- Narrow lumen - Contractile wall - Controls resistance and pressure of blood by altering lumen size

The Vascular System Flashcards by KJ Hall

Describe arteries:

Wide lumen
elastic wall
maintains pressure

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Describe arterioles:

Narrow lumen
Contractile wall
Controls resistance and pressure of blood by altering lumen size

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Describe capillaries:

Narrow lumen
Thin walls
Site of exchange of nutrient, oxygen and metabolic waste

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Describe venues and veins:

Wide lumen
Compliant wall
Low resistances
Blood reservoir
Valves to prevent back flow

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There are 3 major types of capillaries; continuous,
fenestrated and sinusoidal. Which of the following best
describes fenestrated capillaries?

Select one:
A. Located in the bone, liver and endocrine glands, very
permeable allowing larger
molecules such as plasma
proteins between blood and
interstitial space
B. Located in specialist areas of
the body, highly permeable,
contains ‘windows’ allowing
small peptides
C. Located in most regions of the body, semi-permeable
allowing H2O and small solutes

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What are continues capillaries?

Supplies most of the body - allows small solutes and H2O to cross

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What adaptions do continuous capillaries have?

Blood-brain barrier, whereby gap junctions between endothelial cells
prevent movement between the blood and interstitial space

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What are fenestrated capillaries?

Contain pores – allows much greater movement between blood and
interstitial space; including that of small peptides

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Where are fenestrated capillaries located?

Specialised areas

-Endocrine, intestines and glomerulus

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What are sinusoidal capillaries?

Resemble fenestrated capillaries but more ‘pores’ allowing larger molecules such as plasm proteins to cross

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Where are sinusoidal capillaries located?

Bone, liver and other endocrine organs

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What are three different types of capillaries?

Continuos capillaries
Fenestrated capillaries
Sinusoidal capillaries

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What three factors determine how blood travels through blood vessels?

Pressure
Flow
Resistance

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What is pressure in relation to blood flow?

The driving force behind blood flow, generated by the heart. Blood flows
from high to low pressure regions

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What is flow in relation it blood flow?

Volume per unit time (L/min; Q). Blood flow is determined by ΔP (starting point vs endpoint) and
resistance to flow

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What is resistance in relation to blood flow?

An impediment to flow; high

resistance means a higher ΔP is needed to achieve the same flow

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What is the equation for blood flow?

Change in pressure / resistance

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What factors does resistance to blood flow depend on?

Blood viscosity
Vessel length
Vessel radius

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How does blood viscosity affect resistance to blood flow?

The thicker the blood, the higher the resistance to flow

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How does vessel length affect resistance to blood flow?

The longer the vessel, the higher the resistance to flow

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How does vessel radius affect resistance to blood flow?

The narrower a vessel is, the higher the resistance to flow

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What is the equation for resistance?

(8 x blood viscosity x blood length) / ( π x vessel radius^4)

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What is the function of the cardiovascular system?

Delivery of oxygen and nutrients to tissue and removal of waste products

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What does the cardiovascular system consist of?

Pump (heart), pipes (blood vessels) and a carrier (blood)

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Do we have a singular or double circulation is the cardiovascular system?

Double circulation

What is the double circulation in the cardiovascular system?

- Pulmonary circulation | - Systematic circulation

What is the pulmonary circulation?

Specialised circulation that is relatively short, simple and operates at a lower pressure than systematic circulation

Is there a difference in cardiac output in two circulations of the cardiovascular system?

No - equal

Is there a difference in resistance to flow in two circulations of the cardiovascular system?

Pulmonary - short | Systematic - high

Is there a difference in pressure in two circulations of the cardiovascular system?

Pulmonary - short | Systematic - high

What is the normal pressure in the pulmonary circulation?

25/10 mmHg

What is the normal pressure in the systematic circulation?

120/80 mmHg

What is the major determination of blood pressure and flow?

Resistance determined by radius of blood vessels

What does mmHg stand for?

millimeters mercury

What is another name for mean arterial blood pressure?

Blood pressure

How do you calculate the mean arterial blood pressure?

2(diastolic) + systolic / 3

How many times longer is the diastole to systole at rest?

Twice

How does a dicrotic notch occur?

- Left ventricle contracts - Blood forced into aorta - Aortic valve closes rapidly - Sends pressure wave within the aorta

Where is the biggest drop in pressure in the circulation?

Arterioles

Why is the biggest drop in pressure in the arterioles?

Due to their small radius and high resistances

What blood vessel holds the largest share of blood in the whole circulation?

Veins

What is the word for the veins having the largest share of blood?

Capacitance

How is mean arterial blood pressure determined by?

- Cardiac output - Total peripheral resistances - Blood volume

How does cardiac output affect the mean material blood pressure?

Heart rate and stroke volume

How does total peripheral resistance affect the mean material blood pressure?

Constriction or dilating muscular arteries and arterioles

How does blood volume affect the mean material blood pressure?

Reduction or increases affects cardiac output

What is the equation for blood pressure?

Cardiac output x total peripheral resistance

How is blood pressure regulated?

- Neurological | - Humoral

How is blood pressure regulated humorally?

- Aldosterone, adrenaline, ADG, ANP and BNP etc - Short and long term - Influences vascular resistance and blood volume

How is blood pressure regulated?

- Autonomic nervous system - Short term regulation - Influences cardiac output and vascular resistance

Where are arterial baroreceptors located?

Aortic arc AND carotid sinus

What do arterial baroreceptors do?

-Continuously monitor atrial blood pressure -Input to cardiovascular centre in medulla oblongata -Output is autonomic nervous system response -Responsible for rapid, short-term control of blood pressure

What is the frequency of arterial baroreceptors dependent on?

Arterial blood pressure

Do the frequencies of the arterial baroreceptors increase or decrease when lower material pressure?

Decrease

Do the frequencies of the arterial baroreceptors increase or decrease when higher material pressure?

Increase

Describe how baroreceptors control of increased blood pressure:

- Baroreceptors detect stretch in vessels walls - Aortic arch and carotid artery increase firing rate - Carotid baroreceptors send information up through glossopharyngeal nerve - Aortic arch sends information through Vegas nerve to CV centre within medulla oblongata - Response though parasympathetic nerve and vagus nerve efferent - Increasing activity of parasympathetic output to Sino-artial node - Sympathetic output decreases to sino martial node - Decreasing the activity of B1 receptors - Decrease in heart rate and cardiac output - Vasoconstriction decreases and resistances - Blood pressure falls

What are the five main blood vessels?

- Arteries - Arterioles - Capillaries - Venules - Veins

What is the general three layer in vessel structure?

- Tunica interna - Tunica media - Tunica externa

What is tunica interna in relation to the layers of the blood vessels?

- Innermost - Endothelial Cells - Basement Membrane (‘anchor’) - Connective Tissue

What is tunica media in relation to the layers of the blood vessels?

-Middle -Boundary marked by internal and external elastic lamina (sheet) -Smooth muscle cells (encircle vessel) -Elastin and collagen

What is tunica externa in relation to the layers of the blood vessels?

- Outer - Connective tissue - Nerves, blood vessels - Collagen and elastin

What is the average wall to lumen thickness of an aorta?

2mm/25mm

What is the average wall to lumen thickness of muscular artery?

1mm/4mm

What is the average wall to lumen thickness of arteriole?

30 micrometer to 30 micrometer

Fill in the gap the sentence: | Vessel structure is ... to suit function

modified

What varies between blood vessels?

Wall thickness and diameter of lumen

What doe large arteries buffer?

Systolic rise in pressure, convert intermittent flow to continuous flow and maintain blood flow and pressure during diastole

What does a thick media of an artery contain?

-Lots of elastin fibres that allow stretching during systole and rebound during diastole

What does a wide lumen in an artery provide?

Low resistances allowing pressure and velocity to drop

What do large arteries absorption and return helping to propel blood during diastole?

Energy

What do muscular arteries do?

Distribute flow, resist collapse at joints and adjust blood flow to tissue/organs

Why do muscular arteries have thick smooth muscle media?

Degree of vasoconstriction and dilation to adjust blood flow

Why do muscular arteries have thick tunica externa?

Loose structure and longitudinal collagen fibres prevent retraction when cut

Why do arterioles have abundant sympathetic nerve endings?

Allow extensive vasoconstriction and vasodilation

What is arteriolar vasoconstriction?

Increases upstream arterial blood pressure, but reduces downstream blood flow to tissue

How do arterioles regulate blood flow to tissues?

vasoconstrict/dilatate rapidly and extensively allows them to adjust blood flow to tissues according to metabolic demand

What do capillaries provide?

Large cross-section for gaseous/nutrient exchange

Where is there a higher abundance of capillaries?

Metabolically active tissue

What is the equation for velocity?

Blood flow/cross-sectional areas

Finish the sentence: | The larger the cross-sectional area of capillaries slow velocity meaning...

Gaseous and nutrients exchange more affectivity

What is the fluid exchange between capillaries and surrounding tissue fluid determine by?

- Hydrostatic pressure | - Osmotic pressure

What is hydrostatic pressure?

- determined by flow and vessel resistance (i.e. blood pressure) - force that ‘pushes’ water out of blood vessels

What is osmotic pressure?

-determined mainly by charged proteins in the blood -‘pulls’ water into blood vessels

How are excess fluid returned to the circulation

via lymphatic system

What aids venous return from lower half of the body?

Skeletal muscle pump and respiratory pump

What is a venoconstriction?

Shunts blood from peripheral to central vessels to increase stroke volume