Ch. 19 LEC - Blood Vessels

Lecture Exam 2

define “blood vessels”

blood delivery system that begins and ends at the heart

define artery

blood vessel that carries blood away from the heart

define vein

blood vessel that carries blood toward the heart

define capillary

blood vessel that contact tissue cells and directly serve cellular needs

name the layers that make up arteries and veins from deep to superficial

1. tunica interna

2. tunica media

3. tunica externa

define lumen

central blood-containing space surrounded by tunics

what are capillaries composed of?

endothelium with sparse basal lamina

what is the function of the tunica interna?

to line the lumen of all vessels with a frictionless surface for blood flow

what is the function of the tunica media?

to control vasoconstriction/vasodilation of vessels (innervated by sympathetic nervous system)

what is the function of the tunica externa?

to protect and reinforce vessels with collagen fibers

define “vasa vasorum (vessels of the vessels)”

a network of microvessels that supply blood and nutrients to the external tissues of large arteries and veins

name the types of arteries from largest diameter to smallest

1. elastic artery

2. muscular artery

3. arteriole

name the type of artery that fits this description:

• thick-walled arteries near the heart (can withstand high pressure)

  • e.g., aorta and its major branches

• large lumen (to lower pressure)

• contains elastin in all 3 tunics

• acts as pressure reservoirs (i.e., can expand and recoil as blood is ejected from the heart)

elastic (conducting) artery

name the type of artery that fits this description:

• distal to elastic arteries

• deliver blood to body organs

• thick tunica media with more smooth muscle

• active in vasoconstriction

muscular (distributing) arteries

name the type of artery that fits this description:

• smallest artery

• leads to capillary beds

• controls flow into capillary beds via vasodilation and vasoconstriction

arterioles

name the blood vessel that fits this description:

• microscopic blood vessel

• structure: 1 wall of thin tunica interna (1 cell thick)

• pericytes help stabilize their walls and control permeability

• small size = 1 RBC passes at a time

• present in all tissue except for cartilage, epithelia,, cornea, and lens of eye

• FUNCTION: exchange gases, nutrients, waste, hormones, etc.

capillary

name the 3 structural types of capillary and examples of organs they are present in

• continuous capillaries — muscle, nervous system

• fenestrated capillaries — liver, kidney, spleen

• sinusoidal capillaries — red bone marrow

name the type of capillary that fits this description:

• abundant in skin and muscles

• these capillaries form the blood-brain barrier

continuous capillaries

name the type of capillary that fits this description:

• some endothelial cells contain pores

• more permeable than continuous capillaries

• function in absorption or filtrate formation (e.g., small intestine, endocrine glands, kidneys)

fenestrated capillaries

name the type of capillary that fits this description:

• fewer tight junctions, larger intercellular clefts, large lumens — most permeable

• usually fenestrated (has pores)

• allows large molecules and blood cells to pass between blood and surrounding tissues

• found in liver, bone marrow, spleen

sinusoidal capillary

define “precapillary sphincter”

the cuff of smooth muscle that surrounds each true capillary; regulates blood flow into capillary

what are venules?

blood vessel part of the venous system that is formed when capillary beds unite; allows fluids and WBCs to pass from the bloodstream to tissues

what are postcapillary venules?

small venules composed of endothelium and a few pericytes

true/false: large venules have one or two layers of smooth muscle (tunica media)

true

[ARTERIES/VEINS] are formed when venules converge

veins

veins are also known as [NAME] or blood reservoirs that contain [NUMBER]% of the blood supply

capacitance vessels, 65

true/false: arteries have much lower blood pressure and thinner walls than veins

false — veins have much lower blood pressure and thinner walls than arteries

identify the special adaptations veins have to ensure blood returns to the heart (2 possible answers)

• large-diameter lumens: little flow resistance

• valves: prevent backflow

what are venous sinuses?

specialized, flattened veins with extremely thin walls (e.g., coronary sinus of the heart)

what are vascular anastomoses

merging blood vessels that provide alternate pathways (collateral channels) for blood to reach a target region

define “blood flow”

the actual volume of blood flowing through a vessel, an organ, or the entire circulation in a given period (mL/min); equivalent to cardiac output (CO) (if considering the entire vascular system)

define “blood pressure (BP)”

force per unit area exerted on the wall of a blood vessel by its contained blood (mmHg)

define (peripheral) resistance

opposition to flow

identify the sources of resistance

• blood viscosity

• total blood vessel length

• blood vessel diameter

if blood viscosity [DECREASES/INCREASES], resistance increases

increases

if total blood vessel length [DECREASES/INCREASES], resistance increases

increases

if blood vessel diameter [DECREASES/INCREASES], resistance increases

decreases

true/false: abrupt changes in diameter or fatty plaques from atherosclerosis (i.e., hardening of arteries) increase blood flow resistance

true

what is the equation that relates blood flow (F), blood pressure (P), and resistance (R) to one another?

F = delta P / R

if blood pressure increases, blood flow [SLOWS DOWN/SPEEDS UP]

speeds up

if resistance increases, blood flow [DECREASES/INCREASES]

decreases

systemic blood pressure is highest in the [LOCATION] and 0 mmHg in the [LOCATION]

aorta, right atrium

what 2 things does arterial blood pressure reveal about the arteries close to the heart?

• the arteries’ elasticity (compliance or distensibility)

• the amount of blood forced into them at any given time

define “systolic pressure”

pressure exerted on atrial walls during ventricular contraction

define “diastolic pressure”

the lowest level of arterial pressure

define “mean arterial pressure (MAP)”

pressure that propels the blood to the tissues (average blood pressure in an individual)

list the factors aiding venous return

• respiratory pump:

  • pressure change created during breathing

  • moves blood towards the heart by squeezing abdominal veins as thoracic veins expand

• muscular pump:

  • contraction of skeletal muscles bring blood towards the heart

• vasoconstriction of veins under sympathetic control

• one-way valves

list the factors influencing blood pressure

• cardiac output (CO)

• peripheral resistance (PR)

• blood volume

if cardiac output increases, blood pressure [DECREASES/INCREASES]

increases

if peripheral resistance increases, blood pressure [DECREASES/INCREASES]

increases

if blood volume increases, blood pressure [DECREASES/INCREASES]

increases

identify the equation that relates blood pressure (BP), cardiac output (CO), and peripheral resistance (PR)

BP = CO * PR

resting heart rate is controlled by [NEUROLOGICAL STRUCTURE]

the cardioinhibitory center of the medulla oblongata via the vagus nerve

under stress, increased heart rate and stroke volume is controlled by [NEUROLOGICAL STRUCTURE]

the cardioacceleratory center of the medulla oblongata

the [KIDNEY/NERVOUS SYSTEM AND HORMONES] alter peripheral resistance, which is a [SHORT-TERM/LONG-TERM] solution to counteract fluctuations in blood pressure

nervous system and hormones, short-term

the [KIDNEY/NERVOUS SYSTEM AND HORMONES] alter blood volume, which is a [SHORT-TERM/LONG-TERM] solution to counteract fluctuations in blood pressure

kidney, long-term

define “cardiovascular center”

part of the medulla oblongata; consists of the vasomotor center and the cardiac centers that integrate blood pressure control by altering cardiac output and blood vessel diameter

define “vasomotor center”

a group of neurons in the brain’s medulla oblongata that oversees changes in blood vessel diameter

• increased sympathetic activity causes:

  • [VASOCONSTRICTION/VASODILATION] and [DECLINE/RISE] in blood pressure

• decreased sympathetic activity causes:

  • blood pressure to [DECLINE/RISE]

vasoconstriction, rise, decline

blood pressure is regulated by chemoreceptors sensitive to [ELEMENT] and [COMPOUND]

oxygen, carbon dioxide

where are prominent BP-regulatory chemoreceptors found?

the carotid and aortic bodies

list the chemicals that increase blood pressure via vasoconstriction

• adrenal medulla hormones (epinephrine and norepinephrine)

• antidiuretic hormone (ADH)

• angiotensin II

list the chemicals that decrease blood pressure

• atrial natriuretic peptide (ANP)

• nitric oxide (NO)

• inflammatory chemicals (histamine)

• alcohol

how do the adrenal medulla hormones (epinephrine and norepinephrine) increase blood pressure?

cause vasoconstriction and increase cardiac output

how does ADH increase blood pressure?

cause intense vasoconstriction in cases of extremely low BP

how does Angiotensin II increase blood pressure?

kidney release of renin generates this chemical, causing vasoconstriction

how does atrial natriuretic peptide (ANP) decrease blood pressure?

cause blood volume and pressure to decline by inhibiting aldosterone

how does nitric oxide (NO) decrease blood pressure?

cause brief but potent vasodilation

how do inflammatory chemicals (histamine) decrease blood pressure?

cause vasodilation

how does alcohol decrease blood pressure?

inhibition of ADH

what organ of the body controls blood pressure long-term by altering blood volume?

the kidneys

the [HEART/KIDNEY] act directly and indirectly to maintain long-term blood pressure:

1. direct renal mechanism alters [BLOOD VOLUME/DIAMETER OF BLOOD VESSELS]

2. indirect renal mechanism involves the [NAME] mechanism

kidney, blood volume, renin-angiotensin

direct renal mechanism to alter long-term blood pressure:

• increased BP or blood volume causes the [KIDNEY/LIVER] to eliminate [LESS/MORE] urine, thus [DECREASING/INCREASING] BP

• decreased BP or blood volume causes the [KIDNEY/LIVER] to conserve water, and BP [DECREASES/INCREASES]

kidney, more, decreasing, kidney, increases

indirect renal-angiotensin mechanism to alter long-term blood pressure:

1. [LOW/HIGH] arterial BP → release of renin

2. renin → production of [CHEMICAL]

3. [CHEMICAL] is a potent vasoconstrictor and causes aldosterone and ADH release from other endocrine glands

4. aldosterone → renal reabsorption of [ELEMENT] and [LOW/HIGH] urine formation

low, angiotensin II, angiotensin II, Na+, low

what are the main measurements that asses the efficiency of the blood circulation?

pulse and blood pressure

define “vital signs”

pulse, blood pressure, respiratory rate, body temperature

define pulse

pressure wave caused by the expansion and recoil of elastic arteries

define sphygmomanometer

a blood pressure monitor consisting of an inflatable arm cuff, an inflation bulb, and pressure gauge

measuring blood pressure with a sphygmomanometer:

• the first sound heard is recorded as the [SYSTOLIC/DIASTOLIC] pressure (normally [NUMBER RANGE] mmHg)

• the pressure when sound disappears is recorded as the [SYSTOLIC/DIASTOLIC] pressure (normally [NUMBER RANGE] mmHg)

systolic, 110-140, diastolic, 70-80

define hypotension

low blood pressure; systolic pressure below 100 mmHg

name the condition that is characterized by temporary low BP and dizziness when suddenly rising from a sitting or reclining position

orthostatic hypotension

name the condition that is caused by poor nutrition and is a warning sign for Addison’s disease (adrenal insufficiency) or hypothyroidism

chronic hypotension

name the condition that is an important sign of circulatory shock

acute hypotension

define hypertension

high blood pressure; sustained elevated arterial pressure of 140/90 or higher

prolonged [DISEASE] is a major cause of heart failure, vascular disease, renal failure, and stroke

hypertension

[PRIMARY/SECONDARY] hypertension:

• 90% of hypertensive conditions

• risk factors: heredity, diet, obesity, age, stress, diabetes mellitus, smoking

primary

[PRIMARY/SECONDARY] hypertension:

• less common

• due to identifiable disorders: kidney disease, arteriosclerosis, and endocrine disorders (e.g., hyperthyroidism and Cushing’s syndrome (hyperadrenalism))

secondary

define autoregulation

automatic adjustment of blood flow to each tissue in proportion to its requirements at any given point in time

define angiogenesis

the formation of new blood vessels from pre-existing ones; occurs when short-term autoregulation cannot meet tissue nutrient requirements

what occurs during angiogenesis?

• the number of vessels to a region increases

• existing vessels enlarge

create a short flowchart to show the blood flow’s skeletal muscle regulation

physical activity → vasodilation → increased muscle blood flow

blood flow: brain

• blood flow to the brain is constant because neurons are intolerant to [CONDITION]

• metabolic controls

  • decline in pH and rise in carbon dioxide cause [VASOCONSTRICTION/VASODILATION]

• myogenic controls

  • decrease in [NAME] (MAP) cause cerebral vessels to [CONSTRICT/DILATE]

  • increases in MAP cause cerebral vessels to [CONSTRICT/DILATE]

ischemia, vasodilation, mean arterial pressure, dilate, constrict

MAP below [NUMBER] mmHg can cause syncope (fainting)

60

MAP above [NUMBER] mmHg can result in cerebral edema

160

what are the functions of blood flowing near the skin?

• supplies nutrients to cells in response to oxygen need

• helps maintain body temperature

• provides a blood reservoir

blood flow: heart

• during strenuous exercise

  • [NAME] vessels dilate in response to local accumulation of vasodilators

  • blood flow may [DECREASE/INCREASE] 3 to 4 times

coronary, increase

define “circulatory shock”

• any condition in which

  • blood vessels are inadequately filled

  • blood cannot circulate normally

• results in inadequate blood flow to meet tissue needs

identify the type of circulatory shock that results from large-scale blood loss

hypovolemic shock

identify the type of circulatory shock that is characterized by poor circulation resulting from extreme vasodilation (e.g., anaphylactic shock from a systemic allergic reaction)

vascular shock

identify the type of circulatory shock that is characterized by the heart being unable to sustain adequate circulation (e.g., myocardial damage due to heart attack/infarcts)

cardiogenic shock