Circulatory System Flashcards
1
Q
How does having a gastrovascular cavity allow gases, nutrients, and wastes to move in and out of the body?
A
Because diffusion is rapid over short distances, one adaptation is to place most or all cells in contact with the outside environment.
2
Q
How does having a circulatory system allow gases, nutrients, and wastes to move in and out of the body?
A
A circulatory system can move fluid between each cell’s immediate surrounding the body tissues where exchange with the environment occurs.
3
Q
What are the three components of a circulatory system?
A
- Circulatory fluid
- Interconnecting vessels
- Heart
4
Q
What is a heart?
A
A heart is a muscular pump that drives circulation.
5
Q
What is the purpose of the heart?
A
It elevates the circulatory fluid’s hydrostatic pressure, powering it to flow through the vessels and back to the heart.
6
Q
What are the two types of circulatory systems?
A
- Open
- Closed
7
Q
What is the circulatory fluid in open c. systems?
A
The fluid is called hemolymph and is both the circulatory fluid and the interstitial fluid.
8
Q
Which type of organisms have open c. systems?
A
Arthropods, insects, and some mollusks.
9
Q
What are the pros of having an open c. system?
A
Less costly since there is lower pressure.
10
Q
What are the cons of having an open c. system?
A
Lower transport efficiency and local regulation.
11
Q
What is the circulatory fluid in closed c. systems?
A
Blood, which is confined to the vessels.
12
Q
Which type of organisms have closed c. systems?
A
Annelids, cephalopods, and vertebrates.
13
Q
What are the pros of having a closed c. system?
A
Higher transport efficiency and local regulation.
14
Q
What are the cons of having a closed c. system?
A
Energetically costly (higher pressure).
15
Q
Describe the general structure of a vertebrate heart.
A
It contains one or two pumps, each with two muscular chambers. Atria receive blood entering the heart while ventricles pump blood out of the heart.
16
Q
What are the characteristics of a single circulation system?
A
The heart has one pump, and the blood passes through two capillary beds, which reduces blood pressure.
17
Q
What are the characteristics of a double circulation system?
A
The heart has two pumps. The first delivers blood to the oxygenating tissues, while the second receives oxygenated blood and delivers it to the internal tissues.
18
Q
Where does blood go after the right ventricle?
A
The right ventricle pumps blood to the lungs via the pulmonary arteries; in the capillary beds, blood loads O2 and unloads CO2.
19
Q
Where does blood go after the pulmonary arteries and capillary beds?
A
Blood flows via the pulmonary veins to the left atrium of the heart.
20
Q
Where does blood go after the left atrium?
A
Oxygenated blood flows into the left ventricle, which pumps it into the systemic circuit via the aorta.
21
Q
Where does blood go after the left ventricle?
A
The aorta delivers blood to capillary beds in the head and forelimbs, and capillary beds in the abdominal organs and legs.
22
Q
Where does blood go after the aorta and capillary beds?
A
Oxygen-poor blood is funneled into two large veins: the superior vena cava and the inferior vena cava.
23
Q
Where does blood go after the venae cava?
A
The two venae cava empty their blood into the right atrium, and blood moves to the right ventricle.
24
Q
Where does the heart have valves?
A
It has four valves–one between each atrium and each ventricle. It also has a valve from the right ventricle into the pulmonary arteries and a valve from the left ventricle into the aorta.
25
What is the purpose of the heart valves?
They prevent backflow of blood.
26
How does blood pass from an atrium into a ventricle?
It passively flows in.
27
What happens when a ventricle contracts?
1. It pushes the valve between the atrium and ventricle closed.
2. It pushes the blood forward.
28
What does systole mean?
Contraction
29
What does diastole mean?
Relaxation
30
What is cardiac output?
The blood pumped per minute by each ventricle (about 5 L)
31
What is heart rate?
The frequency of cardiac cycles, in beats per minute (about 72 bpm)
32
What is stroke volume?
The blood pumped by a ventricle in a contraction (about 70 ml).
33
What is cardiac output?
The heart rate x stroke volume.
34
What is a heart murmur?
The backflow of blood in the heart.
35
What is the cardiac cycle?
The complete sequence of contraction and relaxation of the heart.
36
Where does a heartbeat originate?
The heartbeat originates within the heart: electrical impulses travel via gap junctions that connect cardiac muscle cells.
37
What does the sinoatrial node do?
Auto-rhythmic cells clustered in the SA node produce the electrical impulses and are the pacemaker.
38
What does the atrioventricular node do?
Impulses from the SA node trigger atrial contraction, and 0.1 sec later the AV node fires, contracting the ventricles.
39
What factors affect the pacemaker of the heart?
1. Temperature
2. Hormones like epinephrine
3. Sympathetic innervation (increases)
4. Parasympathetic innervation (decreases)
40
What happens after the SA node fires?
Its signal travels to both atria and tells them to contract.
41
Where is the SA node located?
The right atrium.
42
What happens when information reaches the AV node?
There is a pause; signal is delayed at the AV node. Then, it will fire.
43
Why is the pause at the AV node important?
The ventricle has to wait until it's been filled by the atrial contraction before the ventricles themselves contract.
44
What happens after the AV node fires?
This signal passes through bundle branches to the heart apex and then to the ventricles, causing them to contract.
45
Describe the structure of blood vessels.
Blood vessels contain a central lumen lined by an endothelium. Arteries and veins are surrounded by smooth muscle and elastic connective tissue.
46
What impacts the flow and pressure of arteries and veins?
The contraction of smooth muscle.
47
How does the thickness of the walls of arteries and veins compare?
The walls (smooth muscle) of arteries are much thicker than those of veins, and recoil between contractions, maintaining blood pressure.
48
How large is the diameter of capillaries?
The diameter is slightly greater than a red blood cell (erythrocyte). This is where chemical exchange happens.
49
When is arterial pressure greatest?
During ventricular systole: systolic pressure, which is felt as a pulse.
50
When is arterial pressure lowest?
During ventricular diastole: diastolic pressure.
51
How does the cross-sectional area of the blood vessels change as the blood flows from the heart?
The blood leaves the heart through the aorta, which has a diameter of about 5 cm. From there, the arteries split and split, increasing the cross-sectional area. When they transition into veins, the cross-sectional area begins to decrease as the blood moves back to the heart.
52
How does the cross-sectional area of the aorta compare to the summed area of the veins that enter the heart?
The area of the veins is larger.
53
How does the cross-sectional area of the blood vessels affect the velocity of the blood?
The velocity of the blood drops dramatically when it hits the capillaries (the highest cross-sectional area) and increases again when it leaves.
54
Why does blood pressure decrease when the blood reaches the capillaries?
The capillaries have the highest cross-sectional area, so when the blood is in the capillaries, a lot of space is created, causing the blood pressure to decrease.
55
Why does the velocity of the blood increase after leaving the capillaries and entering the veins?
1. Even though your pressure has decreased, because you are joining the blood vessels back together, there is less space to pass the blood through. This means the blood simply has to pass through there faster.
2. Veins reduce friction.
3. The blood is moving to the right atrium--an area of extremely low pressure.
56
What modulates blood pressure?
Cardiac output and smooth muscle contraction.
57
What is the role of gravity in blood flow?
1. Assists blood flow to areas lower than the heart.
2. Hinders blood return from areas lower than the heart.
58
How does venous blood return from lower areas of the body?
Veins have valves that prevent backflow, and smooth muscle assists the return of venous blood to the heart. During exercise, skeletal muscle also assists venous flow.
59
What is the role of nitric oxide and histamine in smooth muscle?
They increase vasodilation.
60
What is the role of endothelin in smooth muscle?
It increases vasoconstriction.
61
What two factors control when capillaries receive blood? (since they don't all receive blood at the same time)
1. Constriction or dilation of the arterioles
2. Precapillary sphincters.
62
What controls the smooth muscle of precapillary sphincters?
Nerve impulses, hormones, and chemicals (e.g. vasodilating histamine).
63
What two opposing forces mediate the net loss of fluid at the capillaries?
1. Blood pressure
2. Osmotic pressure
64
What is hydrostatic pressure?
In the capillaries and blood vessels, this refers to the blood pressure that is pushing out.
65
Why do capillaries have high osmotic pressures?
They leak fluid into the interstitial fluid--about 20 L a day. This makes the ions, proteins, and other molecules in the capillaries super concentrated.
66
What is the effect of having high osmotic pressure inside the capillaries?
It works to balance the force of blood pressure. While blood pressure forces fluid out of the capillaries, osmotic pressure brings it back in.
67
What happens to the 3 L of fluid lost by the capillaries? And what is this fluid called?
It is returned to the blood by the lymphatic system. This fluid is called lymph.
68
Where does the lymphatic system drain?
It drains into large veins at the base of the neck. Flow in lymph vessels is similar to flow in veins.
69
What are lymph nodes?
Along the lymph vessels are the lymph nodes, which are filled with white blood cells and play critical roles in defense.
70
What happens when lymph flow is blocked?
Edema.
71
What is the definition of blood?
Connective tissue made of cells in a fluid matrix called plasma.
72
Describe the composition of blood.
55% plasma (fluid matrix)
45% cellular elements
73
What are the major components of the blood plasma?
1. Water
2. Ions (blood electrolytes)
3. Plasma proteins
4. Substances transported by blood
74
What type of ions are found in the plasma?
Sodium, potassium, calcium, magnesium, chloride, and bicarbonate.
75
What is the function of the ions in the plasma?
1. Osmotic balance
2. pH buffering
3. Regulation of membrane permeability
76
What type of proteins are in the plasma?
1. Albumin
2. Immunoglobulins (antibodies)
3. Apolipoproteins
4. Fibrinogen
77
What is the function of the plasma proteins?
1. Osmotic balance
2. pH buffering
3. Defense and immunity
4. Lipid transport
5. Blood clotting
78
What is the purpose of albumin in the blood plasma?
There is a lot of albumin in the blood. It can serve as a transport protein and keeps the osmotic pressure in the blood really high, preventing you from losing too much fluid into the interstitial space.
79
What is the function of apolipoproteins in the blood plasma?
They transport lipid molecules such as steroids.
80
What is the function of fibrinogen in the blood plasma?
It is essential for blood clotting.
81
What is the main component of the cellular elements of the blood?
The erythrocytes (red blood cells). (they lack a nucleus)
82
How much hemoglobin can an erythrocyte contain?
Each contains about 250 million molecules of hemoglobin, and each can transport 4 O2.
83
What are platelets?
Cell fragments involved in blood clotting.
84
What is the function of the erythrocytes?
They are involved in the transport of O2 and some CO2
85
What are the five subtypes of leukocytes?
1. Basophils
2. Lymphocytes
3. Eosinophils
4. Neutrophils
5. Monocytes
86
Where are multipotent stem cells located?
The red marrow inside bones.
87
How do multipotent stem cells reproduce?
Mitosis results in one stem cell and a cell that differentiates.
88
What are the two stem cell lineages?
1. Lymphoid stem cells
2. Myeloid stem cells
89
What three types of cells does the myeloid progenitor cells give rise to?
1. Erythrocytes
2. Platelets
3. Cells involved in innate immunity
90
Which types of white blood cells are involved in innate immunity?
1. Neutrophils
2. Basophils
3. Monocytes
4. Eosinophils
91
What do lymphoid progenitor cells give rise to?
The lymphocytes: B cells and T cells.
92
What types of cells are involved in adaptive immunity?
The lymphocytes, which are B cells and T cells.
93
What does the hormone erythropoietin (EPO) do?
It stimulates erythrocyte (RBC) production.
94
What causes sickle cell anemia?
Sickle cell anemia results from abnormal polymerization of hemoglobin in RBCs. SCA is a genetic disorder.
95
What happens during coagulation, and what is coagulation?
A break in a blood vessel exposes proteins that attract platelets and initiate coagulation: the conversion of liquid components of blood into a solid clot.
96
What is hemophilia?
The inability to properly form clots.
97
What is a thrombus?
A clot formed in the absence of injury.
98
What triggers coagulation?
A break in a vessel which attracts platelets.
99
What happens after coagulation platelets are triggered?
A platelet plug comes in to block the wound site. At the same time, there is an enzymatic cascade in the plasma that leads to a fibrin clot.
100
What does a fibrin clot form?
A mesh network that blocks the wound.
101
What happens during the enzymatic cascade of coagulation?
The cascade cleaves prothrombin into thrombin. Thrombin then takes fibrinogen and converts it into fibrin.
102
Why does thrombin positively feedback to the enzymatic cascade?
The wound needs to be healed quickly. This triggers the additional conversion of prothrombin into thrombin, and then fibrinogen into fibrin.
103
What causes atherosclerosis?
Hardening of arteries by fatty deposits; cholesterol accumulates into a plaque, which is followed by inflammation and thrombus formation. In short, an artery that becomes blocked.
104
What decreases LDL:HDL, and what increases it?
Exercise decreases it whereas smoking and trans-fats increases it.
105
What is a myocardial infarction?
A heart attack. This is damage or death of cardiac muscle from blockage of one or more of the coronary arteries that supply O2 to the heart.
106
What is a stroke?
Death of nervous tissue in the brain due to a lack of O2.
107
What are the consequences of hypertension?
Damage to the blood vessels and contribution to heart attack and stroke.
108
What is an aneurysm?
This occurs when the wall of a vessel weakens and balloons outward.
109
How is a stent used to help with atherosclerosis?
A stent and balloon are inserted into an obstructed artery. Inflating the balloon expands the stent, widening the artery. The balloon is removed, leaving the stent in place. This increases blood flow.
110
What is ventilation?
The movement of the respiratory medium over the respiratory surface.
111
What are the two surfaces of gas exchange?
1. Respiratory surface
2. Body tissues
112
What happens at the respiratory surface?
The uptake of O2 and release of CO2.
113
What happens at the body tissues during gas exchange?
The release of O2 and uptake of CO2.
114
How does the movement of O2 and CO2 across respiratory surfaces occur?
Via diffusion. This occurs from regions of high partial pressure to regions of low partial pressure.
115
How is diffusion related to the surface area across which it occurs?
Diffusion is proportional to the surface area across which it occurs.
116
How is diffusion related to the distance the molecules must move?
Diffusion is inversely proportional to the square of the distance the molecules must move.
117
What are the two approaches to effective ventilation?
1. Have respiratory structures that are large and thin.
2. Have all cells close enough to the outside environment so that no respiratory structures are needed.
118
How is the insect tracheal system different from the mammalian respiratory system?
Insect hemolymph does not carry gases to and from cells. Instead, a network of tubes that branches throughout the body deliver gases to and from cells. This system of diffusion limits how large an insect can be.
119
Where do the largest tubes of a tracheal system open to?
The trachea--the largest tubes--open to the outside.
120
Where do the smallest tubes of a tracheal system open to?
The tracheoles--the smallest tubes--extend to nearly every cell.
121
What affects the state of the trachea in a tracheal system?
Changes in body pressure compress and relax the trachea, moving the air.
122
What does the spiracle do in insects?
It allows gases to enter from the outside of the insect into the larger trachea where they can be delivered directly to the cells.
123
What are lungs?
Lungs are internal, localized respiratory organs.
124
What carries air to lungs located within the thoracic cavity?
A system of branching ducts.
125
Where does gas exchange occur in the lungs?
Alveoli.
126
What is the purpose of surfactant on the alveoli?
Surfactant reduces surface tension by breaking down the H-bonds within the water or fluid to create a really thin surface
127
How does the surface area of the alveoli compare to the surface area of the skin?
The surface of the alveoli is 50 times the surface area of the skin.
128
Describe the path air takes through the respiratory structures.
1. Nasal cavity
2. Pharynx
3. Larynx (esophagus)
4. Trachea
5. Bronchi
6. Bronchioles
7. Alveoli
129
What happens during negative pressure breathing?
Contraction of the diaphragm and external intercostal (rib) muscles increases the size of the thoracic cavity, pulling air into the lungs.
130
What is the tidal volume?
The amount of air inhaled and exhaled with each normal breath (about 500 ml).
131
What is vital capacity?
The tidal volume during maximum inhalation (about 4 L).
132
What is the residual volume?
The amount of air that remains in the lungs after forced exhalation.
133
How is breathing controlled?
Neurons in the medulla oblongata form a pair of "breathing control centers" that establish the breathing rhythm.
134
How is the rate of breathing established?
Negative feedback prevents overexpansion of the lungs, and blood pH determines the rate of breathing--higher CO2 decreases the pH.
135
Why is the amount of CO2 in the blood determinant of the rate of breathing?
If you have CO2 in your blood, it mixes with water, forming carbonic acid. Carbonic acid dissociates into hydrogen ions and bicarbonate ions. The bicarbonate ions are sequestered inside the erythrocytes, but the hydrogen ions go into the plasma, creating an acidic environment. As the plasma acidifies, it tells the body to breathe faster.
136
How many O2 molecules can each hemoglobin molecule bind?
Four, via the use of hemes.
137
What happens when hemoglobin binds to one O2 molecule?
It causes a conformational shift that assists in loading the others.
138
What happens when hemoglobin releases one O2 molecule?
It causes a conformational shift that assists in releasing the others.
139
What is the Bohr shift/effect?
When the body is using a lot of oxygen (high metabolic rates), this increases CO2, which lowers the pH. Low pH decreases the affinity of hemoglobin to O2, inducing its release.
140
What is the Haldane effect?
Low O2 increases the affinity of hemoglobin to CO2.
141
How much CO2 does hemoglobin bind?
About 20%. The CO2 is bound to a protein part of the molecule, not the heme part that carries oxygen.
