The Circulatory System

Question 1

Describe the histology of Tunica external and what it contains

Answer 1

CT w loose weave of collagen/elastic fibres

Thicker when found in veins

Contains
Nervi vasorum, lymphatics and vasa vasorum (only in larger vessels)

Question 2

Describe the histology of Tunica media and the significance of this.

Answer 2

Smooth muscle and loose CT

Smooth muscle = maintains patency and controls vessel diameter =stabilises and influences BP

Question 3

Describe the histology of Tunica intima and what it contains

Answer 3

CT w elastin

Inner endothelium = friction free surface for easy blood flow

Question 4

What are anastomoses?

Answer 4

connection between 2 peripheral vessels, without an intervening capillary bed

Question 5

What are the three main parts of Blood vessel anatomy?

Answer 5

Tunica Externa
Tunica Media
Tunica Intima

Question 6

What is Vascular Tone?

Answer 6

degree of constriction experienced by a blood vessel

Question 7

What are the three factors that regulate vascular tone?

Answer 7

Membrane potential of smooth muscle

Chemical ligands

Mechanical stimuli/ myogenic mechanism

Question 8

How does the Membrane potential of smooth muscle regulate vascular tone?

Answer 8

Hyperpolarisation = relaxation

Depolarisation = contraction

Question 9

Explain the chemical ligand control of vascular tone

Answer 9

A-adrenoreceptors on arterioles in skin and salivary glands = vasoconstriction

B-adrenoreceptors of coronary and muscle arterioles = vasodilation

Question 10

What are the two mechanisms of mechanical stimuli/myogenic mechanism regulation of vascular tone?

Answer 10

Stretch-induced contraction
pressure induced contraction

Question 11

Where does the following occur:

a) Stretch-induced contraction
b) Pressure-induced contraction

Answer 11

a) arteries and large arterioles

b) terminal resistance arterioles

Question 12

What is the consequence of a sympathetic surge in arteries?

Answer 12

Noradrenaline released from a1-adrenergic receptors on smooth muscle = vasocontriction

B-Adrenergic receptors cause vasodilation to ensure cardiac tissue not compromised

Question 13

What is the consequence of Loss of nervous input

Answer 13

vasodilation

Question 14

Do arteries carry Oxy or Deoxy blood in
a) systemic circulation
b) pulmonary circulation ?

Answer 14

a) oxy
b) deoxy

Question 15

What are the three main anatomical features of arteries?

Answer 15

External elastic membrane/lamina

Internal elastic membrane/ lamina

circumferential Smooth Muscle

Question 16

What is External elastic membrane/lamina and where is it found?

Answer 16

Band of elastic CT at outer surface of tunica media

Question 17

What is Internal elastic membrane/lamina and where is it found?

Answer 17

Band of elastic fibres at the outer surface of tunica intimia

Question 18

What are the two types of arteries?

Answer 18

Elastic/conducting

Muscular/distributing

Question 19

What are the structural features of Elastic/conducting arteries and what is the significance of them?

Answer 19

LARGEST

Most proximal to heart (resilient)

Thick walls and wide lumen (laminar blood flow)

High density elastin in tunica media (withstand pressure from ejection and dampen oscillation)

Few smooth muscle fibres (oppose stretch, maintain paten

Question 20

What are the structural features of muscular/directing arteries?

Answer 20

Distal to elastic

Thickest tunica media

Limited vasoactivity

Question 21

features and function of arterioles

Answer 21

Features
Distal to both types of arteries
Larger ones = poorly defined arteries
No tunica advenitia in terminal/resistance arterioles

Function
Vasoactive (strong influnce on blood flow)

Question 22

What is the effect of injury for elastic arteries?

Answer 22

Loss of elastin

Aneurysm

Question 23

What is the effect of injury for muscular arteries?

Answer 23

Aneurysms

More tendency to develop atherosclertoic plaque

Thick tunica media = protects against crushing

Question 24

How does smoking/ nicotine damage arteries?

Answer 24

causes loss of elastin by stimulating the release of elastase

Question 25

Why not take carotid pulse in an elderly patient?

Answer 25

elastin is lost with age so the artery may not rebound after compression OR dislodge a plaque.

Question 26

True vs false aneurysm

Answer 26

True = all three walls affected False = 1-2 walls affected

Question 27

How is blood moved in elastic vs muscular arteries?

Answer 27

E= elastic recoil M= pressure difference using force from V ejection and previous elastic recoill

Question 28

Systolic pressure in exercise

Answer 28

SNS stimulates inceased CO = more blood into arteries = large INCREASE in S.

Question 29

Describe what determines Diastole pressure and how it is impacted in Exercise

Answer 29

Rate of blood moving out determined by pressure drops between beats this is determined by Peripheral Vascular Res. Therefore PVR = major determinat of D D doesn’t really change in exercise

Question 30

do veins carry blood towards heart that is oxy or deox in a) systemic b) pulmonary

Answer 30

a deoxy b oxy

Question 31

Anatomical features of Veins

Answer 31

Valves Large ones may have 1-2 layers of smooth muscle

Question 32

Why is skeletal muscle activity important for venous blood flow?

Answer 32

Muscle pumping promotes venous return

Question 33

What is a Vascular Venous Pump

Answer 33

Venae comitantes = artery coupled with a pair of veins wrapped in CT

Question 34

What is the purpose of the Vascular venous pump?

Answer 34

When arterial pulse flows through artery, the artery expands = compresses vein = pushes blood towards the hearts

Question 35

what 2 resp pumps aid in Venous return and how?

Answer 35

Thoracic V pump and Abdomino-throacic pump Aids in V retrun via Negative pressure allowing the chest to suck blood up

Question 36

What are the three types of capillaries?

Answer 36

Continuous Fenestrated Sinsusoid

Question 37

Structural features of continuous capillaries

Answer 37

uninterrupted endothelium partially or completely impermeable within most tissue

Question 38

Structural features of Fenestarted capillaries

Answer 38

fenestrated endothelium - pores between cells allow easier fluid/ protein movement

Question 39

Structural features and location of Sinsusoid Capillaries

Answer 39

Very leaky - intercellular gaps allow larger molecules to pass usually also fenestrated may have large and irregular lumens within the liver, bone marrow, lymphoid tissues, and some endocrine organs

Question 40

How is systemic capillary bed exchange controlled?

Answer 40

- substance movement under greater (continuous) or lesser (sinusoid) control - substances move according to concentration gradients - fluid movement governed by pressure and osmotic/ oncotic gradients

Question 41

What is the formula for NFP?

Answer 41

NFP = Net Hydrodtatic pressure - net colloid osmotic pressure NFP= (Pc-Pif) - (IIp - IIif)

Question 42

What is the jugular a peak?

Answer 42

right atrium systole

Question 43

What is the jugular AV dip.

Answer 43

right atrium diastole

Question 44

what is the jugular C peak?

Answer 44

early R ventricular systole Pressure rise causes tricupsid valve bulging

Question 45

What is the jugular X-dip?

Answer 45

ventrical sytole heart shortens = pulls and elongates veins

Question 46

what is the jugular V peak?

Answer 46

RA filling when tricupsid closes

Question 47

what is the jugular y-dip?

Answer 47

blood speeds out of jugular during rapid ventricular filling

Question 48

What occurs at the dicrotic notch?

Answer 48

small increase in aortic pressure caused by the brief backward flow of blood as the aortic valve snaps shut

Question 49

What is the consequence of MI on the Ventricular Pressure curve?

Answer 49

less contractibility = decreased peak Systole pressure increased diastole pressure --> stiff and less compliant = can't relax enough = less step rise and fall

Question 50

What is the impact of increasing SNS on ventricular pressure curve?

Answer 50

increased ionotrophy = increased peak systolic pressure curve increased chronotrophy = shortened duration of systole and diastole increased lusitropy = diastole curve falls fast

Question 51

What are the chemoreceptors and where are they located?

Answer 51

what: regulate resp activity and cardiovascular function where: carotid and aortic bodies