Ch 7 - The Cardiovascular System Flashcards
1
Q
What is the heart composed of and what does it support?
A
- composed of cardiac muscle and supports 2 different circulations: the pulmonary and systemic circulation
- each side of the heart consists of an atrium and a ventricle
2
Q
How is the atria separated from the ventricles?
A
by the atrioventricular valves (tricuspid on the right, bicuspid - mitral - on the left)
3
Q
How are the ventricles separated from the vasculature?
A
by the semilunar valves (pulmonary on the right, aortic on the left)
4
Q
What is the pathway of blood starting from the R atrium?
A
- R atrium through tricuspid valve to R ventricle
- through pulmonary valve to pulmonary artery
- to lungs to pulmonary veins to L atrium
- through mitral valve to L ventricle
- through aortic valve to aorta
- to arteries to arterioles to capillaries to venules to veins to vena cava to R atrium
5
Q
Why does the right side of the heart have less cardiac muscle than the left side?
A
- R side pumps blood into a low-resistance circuit and must do so at lower pressures; therefore, it requires less muscle
- L side pumps blood into a higher-resistance circuit at higher pressures, requiring more muscle
6
Q
What is the pathway for the electrical conduction of the heart?
A
- starts at the SA node through both atria (contracting both) then goes to the AV node (slowing down conduction allowing completion of atrial contraction and ventricular filling)
- from AV, electrical impulses travel to the bundle of His before traveling through the Purkinje fibers
7
Q
What is the difference between systole and diastole?
A
- systole refers to the period during ventricular contraction when the AV valves are closed
- during diastole, the heart is relaxed and the semilunar valves are closed
8
Q
What is the cardiac output?
A
product of heart rate and stroke volume
9
Q
How does the sympathetic and parasympathetic NS affect the heart rate?
A
- sympa: increases HR and contractility
- para: decreases HR
10
Q
What are arteries?
A
- thick, highly muscular structures with an elastic quality (smooth muscle present, no valves)
- allows for recoil and helps to propel blood away from heart
11
Q
What are arterioles?
A
- small muscular arteries
- control flow into capillary beds
12
Q
What are capillaries?
A
- have walls that are one cell thick, making them so narrow that RBCs must travel through them single file
- the sites of gas and solute exchange
- carry blood from arterioles to venules (no smooth muscle or valves)
13
Q
What are veins?
A
- inelastic, thin walled structures that support blood to the heart
- able to stretch in order to accomodate large volumes of blood but do not have recoil capability
- compressed by surrounding skeletal muscles and have valves to maintain one way flow
14
Q
What are venules?
A
small veins
15
Q
How does blood travel in the hepatic portal system?
A
blood travels from the gut capillary beds to the liver capillary bed via the hepatic portal vein
16
Q
How does blood travel in the hypophyseal portal system?
A
blood travels from the capillary bed in the hypothalamus to the capillary bed in the anterior pituitary
17
Q
How does blood travel in the renal portal system?
A
blood travels from the glomerulus to the vasa recta through an efferent arteriole
18
Q
What is blood composed of?
A
cells and plasma, an aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins
19
Q
What do erythrocytes lack and why?
A
- RBCs lack mitochondria, a nucleus, and organelles in order to make room for hemoglobin, a protein that carries oxygen
20
Q
Where are leuckocytes formed?
A
WBCs are formed in the bone marrow (crucial part of the immune system)
21
Q
What is the difference between granular leukocytes and agranulocytes?
A
- granular such as neutrophils, eosinophils, and basophils play role in nonspecific immunity
- agran, including lymphocytes and monocytes, also play a role in immunity, with lymphocytes playing a large role in specific immunity
22
Q
What are thrombocytes?
A
platelets are cell fragments from megakaryocytes that are required for coagulation (no nucleus)
23
Q
What is the difference between the surface antigens A, B, O, and Rh (D) factor in blood?
A
- A and B alleles are codominant and O allele is recessive
- an individual has antibodies for any AB alleles he or she does not have
- positive Rh is dominant
- Rh-negative individual will only create anti-Rh antibodies after exposure to Rh-positive blood
24
Q
What is blood pressure and how is it measured?
A
- the force per unit area that is exerted on the walls of blood vessels by blood
- divided into systolic and diastolic components
- measured with a sphygmomanometer
25
How is a stable blood pressure determined?
it must be high enough to overcome the resistance created by arterioles and capillaries, but low enough to avoid damaging the vasculature and surrounding structures
26
How is blood pressure maintained?
by baroreceptor and chemoreceptor reflexes
27
What does low and high blood pressure promote?
- low BP promotes aldosterone and antidiuretic hormone (ADH or vasopressin) release
- high blood osmolarity also promotes ADH release
- high BP promotes atrial natriuretic peptide (ANP) release
28
Where does gas and solute exchange occur and what does it rely on?
- occurs at the level of the capillaries
- relies on the existence of concentration gradients to facilitate diffusion across the capillary walls
- capillaries are also leaky, which aids in the transport of gases and solutes
29
What is the difference between hydrostatic and osmotic (oncotic) pressure in starling forces?
- hydro: pushes fluid out of vessels and is dependent on blood pressure generated by the heart and the elastic arteries
- osmo: pulls fluid back into the vessels and is dependent on the number of particles dissolved in the plasma (mostly proteins - oncotic pressure)
- O > H at the venous end of capillary bed
30
What carries oxygen?
hemoglobin
31
What is cooperative binding?
- in the lungs, there is a high partial pressure of oxygen, resulting in loading of oxygen onto hgb
- in the tissues, there is a low partial pressure of oxygen, resulting in unloading
- with cooperative binding, each successive oxygen bound to the hgb increases the affinity to the other subunits, while each successive oxygen released decreases the affinity of the other subunits
32
How is carbon dioxide carried in blood and why?
- largely carried in the blood in the form of carbonic acid, or bicarbonate and hydrogen ions
- it is nonpolar and not particularly soluble, while bicarbonate, hydrogen ions, and carbonic acid are polar and highly soluble
33
What is coagulation a result of?
activation cascade
34
When is there a shift in the oxyhemoglobin dissociation curve?
- a high PaCO2, high [H+], low pH, high temperature, and high concentration of 1,3-BPG can cause right shift, reflecting a decreased affinity for oxygen (exercise)
- left shift can be seen for fetal hgb compared to adult hgb (fetal has higher affinity for oxygen)
35
What happens when the endothelial lining of a blood vessel is damaged?
- the collagen and tissue factor underlying the endothelial cells are exposed
- resulting in a cascade of events (coagulation cascade), restingin in the formation of a clot over the damaged area
- plt bind to the collagen and are stabilized by fibrin, which is activated by thrombin
36
How can clots be broken down?
by plasmin
37
What would happen if all autonomic input to the heart were cut?
- the heart would continue beating at the intrinsic rate of the pacemaker (SA node)
- the individual would be unable to change HR via the sympathetic or parasympathetic NS, but the heart would not stop beating
38
What are antigens?
- the stimuli for B cells to make antibodies
| - after exposure of a B cell to its specific antigen, the cell becomes an antibody-producing factory
39
Who could a B+ blood type receive blood from? Who could they donate to?
- could receive from B+, B-, O+, or O-
| - donate to B+ or AB+
40
What does hematocrit measure and what are the units?
- measures the percentage of a blood sample occupied by RBCs
| - percentage points
41
Where does the largest drop in BP occur?
across arterioles; critical because the capillaries are thin walled and unable to withstand the pressure of the arterial side of the vasculature
42
Where is amount of oxygen delivery indicated on the oxyhemoglobin dissociation curve?
seen as a drop in the y value (percent hgb saturation)
43
What is the chemical equation for the bicarbonate buffer system and what enzyme catalyzes it?
CO2 (g) + H2O (l) H+ (aq) + HCO3- (aq)
| catalyzed by carbonic anhydrase
44
What effect does bacterial sepsis have on the blood pressure and heart?
- opening up more capillary beds will decrease the overall resistance circuit
- the cardiac output will therefore increase in an attempt to maintain constant BP which is a risk to the heart because the increased demand on the heart can eventually tire it leading to an MI or a precipitous drop in BP
45
How is Ohm's law applied to circulation?
pressure differential across the circulation = cardiac output x total peripheral resistance (TPR)
46
How is hemoglobin's affinity to O2 affected according to Bohr's effect?
decreasing pH in the blood decreases hgb affinity to O2
| - affinity generally lowered in exercising muscle to facilitate unloading of oxygen to tissues
47
How is blood pressure in the aorta compared to the superior vena cava?
- aorta BP (between 120 and 80 mmHg) > superior vena cava BP (0) always
48
Which feature of veins allows there to be more blood in the venous system than the arterial system at any given time?
- relative lack of smooth muscle in venous walls allows stretching to store most of the blood in the body
49
Which vascular structure creates the most resistance to blood flow?
arterioles; they are highly muscular and have the ability to contract and dilate in order to regulate BP
50
Where are the electric conduction system components located?
- SA node near the top of R atrium
- AV node between the 2 AV valves
- bundle of His within the wall between the ventricles
