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Physiology And Pharmacology Of Systems > The Vasculature > Flashcards

The Vasculature Flashcards

1
Q

Definition of atherosclerosis

A

Build up of cholesterol rich plaques, causes stenosis of artery
Made up of an atherosclerotic lesion and fibrous cap

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2
Q

Definition of acute coronary syndrome

A

Symptoms associated with decreased blood flow in coronary arteries
As a result, part of heart muscle can’t function/dies

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3
Q

Definition of tunica adventitia

A

Tough outermost layer of collagen fibres, supportive element (ext elastic lamina)

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4
Q

Definition of tunica media

A

Mainly made up of smooth muscle and elastic fibres

Thickest layer

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5
Q

Definition of tunica intima

A

Made up of 1 layer of endothelial cells, supported by int elastic lamina

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6
Q

Definition of oxidative stress

A

Overproduction of reactive oxygen species

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7
Q

Definition of resistance arteries

A

Small diameter blood vessel in microcirculation that contributes to creation of resistance to flow

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8
Q

Definition of autoregulation

A

Blood flow in vascular beds remain fairly constant over a wide range of pressures
Due to myogenic response and effects of flow on local conc of metabolites

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9
Q

Definition of hyperaemia

A

Increased volume of blood supplying the vessels

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10
Q

Definition of reactive hyperaemia

A

If local blood flow cut off, metabolites accumulate => VD

When blood flow resumed, transiently enhanced until metabolites wash out

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11
Q

Definition of pericytes

A

Smooth muscle found in CNS capillaries

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12
Q

Definition of orthostasis

A

Decreased BP when you stand up

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13
Q

What are the functions of the 3 circulatory systems

  • arterial
  • venous
  • micro
A

Arterial
-regulates blood distribution as high pressures can damage

Venous

  • 60-70% of all blood here
  • VC redistributes blood to maintain CO, BP

Micro
-gas, nutrient, waste product exchange

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14
Q

Describe the composition of arteries

  • tunica ext
  • tunica med
  • tunica int
A

Tunica ext
-collagen, vessels, fibroblasts, sympathetics

tunica med

  • surrounded by ext/int elastic lamina
  • SM, control diameter

tunica int
-endothelium (regulate VD, VC, angiogenesis)

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15
Q

Describe the importance of vascular tone

-2 reasons

A

Maintain flow to organs via VC, VD

Control BP via CO, TPR

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16
Q

Describe the mechanism for SM contraction and relaxation

-what inhibits and activates MP

A

Myosin + Calmodulin + Ca2+ = (MLCK)=> MyosinPi

MyosinPi =(MP)=> Myosin + Calmodulin + Ca2+

MP
-activated by NO via cGMP => decreases Ca sensitivity

-inhibited by rho kinase => increases Ca sensitivity

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17
Q

Describe how vascular smooth contraction is stimulated by a1 (NA, angiotensin II)

A

Rho kinase activated => Ca sensitization

Phospholipase C splits PIP2 => IP3

IP3 acts on SR => increase [Ca]
IP3 + DAG activates receptor gated Na channels => increase [Na]

Stretch activated Na activate => increase [Na]

Increased [Na] => depolarization => opening of voltage gated Ca channels => increases [Ca]

18
Q

How is NO released from the endothelial cells

A

VD substance binds to receptor => increased [Ca] => activates eNO synthase

Sheer flow phosphorylates Akt =>activates eNOs

Arginine =(eNOs)=> NO

NO diffuses across to smooth muscle

19
Q

How does NO cause smooth muscle relaxation

A

NO activates GC

GC converts GTP => cGMP => Ca desensitization

cGMP => Ca uptake into SERCA and Ca removal via CaATPase

cGMP => K removal via K channels => hyperpolarisation
=> voltage gated Ca close, inhibit Ca uptake

PDE converts cGMP => GMP

20
Q

How does the endothelium promote VD when the NO system is not working sufficiently
-2 mechanisms

A

VD substances => VGKC open => K out => hyperpolarisation spreads

EETs released by endothelium => activate SM K channels

21
Q

Describe how VD substances can cause VD in SM

A

Activation of B2, PGI2, ADO receptors of SM => AC => increased cAMP => PKA => VD

22
Q

How does the SNS regulate vascular tone

  • what is the function
  • which regions are affected
A

Redistributes flow by increasing TPR

Widespread constriction in

  • splanchnic
  • renal
  • cutaneous
  • muscle
23
Q

How does the PNS regulate vascular tone

  • what is the function
  • what regions are affected
A

V discrete effects, no change in TPR

Regulates organ flow

  • salivary
  • GI
  • penile
  • pancreas
24
Q

How do these hormones affect vascular tone

  • Adrenaline
  • AngII, ADH
A

Adrenaline
-VD => increase flow to muscles

AngII, ADH
-VC => increase BP

25
Q

How do these local metabolites affect vascular tone

  • Prostaglandins (endothelium released)
  • Seretonin

-ADO

  • Endothelin (endothelium released)
  • EET (endothelium released
A

Prostaglandins
-VD, oppose haemostasis

Seretonin
-VC, promote haemostasis

ADO
-VD, muscle metabolite

Endothelin
-VC

EET
-VD

26
Q

What molecules promote NO release from the endothelium

-what are their effects

A 
Bradykinin
ATP
Histamine
Increased CO2
Ach
Blood flow

VD

27
Q

Describe the myogenic response

  • what arterioles does this occur in
  • what is its function
A

Sudden increase in P => increased diameter => increased F => SAC activated, depolarize, contract => VC

Decreased P => decreased F => slow VD

MAINTAIN CONSTANT LEVEL OF FLOW

Larger arterioles

28
Q

Describe the metabolic regulatory response

  • what arterioles does this occur in
  • what is its function
A

Metabolites => VD => increased F
Metabolites washed away => decreased VD => increased R => decreased F

LIMITED TO ACTIVE MUSCLE
FLOW PROPORTIONAL TO METABOLIC RATE

Smaller arterioles

29
Q

Describe reactive hyperemia

-what types of exercise result in this

A

Local flow cut off => VD due to accumulation of metabolites => increased F until metabolites washed away

ISOMETRICS

30
Q

Describe the CO distribution at rest

  • what organs get the most
  • what are the properties of flow here
A

Kidney, brain, heart

  • v low R
  • vulnerable to changes in F and P
31
Q

What are the anatomical adaptations of coronary flow

A

Coronary collaterals

1 cap/myocytes

32
Q

What are the physiological adaptations of coronary flow

A

Myogenic, metabolic response

High O2 extraction, only increased via increased F

33
Q

What are the drawbacks of coronary flow

A

Flow in L coronary occluded in LV systole => endocardium perfused in diastole

If diastole shortens => reduced F

34
Q

Describe how the coronary flow reserve normally operates

What happens when the VD mechanism does not function

A

F = ∆P/R

Normally as R increases => ∆P increases => F maintained

As R increases => ∆P does not increase enough => F falls

35
Q

What are the anatomical adaptations of cerebral flow

A

Circle of Willis anastomosis

High capillary density
BBB controls substance mv

36
Q

What are the physiological adaptations of cerebral flow

A

Metabolic hyperemia

Weak ANS control

37
Q

Describe how VC is stimulated in the cerebral circulation

A

Neuronal glutamate release => Astrocytes release 20HETE

38
Q

Describe how VD is stimulated in the cerebral circulation

A

Neuronal NO, PGE2

Neuronal glutamate => Astrocytes release K, EET, PGE2

Hyperpolarization spread via gap junctions

39
Q

Describe the typical composition of veins

A

Same as arteries but

  • sparse SM
  • collapsible
40
Q

How does venous blood return to the heart

A

Decreased R than arterial system
Skeletal muscle pump of deep veins w valves
Resp pump, inspiration reduced thorax P => decreased vena cava P => increased P difference => draws blood in

41
Q

Describe the composition of capillaries

-2 structures

A

Basal lamina
-fibrous support for endothelium

Endothelium
-material exchange

Physiology And Pharmacology Of Systems (22 decks)

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