Ch 19: Blood Vessels and Circulation

94問 • 1年前

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問題一覧

___: (afferent) carry blood away from the heart

arteries

___: are small arteries that regulate blood pressure

arterioles

___: microscopic vessels between arterioles and venules

capillaries

• Made of one layer of epithelial tissue • Form beds of vessels where exchange with body cells occurs • Combined large surface area

capillaries

Small veins that receive blood from the capillaries

venules

(Efferent) carry blood toward the heart

veins

Structure of blood vessels

tunica interna (intima); tunica media; tunica externa (adventitia)

• Direct contact with blood • Endothelium = squamous epithelial tissue • Endithelium is slippery, minimizes friction

tunica interna (intima)

• Circular smooth muscle + elastin • Controlled by sympathetic nervous system • Vasoconstriction - smooth muscle contracts and lumen diameter is reduced • Vasodilation - smooth muscle relaxes and lumen diameter increases

tunica media

• Collegan fibers: protection and anchoring • Possesses nerve fibers, lymphatic vessels • Vasa vasorum: network of tiny vessels that nourish the tunica externa

tunica externa (adventitia)

Thick-walled, bear heart (aorta + branches)

elastic arteries

___ has largest diameter of all arteries

lumen

• Lumen has largest diameter of all arteries • High in elastin content; present in all 3 tunics • Elastin content allows expansion and retraction in response to blood from heart; constant flow

elastic arteries

Deliver blood to organs; most of the arteries

muscular arteries

• Thickest tunica media of all vessels; intermediate lumen diameter • More smooth muscle, less elastin in tunica media than elastic arteries • Better at vasoconstriction (moving blood)

muscular arteries

Delivers blood to capillary beds within tissues

arterioles

• Lumen has smallest diameter of all arteries • Tunica media mostly smooth muscle; few elastin fibers • Play a major role in determining blood flow

arterioles

Small of all blood vessels

capillaries

• Site of exchange between blood and tissues (nutrients, hormones, etc.) • Walls consist of only tunica interna • Pericytes (spider-shaped smooth muscle-like cells) stabilize capillary wall, control permeability, important in brain • lumen diameter allows RBC’s to travel through in single file

capillaries

Three types of capillaries

continuous; fenestrated; sinusoidal

Occur in most tissues (abundant in skin and muscle)

continuous

• No breaks between endothelial cells • Intercellular cleft: small gaps between tight junctions • Pinocytotic vesicles: shuttle materials through cell membrane

continuous

Have pores covered by membrane

fenestrated

• Much more permeable to fluids and solutesvthan continuous capillaries • Found often where capillaries need to absorb materials released by organs (endocrine system) • Found often where filtrate formation occurs (e.g., kidneys)

fenestrated

Leaky capillaries with large lumen and fenestrations

sinusoidal

• Fewer tight junctions; larger intercellular clefts • Large molecules allowed to pass • Found in liver, bone marrow, lymphoid tissues, and endocrine organs • Often have specialized macrophages (Kupffer cells) • Blood flow is slow

sinusoidal

Capillaries organized into networks called ___ - usually supplied by a single ___ (vascular shunt)

capillary beds; metarteriole

Metarteriole that continues through capillary bed to venue

thoroughfare channel

Control which beds are well perfused

precapillary sphincters

When sphincters are open, the capillaries are well perfused with blood and engage in exchanges with tissues

vasodilation

When the sphincters are closed, little to no blood flow occurs (skeletal muscles at rest)

vasoconstriction

___ lie alongside capillary befs

lymphatic capillary beds

When lymphatic capillaries take up excess fluid it becomes ___

lymph

Lymph returns to the ___ in the chest

cardiovascular veins

___ sphincters can shut down a blood capillary, and blood then glows through the shunt

precapillary

Result from convergence of capillaries

venules

• Endothelium plus some pericytes • Highly porous (fluid and WBCs freely move across walls) • Larger venules have smooth muscle layers (tunica media) and thin tunica externa

venules

Result from convergence of venules

veins

• 3 tunics: walls thinner and lumens larger than arteries • Very little smooth muscle in tunica media • Thick tunica externa with thick collagen fibers and elastic fibers • Blood pressure lower in veins but poses problems of getting blood back to heart • Large lumens provide little resistance to blood flow • Venous valves of the tunica intima (similar to semilunar valves of heart)

veins

Pulse and blood pressure, along with respiratory rate and body temp

vital signs

Pressure wave caused by expansion and recoil of arteries

pulse

Taken at wrist; routinely used

radial pulse

Where arteries close to body surface; can be compressed to stop blood flow

pressure points

Volume of blood flowing through a vessel, organ, or entire circulation in a given period; for entire vascular system = cardiac output

blood flow

Opposition of flow; the friction the blood encounters as it passes through vessels

resistance

• Force per unit area exerted by blood on a vessel wall (mmHg); typically refers to arterial blood pressure in aorta and its branches • Would NOT want to measure this in the veins (low blood pressure)…blood flows from high to low pressure

blood pressure

___ = blood pressure gradient / resistance

blood flow

The ___ the pressure difference between two points, the greater the flow

greater

The greater the resistance, the ___ the flow

less

Arterial blood pressure: 2 factors 1. ___ of elastic arteries near the heart 2. ___ of blood forced into the elastic arteries

distensibility; volume

Pressure rises and falls with regularity

pulsatile pressure profile

___ (contractile) pressure = blood is forced out of left ventricle into aorta (120 mmHg)

systolic

___ (relaxed) pressure = aorta recoils (70-80 mmHg)

diastolic

___ = systolic minus diastolic pressure (120-75 = 45 mmHg)

pulse pressure

MAP =

mean arterial pressure

It is the ___ that most influences the resin of disorders (atherosclerosis, kidney failure, aneurysm, etc.)

MAP

Three factors determine blood pressure:

cardiac output; blood volume; resistance

Volume of blood flowing through the entire vascular system

cardiac output

Amount of blood in the body

blood volume

Friction blood encounters as it moves through vessels in the systemic circulation; resistance hinges on three variables: blood viscosity, blood vessel length, blood vessel radius

resistance

Thickness of blood (RBC count, # proteins)

blood viscosity

Longer vessels have greater resistance

blood vessel length

Smaller tubes, greater friction (more blood contacts vessel walls)

blood vessel radius

• From aorta to capillaries, ___ (speed) decreases - Greater distance, more ___ to reduce speed - Smaller radii of arterioles and capillaries offers more ___ - Father from heart, the number of vessels and their total ___ become greater and greater - ___ are most significant point of control over peripheral resistance and flow

blood velocity; friction; resistance; cross-sectional area; arterioles

The flow of blood back to the heart. Five basic mechanisms: • pressure gradient • central venous pressure • gravity • skeletal muscle pump • thoracic (respiratory) pump • cardiac suction

venous return

Most important force in venous return

pressure gradient

Venules to ___: point where the venae cavae enter the heart

central venous pressure

___ drains blood from head to neck

gravity

___ in the limbs; contracting muscle squeezes out of compressed part of vein

skeletal muscle pump

Slight suction that draws blood into atria from vena cava

cardiac suction

___ (cluster of neurons in medulla) regulate vessel diameter

vasomotor center

___ > vasoconstriction > increased blood pressure

increased sympathetic activity

___ > vasodilation > decreased blood pressure

decreased sympathetic activity

Stretch in response to increased arterial pressure

baroreceptors

• Respond to changes in blood levels of O2, CO2, H+ • Increase blood return to lungs when deficient in O2 or when increased CO2 is sensed (pH)

chemoreceptors

Hypothalamus, cerebral cortex relay info to medulla

higher brain centers

The “salt-retaining hormone” body retains Na and water helps maintain blood volume and pressure

aldosterone

• Makes collecting dust more permeable to water • Water in the tubular fluid reenters the tissue fluid and bloodstream rather than being lost in urine = less urine output

antidiuretic hormone

• Secreted by atrial myocardium of the heart in response to high blood pressure • Severak actions result in the excretion of more salt and water in the urine, thus reducing blood volume and pressure • = MORE urine output

atrial natriuretic hormone

• Tissues to regulate their own blood supply: if tissue is not getting adequate blood flow, wastes accumulate stimulating vasodilation which increases flow - Bloodstream delivers oxygen and removes metabolites - When wastes are removed, vessels constrict

autoregulation

• Substances secreted by platelets, endothelial cells, and pervascular tissue to stimulate vasomotion 1. During trauma, inflammation, and exercise: • Histamine • Bradykinin • Prostaglandins • All stimulate vasodilation 2. Naturally in balance locally: • Prostacyclin and nitric oxide (vasodilators) • Endothelins (vasoconstrictor)

vasoactive chemicals

• Growth of new blood vessel. Typically in tissues with long-term hypoxia; occurs in regrowth of uterine lining, around coronary artery obstructions, in exercised muscle, and malignant tumors

angiogenesis

Any state in which cardiac output is insufficient to meet the body’s metabolic needs

shock

Inadequate pumping of heart (MI)

cardiogenic shock

Cardiac output is low because too little blood is returning to the heart

low venous return

Most common type of shock • Loss of blood volume: trauma, burns, dehydration

hypovolemic shock

• Extreme vasodilation and decreased peripheral resistance • Anaphylactic (histamine) • Venous pooling: long periods of standing, sitting, or widespread vasodilation

vascular shock

• It’s build up of plaque in blood vessels • Plague that is stationary is called thrombus, and an embolus when it detached and can move to distant sites • It’s associated with a stroke, heart attack, and aneurysm

atherosclerosis

• High blood pressure results when blood moves through vessels at a rate higher than normal, often due to arterial plague • Ex: 140 / 90 mmHg • It is a silent killer because there are few symptoms • It can lead to a heart attack, stroke, or kidney failure

hypertension

• It is a ballooning of a blood vessel • Atherosclerosis and hypertension can weaken a vessel and cause ballooning • The most commonly affected is the abdominal artery or the arteries leading to the brain

aneurysm

• This is also known as a cerebrovascular accident (CVA) • It usually occurs when a cranial artery is blocked or bursts • Part of the brain dies due to lack of oxygen • Symptoms: numbness of hand / face, difficulty speaking, inability to see in one eye

stroke

___ is a drug that dissolves blood clots

t-PA

Usually a vein from the leg is taken and used to bypass a clogged artery

bypass surgery

Wire mesh cylinder inserted into a clogged artery to hold it open

stents

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問題一覧

___: (afferent) carry blood away from the heart

arteries

___: are small arteries that regulate blood pressure

arterioles

___: microscopic vessels between arterioles and venules

capillaries

• Made of one layer of epithelial tissue • Form beds of vessels where exchange with body cells occurs • Combined large surface area

capillaries

Small veins that receive blood from the capillaries

venules

(Efferent) carry blood toward the heart

veins

Structure of blood vessels

tunica interna (intima); tunica media; tunica externa (adventitia)

• Direct contact with blood • Endothelium = squamous epithelial tissue • Endithelium is slippery, minimizes friction

tunica interna (intima)

tunica media

• Collegan fibers: protection and anchoring • Possesses nerve fibers, lymphatic vessels • Vasa vasorum: network of tiny vessels that nourish the tunica externa

tunica externa (adventitia)

Thick-walled, bear heart (aorta + branches)

elastic arteries

___ has largest diameter of all arteries

lumen

• Lumen has largest diameter of all arteries • High in elastin content; present in all 3 tunics • Elastin content allows expansion and retraction in response to blood from heart; constant flow

elastic arteries

Deliver blood to organs; most of the arteries

muscular arteries

• Thickest tunica media of all vessels; intermediate lumen diameter • More smooth muscle, less elastin in tunica media than elastic arteries • Better at vasoconstriction (moving blood)

muscular arteries

Delivers blood to capillary beds within tissues

arterioles

• Lumen has smallest diameter of all arteries • Tunica media mostly smooth muscle; few elastin fibers • Play a major role in determining blood flow

arterioles

Small of all blood vessels

capillaries

Three types of capillaries

continuous; fenestrated; sinusoidal

Occur in most tissues (abundant in skin and muscle)

continuous

• No breaks between endothelial cells • Intercellular cleft: small gaps between tight junctions • Pinocytotic vesicles: shuttle materials through cell membrane

continuous

Have pores covered by membrane

fenestrated

Leaky capillaries with large lumen and fenestrations

sinusoidal

Capillaries organized into networks called ___ - usually supplied by a single ___ (vascular shunt)

capillary beds; metarteriole

Metarteriole that continues through capillary bed to venue

thoroughfare channel

Control which beds are well perfused

precapillary sphincters

When sphincters are open, the capillaries are well perfused with blood and engage in exchanges with tissues

vasodilation

When the sphincters are closed, little to no blood flow occurs (skeletal muscles at rest)

vasoconstriction

___ lie alongside capillary befs

lymphatic capillary beds

When lymphatic capillaries take up excess fluid it becomes ___

lymph

Lymph returns to the ___ in the chest

cardiovascular veins

___ sphincters can shut down a blood capillary, and blood then glows through the shunt

precapillary

Result from convergence of capillaries

venules

• Endothelium plus some pericytes • Highly porous (fluid and WBCs freely move across walls) • Larger venules have smooth muscle layers (tunica media) and thin tunica externa

venules

Result from convergence of venules

veins

Pulse and blood pressure, along with respiratory rate and body temp

vital signs

Pressure wave caused by expansion and recoil of arteries

pulse

Taken at wrist; routinely used

radial pulse

Where arteries close to body surface; can be compressed to stop blood flow

pressure points

Volume of blood flowing through a vessel, organ, or entire circulation in a given period; for entire vascular system = cardiac output

blood flow

Opposition of flow; the friction the blood encounters as it passes through vessels

resistance

blood pressure

___ = blood pressure gradient / resistance

blood flow

The ___ the pressure difference between two points, the greater the flow

greater

The greater the resistance, the ___ the flow

less

Arterial blood pressure: 2 factors 1. ___ of elastic arteries near the heart 2. ___ of blood forced into the elastic arteries

distensibility; volume

Pressure rises and falls with regularity

pulsatile pressure profile

___ (contractile) pressure = blood is forced out of left ventricle into aorta (120 mmHg)

systolic

___ (relaxed) pressure = aorta recoils (70-80 mmHg)

diastolic

___ = systolic minus diastolic pressure (120-75 = 45 mmHg)

pulse pressure

MAP =

mean arterial pressure

It is the ___ that most influences the resin of disorders (atherosclerosis, kidney failure, aneurysm, etc.)

MAP

Three factors determine blood pressure:

cardiac output; blood volume; resistance

Volume of blood flowing through the entire vascular system

cardiac output

Amount of blood in the body

blood volume

Friction blood encounters as it moves through vessels in the systemic circulation; resistance hinges on three variables: blood viscosity, blood vessel length, blood vessel radius

resistance

Thickness of blood (RBC count, # proteins)

blood viscosity

Longer vessels have greater resistance

blood vessel length

Smaller tubes, greater friction (more blood contacts vessel walls)

blood vessel radius

blood velocity; friction; resistance; cross-sectional area; arterioles

The flow of blood back to the heart. Five basic mechanisms: • pressure gradient • central venous pressure • gravity • skeletal muscle pump • thoracic (respiratory) pump • cardiac suction

venous return

Most important force in venous return

pressure gradient

Venules to ___: point where the venae cavae enter the heart

central venous pressure

___ drains blood from head to neck

gravity

___ in the limbs; contracting muscle squeezes out of compressed part of vein

skeletal muscle pump

Slight suction that draws blood into atria from vena cava

cardiac suction

___ (cluster of neurons in medulla) regulate vessel diameter

vasomotor center

___ > vasoconstriction > increased blood pressure

increased sympathetic activity

___ > vasodilation > decreased blood pressure

decreased sympathetic activity

Stretch in response to increased arterial pressure

baroreceptors

• Respond to changes in blood levels of O2, CO2, H+ • Increase blood return to lungs when deficient in O2 or when increased CO2 is sensed (pH)

chemoreceptors

Hypothalamus, cerebral cortex relay info to medulla

higher brain centers

The “salt-retaining hormone” body retains Na and water helps maintain blood volume and pressure

aldosterone

• Makes collecting dust more permeable to water • Water in the tubular fluid reenters the tissue fluid and bloodstream rather than being lost in urine = less urine output

antidiuretic hormone

atrial natriuretic hormone

autoregulation

vasoactive chemicals

• Growth of new blood vessel. Typically in tissues with long-term hypoxia; occurs in regrowth of uterine lining, around coronary artery obstructions, in exercised muscle, and malignant tumors

angiogenesis

Any state in which cardiac output is insufficient to meet the body’s metabolic needs

shock

Inadequate pumping of heart (MI)

cardiogenic shock

Cardiac output is low because too little blood is returning to the heart

low venous return

Most common type of shock • Loss of blood volume: trauma, burns, dehydration

hypovolemic shock

• Extreme vasodilation and decreased peripheral resistance • Anaphylactic (histamine) • Venous pooling: long periods of standing, sitting, or widespread vasodilation

vascular shock

atherosclerosis

hypertension

aneurysm

stroke

___ is a drug that dissolves blood clots

t-PA

Usually a vein from the leg is taken and used to bypass a clogged artery

bypass surgery

Wire mesh cylinder inserted into a clogged artery to hold it open

stents