Week 6, Lec 1 Flashcards

Question

what are the 5 muscular arteries (distributing arteries)

Answer 1

* Radial artery * Femoral artery * Brachial artery * Coronary arteries * Popliteal artery

Answer 2

arterioles * Control systemic blood pressure and direct blood flow into capillary beds through smooth muscle constriction and dilation.

Answer 3

metarterioles

Answer 4

arterioles and metarterioles ▪ Arterioles can constrict significantly and restrict blood flow to a capillary bed ▪ Pre-capillary sphincters at the junction of metarterioles and capillaries can greatly reduce flow to a capillary bed AND metarterioles can shunt blood directly to venules

Answer 5

1. continuous capillaries 2. fenestrated capillaries 3. sinusoidal capillaries

Answer 6

continuous- least sinusoidal- most

Answer 7

Least permeable, found in tissues that need tight control over what passes through

Answer 8

* Moderately permeable, allowing larger molecules to pass, found in organs involved in filtration and absorption

Answer 9

* Highly permeable, allowing large particles like proteins and cells to pass, found in specialized organs

Answer 10

continuous capillaries

Answer 11

▪ Intercellular junctions allow movement of water-soluble substances

Answer 12

or areas that require higher filtration or increased delivery of soluble substances ▪ Glomerulus in the kidney ▪ Endocrine glands, lamina propria of the intestines ▪ Fenestrae are covered/altered by proteins that form a sort of diaphragm whose properties can be altered

Answer 13

ie. absorb and filter = kidneys, endocrine glands, intestines

Answer 14

* liver, spleen, lymph nodes * bone marrow

Answer 15

gaps btw intercellular junctions and discontinuous basal lamina

Answer 16

▪ Discontinuous basal lamina ▪ Larger diameter ▪ Massive gaps between the intercellular junctions ▪ Specialized for allowing cells to move in and out of them

Answer 17

sinusoidal capillaires

Answer 18

CT, muscle, neural tissue; modified in brain tissue

Answer 19

smallest is continous largest is sinusoidal

Answer 20

tight junctions= continuous and fenestrated capillaries discontinous= sinusoidal capillaries

Answer 21

Vena cava, pulmonary veins, portal vein.

Answer 22

* Tunica Intima: Well-developed, with endothelium and a prominent subendothelial layer. * Tunica Media: Thin, containing relatively fewer smooth muscle cells compared to arteries. * Tunica Adventitia: Thickest layer, composed of dense connective tissue, collagen, and elastic fibers. Contains vasa vasorum (small blood vessels) to nourish the vein wall.

Answer 23

tunica adventitia

Answer 24

large- yes medium- sometimes small- no

Answer 25

less than arteries

Answer 26

Large veins return deoxygenated blood to the heart from systemic circulation. They are able to accommodate large blood volumes.

Answer 27

Femoral vein, renal vein, brachial vein.

Answer 28

* Tunica Intima: Thin, with endothelium and a thin subendothelial layer. * Tunica Media: Thinner than arteries, with scattered smooth muscle cells. * Tunica Adventitia: The thickest layer, with collagen and elastic fibers. May have some vasa vasorum.

Answer 29

valves Present, especially in the limbs, to prevent backflow of blood due to low pressure.

Answer 30

These veins drain blood from organs and limbs, using valves to direct blood flow toward the heart.

Answer 31

Postcapillary venules, collecting venules.

Answer 32

* Tunica Intima: Endothelial cells with a thin basal lamina. * Tunica Media: Very few layers of smooth muscle cells or absent in the smallest venules. * Tunica Adventitia: Thin layer of connective tissue.

Answer 33

Venules collect blood from capillaries and begin the process of returning it to larger veins. Postcapillary venules also play a role in inflammatory responses, allowing white blood cells to exit the bloodstream and enter tissues.

Answer 34

forms from reflections of tunica intima found in large and medium veins more in lower extremities than upper

Answer 35

Lumen of veins is much larger and much less likely to be constricted than that of an artery

Answer 36

Large and medium veins can constrict somewhat in response to increased secretion of catecholamines

Answer 37

study of how blood moves in the vascular compartments

Answer 38

Impacted by properties of the vessels, properties of the blood, activity of the heart, and the presence of gravity (and position of the patient)

Answer 39

when standing way more pressure in legs and less near head way less and more evenly spread pressure when laying

Answer 40

▪ Describes the flow of an incompressible and Newtonian fluid (like blood in small vessels) through a cylindrical pipe or tube. ▪ It relates fluid flow rate to the vessel's dimensions and pressure differences.

Answer 41

pressure gradient radius of vessel viscosity length of vessel

Answer 42

higher resistance

Answer 43

higher resistance

Answer 44

* Flow increases with increased pressure and vessel radius. * Flow decreases with increased viscosity and vessel length.

Answer 45

ONLY WITH LAMINAR FLOW not turbulent!!!

Answer 46

in turbulent flow

Answer 47

where fluid moves in parallel layers, and each layer flows smoothly without mixing with adjacent layers.

Answer 48

no longer applies * If flow becomes turbulent, then flow is proportional to the square root of the pressure gradient ▪ turbulent flow is less “energy efficient”

Answer 49

In turbulent flow, fluid movement is irregular, with eddies, vortices, and chaotic mixing between layers . ▪ This typically occurs at high flow velocities or in areas with sharp changes in vessel diameter (e.g., bifurcations, atherosclerotic plaques).

Answer 50

constant resistance In turbulent flow, Poiseuille’s law does not apply because the law assumes a constant resistance to flow. However, in turbulent flow, the resistance increases unpredictably due to chaotic fluid motion and energy dissipation.

Answer 51

Reynolds number

Answer 52

to predict when turbulent flow will occur

Answer 53

fluid density diameter of vessel velocity of fluid viscosity

Answer 54

* Atherosclerosis * Stenosis * Hypertension * Aneurysms * Valvular heart disease,

Answer 55

Turbulent flow is more likely when blood velocity increases, vessel diameter is irregular or constricted, or viscosity decreases.

Answer 56

turbulent flow

Answer 57

turbulent flow

Answer 58

Q= (P1-P2) pi r^4/ 8nl Q= flow (p1-p2)= pressure gradient r= radius of vessel n= viscosity l= length of vessel

Answer 59

pressure is constant in a system, regardless of velocity

Answer 60

As forward velocity increases, while the dynamic pressure may increase, if the static pressure decreases due to the conservation of energy in the system, the overall impact on the force against the vessel wall can vary. (chat gpt) Bernoulli says pressure is constant, regardless of veloctiy

Answer 61

* Pressure: Decreases significantly. * Velocity: Decreases significantly (slowest in capillaries).

Answer 62

* Pressure: Continues to decrease but at a slower rate. * Velocity: Increases as blood moves back toward the heart.

Answer 63

aorta and large arteries

Answer 64

* Blood pressure is highest in the aorta and large arteries (around 120 mm Hg during systole). * As blood travels through smaller arteries, the pressure gradually decreases but remains relatively high compared to other vessels.

Answer 65

* Blood velocity is high in the aorta due to the forceful contraction of the heart. * As blood moves into smaller arteries and arterioles, the velocity starts to decrease slightly due to the increased cross-sectional area.

Answer 66

for nutrient and waste exhange

Answer 67

* Pressure drops significantly in the capillaries, usually around 30 mm Hg or lower. * This reduction in pressure is crucial for facilitating the exchange of nutrients and waste between the blood and surrounding tissues.

Answer 68

capillaries

Answer 69

* Blood velocity is lowest in the capillaries. This is essential because slower flow allows more time for the exchange processes to occur. * The vast network of capillaries (huge total cross-sectional area) contributes to this reduction in velocity.

Answer 70

pressure continues to drop velocity increases

Answer 71

* After passing through the capillaries, pressure continues to drop as blood enters the venules and larger veins, eventually reaching around 5-10 mm Hg near the vena cava. * The pressure in veins is significantly lower than in arteries.

Answer 72

* Blood velocity begins to increase as it returns to the heart through the venules and larger veins, even though the pressure is low. * The cumulative effect of the return flow through the veins results in a higher velocity as it approaches the heart, despite the low pressure.

Answer 73

parallel and series

Answer 74

In a series arrangement, blood flows through one vessel, then directly into the next, one after the other. This is less common in the body. Example: The arrangement of blood flow from the heart through the aorta and then through various arteries to a single capillary bed is somewhat sequential but isn't truly series in a broad physiological sense.

Answer 75

In a series circuit, the total resistance to blood flow is the sum of the resistances of each individual vessel. This can lead to higher overall resistance and potentially less efficient blood flow.

Answer 76

In a parallel arrangement, blood can flow through multiple vessels simultaneously. This is the predominant arrangement in the body. * Example: The systemic circulation is characterized by many capillary beds in parallel. For instance, when blood reaches an organ, it can be distributed through multiple arterioles leading into many capillaries, allowing different tissues to receive blood concurrently.

Answer 77

parallel circulation

Answer 78

In a parallel circuit, the total resistance is less than the resistance of any individual vessel. This is because each additional pathway provides an alternative route for blood flow, which reduces the overall resistance and enhances perfusion. This allows for efficient distribution of blood to various tissues and organs

Answer 79

* Despite individual capillaries having high resistance due to their small radius * their parallel arrangement results in low cumulative resistance, enabling effective blood flow and nutrient exchange in the systemic circulation.

Answer 80

5 L majority in veins

Answer 81

▪ 80% in the systemic circulation ▪ 60% in systemic veins ▪ Small arteries and capillaries – 20% of blood volume

Answer 82

Veins are very compliant – they’re “floppy” and are easy to distend (up to a point) ▪ If you give someone 500 mL of normal saline, 80% of that stays in the systemic circulation, and most of it (95%) locates in the veins...

Answer 83

very little- very floppy

Answer 84

describes how much pressure is required to change the diameter (volume) of a structure the ability of a blood vessel to expand and accommodate changes in blood volume or pressure.

Answer 85

small amount of pressure ! large change in volume ▪ In general, veins are more compliant than arteries

Answer 86

▪ Compliance of a vessel – especially larger arteries -decreases with age; vessels become “stiffer” * Atherosclerosis * Calcification * Compliance decreases with contraction of smooth muscle within blood vessels

Answer 87

Arterial compliance is the ability of arteries to stretch and expand when blood pressure increases during systole (heart contraction).

Answer 88

Arteries have relatively low compliance, meaning they do not stretch easily. This is due to their thick muscular walls and elastic fibers, which allow them to withstand high pressure from the blood being pumped by the heart.

Answer 89

The low compliance helps maintain high blood pressure, ensuring efficient blood flow to various organs. Arteries can also dampen the pressure fluctuations caused by the heartbeat.

Answer 90

High Compliance: Veins have high compliance, allowing them to accommodate larger volumes of blood at lower pressures. Their walls are thinner and less muscular compared to arteries.

Answer 91

Venous compliance is the ability of veins to expand and hold more blood without a significant increase in pressure.

Answer 92

bc act as blood reservoir This high compliance serves as a blood reservoir. During periods of rest or when blood volume increases, veins can expand to store extra blood without a drastic increase in pressure, which helps regulate blood flow and maintain venous return to the heart.

Answer 93

▪ vena cavae ▪ heart ▪ pulmonary circulation

Answer 94

▪ determining preload of the heart (optimal ventricular stretch-->optimal force of contraction) ▪ pathologic situations like pulmonary edema due to congestion

Answer 95

by varying the amount in the peripheral compartments ▪ Peripheral compartments – veins in the abdominal cavity or limbs

Answer 96

the tendency for a structure to resume it’s original shape once a distending force (pressure) is removed

Answer 97

compliant yet elastic arteries

Answer 98

increases cardiac output due to improve actin-myosin overlap at optimal preload * ... but at the same time, as cardiac output increases, the central venous blood volume is removed more quickly ▪ due to increased movement of fluid

Answer 99

valves in leg veins or lower body surround leg veins with skeletal muscle (contracts with standing) ▪ Breathing in decreases intrathoracic pressure... * Which draws blood upwards

Answer 100

Pulse pressure (PP) = systolic pressure (SP) – diastolic pressure (DP) MAP = DP + PP/3 OR MAP = Diastolic Pressure + 1/3(Systolic Pressure - Diastolic Pressure)

Answer 101

When an artery enters an organ, it undergoes multiple branches (six to eight times). These arteries are known as distributing arteries, as they distribute blood to different regions of the organ.

Answer 102

the distributing arteries branch into arterioles, which are smaller blood vessels with a diameter of about 10 to 15 microns.

Answer 103

arterioles typically branch two to five times and serve as the primary site for regulating blood flow into the capillaries. They play a key role in controlling resistance and blood pressure.

Answer 104

regulating blood flow, controlling resistance and blood pressure

Answer 105

As arterioles continue to branch, they lead to metarterioles, which are transitional vessels between arterioles and capillaries.

Answer 106

* Muscle Layer: Muscular arterioles (the larger arterioles) usually have a single layer of smooth muscle that helps regulate blood flow . * Discontinuous Muscle: Metarterioles have a discontinuous layer of smooth muscle along their length, which is not uniform like in the larger arterioles.

Answer 107

discontinuous layer of smooth

Answer 108

Metarterioles lead directly to capillaries, which have an internal diameter ranging from 3 to 9 microns.

Answer 109

site of nutrient and gas exhange

Answer 110

Capillaries are the sites of nutrient and gas exchange between the blood and surrounding tissues. Their small diameter allows red blood cells to pass through in single file, facilitating this exchange.

Answer 111

At the junction of metarterioles and capillaries are pre-capillary sphincters. These are small bands of smooth muscle that regulate blood flow into the capillary beds.

Answer 112

When the sphincters are contracted, blood flow into the capillaries is reduced or halted, directing blood flow to other areas or minimizing flow when tissues are not active. When relaxed, they allow more blood to flow into the capillaries for exchange.

Answer 113

type IV collagen

Answer 114

The basement membrane of capillaries is primarily formed by Type IV collagen. This structure supports the capillary walls and provides a scaffold for endothelial cells, ensuring the integrity and functionality of the capillaries.

Answer 115

Continuous capillaries are characterized by an uninterrupted endothelial lining, which allows them to maintain a relatively tight barrier between the blood and surrounding tissues. Most continuous capillaries are considered “leaky,” permitting the free movement of small, water-soluble substances (like ions, glucose, and amino acids) while restricting larger molecules and cells.

Answer 116

* Blood-Brain Barrier (BBB) * Blood-Testes Barrier they have tight junctions and are less permeable

Answer 117

continuous capillaries with tight junctions formed by proteins called occludins and claudins. These proteins connect adjacent endothelial cells and form a more complete seal compared to regular continuous capillaries.

Answer 118

reduced paracellular permeabilty , ensuring that only specific substances can cross the endothelial barrier

Answer 119

Continuous capillaries engage in a process known as pinocytosis, where they continuously endocytose (internalize) small pockets of extracellular fluid from the vascular space. This involves the formation of small vesicles that capture fluid and any dissolved substances.

Answer 120

ransport Across the Basement Membrane: Once internalized, these vesicles transport the fluid and its contents across the endothelial cells and release them into the surrounding tissue. This mechanism allows for the regulated exchange of substances between the bloodstream and the tissue, even in areas where tight junctions restrict other forms of transport.

Answer 121

increases it in continuous capillaries --> increased fluid up to transport immune cells for infalmatory response (antibodies and nutrients)

Answer 122

increases it ; allow larger molecules and immune cells to pass to respond to injury or infection

Answer 123

Caveolae – “small caves” ▪ endocytosis and transcytosis of macromolecules across endothelial cells ▪ vesicles can move slowly through the endothelial cell

Answer 124

acilitate the endocytosis and transcytosis of macromolecules. allow for controlled transport across the endothelial barrier while intercellular clefts provide a selective pathway for small molecules.

Answer 125

pinocytic vesicles

Answer 126

just small enough so albumin doesn’t get through

Answer 127

* Substances move down their concentration gradient (diffusion) except for water ▪ Water moves down its concentration gradient AND down its hydrostatic gradient

Answer 128

speed of which substances diffuse down their gradient

Answer 129

Starling forces govern fluid exchange in the body by balancing the hydrostatic pressure that pushes fluid out of capillaries and the oncotic pressure that pulls fluid back in.

Answer 130

leakiness of capillary wall hydrostatic pressure osmotic pressure fluid in capillary fluid in interstitial space how much protein leaks through capillary wall

Answer 131

describes the diffusion of substances, particularly the movement of gases or solutes across a barrier, such as cell membranes or capillary walls.

Answer 132

flow/flux concentration gradient surface area thickness of membrane

Answer 133

▪ albumin and other plasma proteins * a small amount leaks through ! a small oncotic pressure in the interstitial space

Answer 134

GAGs and lymphs ▪ glycosaminoglycans that absorb water like a “sponge” (lots of CHO moieties) ▪ lymphatics in most tissue

Answer 135

intrinsic ability of a capillary bed to regulate its own blood flow based on local tissue factors, rather than relying on systemic factors like overall blood pressure.

Answer 136

▪ Maintains a relatively constant rate of tissue flow despite changes in MAP * Higher pressures in the vessel (smaller vessels, i.e. arterioles)--> smooth muscle stretching → increased constriction (stretch-activated calcium channels) * Decreased pressure!decreased stretch → dilation

Answer 137

80-125% of normal arterial pressures of 60-160 mmHg

Answer 138

* Atpressuresabove about 160 mm Hg, vascular resistance decreases because the pressure forces dilation to occur * at pressures below 60 mm Hg, the vessels are fully dilated, and resistance cannot be appreciably decreased further.

Answer 139

O2, CO2, H+, lactate, adenosine, K+ mitochondria will produce H2S in hypoxic situations – may be the major metabolic autoregulatory mediator in some tissues

Answer 140

▪ increased blood flow leads to washout of the same metabolites ▪ Can lead to reactive hyperemia – after a period of vasoconstriction, metabolites build up and lead to a period of vasodilation and greatly increased perfusion

Answer 141

vasodilation

Answer 142

shear stress NO is produced by endothelial cells - shear stress causes its release from the endothelium

Answer 143

the force placed on a blood vessel along the axis of blood flow (increases with pressure, velocity of flow, turbulence)

Answer 144

Detected by mechanoreceptors that modulate nitric oxide synthase (which produces NO from L-arginine)

Answer 145

NO activates soluble guanylyl cyclase! cGMP production! activation of PK G ! relaxation (through dephosphorylation of myosin) of smooth muscle

Answer 146

shear stress increases --> nitric oxide production --> vasodilation in arterioles --> a decrease in shear stress

Answer 147

l arginine

Answer 148

vasodilation

Answer 149

circulating protein, activated by inflammatory signals ▪ Potent vasodilator

Answer 150

vasodilates arterioles, constricts venules → edema

Answer 151

vasocontriction

Answer 152

vasocontrict- alpha 1 vasodilate- beta 2

Answer 153

compresss capillaries to restrict blood flow help veins pumo blood back to heart Compression of Capillaries: During muscle contractions, the skeletal muscle fibers shorten and exert pressure on the capillaries that supply blood to the muscle. This compression can temporarily restrict blood flow within the capillary bed during contraction. Emptying the Venous Tree: When skeletal muscles contract, they help pump blood back to the heart by compressing veins. This is particularly effective in emptying the venous tree, which can increase the pressure gradient driving blood flow from arteries to veins.

Answer 154

increases After the muscle contractions stop, there is a rapid increase in blood flow to the capillary beds. This increased flow delivers oxygen and nutrients necessary for recovery and continued activity.

Answer 155

* Lactate: Produced during anaerobic metabolism, signaling the need for increased blood flow and oxygen delivery. * Potassium (K+): Released by muscle cells during activity, causing local vasodilation to increase blood flow. * Adenosine: Released as a result of ATP breakdown; acts as a potent vasodilator. * These metabolites override the vasoconstrictive effects mediated by the ANS, leading to vasodilation and enhanced blood flow to active skeletal muscles.

Answer 156

25-30% blood flow increases up to 20 fold in exercise bc of vasodilation, capillaries need more gas and nutrient exchange up to 90% oxygen need during exercise bc of heightened metabolic needs

Answer 157

ANS, intracranial pressure, ph, adenosine

Answer 158

▪ mostly mediated by local increases in H+/adenosine or by carbon dioxide diffusing across the BBB ▪ Other vasomediators blocked by BBB, so it doesn’t really respond to circulating vasodilatory/constricting influences

Answer 159

* Brain is also capable of modulating ANS activity, thus it can control blood flow to other tissues ▪ wide range of mechanisms, including baroreceptor input, CO2 concentrations, endocrine feedback loops

Answer 160

decreased perfusion

Answer 161

↑ intracranial pressure → ↓ perfusion ▪ in response to this, the brain increases mean arterial pressure (Cushing reflex)

Answer 162

alpha 1 receptors for constriction (sympathetic) - regualte body temperature

Answer 163

low oxygen concentraions = constriction Pulmonary circulation is unique in that it constricts in response to low oxygen levels (hypoxia), whereas most other vascular beds in the body respond to low oxygen by dilating. enhances gas exchange efficiency

Answer 164

oxygen and adenosine Mechanical compression during systole → poorer blood flow

Answer 165

myogenic and tubuloglomerular feedback, catecholamines, angiotensin II

Answer 166

* Decreased Venous Return: Blood pools in lower extremities, reducing preload. * Reduced Stroke Volume & Cardiac Output: Less blood fills the heart, decreasing output. * Compensatory Tachycardia: Heart rate increases to maintain blood pressure. * Peripheral Vasoconstriction: Sympathetic response causes vessel constriction to maintain pressure. * Hypotension Risk: Prolonged LBNP can lead to a dangerous drop in blood pressure.

Week 6, Lec 1 Flashcards

(198 cards)