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Semester 3 > deck_16304278 > Flashcards

deck_16304278 Flashcards

1
Q

blood vessels function

A

deliver blood to the organs and tissues in your body

help maintain homeostasis via vasoconstriction/vasodilation

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2
Q

note that many capillary sphincters are often constricted to make blood’s delivery of oxygen/nutrients efficient for tissues that require it most

A

..

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3
Q

how many km of blood vessel does left side pump through?

A

The left side of the heart pumps blood through an estimated 100,000 km of blood vessels

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4
Q

major types of BV

A

Arteries (efferent vessels)
Blood vessels that carry blood AWAY from the heart

Arterioles
Smaller than arteries, carries blood AWAY from the heart

Capillaries
Smallest blood vessels where O2 & CO2 can be exchanged

Venules
Smaller than veins, carries blood TOWARDS the heart

Veins (afferent vessels)
Blood vessels that carry blood TOWARDS the heart

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5
Q

arteries about

A

Also called efferent vessels

carry blood away from the heart to other tissues

High pressure/low volume reservoir

Have thick elastic walls.

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6
Q

characteristic of wall of arteries

A

thick elastic walls.

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7
Q

arterioles about

A

Small arteries that are less elastic

Have more smooth muscles

Provide the greatest resistance to the blood flow that help to regulate blood pressure

Regulate flow into capillary beds

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8
Q

arterioles vs arteries

A

arterioles less elastic

arterioles have more smooth muscle

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9
Q

which vessels contribute most to regulating BP

A

arterioles

Provide the greatest resistance to the blood flow that help to regulate blood pressure

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10
Q

capillaries about

A

The site of exchange with tissues

Exchange of gases and nutrients between blood and tissue cells

Compose of single layer of the endothelial cells, (thin flattened cells that line the inner wall of all vessels)
+
and basal membrane

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11
Q

venules and veins, about

A

Also called afferent vessels

carry blood away from the tissues to the heart

Low pressure/High volume reservoir

Regulate cardiac filling (how much blood is returning to the heart)

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12
Q

what is known as low pressure / high volume reservoire

A

veins / venules

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13
Q

how do veins regulate cardiac filling?

A

Neurohumoral mechanisms can mobilize the blood in veins to maintain filling pressure in the right heart when required.

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14
Q

3 layers of wall of blood vessel

A

Tunica interna
Innermost layer, adjacent to lumen

Tunica media
Middle layer of smooth muscle and elastic CT

Tunica externa
Outermost layer, CT outer covering

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15
Q

tunica interna aka

A

TUNICA INTIMA

more commonly known as “

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16
Q

tunica externa aka

A

tunica adventitia

we will refer to it as tunica externa

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17
Q

how are the 5 vessels structurally different?

A

some structural variations correlate to the different functions of the 5 major blood vessel types

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18
Q

about Tunica Intima (tunica interna)

A

Forms the inner lining of the blood vessel and is in direct contact with the blood

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19
Q

3 components of tunica intima

A

3 components:

Endothelium (simple squamous epithelium)

Basement membrane (reticular fibers)

Internal elastic lamina forming the boundary between the tunica interna and tunica media
—> (contributes to distensibility & stretch of vessel)

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20
Q

basement membranes function (general function – maybe not applicable here?)

A

Functionally, the BM is important for providing physical and biochemical cues to the overlying cells, sculpting the tissue into its correct size and shape.

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21
Q

tunica media – about

A

Muscular and CT layer that displays the greatest variation among the different vessel types

Composed of smooth muscle and elastic fibers

External elastic lamina separating the tunica externa from tunica media

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22
Q

which component of vessels has the greatest variation b/w the different types?

A

TUNICA MEDIA (esp because some vessels require more smooth muscle than others, depending on function)

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23
Q

Note external elastic lamina

A

shown as part of tunica externa in diagram, but notes include it as part of tunica MEDIA

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24
Q

more about role of tunica media

A

Regulates the diameter of the lumen, ultimately effecting the rate of blood flow and pressure

Helps limit blood loss with injury (VASOCONSTRICTION)

Allows stretch and recoil of the blood vessel

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25
Q

note hemostasis (vascular phase & tunica media)

A

(Helps limit blood loss with injury)

recall:
1) vascular phase
2) platelet phase
3) coagulation phase

tunica media contributes to vasoconstriction (during vascular phase)

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26
Q

tunica media and stretch/recoil

A

“Allows stretch and recoil of the blood vessel”

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27
Q

tunica externa (adventitia) – about

A

Consists of elastin and collagen fibers, numerous nerves and blood vessels (VASA VASORUM)

Contains the vasa vasorum
Small blood vessels that supply blood to the tissues of the vessels

Helps anchor vessel to surrounding tissues

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28
Q

vasa vasorum

A

Vasa vasorum are defined as small blood vessels that supply or drain the walls of the larger arteries and veins, and connect with a branch of the same vessel or a neighboring vessel to form a network of small blood vessels

Supply the vessel tissue with blood (oxygen and nutrients)

small arteries and veins in the tunica externa

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29
Q

NOTE diagram cmoparing vein vs artery

A

may not always be the case, but —>

in diagram shows that vein does not have internal/external ELASTIC LAMINA

otherwise, both have all the same components in diagram

SMOOTH MUSCLE (tunica media) layer is esp THICKER in artery

and Tunica externa is also considerably thicker in artery

tunica interna is roughly same

(all according to this diagram, in slides)

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30
Q

also note LUMEN

A

also note that LUMEN is much LARGER in vein

Seems that both are roughly same size externally, but due to increased mass of TUNICA MEDIA (smooth muscle layer) in ARTERY –> lumen size is relatively smaller

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31
Q

note differences

A

Arteries: thickest walls

Veins: largest lumens

Movement in vessel:
—> Arteries: pressure from heart
—> Veins: have valves and use skeletal muscle actions to move blood

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32
Q

vein valves

A

esp lower extremity

prevent backflow

as skeletal muscles assist in pushing blood upward, past valves, back to heart

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33
Q

arteries – HIGH COMPLIANCE

A

somewhat similar in concept to “plasticity”

Compliance:
“the ability of an organ to distend in response to applied pressure.”

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34
Q

why arteries high compliance

A

High compliance due to numerous elastic fibers

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35
Q

smooth muscle innervation in arteries

A

Smooth muscle innervated by autonomic nervous system

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36
Q

smooth muscle innervation vs VASOCONSTRICTION

A

Vasoconstriction:
—> sympathetics cause a decrease in the diameter of an artery or arteriole
—> increases BP or restricts blood flow to a damaged area

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37
Q

smooth muscle innervation vs VASODILATION

A

Vasodilation:
—> The process by which a decrease in sympathetics causes an increase in the diameter of the artery or arteriole.
—> via an increased need for blood supply or changes to body metabolism
(E.g. via effect of drugs)

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38
Q

are parasympathetics involved in vasodilation?

A

No

reduced sympathetic nervous signals is responsibly for vasodilation

also
what about effect of drugs?
E.g.
NO as mediator of vasodilation

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39
Q

medication vs vasodilation (E.g. NO)

A

NO and Vasodilation Mechanism

NO diffuses into the smooth muscle cells of blood vessels and activates an enzyme called guanylate cyclase,

which in turn increases the production of cyclic guanosine monophosphate (cGMP).

Elevated levels of cGMP cause the relaxation of smooth muscle cells, leading to vasodilation.

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40
Q

types of arteries

A

Elastic arteries (aka conducting arteries)

Muscular arteries (aka distributing arteries)

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41
Q

elastic arteries (aka conducting arteries)

A

LARGE DIAMETER

More elastic fibers, less smooth muscle

Function as pressure reservoirs

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42
Q

E.g. of elastic arteries

A

aorta and pulmonary arteries

contain much more elastic tissue in the tunica media than muscular arteries

high compliance of aorta

also note DICROTIC NOTCH and elasticity of AORTA

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43
Q

Muscular arteries (aka distributing arteries)

A

Medium diameter

More smooth muscle, fewer elastic fibers

smooth muscles allow vessels to regulate blood supply constricting or dilating.

Distribute blood to various parts of the body

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44
Q

more about elastic arteries

A

Largest diameter arteries in the body

Their walls are relatively THIN compared to their large DIAMETER.

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45
Q

internal and external lamina of ELASTIC ARTERIES

A

Well defined internal and external elastic lamina

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46
Q

(Elastic arteries)

thick tunica media, but primarily of which composition?

A

Thick tunica media made primarily of ELASTIC FIBRES called ELASTIC LAMELLAE

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47
Q

more about function of elastic arteries

A

they stretch & expand to accommodate a surge of blood during ventricular systole (E.g. Aorta)

Store mechanical energy – functioning as a “pressure reservoir”

When the ventricles of the heart are relaxed, these arteries may still propel the blood forward
—> VIA ELASTIC “recoil” (??)

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48
Q

again, E.g.

A

Examples: aorta, pulmonary trunk, aorta’s major initial branches

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49
Q

more about structure of muscular arteries (distributing arteries)

A

Medium-sized arteries

Tunica media contains more smooth muscle and fewer elastics fibers than elastic arteries

Well defined internal elastic lamina, thin external elastic lamina
—> external lamina that is part of tunica media does not need to be as thick

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50
Q

more about function of muscular arteries

A

Branch and ultimately distribute blood to each of the various organs

Capable of greater vasoconstriction and vasodilation
—> Responsible for control of blood flow rate

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51
Q

muscular arteries and “VASCULAR TONE”

A

Vascular tone

—> The ability of the smooth muscle to contract and maintain a state of partial contraction

—> Important in maintaining pressure and efficient blood flow

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52
Q

arterioles

A

Not much bigger than capillaries

Thin tunica interna
—> Thin fenestrated internal elastic lamina (disappears at terminal end)

Tunica media
—> consists of 1 to 2 layers of smooth muscle

Tunica externa
—> loose CT containing sympathetic nerves
(these impact blood flow and resistance via diameter changes)

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53
Q

more about important features related to function of arterioles

A

These vessels regulate the flow of blood into the capillary networks

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54
Q

METARTERIOLE & “Thoroughfare Channel”

A

Metarteriole (initial segment?) connects arteriole w/ venule —> VIA THOROUGHFARE CHANNEL (latter segment?)

the channels extending from metarteriole are capillaries
—> forming CAPILLARY BED(s)

a sphincter is at junctions of capillaries @ the metarteriole / thoroughfare channel

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55
Q

Precapillary-sphincters

A

at junction of arteriole and capillary

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56
Q

precapillary sphincter constriction?

A

Increase resistance:
—> Decrease diameter & vasoconstrict
—> Decreases blood flow into capillaries (E.g. when not needed)

Decrease resistance:
—> Increase diameter & vasodilate
—> Increases blood flow into capillaries

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57
Q

About Capillaries

A

Aka “exchange vessels”

Smallest of all vessels, but large total surface area

capillaries contact all body cells

—> The more metabolically active the cell the more capillaries serving it

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58
Q

primary function @ capillaries

A

Exchange of gases and nutrients between the blood and interstitial fluid

No metabolically active tissue is more than a few hundred micrometers from a capillary

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59
Q

capillaries structural characteristics

A

Lack both a tunica media and a tunica externa

Capillary walls are composed of only
—> a single layer of endothelial cells and
—> a basement membrane

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60
Q

average diameter of capillary

A

Average diameter = 8 µm

About the same as a single RBC

sometimes smaller –> requiring RBC to bend

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61
Q

capillary beds

A

interwoven network of many capillaries that supplies an organ or tissue

arises from a single arteriole

the more metabolically active the cells, the more capillaries in the capillary bed

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62
Q

metarterioles (AKA PRECAPILLARY ARTERIOLE)

A

Initial segment of the connection passageway

Contains smooth muscle that can change the vessel’s diameter and adjust flow rate through capillary bed

“Can be bypassed by arteriovenous shunt that directly connects arteriole to venule”

—> “Regulated by sympathetic innervation”

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63
Q

shunt define

A

SURGERY
an alternative path for the passage of the blood or other body fluid.

“shunt surgery”

what about arteriovenous shunt (???)
—> nothing found regarding surgery

—> *** MAY BE REFERRING TO THE METARTERIOLE “[serving] as vascular shunt when precapillary sphincters are closed”

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64
Q

Thoroughfare channel (?)

A

Most direct passageway through capillary bed (bypass)

Contains NO smooth muscle

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65
Q

thoroughfare channel vs metarteriole

A

Note that metarteriole and thoroughfare channel are continuous and connect arteriole with venule

—> however thoroughfare channel me be referring to the latter portion (venous portion?) which does NOT contain smooth muscle

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66
Q

precapillary sphincters

A

Precapillary sphincters:

Bands of smooth muscle that contract and relax to control flow into the capillary bed

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67
Q

more about capillary beds (Arterial collaterals)

A

Capillary bed may be supplied by more than one artery

Multiple arteries called COLLATERALS

—> (ARTERIAL COLLATERALS (via arterial anastomosis?) leading to arteriole?)

—> (collaterals?) fuse before giving rise to arterioles

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68
Q

fusion / arterial anastomosis

A

Fusion is an example of arterial anastomosis

Anastomosis is joining of blood vessels

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69
Q

why arterial anastomosis?

A

Allows continuous delivery of blood to capillary bed even if one artery is blocked or compressed

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70
Q

(note also arteriovenous anastomosis)

A

firectly b/w arteriole and venule

—> possibly also function as backup channels, in this case directly between arterioles and venules

(instead of from small arteries leading into an arteriole)

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71
Q

what about an artery that is the ONLY blood supply to a tissue/organ

A

An artery that is the only blood supply to a tissue or organ is called a terminal artery or an end artery

TERMINAL ARTERY / END ARTERY

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72
Q

Three types of capillaries

A

Continuous capillaries

Fenestrated capillaries

Sinusoids (sinusoidal capillaries)

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73
Q

Continuous capillaries

A

Continuous endothelium with intermittent breaks called intercellular clefts

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74
Q

where continuous capillaries?

A

Found in the brain, lungs, skeletal and smooth mm, CT

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75
Q

why continuous capillaries

A

Permits diffusion of water, small solutes, and lipid-soluble materials

Prevents loss of blood cells and plasma proteins

Some selective vesicular transport

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76
Q

specialized continuous capillaries –> where are they, and what do they do?

A

Specialized continuous capillaries in CNS and thymus have endothelial tight junctions

E.g.
Blood Brain Barrier (?)

Enables restricted and regulated permeability

Esp via vesciles (?)

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77
Q

Fenesterated capillaries

A

Contains “windows,” or pores, penetrating endothelial lining

Permits rapid exchange of
water and larger solutes

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78
Q

where found?

A

Capillaries of hypothalamus,
pituitary, pineal, and
thyroid glands

Absorptive areas of
intestinal tract

Kidney filtration sites

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79
Q

sinusoidal capillaries (aka sinusoids or “Discontinuous” capillaries)

A

Wider and more winding

Unusually large fenestrations

Missing a basement membrane
(OR INCOMPLETE BM w/ very large caps)

Large intercellular clefts

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80
Q

sinusoid etymology

A

sinus (q.v.) + -oid

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81
Q

sinusoidal capillaries – where?

A

Found in RBM, spleen, liver, anterior pituitary, parathyroid glands

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82
Q

Portal system?

A

Portal systems allow passage of blood from one capillary network to another through a portal vein

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83
Q

where are portal systems found?

A

There are 2 locations found in the body:

—> Liver (hepatic portal system)

—> Pituitary gland (hypophyseal portal system)

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84
Q

hepatic portal system

A

the venous system that returns blood from the digestive tract and spleen to the liver

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85
Q

why?

A

It supplies veins with metabolic substrates.

It also ensures that food ingested is processed by the liver first before entering the systemic circulation.

This way, ingested toxins are detoxified by hepatocytes

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86
Q

hypophyseal portal system

A

Capillary beds in the hypothalamus and the anterior pituitary are connected

(Important structures in the endocrine system)

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87
Q

why hypophyseal portal system?

A

Its main function is to quickly transport and exchange hormones between the hypothalamus arcuate nucleus and anterior pituitary gland

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88
Q

3rd example?

A

google says renal portal system

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89
Q

venules

A

Small veins

Drain capillary blood and begins the return flow of blood back to the heart

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90
Q

about POSTCAPILLARY VEINS

A

Postcapillary venules:
Initially receive blood from capillaries

lack a tunica media and resemble expanded capillaries

Are very porous and therefore function as a site for exchange and WBC emigration

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91
Q

common site for WBC emigration (Diapedesis / extravasation)

A

POSTCAPILLARY VEINS

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92
Q

Microcirculation

A

The blood flow through the smallest vessels in the circulatory system

—> arterioles,

venules,

shunts (referring to metarteriole/thoroughfare channel)

and capillaries

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93
Q

which organs don’t have microcirculation?

A

exists in all tissues and organs except for the

cornea and epidermis

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94
Q

veins

A

Veins are formed from the union of several venules

Contain the characteristic 3 layers that make up arteries

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95
Q

how are layers different?

A

Tunica interna & tunica media is thinner in veins

much less smooth muscle and elastic fibers

—> veins look collapsed when dissected

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96
Q

veins vs elastic laminae?

vs recoil dynamics

A

Veins lack the internal and external elastic laminae

(They can increase and decrease in size to adapt to changes in volume & pressure but without the recoil dynamics of arteries.)

97
Q

veins / venules pressure

A

Veins & venules are under very low pressure

blood tends to stop or even pool

98
Q

veins and one-way valves (esp @ lower extremity)

A

One-way valves prevent backflow and keep blood moving forward

Extensions of the tunica interna form valves

point towards the heart and prevent back flow

99
Q

venous system –> pressure and blood flow

A

Blood pressure in peripheral venules is <10 percent of that in ascending aorta (largest artery)

Mechanisms are needed to maintain flow of blood in veins against force of gravity

100
Q

what are the mechanisms used to maintain blood flow against gravity?

A

Valves

Contraction of skeletal muscles

Respiratory pump

Gravity

101
Q

respiratory pump (effect?)

A

The respiratory pump is a mechanism to pump blood back to the heart using inspiration. It aids blood flow through the veins of the thorax and abdomen

102
Q

vascular (venous) sinus

A

A vein with a thin endothelial wall and no smooth muscle to alter its diameter

“DCT replaces the tunica media and externa in providing support”

DCT?????
“Dense Connective Tissue” (?)

E.g.
Coronary sinus, dural venous sinuses

103
Q

vein paths vs arteries

A

Veins follow the same path as arteries, but are more numerous

Double veins connect via venous channels called ANASTOMOTIC VEINS
—> Superficial veins
—> Deep veins

104
Q

varicose veins

A

If valves do not work properly, blood can pool in veins, causing distention and a range of effects

Mild discomfort and cosmetic problems, as with varicose veins (in thighs and legs)

Painful distortion of adjacent tissues, as in hemorrhoids (form in the venous networks of the anal canal)

105
Q

where varicose veins most common

A

Most common in lower extremities & esophagus

106
Q

varicose veins of rectum?

A

hemorrhoids?

107
Q

why varicose veins?

A

Varicose veins in the extremities are usually a result of mechanical stress, repetitive stress, pregnancy (worsen existing), age

Varicose veins in the esophagus are suspected due to eating habits & repetitive reflux/regurgitations

108
Q

varicose veins SSx

A

SSx
Pain & tenderness locally, hardened nodules due to dead cells, localized edema, altered blood flow and itchiness

109
Q

Varicose veins risk factors

A

Genetics, age, smoking, drugs, obesity, inactivity & trauma

110
Q

varicose veins Tx

A

Range from diet & exercise, compression stockings, surgery, laser therapy & light massage

CAREFUL**** – deep stripping NOT recommended for moderate to severe varicose veins

111
Q

hemorrhoids?

A

Hemorrhoids varicose veins in the anal canal

Caused by excessive straining, constipation

112
Q

Angiogenesis

A

Refers to the growth of new blood vessels from existing vasculature

Functions
Wound healing
Uterine lining

113
Q

Tumour angeiogenesis factors (TAFs)

A

Tumor cells secrete proteins called tumor angiogenesis factors (TAFs)

Stimulate blood vessel growth to provide nourishment for the tumor cells

Research to inhibit this and thus inhibit the growth of tumors

114
Q

Blood reservoires

A

Total blood volume distribution

Uneven distribution among arteries, veins, and capillaries

Systemic venous system contains 64% of total blood volume (~3.5 L)

Of that , ~1 L is in venous networks carrying blood from digestive organs to liver (Hepatic portal system??)

Act as blood reservoirs

115
Q

how much blood in systemic arteries?

A

Systemic arteries contain 13 percent total blood volume

116
Q

remaining blood?

A

The remaining blood is in the systemic capillaries, heart, and pulmonary circuit

(23%)

117
Q

Blood reservoires (Venoconstriction)

A

Venoconstriction:
Contraction of smooth muscle fibers in veins

—> Reduces diameter of the veins and the amount of blood in the venous system

Why?
Method of maintaining blood volume in the arterial system even with a significant blood loss

118
Q

venoconstriction via?

A

Controlled by the vasomotor center in the medulla oblongata

Sympathetic nerves stimulate smooth muscles in medium-sized veins

119
Q

…

A

…

120
Q

Capillary exchange

A

The movement of substances between capillaries/blood & interstitial fluid

Involves a combination of diffusion, transcytosis, and filtration

121
Q

combination of 3 processes

A

1) diffusion,

2) transcytosis,

3) filtration

122
Q

Diffusion

A

Net movement of substances from an area of higher concentration to lower concentration

123
Q

Transcytosis

A

Large, lipid-insoluble (HYDROPHILIC?) substances cross the capillary membranes via exocytosis and endocytosis

124
Q

Filtration

A

Net movement of water from an area of higher pressure to lower pressure

(Vs osmosis???)

125
Q

DIffusion

A

Net movement of substances from an area of higher concentration to lower concentration

126
Q

when is diffusion most rapid (what variables)?

A

1) Distances are short

2) Concentration gradient is large

3) Ions or molecules involved are small

DISTANCE,
concentration,
size

127
Q

which part of capillary wall, diffusion ?

A

Occurs continuously across capillary walls

128
Q

what types of subtssances, diffusion?

A

Important for solute exchange (ie. Oxygen, CO2, glucose, aa)

129
Q

what about water-soluble substances (?) –> hydrophilic

A

Water soluble (glucose, aa) move through intercellular clefts or fenestrations

FENSTRATED CAPILLARIES

fenestrations are on cell itself, not just between

130
Q

what about lipid-soluble (hydrophobic) substances?

A

Lipid soluble (oxygen, CO2, steroids) move through endothelial cells

131
Q

can RBC or plasma protein exit?

A

No

132
Q

except

A

can not pass through continuous or fenestrated capillaries but can pass through sinusoids

sinusoids:
liver, spleen, lymph nodes, bone marrow and endocrine glands

liver break down RBC

bone marrow create blood cell

endocrine? hormones???

spleen / lymph nodes (LYMPHOCYTES)

133
Q

2) transcytosis

A

Enters on one side, transported through the cell via a pinocytic vesicle, then exits on the other side

Hormones (E.g. insulin) & certain large proteins (ABs)

134
Q

3) Filtration —> BULK FLOW

A

A passive process in which large numbers of ions, molecules or fluid moves together in the same direction

135
Q

via what type of gradient (Bulk flow)

A

Occurs from an area of high pressure to low pressure

136
Q

what is bulk flow / filtration important for

A

Important for regulation of the relative volumes of blood and interstitial fluid

137
Q

what are two processes involved in bulk flow (?)

A

Depending on the pressure differences, can be either:

1) Filtration
Movement from capillaries —> interstitial fluid

2) Re-absorption
Movement from interstitial fluid —> capillaries

138
Q

a) Filtration is via BHP

A

1) Blood hydrostatic pressure (BHP) or capillary hydrostatic pressure (CHP)

—> The pressure of the blood against vessel walls

—> 35 mmHg at arteriole end, 18 mmHg at venous end

139
Q

a) Filtration is via ISFCOP (oncotic pressure)

A

2) Interstitial fluid colloid osmotic pressure (IFCOP)

—> Pressure that “pulls” fluid from capillaries into interstitial fluid

—> Very low (close to 0 mmHg), few proteins present in interstitial fluid

140
Q

b) Reabsorption is via BCOP

A

3) Blood colloid osmotic pressure (BCOP)

—> Colloid pressure in capillaries caused by large protein molecules that “pulls” fluid from interstitial into blood (mainly albumin)

—> 25 mmHg

141
Q

b) Reabsorption is via ISFHP

A

4) Interstitial Fluid Hydrostatic Pressure (IFHP)

—> The pressure that “pushes” fluid from interstitial space back into the capillaries.

—> It varies from a value of -1mmHg to +1mmHg therefore, for our discussion, it’s 0 mmHg.

142
Q

So net pressure???

A

35mmHg OUT @ ARTERIAL END

18mmHg OUT @ VENOUS END

25mmHg IN via blood proteins (I.e. albumin)

143
Q

what about remaining 15% that doesn’t get re-absorbed?

A

THE REMAINING 15% that doesn’t get re-absorbed returns to blood VIA LYMPH vessels

144
Q

Starling’s law of capillaries

A

States that the movement of fluid between the capillaries and interstitial fluid is due to the net effect of all pressures across the capillary (Starling Forces)

145
Q

what forces are MAIN DETERMINANTS OF NET fluid movement

A

Because IFHP and IFOP are so low, movement across capillary is largely dependent on the balance of

****hydrostatic and osmotic pressure of the blood

146
Q

NFP
NET FILTRATION PRESSURE

A

the balance of these pressures which determines the direction of fluid flow

NFP = (BHP + IFOP) – (BCOP + IFHP)

147
Q

NFP @ ARTERIAL VS VENOUS ENDS

A

@ arterial end, NFP = (35) – (25) = 10 mmHg
—-> MORE EXITING

@ venous end, NFP = (18) – (25) = -7 mmHg
—-> MORE RETURNING

In total, more still exits than returns via capillaries/ISF

148
Q

what about amount that doesn’t return

A

On average, 85 % of fluid filtered out of the capillaries is reabsorbed.

The other 15 % enters the lymphatic circulation to eventually return back to the heart.

149
Q

NFP positive vs negative number

A

+10 mmHg (a positive # indicates filtration)
–> exit

-7 mmHg (a negative # indicates re-absorption)
–> enter

150
Q

Edema

A

an abnormal increase in interstitial fluid volume

Usually noticeable after interstitial volume has risen to 30% above normal

Is the result of either excess filtration or inadequate reabsorption

151
Q

edema causes

A

Causes include liver disease and damage to the lymphatic system

152
Q

hemodynamics

A

Hemodynamics refers to the factors affecting blood flow

Blood Flow:
—> Volume of blood flowing through tissues in a period of time
—> Measured in mL/min

153
Q

Blood flow 2 key factors

A

1) Pressure Difference

2) Peripheral Resistance

154
Q

1) Pressure difference (and blood flow)

A

Pressure difference (Blood Pressure)

Systolic Blood Pressure: the HIGHEST pressure attained in arteries during systolic contraction

Diastolic Blood Pressure: the LOWEST pressure attained in arteries during diastolic relaxation

Mean Arterial Pressure (MAP): the average BP in the arteries (more later)

155
Q

arterial pressure

A

Blood pressure:
Pressure within the cardiovascular system as a whole

Arterial pressure is much higher than venous pressure

—> Receives blood from the heart

—> Have greater degree of contractile capability

156
Q

Capillary pressure

A

Capillary pressure is lower than artery and arteriole pressure

Increased overall surface area of total capillaries

Blood spreads throughout capillary network

157
Q

capillary pressure vs blood flow speed

A

Drop in capillary pressure causes blood flow in capillaries to be very slow

Allows plenty of time for capillary exchange

Diffusion between blood and interstitial fluid

158
Q

Venous pressure

A

Blood pressure in veins is maintained by:

a) Valves
(prevent backflow, keep even pressure along length)

b) Muscular compression of peripheral veins

159
Q

blood closer to heart vs venous pressure

A

As blood moves toward the heart, vessels get larger, and resistance decreases

160
Q

VENOUS RETURN =

A

Amount of blood arriving at the right atrium each minute

On average, equal to the cardiac output

161
Q

Changes in blood pressure

A

Highest pressure at the aorta

—> Heart generates pressure of about 120 mm Hg

—> Aorta cross-sectional area 4.5 cm2

162
Q

where does pressure drop from the aorta (???

A

Pressure drops at each branching in arterial system

Smaller, more numerous vessels reduce pressure

At start of peripheral capillaries, pressure is
35 mm Hg

At the venules, pressure is 18 mm Hg

163
Q

2) PERIPHERAL RESISTANCE

A

the opposition to blood flow due to friction b/w blood & the blood vessel walls.

must be overcome by sufficient pressure from the heart in order for circulation to occur

Can be altered due to needs

164
Q

HOW IS PERIPHERAL RESISTANCE DETERMINED? 3 factors

A

a) Size of the lumen of the vessel (vessel diameter)

b) Blood vessel length

c) Blood viscosity

165
Q

a) size of lumen

A

Friction occurs between moving fluid layers

Layer closest to vessel wall is slowed most because of friction with endothelial surface

Effect gradually diminishes away from wall

In smaller vessels, more fluid volume is near wall, so higher resistance

In larger vessels, central region unaffected, so lower resistance

166
Q

size of lumen formula

A

Size of the lumen
Resistance (R) = 1/d4

If we increase diameter (d), there is a significant decrease in resistance (inverse relationship).

E.g.
R = 1/24  1/16 = 0.0625
R = 1/44  1/256 = 0.0039

167
Q

b) total blood vessel length

A

the longer the pathway or blood vessel, the more the resistance

Friction occurs between vessel walls and moving blood

Increase in vessel length = increased surface area = increased in friction or resistance

E.g.
Capillaries total length longest (???)

168
Q

c) blood viscosity

A

increased solutes, molecules, protein, & cells will increase the viscosity

Any condition that decreases fluid volume &/or increases viscosity will increase resistance

169
Q

Systemic Vascular Resistance (SVR)

aka total peripheral resistance (TPR).

A

The total resistance of the entire vascular system (arteries, arterioles, capillaries, venules, veins) .

Veins & arteries have large diameters therefore don’t contribute very much to SVR.

Arterioles, capillaries, & venules are much smaller and therefore DO contribute to SVR.

Venules & capillaries have little to no smooth muscle, therefore their contribution to resistance is set and doesn’t change

170
Q

WHAT CONTRIBUTES MOST TO SVR

A

The arterioles however DO contain smooth muscle and undergo vasoconstriction & vasodilation

and thus ARTERIOLES contribute the most to SVR

171
Q

velocity of blood

A

According to the laws of physics, there is an inverse relationship of fluid velocity with cross sectional area of a closed tube.

The larger the total cross sectional area of the tube with associated liquid flow, the slower the velocity.

And conversely, the smaller the total cross sectional area, of the tube, the faster the velocity of flow.

We can see that aortas & arteries have smaller total cross sectional area than capillaries, and thus have a faster velocity. In contrast, capillaries with large cross- sectional area have a very slow the velocity.

172
Q

REGULATION OF BP AND BLOOD FLOW

A

…

173
Q

Homeostatic mechanisms

A

Ensure adequate tissue perfusion (blood flow through tissues)

Blood flow must match changes in demand for oxygen and nutrients

174
Q

perfusion

A

the passage of blood, a blood substitute, or other fluid through the blood vessels or other natural channels in an organ or tissue.

175
Q

Two regulatory pathways

A

1) ​Autoregulation
(LOCAL)

2) Central regulation
(Neural/endocrine)
—> esp if autoregulation ineffective

176
Q

1) autoregulation

A

Involves local changes in blood flow within capillary beds

Regulated by precapillary sphincters in response to chemical changes in interstitial fluid

177
Q

Examples of factors leading to autoregulation:

A

Changes to oxygen levels

Vasodilating and Vasoconstricting chemicals

Low oxygen in systemic tissues –> dilate

Low oxygen in pulmonary tissues –> constrict
WHY??
B/c not efficient to send blood to that area of pulmonary tissue, since there is no O2 to collect –> more efficient to stop sending blood to that part of lung tissue, and instead send it elsewhere where is it functional/useful

178
Q

Vasodilating and Vasoconstricting chemicals

A

Dilation – potassium, H+, lactic acid, adenosine, NO

Constriction – thromboxane A2, serotonin, endothelins

179
Q

2) CENTRAL REGULATION

A

Involves both neural and endocrine mechanisms

180
Q

neural mechanism

A

Activation of cardioacceleratory center or cardioinhibitory center

Activation of vasomotor center (controls peripheral vasoconstriction)

Results:
Can increase cardiac output and reduce blood flow to nonessential or inactive tissues

181
Q

endocrine mechanism

A

Release of vasoconstrictor (primarily NE), producing long-term increases in blood pressure

recall:
beta-blockers BLOCK epinephrine/noepinephrine

182
Q

where do central regulators receive feedback/input from (??)

A

Baroreceptors
Respond to changes in blood pressure

Chemoreceptors
Respond to changes in O2, CO2, pH of blood and CSF

Proprioreceptors
Respond to body movement

Limbic system & higher brain centers
emotional & psychological stress/thoughts will descend from these centers directly onto the CV centers

183
Q

baroceptor reflexes

A

Respond to changes in blood pressure

Receptors are located in walls of:
i) Carotid sinuses

ii) Aortic sinuses

iii) Right atrium

184
Q

i) Carotid sinus

A

regulates pressure in the brain, in R/L internal carotid arteries, travel to the brain via glossopharyngeal (IX) nerve

185
Q

ii) Aortic sinus

A

regulates systemic pressure in the rest of the body, in ascending and arch of aorta, travel to the brain via the vagus (X) nerve

186
Q

iii) RA

A

.

187
Q

WHAT ABOUT BV DIAMETER (??) (Motor output)

A

Vasomotor nerves (sympathetic NS) cause vasoconstriction of blood vessels

Sympathetic neurons that that run from the CV center, exit the spinal cord through all thoracic and L1/2 spinal nerves, pass into the sympathetic trunk ganglia to the blood vessels

Provide constant continuous moderate stimulation of smooth muscles

188
Q

Motor output

A

Cardiac accelerator nerves from the thoracic spinal cord (sympathetic NS) increase HR and contractibility and therefore cardiac output (CO).

Vagus nerves (parasympathetic NS) decrease HR and therefore CO.

189
Q

vasomotor tone

A

Vasomotor tone – the moderate state of vasoconstriction that sets the resting level of tone of most blood vessels (resting SVR)

190
Q

Endocrine response

A

Provide short-term and long-term regulation of cardiovascular function

Utilize endocrine functions of:
The heart

The kidneys

The pituitary gland (antidiuretic hormone, or ADH)

191
Q

HORMONAL RESPONSE TO LOW BP/volume

which homrone???

A

—> Immediate response:
Release of epinephrine (E) and norepinephrine (NE)

Released from the adrenal medullae

Caused increased CO and vasoconstriction = increased BP

Diverts blood to skeletal muscle and coronary circulation

192
Q

other hormones during LOW BP

A

Antidiuretic hormone (ADH)
–> “Anti” + “urinate” –> less water/solutes (?) lost in urine = remain in blood = increase BP

Angiotensin II

Erythropoietin (EPO)
–> more RBC = more formed elements = more BCOP = more fluid = increase BP (?)

Aldosterone

193
Q

Hormonal regulation

A

Renin – Angiotensin –Aldosterone system (RAAS)

juxtaglomerular cells of kidneys detect decrease in BP & volume & in turn secrete renin.

Renin activates angiotensin, angiotensin converting enzyme (ACE) in lungs converts it  angiotensin II.

AG II will increase BP by:
1. Increase vasoconstriction

  1. Stimulates aldosterone which increases re-absorption of Na+ and therefore H2O by the kidneys.
194
Q

hormonal regulation (ADH)

A

Anti-diuretic Hormone (ADH) aka “vasopressin”

released by the post pituitary gland in the brain

It is a powerful vasoconstrictor & helps the kidneys reabsorb H2O.

195
Q

Hormonal regulation —-> DECREASE BP

A

Atrial Natriuretic Peptide (ANP)

released by atrial cells of the heart in response to heart stretch

powerful vasodilator & increase H2O loss in the kidneys (to decrease systemic BP).

196
Q

SYNCOPE

A

together
cut off

MEDICINE
temporary loss of consciousness caused by a fall in blood pressure.

Sudden loss of consciousness due to lack of blood flow to the brain.

Can be related to medications, stress, or orthostatic hypotension (changes to body positions)

197
Q

SHOCK and HOMEOSTASIS

A

What is shock?
Acute cardiovascular crisis marked by:

Low blood pressure (hypotension)

Inadequate peripheral blood flow

Normal homeostatic mechanisms cannot compensate

198
Q

most common cause, shock

A

Most common causes are hemorrhage and heart damage (as in heart attack)

199
Q

TYPES OF SHOCK

A

Hypovolemic Shock – decreased total volume of blood (ie. hemorrhaging or excessive dehydration)

Cardiogenic Shock – poor/lack of normal heart functioning (MI, arrythmias, fibrillations)

Obstructive Shock – blockage of blood flow (thrombus & embolus formations)

Anaphylactic Shock – massive vasodilation in response to an allergen

Neurogenic Shock – damage to nervous system interrupts normal neural BP regulation

Septic Shock – shock in response to sepsis

200
Q

Hypovolemic Shock

A

Hypovolemic Shock – decreased total volume of blood (ie. hemorrhaging or excessive dehydration)

201
Q

Cardiogenic Shock

A

Cardiogenic Shock – poor/lack of normal heart functioning (MI, arrythmias, fibrillations)

202
Q

Obstructive Shock

A

Obstructive Shock – blockage of blood flow (thrombus & embolus formations)

203
Q

Anaphylactic Shock

A

Anaphylactic Shock – massive vasodilation in response to an allergen

204
Q

Neurogenic Shock

A

Neurogenic Shock – damage to nervous system interrupts normal neural BP regulation

205
Q

Septic Shock

A

Septic Shock – shock in response to sepsis

206
Q

..

A

.

207
Q

SSx Shock (systemic drop in BP leads to…)

Muscles/brain

A

Decreased blood to the brain & systemic muscles –

fainting, cyanosis, pallor, changes to skin temp, altered mental state

208
Q

SSx shock (CO, HR, pulse)

A

Pulse is weak and rapid due to decreased cardiac output and rapid heart rate

209
Q

SSx shock, systolic pressure

A

Systole drops to below 90 mmHg

210
Q

where vasoconstriction?

why?

A

Vasoconstriction of abdominal, urinary, & reproduction organs

blood to brain/heart/lungs

helps conserve blood flow to the vital organs (“)

211
Q

BLOOD VESSEL PATHOLOGIES

A

..

212
Q

aging and BV

aging results in…

A

Loss of compliance of the aorta

Reduction in cardiac muscle fiber size

Progressive loss of cardiac muscular strength

Decline in maximum heart rate and CO

Increased systolic blood pressure

213
Q

vasculitis

A

is inflammation of the vessel wall, due to autoimmune disease or infection

Phlebitis is inflammation of a vein,

arteritis is inflammation of an artery

214
Q

phlebitis vs arteritis

A

Phlebitis is inflammation of a vein,

arteritis is inflammation of an artery

215
Q

temporal arteritis

A

Inflammation of the temporal artery in the scalp. Pain in the jaw with chewing and pain over the scalp are common symptoms.

216
Q

atherosclerosis

A

the formation of lipid lumps (atheromas) in the blood vessel wall, is the most common cardiovascular disease

217
Q

most common cardiovascular disease

A

Atherosclerosis

218
Q

coronary artery disease

A

Atherosclerosis with narrowing of the arteries supplying blood to the heart muscle. Coronary artery disease makes a heart attack more likely.

219
Q

most likely cause of heart attack

A

coronary artery disease

220
Q

Carotid artery disease

A

Atherosclerosis with narrowing of one or both of the carotid arteries in the neck. Disease of the carotid arteries makes stroke more likely.

221
Q

Peripheral artery disease

A

Atherosclerosis that causes narrowing of the arteries in the legs or groin. The limitation in blood flow to the legs may cause pain or poor wound healing.

222
Q

Peripheral artery disease

A

any disease of arteries that does not involve heart/brain

“Peripheral vascular disease is the reduced circulation of blood to a body part, other than the brain or heart, due to a narrowed or blocked blood vessel”

223
Q

Chronic Venous Insufficiency

A

CVI damages veins causing blood to pool in your legs. This increases pressure in your leg veins and causes symptoms like swelling and ulcers.

discolouration of feet / lower legs (NECROSIS/gangrene)

224
Q

arterial thrombosis

A

blood clot that develops in an artery. If it obstructs or stops the flow of blood to major organs, such as the heart or brain, it can cause damage.

225
Q

thrombosis vs embolus

A

What is the difference between thrombosis and embolism? Thrombosis is when a blood clot, or thrombus, forms in a blood vessel. An embolus is when a clot, fat, air bubble, or other feature travels through blood vessels, with a risk of lodging elsewhere.

226
Q

checking circulation

A

..

227
Q

checking pulse

A

defined as the traveling pressure wave generated by systole & diastole of the ventricles.

228
Q

generally which vessels can pulse be found?

A

Pulses can be measured in any artery especially the ones closest to the surface, and is too weak to measure in the arterioles, altogether non-existent in capillaries.

229
Q

if vessel is farther from heart, what is the effect on pulse

A

The further away the artery from the heart, the weaker the pulse (generally); the closer the artery, the stronger.

(ie. carotid pulse is stronger than radial or dorsal pedis)

230
Q

arteries that HCP reference for pulse measurement

A

Pulses can be measured at characteristic locations throughout the body that are used by EMS and health care professionals. These are arteries tend to be superficial and are easily accessible.

231
Q

arteries for pulse

A

Superficial Temporal

Facial

Common Carotid
(common measuring point)

Brachial
(most common used to measure systemic BP)

Femoral: inferior to the inguinal ligament

Popliteal

Radial
(common measuring point)

Ulnar

Dorsal pedis

Abdominal: close to umbilicus

232
Q

checking BP

A

a measure of the pressure in the arteries at left ventricular systole & left ventricular diastole.

233
Q

Korotkoff sounds

A

sounds heard through the stethoscope when measuring the BP.

234
Q

systolic vs diastolic BP

A

Systolic Blood Pressure (SBP) – the initial onset of the sounds created upon first release of the cuff

Diastolic Blood Pressure (DBP) – the point in which the sounds disappear

235
Q

Pressure difference (BP)

Mean Arterial Pressure (MAP)

A

a. Systolic Blood Pressure: the HIGHEST pressure attained in arteries during systolic contraction

b. Diastolic Blood Pressure: the LOWEST pressure attained in arteries during diastolic relaxation

MEAN ARTERIAL PRESSURE:
the average BP in the arteries

MAP = diastolic BP + 1/3 (systolic BP –diastolic BP)

In a resting person, MAP = 80 + 1/3 (120 – 80)

MAP = 93 mmHg (using BP of 120/80)

236
Q

Pulse pressure

A

the difference between systolic & diastolic pressures (normally about 40 mmHg)

237
Q

Hypertension

A

any increase in the pulse pressures beyond the normal range. (ie. stress, atherosclerosis, aging, meds).

Current standards are >130 mmHg systolic BP or >80 mmHg diastolic BP.

238
Q

Hypotension

A

any decrease in the pulse pressures beyond the normal range (ie. hemorrhaging, orthostatic changes, meds).

Current standards are <90 mmHg systolic BP or <60 mmHg diastolic BP.

239
Q

vasomotor centre vs cardiovascular centre

A

The vasomotor center (VMC) is a portion of the medulla oblongata.

Together with the cardiovascular center and respiratory center, it regulates blood pressure.

It also has a more minor role in other homeostatic processes.

Semester 3 (32 decks)

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