Chapter 19- Cardiovascular System and Blood Vessels Flashcards
(141 cards)
1
Q
Tunica intima
A
Innermost layer
continuous with the endocardium an contains endothelium of simply squamous cells
Provides slick surface
2
Q
Why is the tunica intima important?
A
Makes blood flow much easier and gives it less resistance - more of a gliding effect
3
Q
What do capillaries have?
A
Endothelium
Basement membrane
4
Q
Tunica media
A
Middle layer
Diameter of blood vessel (controls constriction) and will be the thickest layer
Contains smooth muscle
Maintaining blood pressure and circulation
5
Q
Vasodilation
A
Smooth muscle relaxes and lumen becomes larger
6
Q
Vasoconstriction
A
Smooth mucle contracts and lumen becomes smaller
7
Q
Lumen
A
Free space in which the blood is travelling
8
Q
Where is the tunica media thicker, arteries or veins?
A
Thicker in arteries
They have more smooth muscle tissue to repel the blood
9
Q
Tunica externa
A
Outermost later
protects externally
contains collagen fibers and protects blood vessels and anchors them to surrounding structures
don’t want blood vessels to to test or bend
10
Q
What do larger vessels have?
A
Vasa vasorum
“blood vessels on blood vessels”
11
Q
What is the function of vasa vasorum
A
Heart, pulmonary artery, aorta
Walls are too thick to allow blood to travel through them to diffuse oxygen and stuff to outer layer so they need extra blood vessels to keep them healthy and give them oxygen
12
Q
Arteries
A
Any blood vessel in the body that carries blood AWAY from the heart TOWARDS body tissues
Branches several times to form smaller blood vessels
13
Q
Elastic arteries
A
“Conducting arteries”
Have large lumen - easier to pump blood through
Example- aorta and its branches
Walls have elastin that expands and recoils as heart pumps blood
14
Q
Muscular arteries
A
Derived from elastic arteries
Thicker tunica media
LIttle elastic quality, but are good for vasoconstriction - blood pressure
15
Q
Arterioles
A
Resistance arteries
Small arteries
Flow directly into capillary beds/blood vessels
Constriction or dilation of arterioles affects resistance to blood flow into capillaries
Dilate them and let in a large amount of blood meaning tons can flow into the cap beds and indirectly affect gas exchange
16
Q
Capillaries
A
“exchange” vessels
contact tissue cells → allow for gas exchange, waste removal, etc.
Almost all body cells are either in direct contact with capillaries or are next to one
Diameter so small that RBCs pass through single-file (one at a time; even then, the red blood cell usually has to bend in half and squeeze through)
No tunica externa or media
Structurally suited for exchange
Joined bt tight junction with intercellular clefts that determine permeability
17
Q
Continuous capillaries
A
Most common, but least permeable
Intercellular clefts are small, exchange of smaller substances (Water and respiratory gasses)
Found in skin and muscle tissue
18
Q
Fenestrated capillaries
A
possess large pores, more permeable
Found mostly in places of body where absorption and filtration is frequent
Ex: small intestine and kidneys
Filter blood to produce urine
Larger intercellular clefts, sallow larger substances
19
Q
Sinusoid capillaries
A
least common, but most permeable
Large intercellular clefts between cells with an incomplete basement membrane
Larger lumen than other capillary types
Liver, bone marrow, spleen
Red blood cells could NEVER squeeze themselves through the first two capillaries
20
Q
Microcirculation
A
the flow of blood from an arteriole to a venule through a capillary bed
21
Q
What happens to blood flow through the capillary bed when the anterior dilates or contrstricts?
A
Dilates- more blood flow
Constricts- Less blood flow
22
Q
Why would you want to decrtease the amount of blood in a capillary bed?
A
Not every part of our body needs a ton of blood all the time
(Only need a small amount of blood when your digestive organs are not doing any work when you’re not eating AND If every body tissue was supplied with the exact same amount of blood at the exact same time, it would be fatal)
23
Q
Venule
A
Capillary beds empy into this postcapillary structure where the veins come in
24
Q
Veins
A
Any blood vessel that transports blood TO the heart
Smaller veins merge several times to form larger veins
Systemic veins carry oxygen poor blood, pulmonary veins carry oxygenated blood
Have thinner tunics and larger lumen than arteries of similar size
Allows for large amounts of blood to be stored → blood reservoirs
60/70% of total blood volume
Can tap into the storage for cardiac output or blood pressure quickly
Low pressure within veins
25
What is the problem with lower pressure created in the veins?
Will impair blood flow and slow it down - no pressure means it doesn't push blood very well back towards the heart
26
What direction do veins carry blood relative to the heart?
To the heart (right atrium)
27
Venules
Lead from capillary bed to larger veins
Tend to be very porous, allow easy passage from bloodstream
Water can pass through
28
What is the problem with lower pressure created in the veins?
Will impair blood flow and slow it down - no pressure means it doesn't push blood very well back towards the heart
29
Large diameter lumen
little resistance to blood flow
Benefit: does not take a lot of “work” to move blood through veins
30
Venous valves
Prevents backward flow of blood through veins
Greater number of valves in veins of the appendages
Gravity acts against your veins
31
Varicose veins
leaky valves cause backflow of blood, causing blood to pool and walls of veins to stretch
More common in females or individuals who have had children
Venous valves in the veins are dysfunctional causing blood to pool in the vein
spider veins
32
Blood flow
The volume of blood flowing through a vessel, organ, or the entire circulation in a given period
Blood flows from high-pressure to low pressure
33
Hydrostatic pressure
Difference must exist for blood flow to occur
34
What does having hydrostatic pressure mean?
A difference in pressure exists in the body and blood has the tendency to flow from high-pressure to low pressure
Created by structures already talking about
Thicker tunis and larger lumen
35
Blood pressure
The force exerted on a blood vessel wall by the blood it contains
Blood is always pushed against the vessel wall it is flowing through
36
Where is blood pressure the highest?
Aorta
37
How does blood pressure change as blood circulates from arteries --> capillaries --> veins?
Decrease in pressure
Usually concerned only with arterial blood pressure
38
Resistance
Opposition of blood flow through a vessel due to the friction between the vessel wall and the flowing blood
Peripheral resistance --> Resistance is highest in systemic circulation
Anything systemic in nature, NOT those associated with the lungs
39
Blood viscosity
The "thickness" of blood
More difficult to pump mud than water
The more thick your blood, the more resistance it creates
Don't want blood viscosity to change
40
Vessel length
The longer the blood vessel, the more blood that will rub against the blood vessel, the increase in resistance
Example- Tall people have longer resistance than shorter people
41
Vessel diameter
Changed frequently --> has greatest effect on resistance
Smaller diameter - the more blood in contact with blood vessel wall the more friction and resistance you are creating
Bigger = less resistance because less in contact with blood vessel wall
42
How do changes in blood pressure and resistance affect blood flow?
As change in blood pressure (△P) increases, blood flow (F) increases
As peripheral resistance (R) increases, blood flow decreases
43
Systemic Blood Pressure
The pumping action of the heart generates blood flow. Blood pressure results when blood flow is opposed by resistance
Almost always higher than pulmonary pressure
Pumping action of the heart will generate blood flow
Want blood to flow, but resistance slows it down → increase the pressure
44
Arterial Blood Pressure
Blood pressure in arteries near heart is pulsatile
45
What does pulsatile mean?
Rises and falls in a regular fashion
46
Disensibility of blood vessel walls
degree of stretch of blood vessels
Less elasticity = higher pressure
If you force a lot of blood into a vessel that cannot stretch, you create a ton of pressure
47
Volume of blood being pumped into arteries
Higher blood volume = higher blood pressure
48
Systolic
Pressure in the aorta when ventricle contracts
Forces blood into the aorta and stretches its walls
Healthy adults- 120 mmHg
49
Diastolic
Pressure in aorta when heart is relaxed
Walls of aorta relax and recoil
Still maintain enough pressure to move blood
Healthy adults- 70/90 mm Hg
Low pressure, but enough to move blood for systemic circulation
50
Pulse pressure
The difference between systolic and diastolic blood pressure
Represents the force the heart generates with each contraction
The larger the difference between systolic and diastolic, the harder your heart has to work
51
What is the pulse pressure for person 1 with a blood pressure of 120/80?
40 pulse pressure
52
What is the pulse pressure for a person 2 with a blood pressure of 135/70?
65 pulse pressure
Not bad, but this pulse pressure is indicating that this person's heart is working harder than the person with 40 pulse pressure
53
What is the pulse pressure for a person 3 with a blood pressure of 180/140?
40 pulse pressure
Even though it's the same as person 1, they are not as healthy as person 1
54
Capillary Blood Pressure
Low blood pressure is typical in capillary beds
Thin walls of capillaries could burst under high-pressure and low pressure
55
Where is the steepest drop in blood pressure in the capillary blood pressure?
Arterioles
56
Venous blood pressure
Not pulsatile - more steady than in arteries
If you cut into a vein, they will have a slow trickle of blood down
57
Is blood pressure in venous veins usually low or high?
Low
Prevents efficient blood return
58
Use of skeletal muscle
Contracting muscles "squeeze" veins - push blood forward
59
Respiratory pump
Inhaling- Increases pressure in the thorax, pushes blood in veins towards heart
Exhaling- Pressure in chest drops, allowing vessels to expand --> blood flows into right atrium
60
Sympathetic vasoconstriction
Vessel walls constrict, reducing venous volume and pushing blood toward the heart
Needs to be strong to have a substantial effect
61
Remember factors affecting Cardiac Output
Stroke volume (increase CO = Increase SV)
Heart rate (increase CO = Increase HR)
62
Remember factors affecting Resistance
Blood viscosity (increase R = increase viscosity)
Blood vessel length (increase R = increase vessel length)
Blood vessel Diameter (Increase BP = Increase BV)
63
Neural Controls
Type of short term regulation
64
Cardiovascular center
In medulla oblongata
Alters cardiac output and blood vessel diameter via two “sub-centers” called cardiac and vasomotor centers
65
Cardiac center
cardioacceleratory center & cardioinhibitory center
66
Vasomotor center
controls blood vessel diameter
Primarily affects diameter of arterioles
Sympathetic activity causes vasoconstriction → increase in blood pressure
67
Change in cardiovascular center (Increase in BP)
Increase cardioacceleratory center by increasing both stroke volume and heart rate
Increase vasomotor center by increasing vasoconstriction
68
Baroreceptors
stretch receptors in walls of large arteries of neck & thorax
Monitor degree of stretch in blood vessel wall and causes baroreceptors to fire
Best for short-term changes in blood pressure → baroreceptors act quickly; send info quickly to cardiovascular center
When stretched, inhibits the cardioacceleratory system
69
How does Baroreceptors affect blood pressure?
To increase blood pressure → decrease baroreceptor stretch
Decreased Cardiac Output: parasympathetic activity increases → heart rate and contractile force drop
70
Chemoreceptors
Changing CO2 levels, blood pH, oxygen content in body affect blood pressure
Increase in CO2, decrease in blood pH, or oxygen content drops → stimulates cardioacceleratory center
Increase in CO & vasoconstriction occur
Pick up on... decreased blood pH, O2, and increased CO2
71
Higher brain centers
affect blood pressure
Increase higher brain activity
72
Hormonal controls
Short or long term, depending on the hormone
73
Epinephrine and norepinephrine
Short-term
Release causes increase CO → increase blood pressure via vasoconstriction
Sympathetic division is more active
Increase blood pressure = Increase Epi and Norepi
Increases cardioacceleratory center activity
74
Angiotension II
Produced by kidneys
Release stimulates intense vasoconstriction → raises blood pressure quickly
Increase blood pressure = Increase Angiotensin II
Intense, so you don’t need a lot to increase the BP
The more you release, the more intense the vasoconstriction is, the more increase in blood pressure you have
Substantial drop-off in blood pressure
75
When is angiotensin released?
Low blood volume stimulates the release
Dehydration and severe hemorrhage
76
Atrial Natriuretic peptide
Produced by atria of the heart
Release causes increase in excretion of solutes/water form the body via the kidneys
When your heart is working too hard, it will release ANP so that your kidneys would get rid of more water
77
What happens to blood volume and blood pressure for Atrial natriuretic peptide (ANP)?
If you are removing water from the bloodstream → Decrease blood volume = Increase blood pressure
Increase blood pressure = Decrease ANP
78
Antidiuretic hormone (ADH)
Produced by hypothalamus
Antiurine formaiton hormone released by kidneys
Release causes increase in water reabsorption by kidneys - increase blood volume and blood pressure
Not great for short term fixes (more for the long term)
Exception- severe hemorrhage
Increase blood pressure = increase ADH
79
Long term regulation
Renal (kidney) mechanisms
80
Renal Mechanisms
Depending mostly on altering blood volume
Uses kidneys to increase/decrease blood volume
Kidneys constantly adjust to maintain blood volume to around 5 Liters (healthy adult) -> maintains BP
81
Renal Kidneys Affect on blood volume
Increase blood volume = decrease kidney filtration
Urine formation = Less urine formation = Less water loss
82
What effect does increasing have on urine production? How does this change BP?
Decreases urine production
Increases blood pressure
83
Indirect mechanism for long term regulation
Renin Angiotensin aldosterone - increases blood pressure
Enzyme renin catalyzes reaction to create angiotensin I
Converted to angiotensin II that causes...
A. Aldosterone release from adrenal cortex → Na+ reabsorption increases
B. Stimulates pituitary to release antidiuretic hormone (ADH)
C. Stimulates thirst center of brain
D. Stimulates vasoconstriction
84
What affect does aldosterone release cause in terms of water reabsorption and Blood pressure?
Increase in water being brought into the blood, increase blood pressure
85
What affect does the ADH hormone have on water reabsorption?
Increase in water reabsorption
86
What affect does the thirst center fo the brain have on water reabsorption?
Increases the blood volume
87
What effect does vasoconstriction have on blood pressure?
Increase vasoconstriction = increase in blood pressure
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Hypertension
Consistently high blood pressure
140/90
Crisis hypertension is reached when systolic is 180+ and diastolic is 120
89
Chronic hypertension can lead to...
Heart failure, vascular disease, stroke, and renal failure
90
Heart Failure
myocardium is constantly in “over-drive” walls weaken, heart fails
If you make your heart work harder in the long term over months or years, eventually your heart will fail
91
Vascular disease
atherosclerosis (blocking & hardening of blood vessels)
Affects...
Brain- Capillaries will burst open and brain will not get any of the blood and will lead to a hemorrhagic stroke
Kidneys- All the little tubes that filter the blood will burst open and if the capillaries responsible for filtering blood in the kidneys, the kidneys won’t filter blood, and they will have nothing else to do
Retinas- bursting can cause complete blindness
92
Primary Hypertension
No underlying cause for hypertension
Can be caused by: heredity, diet, obesity, age, stress, smoking, and/or some other conditions (ex: diabetes mellitus)
Chance of hypertension increases with age
Cannot be cured, only treated → dietary restrictions, weight loss, stop smoking, diuretics (aka water pulls) , ACE inhibitors (decrease blood pressure), etc.
93
Secondary hypertension
caused by another identifiable condition
Ex: obstructed arteries, kidney disease, hyperthyroidism (overactive thyroid/ /thyroid hormone being the metabolic hormone and will become more metabolically active and the heart will beat faster and harder)
Can be treated/cured by correcting the underlying condition
94
Hypotension
Consistently LOW blood pressure
90/60
Not as serious as hypertension
Individual variation based on a variety of factors
Becomes a problem when blood flow to necessary tissues is exceptionally low
95
Orthostatic hypotension
dizzy-feeling resulting from fast change in head position
Blood pools temporarily in feet due to gravity → not as much blood reaches the brain
Sympathetic nervous system usually quickly corrects this problem
Example- when you are laying in bed and quickly change positions because it’s usually corrected within 10/15 seconds to get blood back into your brain
96
Chronic Hypotension
low blood pressure caused by some underlying condition
Ex: hypothyroidism (underactive thyroid gland leading to low metabolic rates), severe malnutrition, inadequate adrenal cortex function (release of antidiuretic hormone)
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Shock
Inadequate circulation of blood to body tissues
Oxygen needs and waste disposal needs of tissues not met
If sustained, shock causes cell death and tissue death
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Hypovolumic Shock
shock resulting from severe hemorrhage, severe 3rd degree burns, excessive vomiting/diarrhea
Blood volume drops to dangerously low levels
Weak pulse, intense vasoconstriction
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Vascular shock
Poor circulation due to extreme vasodilation
Blood volume is normal***
Blood vessel problem
100
Anaphylactic shock
Allergic reaction occurs and massive release of histamine causes vasodilation
Epi reverses effects of histamine
101
Neurogenic shock
Autonomic nervous system incorrectly regulated -> parasympathetic influence
usually due to severe spinal cord injury in thoracolumbar region
102
Septic shock
Severe systemic bacterial infection
Sepsis leads to septic shock
Occurs when bacteria gets into blood
Many of the substances have the effect of causing extreme vasodilation
103
Cardiogenic shock
Heart is insufficient to provide blood to tissues
Caused by myocardial damage --> multiple infarcations
Individuals with multiple heart attacks have a bunch nonfunctional scar tissue
104
Blood flow through tissues
Important for gas exchange to the lungs, filtration in kidneys, delivery of oxygen and nutrients to tissue cells, absorption from digestive tract, waste removal
IMPORTANT- not all tissues need large amounts of blood at the same time
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What would happen if every tissue in the body received the same amount of blood at the same time?
Could kill you quickly
106
Autoregulation
Automatic adjustment of blood flow to each tissue in proportion to the tissue requirement
Independent of hormones or neural mechanisms
107
How do organs change blood flow?
Changing the diameter of the arterials so it can bypass the capillary beds so the organ gets less blood overall
By changing resistance in arterioles
decrease arterials = decrease resistance = blood travels easier = more blood to that area
Can be accomplished via metabolic (chemical) changes or myogenic (physical) changes
108
Metabolic control
Autoregulation due to inadequate blood supply leading to build up of waste or tissue hypoxia
Release of nitric oxide in tissues
NO release dilates arterioles --> increasing blood supply to the capillary beds does that temporarily
End effect of vasodilation of arterioles allows more blood into the capillary beds
Highly localized
109
Myogenic control
Smooth muscle tissue in blood vessel wall
Increased pressure within vessels results in an increased tone of smooth muscle
Decreased pressure within vessels causes vasodilation
110
When will increased pressure within vessels results in increased tone of smooth muscle
occur?
When an organ is receiving too much blood, you constrict the blood vessels and cut them off from the capillary bed and it will go somewhere else
111
When will decreased pressure causing vasodilation occur?
When a tissue is not receiving what it needs
112
Skeletal Muscle
Blood flow increases when skeletal muscle is used more
Need more oxygen ATP to keep things going
113
Active Hyperemia
Increase in blood flow that is proportional to increased metabolic activity of muscle
O2 levels low and metabolic waste production increases during activity
114
What does sympathetic input have to do with Active hyperemia?
Skeletal muscle tissue can ignore the effectof the sympathetic division so that vasoconstriction can still occur and the blood vessels can dilate
115
What causes vasoconstriction?
Norepinephrine
116
The brain
Constantly Maintained
Not an organ that is diverted during exercise
117
What happens to blood vessels during exercise?
Dilate
118
When blood pressure increases, what happens to blood vessels?
Vasoconstriction
Diverts the blood away from the tiny blood vessels to ensure they don't burst open
119
When blood pressure decreases, what happens to blood vessels?
Vasodilation
Ensures the brain gets the blood it actually needs
120
The skin
Maintains body temperature
121
Venous plexus
extensively branched network of blood vessels under the skin
Blood flow ranges from 50 ml/min to 2500 ml/min
122
What happens to blood vessels in skin when internal body temps increase?
What is the effect? Too high → in this instance, you get rid of excess body heat and more heat will be supplied to the venus polexus and will fill with excess blood
Because blood has a large water component and if you out that blood close to the skin, it will radiate away from the body and will decrease body temperature back to normal
123
What happens to blood vessels in skin when internal body temps decrease? What is the effect?
If internal body temperature is too low, it will constrict an bypass the skin, keeping it closer to the visceral organs and will have an end effect of increasing your body temperature so the heat doesn’t radiate off of you
124
Where does blood flow the slowest?
In vessels that have the greatest cross-sectional area
CAPILLARIES
RBC's have to travel through them single file
125
How is slow blood flow possible if the individual capillaries have smaller lumen than large arteries (e.g., the aorta)?
Can fit millions of red blood cells at a time - what the capillaries are taking into account
The walls of the aorta are just too thick
The capillaries of the body have a greater combined cross-sectional area than the aorta
Aorta is 2.5 cm2, combined capillaries is 4500 cm2
126
Diffusion
Movement from high concentration to low concentration
Main mechanism for change
Gasses, most nutrients, and metabolic wastes pass from blood to tissues through thin capillary walls
127
In what direction does O2 and nutrients move?
From blood supply into tissue
128
In what direction does waste and CO2 move?
Opposite direction (higher ain tissues and diffuses into capillaries)
CO2- Back to lungs
Waste- Filtered out by kidneys
129
Four routes of capillary exchange
1. Diffusion through membrane
2. Movement through intercellular clefts
3. Movement through fenestrations
4. Transport via vesicles
Larger substances to pass through capillary walls
130
What is interstitial fluid?
Fluid around body issue cells
131
Where is fluid filtered out of?
Arteriolar end of the capillary bed
132
Where is almost all the fluid reabsorbed?
Venous end
133
Hydrostatic pressure
force exerted by blood pressing against the blood vessel wall (the “push”)
Hydrostatic pressure mostly pushes fluid through the capillary wall
134
Capillary Hydrostatic Pressure (HPC)
Pressure that forces fluids out of capillary into interstitial space
Higher at the arterial end of the capillary bed
35 mmHg
135
Interstitial fluid hydrostatic pressure (HPIF)
Opposing pressure that forces fluid from interstitial space into capillary
Small value
0 mmHg
136
Colloid Osmotic Pressure
Force that draws water in a certain direction
the "pull" that pulls water back into the capillary at the venous end
Small opposing force
Interstitial space has very few proteins, so this “force” is negligible at 1 mm Hg
136
Colloid Osmotic Pressure
Force that draws water in a certain direction
the "pull" that pulls water back into the capillary at the venous end
Small opposing force
Interstitial space has very few proteins, so this “force” is negligible at 1 mm Hg
136
Colloid Osmotic Pressure
Force that draws water in a certain direction
the "pull" that pulls water back into the capillary at the venous end
Small opposing force
Interstitial space has very few proteins, so this “force” is negligible at 1 mm Hg
137
Colloid Osmotic Pressure
Force that draws water in a certain direction
the "pull" that pulls water back into the capillary at the venous end
Small opposing force
Interstitial space has very few proteins, so this “force” is negligible at 1 mm Hg
138
Net Filtration Pressure
Pressure created by interactions of hydrostatic pressure and osmotic pressure
Net loss of fluids from circulation
Calculation:
NFP= (HPC + OPIF) – (HPIF + OPC)
= (35 mm Hg + 1 mm Hg) – (0 mm Hg + 26 mm Hg)
= 10 mm Hg
139
Where does the “lost” fluid go?
Not losing it at all - it returns to circulation
Lose 20, get back 17
