Lecture 5 - Histology of the Cardiovascular System (MA) Flashcards
1
Q
Does the lymphatic system have a pump?
A
NOPE
2
Q
Describe the CV system pathway with the type of vessels.
A
RA => RV => pulmonary trunk => elastic pulmonary arteries => alveolar capillaries => pulmonary veins => LA => LV => aorta => elastic arteries => muscular arteries => arterioles => capillaries => venules => large veins => vena cavae
3
Q
In which vessels does exchange happen?
A
Capillaries and postcapillary venules
4
Q
What kind of substances are exchanged at capillaries?
A
- Gases
- Fluids
- Nutrients
- Cells
5
Q
How many cells can fit in the lumen of a capillary?
A
1 cell
6
Q
What is found at the arteriole/capillary junction?
A
Precapillary sphincter = small ring of smooth muscle to regulate blood flow in the capillary bed
7
Q
What are the 3 components of capillaries?
A
- Endothelial cells with nucleus
- Basal lamina
- Pericytes
8
Q
Role of pericytes?
A
Maintain the viability of the endothelial cells
9
Q
What color does the basal lamina appear as in histological pictures?
A
White
10
Q
Largest types of arteries?
A
Elastic arteries
11
Q
Other name for muscular arteries?
A
Distributing arteries
12
Q
Can the muscular arteries have elastic fibers?
A
Mainly not but some
13
Q
Largest types of veins?
A
Vena cavae
14
Q
Other name for basal lamina?
A
Basement membrane
15
Q
What are the 3 types of capillaries? Most common one?
A
- Continuous***
- Fenestrated
- Sinusoidal
16
Q
Other name for sinusoidal capillaries?
A
Discontinuous
17
Q
4 locations of continuous capillaries?
A
- Muscle
- Skin
- Lung
- Brain
18
Q
3 locations of fenestrated capillaries?
A
- Intestines
- Endocrine structures
- Kidneys
19
Q
What is special about the kidney capillaries?
A
Fenestrated capillaries without a diaphragm but a thick basement membrane instead that filters the passage of molecules
20
Q
4 locations of sinusoidal capillaries?
A
- Liver
- Spleen
- Bone marrow
- Endocrine structures
21
Q
Describe fenestrated capillaries.
A
Contain fenestrations spanned by a diaphragm which is thinner than the plasma membrane
22
Q
What are fenestrated sinusoids? Locations?
A
Special type of fenestrated capillaries that have a wider diameter than fenestrated capillaries
Locations:
- Adrenal glands
- Adenohypophysis
23
Q
Describe sinusoidal capillaries.
A
Largest diameter capillaries with fenestrations or pores (without diaphragms or basement membrane covering them) and are the most leaky
24
Q
What do fenestrated and sinusoidal capillaries allow compared to the continuous ones?
A
More rapid exchange
25
What are the 5 capillary exchange mechanisms?
1. Open pores/gaps (e.g. sinusoids)
2. Diffusion
3. Filtration
4. Vesicular transport
5. Transendothelial channels
26
What is the capillary like where diffusion happens? What passes through?
Thickness of endothelial cell cytoplasm is thinner
Gases pass through
27
What are the transendothelial channels of capillaries formed by?
Single or fused vesicles
28
At what 2 levels can capillary filtration happen?
1. Basement membrane
| 2. Cytoplasm
29
Other name for vesicular transport in capillaries?
Transcytosis
30
Describe vesicular transport.
System of pinocytotic pits and vesicles which move large molecules across the endothelium of the capillary
31
What are the 3 secretory and metabolic functions of endothelial cells?
1. Contain adhesion molecules to help cells exit the vasculature
2. Produce vasoactive compounds
3. Conduct metabolic conversions
32
What is diapedesis?
Passage of blood cells through the intact walls of the capillaries (usually in response to inflammation)
33
What are 3 examples of vasoactive compounds? Role for each?
1. NO = vasodilation
2. Endothelin = vasoconstriction
3. Anti-thrombogenic factors
34
What is an example of a metabolic conversion conduction by endothelial cells?
Angiotensin I to II for vasoconstriction
35
Purpose of adhesion molecules of endothelial cells?
Allows blood cells to recognize the correct location to exit the capillary
36
What is the end product of taking Viagra?
NO
37
List the 3 types of veins from largest to smallest.
1. Large vein
2. Medium vein
3. Postcapillary venules
38
List the 3 types of arteries from largest to smallest.
1. Elastic artery
2. Muscular artery
3. Arteriole
39
What are the 3 basic layers of arteries and veins? List from inner to outer
1. Tunica intima
2. Tunica media
3. Tunica adventitia
40
3 components of tunica intima? List from inner to outer
1. Endothelium
2. Connective tissue
3. Internal elastic lamina (IEL)
41
What does the IEL look like?
Swiss cheese
42
3 components of tunica media? List from inner to outer
1. Smooth muscle
2. Elastic fibers (optional)
3. External elastic lamina (EEL)
43
How does the tunica media in veins and arteries differ?
Thicker in arteries
44
3 components of tunica adventitia?
1. Connective tissue (sometimes continuous with surrounding connective tissue)
2. Vasa vasorum (VV)
3. Nerves
45
How does the tunica adventitia in veins and arteries differ?
Thicker in veins
46
What are vasa vasori?
Vessels of vessels
47
What layers are sometimes missing in smaller veins?
1. Tunica media
2. IEL of tunica intima
3. EEL of tunica media
48
What can be said of companion arteries and veins?
They have a similar size
49
Compare the lumen of arteries and veins. Explain
- Arteries: open and round because of high pressure and typical presence of smooth muscle
- Veins: collapsed because low pressure and less smooth muscle (if at all)
50
Why does the lumen of arteries sometimes looked collapsed?
Because of histological preparation
51
Do capillaries have smooth muscles?
NOPE
52
How many smooth muscle layers in tunica media of arterioles?
1-5
53
How many smooth muscle layers in tunica media of muscular arteries?
6-40
54
How many smooth muscle layers in tunica media of elastic arteries?
40-60
55
How many smooth muscle layers in tunica media of collecting venules?
None (and some have no tunica media at all)
56
How many smooth muscle layers in tunica media of muscular venules?
1-2
57
How many smooth muscle layers in tunica media of small to medium veins?
Thin or absent
58
How many smooth muscle layers in tunica media of large veins?
Thin tunica media but up to several layers
59
Example of elastic artery?
Aorta
60
Orientation of layers of smooth muscles in the tunica media?
Concentric
61
Histological unique feature of large veins?
Thick tunica adventitia with many longitudinal smooth muscle bundles
62
Elastic lamina of arterioles?
No EEL
| Optional IEL
63
Elastic lamina of muscular arteries?
EEL and IEL (EEL usually more prominent)
64
Which veins have a tunica intima with valves?
Small to medium veins
65
Elastic lamina of elastic arteries?
EEL and IEL and 40-60 layers of elastic fibers throughout the tunica media
66
Elastic lamina of collecting venules?
None
67
Elastic lamina of muscular venules?
None
68
Elastic lamina of small to medium veins?
IEL (vague) only
69
Elastic lamina of large veins?
IEL only
70
What is a unique feature of the circulatory vessels of higher (gnathostome:jawed fish and higher) vertebrates? How come?
Elastic fibers in their arteries
High pressure CV system with a heart
71
Boundaries of tunica media of large arteries?
IEL and EEL
72
Describe the thickness of the tunica intima in all vessels. What is the exception?
Thin in all vessels except in large veins, where it is thick
73
What are the 4 types of microcirculation? Which one is most common?
1. Arteriole-capillary bed-venule***
2. Arteriovenous anastomosis: arteriole-venule
3. Arteriole-capillary-arteriole
4. Venule-capillary-venule
74
Other name for arteriovenous anastomosis?
AV shunt
75
Location of AV shunts?
Skin
76
Describe how circulation works in the skin.
Thermoregulation:
- Hot: AV shunt closes so the blood passes through the capillary bed instead
- Cold: precapillary sphincter shuts off to keep blood in the skin for warmth
77
Location of arteriole-cap-arteriole microcirculation? Purpose?
Kidney
Purpose: high pressure filtration to maintain structure of the glomerulus
78
Location of venule-cap-venule microcirculation?
Liver = portal system
79
Shape of both IEL and EEL?
Scalloped
80
How many cells can fit in lumen of arterioles?
3-4
81
Purpose of arteriovenous anastomosis?
Prevent blood from going through capillary bed
82
In which vessel does blood pressure drop dramatically?
Capillaries
83
In which vessel is permeability the highest?
Capillaries
84
Vessel characteristics affecting BP?
1. Diameter
2. Muscle
3. Wall thickness
4. Total volume of vessels
85
How do venous valves work?
If you squeeze proximal to the valve, it will open
| If you squeeze distal to the valve, it will close
86
How to distinguish veins from lymphatic vessels since they both have valves?
Veins will contain mostly non-nucleated cells (RBCs) whereas lymphatic vessels will contain main nucleated cells (lymphocytes)
87
Describe the evolution of the vertebrate heart.
1. Before fish: no heart, just smooth muscle squeezing vessels/channels
2. Fish: cardiac tube with no chambers
3. Amphibians: cardiac tube with separated atria
4. Reptiles: cardiac tube with separated atria, partially separated ventricles, and separated outflow tracts
5. Mammals: 4 chambers with separated outflow tracts
88
3 layers of cardiac tissue? What is each analogous to?
1. Endocardium - homologous to tunica intima
2. Myocardium - homologous to tunica media
3. Epicardium - homologous to tunica adventitia
89
What is the structure of the heart built on?
Skeleton of high density collagen connective tissue around which the 3 layers are
90
How to distinguish between epicardium and endocardium?
Endocardium contains Pujinke fibers (not to be confused with adipose tissue seen in the epicardium)
91
What are Purkinje fibers?
Modified cardiac muscle cells that transmit the impulses of the heart to enable the beating
92
How are Purkinje fibers connected?
Gap junctions
93
Which are thicker: atria or ventricles?
Ventricles
94
3 functions of lymphatic system?
1. Returns excess 10% of interstitial fluid to blood
2. Transports lipids absorbed from intestines
3. Immunologic support
95
Do the lymphatic vessels have the same 3 layers as CV vessels?
Yes, except do not have a tunica media
96
Pathway of lymphatic system? How does the pressure change in it? Where are the lymphatic valves found?
Blood capillaries => interstitial fluid => lymph capillaries => lymph veins (with nodes) => lymph ducts => large circulatory veins
High to low pressure
Lymphatic valves in all lymphatic vessels
97
Describe a lymphatic capillary. How does it work?
Blind-ended capillaries wrapped around cardiovascular capillaries with openings/flaps open in one direction (so fluid cannot flow back) when the interstitial fluid pressure on the outside is larger than it is on the inside of the capillary
98
What is unique about lymphatic capillaries?
1. Unique permeability characteristics
| 2. Elastic filaments anchor them to connective tissue
99
Does lymph need to be filtered by at least 1 node before re-entering CV system?
YUP
100
How many deaths in the US are MIs responsible for?
25%
101
Describe a Berry aneurism
Defects in tunica media of cerebral arteries which makes rupture more likely
102
What % of CV deaths are due to tobacco use? How many each year?
32%
443,000
103
Describe varicose veins.
Abnormally dilated tortuous veins with valve insufficiency
104
What % of pop will develop varicose veins in the lower legs?
15-20%
105
In what layer are valves found in small to medium veins?
Tunica intima
106
Why does the pressure decline as blood goes through the arterial system?
1. Increased resistance because of decrease in elastic fibers
2. Increased branching causing increased total volume
107
Purpose of arrangement of smooth muscle in arteries and veins?
- Arteries: concentric to constrict vessels to control blood flow
- Veins: longitudinal to increase venous return to the heart
108
Through what transport mechanisms do proteins cross a capillary?
Filtration
109
Describe the thickness of the tunica adventitia in all vessels. What are the 2 exceptions?
Thin in all vessels, except:
1. In small to medium veins
2. In large veins: thick with many longitudinal smooth muscle bundles
110
Compare the lumen and wall size of arteries and veins.
Arteries: about the same size
Veins: much thinner walls
111
In which cardiac layer are Purkinje fibers located?
Endorcardium
112
What kind of arteries are the pulmonary ones?
ELASTIC
