venules merge into veins–>into the 2 pulmonary veins from each lung and return blood to the left atrium.
  • This oxygenated blood will then travel through the systemic circulation.
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24
Q

Describe the process of systemic circulation

A

-Left ventricle pumps blood into aorta–>branches of the aorta take blood into arterioles and capillary networks–>Capillaries merge to form venules and veins–>veins from lower body take blood into inferior vena cava;veins from upper body take blood to the superior vena cave–> these to caval veins return blood to right atrium.

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25
Q

Describe the aorta

A
  • A continoous vessle, but can be divded into sections anatomically:
    1) Asending aorta - the first inch that emerges
    2) Aortic arch curves posteriorly over the heart and turns downward
    3) Thoracic aorta continues down through the chest cavity and through the diaphragm
    4) The abdominal aorta ( (below the diaphragm) continues to the level of the 4th lumbar vertabra, where it divides into two common illac arteries.
  • Aorta has many branches through which blood travels to specific organs and parts of the body
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26
Q

What are the two branches of the ascending aorta?

A

1) Right coronary artery
2) Left coronary artery
- Both supply blood to the myocardium.

27
Q

What are the three branches of the aortic arch?

A
  • Supplies blood to the head and arms
    1) Branciocephalic artery - very short, divides into right common carotid and right sublavian artery
    2) Left carotid artery - right and left common carotid arteries extend into the neck, which divides into an internal carotid artery and external carotid artery, which supply the head
    3) Left subclavian artery - The right and left sublcavian arteries are in the shoulders behind the clavicles and continue into the arms.
  • Sublclavian artery becomes the axxillary artery which becomes the brachial artery.
28
Q

What is the circle of Willis (cerebral arterial circle)

A
  • a “circle” of arteries around the pituitary gland.
  • Formed by the right and left internal carotid arteries and the basilar artery (a union of right and left vertebral arteries)
  • Since the brain needs constant flow of blood (for oxygen and to remove waste) there are 4 vessels that bring blood to the circle of Willis. (right/left common carotid, right/left vertebral)
29
Q

Describe the Thorasic aorta

A

The thorsasic aorta and its branches supply the chest wall and organs within the thoracic cavity.

30
Q

Describe the abdominal aorta.

A

Gives rise to arteries that supply the abdominal wall and organs and to the common iliac arteries which continue into the legs.
Illiac arterty becomes external iliac arterty,, becomes the femoral artery, becomes the poplitereal artery

31
Q

What is Hepatic portal circulation?

A

A subdivision of systemic circulation in which blood from the abdominal digestive organs and spleen circulates through the liver before returning to the heart.

  • Blood from capillaries of stomach, small intestine, colon, pancreas and spleen flow into 2 veins - superior mesenteric vein and splenic vein –> these unite to form the portal vein.
  • Portal vein takes blood into the liver–> branches extensively–> empties blood into sinusoids and capillaries of the liver–>from sinusoids, blood flows into hepatic veins–> to inferior vena cava and back to the right atrium.
32
Q

Why are capillaries / sinusoids in the liver/small intestine important for circulation?

A

They allow for for exchange
i.e glucose is absorbed into capillaries of the small intestine, after a big meal they are greatly ^, if this blood went directly back to the heart and then circulated through the kidneys, some of the glucose might be lost in urine.–> instead, blood from small intestine passes through the liver sinusoid and the liver cells remove the excess glucose and store it as glycogen. Blood that returns to the heart will then have nml blood glucose lvl.s

33
Q

Name the major pulse sites (6)

A

1) Radial (radial artery on thumb side of wrist
2) Carotid (carotid artery lateral to the larynx in the neck)
3) Temporal (temporal artery just in front of ear)
4) Femoral (femoral artery at top of the thigh
5) Popliteal - popliteal artery at back of the knee
6) Dorsalis pedis - dorsalis pedis artery on top of the foot (pedal pulse)

34
Q

What is a pulse deficit

A

When the heart is beating weakly, a radial pulse may be lower than an apical pulse (heard on stethoscope)

35
Q

What is the role of the placenta in fetal circulation?

A

The site of exchange between fetus and mother

  • Contains fetal and maternal blood vessels that are very close to one another.
  • Substances are exchanged by diffusion
  • Fetus connected to the placenta by umbilical cord
36
Q

Describe the umbilical arteries

A
  • Branches of the fetal internal illiac arteries; they carry blood from the fetus to the placenta. In the placenta, CO2 and waste in the fetal blood enter maternal circulation, and O2 and nutrients from the mothers blood enter fetal circulation
  • umbilical vein - carries oxygenated blood from the placenta to the fetus. Branches within the body of the fetus, 1 goes to the fetal liver, but most passes through the ductus venosus to the inferior vena cava to the right atrium.
37
Q

What is the formen Ovale? (fetus)

A

In fetus - an opening in the interatrial septum that permits some blood to flow from the r atrium to the left atrium (as opposed to right ventricle)
-permits blood to bypass fetal lungs (with ductus arteriousus)

38
Q

What is the ductus arteriousus? (fetus)

A

In fetus - a short vessel that diverts most of the blood in the pulmonary artery to the aorta, to the body.
-permits blood to bypass fetal lungs (with Formen Ovale)

39
Q

Describe the velocity of blood flow

A

Speed which blood flows differs in various parts of the vascular system.

  • Inversely related to the cross-sectional area of the particular segment of the vascular system.
  • Capillaries in total have greatest cross-sectional area, and blood velocity there is slowest (<0.1cm per second)
  • Slow rate of blood flow in capillaries permits sufficient time for exchange.
40
Q

Describe blood pressure

A

The force of the blood exerts aginst the walls of blood vessels.
-Filtration in capillaries depends on BP
-Pumping of the ventricles creates BP, measured in mm Hg (millimeters of mercury)
-Systolic BP represents the pressure when left ventricle is contracting
Diastolic BP - represent the pressure when the left ventricle is relaxed and does not exert force. Maintained by arteries and arterioles.
-Std is 120/80, nmml is 89-120/60-80

41
Q

What is hypotension?

A

BP that is consistently lower than nml range (90-120/60-80)

42
Q

What is hypertension?

A

BP that is consistently higher than nml range (190-120/60-80)
-any reading above 130/80 now considered HTN
Stage 1 HTN -Systole between 130-140 and diastol between 80-90

43
Q

What is pulmonary BP?

A

Created by the right ventricle (has 1/6th the force of left ventricle)

  • Always low pressure - 20-25/8-10 mm Hg
  • Important to prevent filtration in pulmonary capillariesm which prevents tissue fluid from accumulating in the alveoli of the lungs
44
Q

How is systemic BP maintained (7)?

A

1) Venous return - the amount of blood that returns to the heart by veins. (Constriction of veins, skeletal muscle pump and respiratory pump)
2) Heart rate and force -
3) Peripheral Resistance
4) Elasticity of the large arteries
5) Viscosity of the blood
6) Loss of blood
7) Hormones

45
Q

What is starlings law?

A

If venous return decreases, cardiac muscle fibers will not be stretched, making the force of ventricular systole decrease resulting in decreased blood pressure.

46
Q

What are the 3 mechanisms help promote venous return?

A

Venous return - the amount of blood that returns to the heart by veins.

1) Constriction of veins - (veins have smooth muscle, which enables them to constrict and force blood toward the heart; valves prevent back flow)
2) Skeletal muscle pump - (veins surrounded by skeletal muscles that contract and relax)
3) Respiratory pump - (affects veins that pass through chest cavity. Pressure changes of inhalation and exhalation alternatively expand and compress the veins, and blood is returned to the heart

47
Q

What is the role of heart rate/force in the maintenance of systemic BP?

A

If heart rate and force increase, BP increases (like during exercise)

48
Q

What is peripheral resistance? What is its role in the maintenance of systemic BP?

A

the resistance of vessels offer to the flow of blood. nml vasoconstriction makes the vessels smaller than the volume of blood so that the blood will exert pressure even when the left ventricle is relaxed.

49
Q

What is the role of Elasticity of the large arteries in the maintenance of systemic BP?

A

When the left ventricle contracts, the blood that enters the large arteries stretches the arteries walls (which absorb some of the force). When it relaxes, the arterial walls recoil (snap back), and help keep diastolic within nml range.
-Normal elasticity lowers systolic pressure, raises diastolic pressure and maintains nml pulse pressure.

50
Q

What is the role of viscosity of the blood in the maintenance of systemic BP?

A
  • Blood viscosity depends on presence of RBCs and plasma cells (especially albumin)
  • Decreased number of RBCs (like in severe anemia) will decrease blood viscosity and BP resulting in vasconstriction to maintain BP
  • Increased RBC is rare (polycythemia veria, heavy smokers), will ^ blood viscosity and BP.
51
Q

What is the role of loss of blood in the maintenance of systemic BP?

A
  • small loss of blood will cause a temporary drop in BP followed by rapid compensation in the form of a more rapid heart rate and greater vasoconstriction.
  • With severe hemorrhage, these compensating mechanism may not be sufficient to maintain nml BP.
  • A person may survive loss of 50% of body total blood, but possibility of brain damage increase as more blood is lost and not replaced rapidly.
52
Q

What are the role of hormones in the maintenance of systemic BP?

A

1) Adrenal medulla secretes norepinphrine and epinephrine in stressful situations (norepinephrine stimulates vasoconstriction, epinephrine increases vasconstriction and heart rate and force of contraction = ^ in BP)
2) Antidiuretic hormone (ADH) is secreted by the posterior pituitary gland when the water content of the body decreases. ADH increases re absorption of water by the kidneys to prevent further loss of water in urine and further decrease in BP
3) Aldosterone - from the adrenal cortex- when BP drops, secretion of aldosterone stimulates the re absorption of Na+ ions by the kidneys. Water follows sodium back to the blood, which maintains blood volume to prevent a further drop in BP
4) Atrial natriuretic peptide (ANP) is secreted by the atria of the heart - functions in opposition to aldosterone. ANP increase the excretion of Na+ ions and water by the kidneys, which decreases blood volume and lowers BP

53
Q

Describe the distribution of blood flow

A
  • Blood volume is relatively constant within the nml range appropriate to their size.
  • Active tissues require more blood (oxygen) then less active tissues
  • Precapillary sphincter dilate in active tissues and constrict in less active ones, which ensures metabolically active organs receive enough oxygen to function properly and BP is maintained WNL.
54
Q

Name the two types of mechanisms that regulate systemic BP

A

1) Intrinsic mechanisms - do not require nerve impulses

2) Nervous mechanisms - involve nervous system

55
Q

Describe how intrinsic mechanisms regulate BP

A

They work d/t internal characteristics of certain organs

1) The heart - when venous return increases, cardiac muscle fibers are stretched, ventricles pump more forcefully (starlings law) - thus increase cardiac output and BP. (think during exercise)
2) The kidneys - when blood flow through the kidneys decreases, the process of filtration decreases and less urine i=s formed. This decrease in urine output preserves blood volume so it does not further decrease. Also involved in renin-angiotensin mechanism.
- Influenced by diet - amounts of potassium and sodium - our blood level of sodium is often high with respect to the level of potassium, which increases the muscle tone of the smooth muscle layer of blood vessels which raises resting BP.

56
Q

What is the renin-angiotensin mechanism?

A

When BP decreases, kidneys secrete the enzyme renin, which initiates a series of reactions result in the formation of angiotensis II, which causes vasoconstriction and stimulates secretion of testosterone by the adrenal cortex–> aldosterone ^ re-absorption of Na+ ions and water by the kidneys, and vasoconstriction decreases size of the “container” for blood; both ^ BP.

57
Q

Describe how nervous mechanism regulate BP

A

Medulla and autonomic nervous system are directly involved in the regulation of BP.

  • Medulla contains the vasomotor center (Vasoconstriction area and vasodilator area, which)
  • Sympathetic vasoconstrictor fibers innervate the smooth muscle of all arteries and veins. Several impulses per second along these fibers maintains nml vasoconstrictions. More impulses bring greater constriction, less impulses casuses vasodilation.–> medula receives the info to make such changes from the pressorecptors in the carotid sinuses and aortic sinus.
58
Q

What effect does again have on the vascular system?

A
  • Aging of blood vessels begins in childhood, but effects are not apparent for decades.
  • Cholesterol deposits of atherosclerosis are to be expected with ^ age.
  • A degree of arteriosclerosis is to be expected
  • Average resting BP may increase, which further damages arterial walls.
  • Veins deteriorate with age (thin walls weaken and stretch, making their valves incompetent - usually in legs).
  • Varicose veins and phlebitis are more likely.
59
Q

What is circulatory shock?

A

Any condition in which cardiac output decreases to the extent that tissues are deprived of oxygen and waste products accumulate.

60
Q

What is carcinogenic shock

A

Occurs most often after severe myocardial infarction, can be result of ventricular fibrillation.

  • The heart is no longer an efficient pump,
  • cardiac output decreases.
61
Q

What is hypovolemic shock?

A

Result of decreased blood volume (usually d.t severe hemorrhage)
-The heart simply does not have enough blood to pump. Cardiac output decreases.

62
Q

What is anaphylactic shock?

A

Massive allergic reaction in which great amounts of histamine increase capillary permeability and vasodilation throughout the body. Plasma is lost to tissues spaces, decreasing blood volume, BP and cardiac output.

63
Q

What is septic Shock (sepsis)

A

The result of septicemia (bacteria in the blood)

  • Bacteria, damaged tissues and WBCs release inflammatory chemicals that cause vasodilation and extensive loss of plasma into tissues spaces.
  • Continuing and excessive response by the immune system is major factor in rapid progression and possibly fatal outcome.
64
Q

What are the stages of shock?

A

1) Compensated shock - responses by the body to maintain cardiac output. i.e. small hemorrhage, ^ HR, blood vessels constrict, kidneys decrease urinary output to conserve water - helps to maintain BP, cardiac output, blood volume and blood flow.
2) Progressive shock - A state of shock that leads to more shock. i.e. severe hemorrhage –> cardiac output decreases and myocardium is deprived of blood–> heart weakness, further decreasing output–> arteries are deprived of their blood supply cannot remain constricted. Medical intervention is required.
3) Irreversible shock - no amount of medical assistance can restore cardiac output to nml. i.e. severe myocardial infarction, massive hemorrhage or speticemia.

Essentials Of Anatomy and Physiology (6 decks)

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