circulation and gas exchange Flashcards
1
Q
what is the internal transport system that conveys fluid that humans have
A
blood or interstitial fluid
2
Q
what is interstitial fluid?
A
the fluid filling the spaces between cells in most animals
3
Q
what does the transport of fluids allow for?
A
The transport of fluids throughout the body connects the aqueous environment of the cells to the organs that exchange gases, absorb nutrients, and dispose of wastes.
4
Q
what gas exchange happens in the lungs?
A
In the lung, oxygen from inhaled air diffuses across a thin epithelium and into the blood, while carbon dioxide diffuses out.
5
Q
what does bulk fluid movement in the body allow for?
A
Bulk fluid movement in the circulatory system quickly carries the oxygen-rich blood to all parts of the body
6
Q
do humans have a closed or open circulatory system?
A
The human uses a closed circulatory system (cardiovascular system)
7
Q
how does the heart allow for circulation?
A
metabolic power
8
Q
what does metabolic power in the heart allow for?
A
elevate the hydrostatic pressure of the blood (blood pressure), which then flows down a pressure gradient through its circuit back to the heart.
9
Q
how are materials between tissues exchanged?
A
Materials are exchanged by diffusion between the blood and the interstitial fluid bathing the cells
10
Q
what are the 3 main kind of blood vessels?
A
Arteries, veins, and capillaries
11
Q
what do arteries do?
A
carry blood away from the heart to organs.
All arteries carry blood from the heart toward capillaries
12
Q
what are arterioles?
A
Within organs, arteries branch into arterioles, small vessels that convey blood to capillaries
13
Q
what are capillary beds?
A
Capillaries with very thin, porous walls form networks, called capillary beds,
that infiltrate each tissue.
14
Q
how are chemicals and dissolved gases exchanged?
A
Chemicals, including dissolved gases, are exchanged across the thin walls of the capillaries between the blood and interstitial fluid
15
Q
what happens at the downstream end of capillaries?
A
At their “downstream” end, capillaries converge into venules, and venules converge into veins, which return blood to the heart.
16
Q
how are arteries and veins distinguished?
A
Arteries and veins are distinguished by the direction in which they carry blood, not by the characteristics of the blood they carry
17
Q
what do veins do?
A
Veins return blood to the heart from capillaries
18
Q
what does the left side of the heart do?
A
Left side of the heart receives and pumps only oxygen-rich blood
19
Q
what does the right side of the heart do?
A
Right side handles only oxygen-poor blood
20
Q
what does double circulation in the heart allow for?
A
Double circulation restores pressure to the systemic circuit and prevents mixing of oxygen-rich and oxygen-poor blood
21
Q
what is the difference between the pulmonary and systemic system?
A
Systemic circulation transports oxygenated blood from the heart throughout the body. pulmonary circulation brings deoxygenated blood back to the heart.
22
Q
true or false, the pulmonary system and systemic system function in unison?
A
true! ventricles are active almost at the exact same time
23
Q
what happens within the capillaries in the body after blood gets oxygenated?
A
1) blood gives up much of its O2
2) picks up CO2 produced by cellular respiration.
24
Q
where is the mammalian heart located?
A
located beneath the breastbone (sternum) and consists mostly of cardiac muscle.
25
what are the atria for?
The two atria have relatively thin walls and function as collection chambers for blood returning to the heart
26
what is the difference between the atria and the ventricles?
The two atria have relatively thin walls and function as collection chambers for blood returning to the heart.
The ventricles have thicker walls and contract much more strongly than the atria
27
what are coronary arteries?
The first branches from the aorta are the coronary arteries, which supply blood to the heart muscle
28
what does one complete cardiac cycle consist of?
A cardiac cycle consists of one complete sequence of pumping, as the heart contracts (systole) , and filling, as it relaxes (diastole) and its chambers fill with blood
29
what do we call the heart contracting? what happens?
(systole). it pushes blood out
30
what do we call the heart relaxing? what happens?
(diastole) and its chambers fill with blood
31
on average, how long is a cardiac cycle?
0.8 sec
32
what are the steps of the heart circulation?
1) during the relaxation phase (atria and ventricles in diastole) lasting about 0.4 sec, blood returning from the large veins flows into atria and ventricles.
2) a brief period (about 0.1 sec) of atrial systole forces all the remaining blood out of the atria and into the ventricles.
3) during the remaining 0.3 sec of the cycle, ventricular systole pumps blood into the large arteries.
33
what does cardiac output depend on?
1) the rate of contraction or heart rate (number of beats per minute)
2) stroke volume, the amount of blood pumped by the left ventricle in each contraction.
34
what is stroke volume?
the amount of blood pumped by the left ventricle in each contraction
35
what is the average stroke volume of a human?
average stroke volume for a human is about 75 mL
36
what is the resting cardiac output?
5.25 L / min, is about equivalent to the total volume of blood in the human body
37
what is pulse?
the rhythmic stretching of arteries caused by the pressure of blood pumped by the ventricles
38
what are the four valves in the heart?
2 atrioventrical
2 semilunar
39
what are the 2 atrioventrical?
mitral (bicuspid) valve and the tricuspid valve
40
what is the mitral valve?
between the left atrium and left ventricle
41
what is the tricuspid valve?
between the right atrium and right ventricle
42
how many cusps are in the mitral and tricuspid valve?
tricuspid: 3
mitral: 2
43
what are the 2 semilunar valves?
aortic and pulmonary valve
44
what does the pulmonary valve connect?
right ventricle and pulmonary artery
45
what are the heart beats on a stethoscope caused by?
The heart sounds we can hear with a stethoscope are caused by the closing of the valves
46
what is lub caused by?
lub is created by the sound of blood rushing through the AV valves, as they are narrowing and about to close
47
what is dup caused by
dup is created by the sound of blood rushing through the semilunar valves, as they are narrowing and about to close
48
what causes a heart murmur?
A defect in one or more of the valves causes a heart murmur which may be detectable as a hissing sound when a stream of blood squirts backward through a valve.
49
how do defects in the valves happen?
either from birth or because of infection
50
how do certain cardiac cells allow for the heartbeat to continue?
Certain cells of vertebrate cardiac muscle are self-excitable, meaning they contract without any signal from the nervous system.
51
what is the sinoatrial node?
sets the rate and timing at which all cardiac muscle cells contract
52
where is the sinoatrial node located?
SA node is located in the wall of the right atrium
53
how is the cardiac cycle regulated?
The cardiac cycle is regulated by electrical impulses that radiate throughout the heart.
Cardiac muscle cells are electrically coupled by intercalated disks between adjacent cells
54
why is the impulse from the SA node delayed by 0.1 seconds at the atrioventricular node?
The impulse from the SA node is delayed by about 0.1 sec at the atrioventricular (AV) node, the relay point to the ventricle, allowing the atria to empty completely before the ventricles contract.
55
what are the specialized muscle fibers in the heart? what do they do?
bundle branches and Purkinje fibers
conduct the signals to the apex of the heart and (4) throughout the ventricular walls
56
how do electrical signals get transmitted throughout the heart?
SA node generates electrical impulses
spread through wall of atria
ventricles then get signal, as it transfers to the atrioventricular node
goes to apex of the heart and throughout ventricular walls
57
how do the ventricles contract? what does this cause?
This stimulates the ventricles to contract from the apex toward the atria, driving blood into the large arteries
58
how can the hearts electric impulses be detected near the skin?
The impulses generated during the heart cycle produce electrical currents which are conducted through body fluids to the skin
- currents can be detected by electrodes
- recorded as an electrocardiogram (ECG or EKG).
59
what does depolarization and repolarization refer to?
depolarization: Depolarization is what causes the contraction of cardiac chambers
repolarization: Repolarization refers to relaxation of cardiac chambers.
60
what happens during P wave?
depolarization of SA node and atria
61
what is QRS complex?
QRS complex: ventricular depolarization and atrial repolarization
62
what is T wave?
ventricular repolarization
63
what does the SA node do to the tempo of the heart?
sets the tempo for the whole heart
64
what are different things that affect heart rate?
1) Two sets of nerves affect heart rate with one set speeding up the pacemaker and the other set slowing it down
2) also influenced by hormones:
ex epinephrine from the adrenal glands increases heart rate.
3) increases in response to increases in body temperature and with exercise
65
true or false, all blood vessel is made of similar tissue
true!
66
what are the 3 layers of blood vessels
On the outside, a layer of connective tissue with elastic fibers allows the vessel to stretch and recoil.
A middle layer has smooth muscle and more elastic fibers.
Lining the lumen of all blood vessels, including capillaries, is an endothelium, a single layer of flattened cells that minimizes resistance to blood flow.
67
what are the differences between capillaries, arteries and veins (difference from 3 layers of blood vessels)?
1) Capillaries lack the two outer layers and their very thin walls consist of only endothelium and its basement membrane, thus enhancing exchange.
2) arteries: Arteries have thicker middle and outer layers than veins
3) veins:The thinner-walled veins convey blood back to the heart at low velocity and pressure.
68
why are arteries thicker than other blood vessels?
The thicker walls of arteries provide strength to accommodate blood pumped rapidly and at high pressure by the heart.
Their elasticity helps maintain blood pressure even when the heart relaxes
69
what does blood flow mostly result from?
Blood flows mostly as a result of skeletal muscle contractions when we move that squeeze blood in veins
70
what happens in larger veins?
Within larger veins, flaps of tissues act as one-way valves that allow blood to flow only toward the heart
71
does blood travel faster in aorta or in capillaries?
aorta
72
why does blood travel faster in the aorta than in capillaries?
total cross-sectional area is much greater in capillary beds than in any other part of the circulatory system and since circulation depends on area, then its slower in capillaries
73
what enhances the exchange off substances between blood and interstitial fluid?
The resulting slow flow rate in capillaries and thin capillary walls
74
what pressure does blood exert against vessel walls?
hydrostatic pressure
75
is blood pressure higher in veins or arteries?
in arteries
76
how is hydrostatic pressure expressed?
mm hg
77
when is blood pressure at its highest in arteries?
Blood pressure is highest in arteries when the heart contracts during ventricular systole, creating the systolic pressure
78
what does the hydrostatic pressure gradient allow for?
Pressure gradient provides driving force that keeps blood moving from higher- to
lower-pressure areas
79
what's peripheral resistance?
– Measurement of amount of friction blood encounters with vessel walls, generally in peripheral (systemic) circulation
80
what are the important sources of resistance?
Blood viscosity
Total blood vessel length
Blood vessel diameter
81
what do arterioles do?
Control flow into capillary beds via vasodilation and vasoconstriction of smooth muscle
82
where is the lowest and highest blood pressure?
highest: aorta
lowest: arterioles
83
what is systolic pressure?
pressure exerted in aorta during ventricular contraction
when the heart contracts, blood enters the arteries faster than it can leave, and the vessels stretch from the pressure. This represents the systolic pressure
84
what is diastolic pressure?
: lowest level of aortic pressure when heart is at rest
85
what are the factors regulating blood pressure?
Cardiac output (CO)
Peripheral resistance (PR)
Blood volume
Elasticity (compliance or distensibility) of arteries close to heart
86
what is the goal of blood pressure regulation?
Goal of blood pressure regulation is to keep blood pressure high enough to provide adequate tissue perfusion, but not so high that blood vessels are damaged
87
what happens if BP is too low?
If BP to brain is too low, perfusion is inadequate, and person loses consciousness
88
what happens if BP is too high?
If BP to brain is too high, person could have stroke
89
what are the two type of stroke?
ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both result in parts of the brain not functioning properly
90
pulse in your wrist is due to the bulge in your artery. what is this surge in pressure due to?
Surge of pressure is partly due to the narrow openings of arterioles impeding the exit of blood from the arteries, the peripheral resistance
91
what happens during diastolic pressure?
elastic walls of the arteries snap back during diastole, so there is a lower but substantial pressure in the arteries when the ventricles are relaxed. This is called the diastolic pressure
92
how does peripheral resistance affect blood pressure?
the state of smooth muscles in arteriole walls. Physical or emotional stress can trigger contraction of muscles in the wall.. leading to increased blood pressure.
93
what causes vasodilation?
nitric oxide
94
what causes vasoconstriction?
endothelia
95
how can we have an increased blood volume?
by eating salt
96
how does vessel elasticity affect blood pressure?
vessel elasticity. There is a loss of vessel elasticity in arteriosclerosis and this will increase blood pressure
97
what is the formula for cardiac output?
Cardiac Output = Heart Rate X Stroke Volume
98
what is a sphygmomanometer?
an inflatable cuff attached to a pressure gauge, measures blood pressure fluctuations in the brachial artery of the arm over the cardiac cycle
99
what is the blood pressure of a healthy human?
arterial blood pressure of a healthy human oscillates between about 120 mm Hg at systole and 70 mm Hg at diastole
100
what is the link between blood pressure and the smooth muscle in arterioles?
-Contraction of smooth muscles in walls of arterioles constricts these vessels, increasing peripheral resistance, and increasing blood pressure upstream in the arteries.
- When the smooth muscle relaxes, the arterioles dilate, blood flow through arterioles increases, and pressure in the arteries falls
101
what controls arteriole wall muscles?
Nerve impulses, hormones, and other signals control the arteriole wall muscles
102
true or false, stress can affect blood pressure.
true!
103
how is peripheral resistance adapted depending on cardiac output?
during heavy exercise the arterioles in the working muscles dilate, admitting a greater flow of oxygen-rich blood to the muscles and decreasing peripheral resistance.
- At the same time, cardiac output increases, maintaining blood pressure and supporting the necessary increase in blood flow.
this adaptation allows for blood flow to stay constant
104
how is blood pressure affected by gravity?
- In addition to the peripheral resistance, additional pressure is necessary to push blood above the level of the heart.
- In a standing human, it takes an extra 27 mm of Hg pressure to move blood from the heart to the brain
105
why is blood pressure not affected much by the action of the heart by the time it reaches veins?
- The resistance of tiny arterioles and capillaries has dissipated the pressure generated by the pumping heart.
106
what happens when we inhale?
Also, when we inhale, the change of pressure in the thoracic cavity causes the venae cavae and other large veins near the heart to expand and fill with blood
107
when do the capillaries have blood flowing through them?
At any given time, only about 5-10% of the body’s capillaries have blood flowing through them
108
where in the body are the capillaries often filled?
Capillaries in the brain, heart, kidneys and liver are usually filled to capacity, but in many other sites, the blood supply varies over times as blood is diverted
109
what happens after a meal?
after a meal blood supply to the digestive tract increases
110
what happens after strenuous exercise?
During strenuous exercise, blood is diverted from the digestive tract and supplied to skeletal muscles
111
what are precapillary sphincters?
sphincters between the arterioles and the venules
112
how do we regulate blood flow in the capillaries?
1) contraction of the smooth muscle layer in the wall of an arteriole constricts the vessel, decreasing blood flow through it to a capillary bed.
When the muscle layer relaxes, the arteriole dilates, allowing blood to enter the capillaries.
2) rings of smooth muscles, called precapillary sphincters control the flow of blood between arterioles and venules.
Some blood flows directly from arterioles to venules through thoroughfare channels which are always open.
113
what are the different methods by which exchanges can happen between blood and interstitial fluid?
1) vesicles that form by endocytosis on one side and then release their contents by exocytosis on the other side.
2) diffusion between the blood and the interstitial fluid across cells
3) transport through the clefts between adjoining cells by bulk flow due to fluid pressure.
114
what are the clefts in capillaries?
gaps between the endothelial cells called intercellular clefts
115
what are the two end of the capillary?
venous and arterial end
115
what are the two opposing forces does blood flow in the capillaries depend on?
hydrostatic pressure and osmotic pressure
115
what is bulk flow?
Bulk flow is the movement of substances in bulk or in masses down a pressure gradient
116
what is hydrostatic pressure? which end is it greater at?
force exerted by fluid pressing against wall; two types
Greater at arterial end (35 mm Hg) of bed than at venule end (17 mm Hg)
117
what is capillary osmotic pressure?
“Sucking” pressure created by nondiffusible plasma proteins pulling water back in to capillary
since solids cannot move across membrane, only fluids can so thats where the osmotic pressure comes from
118
true or false, the hydrostatic pressure pushes fluid out of the capillaries?
true
119
what happens at the upstream end of the capillaries (venule end)
Blood pressure within the capillary pushes fluid, containing water and small solutes, through the capillary clefts.
- causes a net loss of fluid at the upstream of the capillary.
- blood cells and most proteins in the blood are too large to pass through and remain in the capillaries.
120
what happens at the downstream end of the capillary?
As blood proceeds along the capillary, blood pressure continues to drop and the capillary becomes hyperosmotic compared to the interstitial fluids.
- resulting osmotic gradient pulls water into the capillary by osmosis near the downstream end.
121
what happens to the fluid that leaves the blood at the arterial end of the capillary?
About 85% of the fluid that leaves the blood at the arterial end of the capillary bed re-enters from the interstitial fluid at the venous end
122
what happens to the other 15 percent of fluid that doesn't re enter the blood at the venule end of the capillary (downstream end)?
Remaining 15% is eventually returned to the blood by the vessels of the lymphatic system
123
what does a decrease in osmotic pressure lead to?
edema
123
what is edema?
abnormally large fluid volume in the circulatory system or in the tissues between the body's cells, known as the interstitial spaces
124
what can low osmotic pressure be due to?
Can be caused by hypoproteinemia, low levels of plasma proteins caused by malnutrition, liver disease, or glomerulonephritis (loss of plasma proteins from kidneys)
125
is osmotic pressure constant throughout the capillary?
yes
126
is hydrostatic pressure constant throughout the capillary?
no, higher at upstream end
127
how do fluids and some blood that leak return to the cardiovascular system?
Fluids and some blood proteins that leak from the capillaries into the interstitial fluid are returned to the blood via the lymphatic system.
Fluid enters this system by diffusing into tiny lacteals intermingled among capillaries of the cardiovascular system
128
true or false, lymph has a composition similar to interstitial fluid?
true
129
what is the venae cavae?
A large vein that carries blood to the heart from other areas of the body
130
where does the lymphatic system drain into the circulatory system?
near the junction of the venae cavae with the right atrium
131
why do lymph vessels have valves?
Lymph vessels have valves that prevent the backflow of fluid toward the capillaries
132
how do lymph vessels function?
- Rhythmic contraction of the vessel walls help draw fluid into lymphatic capillaries.
- lymph vessels depend mainly on the movement of skeletal muscle to squeeze fluid toward the heart
133
what do lymph nodes do?
-Along a lymph vessels are organs called lymph nodes which filter the lymph and attack viruses and bacteria
-also help to maintain the volume and protein concentration of the blood
134
what are lymph nodes?
A lymph node is a honeycomb of connective tissue with spaces filled with white blood cells specialized for defense
135
what is the link between the lymphatic and digestive system and the circulatory system?
lymphatic system transports fats from the digestive tract to the circulatory system
136
why do lymph nodes swell when we are fighting an infection?
When the body is fighting an infection, these cells multiply, and the lymph nodes become swollen to defend against infection.
137
