Test 1: Wk1: 3 Heart and Vascular Histology - Norton Flashcards
1
Q
4 Tissues of the Heart and Vascular Walls
A
1. Endothelium 2. Smooth muscle 3. Cardiac muscle 4. Connective tissue
2
Q
Endothelium
A
Lines the heart and blood vessels but more than just a lining, it is a sophisticated tissue with multiple functions
3
Q
5 Endothelium Functions
A
1 Provides a nonthrombogenic surface
2 Has antithrombotic and prothrombotic properties
3 Regulates vascular tone and blood flow
4 Plays several roles in inflammation and local immune responses
5 Secretes growth factors
4
Q
How does endothelium regulate vascular tone and blood flow
A
flow by secreting factors that
stimulate smooth muscle contraction (endothelin 1, ACE) and
relaxation (NO, prostacyclin)
5
Q
How does endothelium play a role in inflammation and immune response
A
in
venules induces specific leukocytes to migrate out of the circulation into
injured or infected tissues
6
Q
Smooth muscle found in
A
Found in the walls of all vessels larger than capillaries and in
the endocardium
7
Q
Smooth Muscle arranged
A
Arranged helically in layers
8
Q
Smooth Muscle BP regulation
A
Blood pressure regulation: in small arteries and arterioles,
SMCs are connected by gap junctions and permit
vasoconstriction and vasodilation
9
Q
Connective tissue made of
A
collagen and elastic fibers
10
Q
collagen location
A
subendothelial layer, between smooth muscle layers
and in the outer covering
11
Q
Elastic Fibers (elastin) located in
A
in elastic arteries, layered between
smooth muscle cells
12
Q
Heart
Three major layers
A
1. Endocardium 2. Myocardium 3. Epicardium
13
Q
Endocardium
A
Surface endothelium supported by a layer of fibroelastic
connective tissue + few smooth muscle fibers
14
Q
Subendocardium
A
deep to the surface endothelium, connective
tissue (continuous with connective tissue in the myocardium)
which surrounds variable numbers of modified cardiac muscle
fibers that comprise the heart’s impulse conducting system
15
Q
Myocardium
A
Tightly knit, contractile cardiac muscle fibers arranged spirally
around each heart chamber
16
Q
Myocardium is much thicker in — than —
A
ventricles than atria
17
Q
myocardium of LV is — thicker than RV
A
3x
18
Q
Epicardium
A
Outermost layer
19
Q
Epicardium composed of — which —
A
adipose tissue; cushions the heart
20
Q
Epicardium contains
A
Coronary Vessels
Nerves
Connective Tissue
21
Q
Epicardium covered by
A
Covered by simple squamous mesothelium
22
Q
simple squamous mesothelium composes
A
Composes visceral and parietal pericardium
23
Q
— cells secrete lubricant which reduces friction when the
heart moves during contraction and relaxation
A
Mesothelial cells secrete lubricant which reduces friction when the
heart moves during contraction and relaxation
24
Q
Cardiac skeleton
A
Masses of irregular, dense
connective tissue, primarily in the
endocardium
25
Cardiac skeleton function
Anchors valves
Provides insertions for cardiac
muscle
26
Cardiac Skeleton surrounds
the two atrioventricular canals
27
cardiac skeleton separates
atria from the ventricles
28
Conducting system
Initiates the electrical impulse
| for contraction
29
Conduction System spreads impulse through the
myocardium
30
Modified cardiac muscle fibers
| form: 5
•
Sinoatrial node
Atrioventricular nodes
Atrioventricular bundle of His
Bundle branches right and left
Purkinje fibers
31
Purkinje fibers branches of
right and left bundles
32
Purkinje fibers located
in subendocardium of both ventricles
33
Purkinje fibers stain
pale
34
-- have greater diameter than contractile muscle fibers
Purkinje fibers
35
Purkinje fibers have abundant --- and sparse bundles of ---
glycogen; myofibrils
36
Purkinje fibers merge with
contractile muscle fibers
37
--- trigger waves of contraction through ventricles
Purkinje fibers
38
Cardiac muscle fibers are --- like skeletal muscle, but they consist of individual
--- cells rather than fused cells like in skeletal muscle
Cardiac muscle fibers are striated like skeletal muscle, but they consist of individual
cylindrical cells rather than fused cells like in skeletal muscle
39
Cells contain one or two central nuclei and are linked by adherent and gap junctions at
prominent ---
Cells contain one or two central nuclei and are linked by adherent and gap junctions at
prominent intercalated discs
40
Mitochondria occupy --- of the cell volume
40%
41
Sarcomeres of cardiac muscle are organized and function similarly to those of ---
Sarcomeres of cardiac muscle are organized and function similarly to those of skeletal muscle
42
Contraction of cardiac muscle is ---
Contraction of cardiac muscle is all or none
43
Impulses for contraction are initiated, regulated and coordinated by the --- and
--- nodes
Impulses for contraction are initiated, regulated and coordinated by the sinoatrial and
atrioventricular nodes
44
--- nerves regulate the rate of contraction
autonomic
45
Vessels
| Three major layers (tunics)
Intima
Media
Adventitia
46
Intima
endothelium, thin subendothelial layer of connective
tissue +/ SMCs, and internal elastic lamina, in larger vessels.
In large and medium veins, the intima folds to form valves
47
Media
alternating layers of smooth muscle and collagen or
| elastic lamellae
48
Adventitia
```
connective tissue (type I collagen and elastic
fibers), small vessels (vasa vasorum) and nerves
```
49
Arteries
| Grouped by size and wall composition
Elastic arteries - largest
Muscular - medium
Small
50
Elastic arteries diameter
>10mm
51
Elastic A Intima
Intima: Endothelium, connective tissue with smooth muscle
52
Elastic A Media
Media: Many elastic lamellae alternating with smooth muscle
53
Elastic A Adventitia
Adventitia: Connective tissue, thinner than media, with vasa
| vasorum
54
Elastic A Role in Circulation
Role in Circulation: Called conducting arteries because they conduct
blood from heart to smaller arteries.
55
Expand when heart contracts, reducing blood pressure
Elastic A
56
recoil during diastole helps move blood forward under steady pressure
Elastic A
57
Elastic A Ex
Examples: aorta, pulmonary arteries and their largest branches
58
Muscular A diameter
1-10mm
59
Muscular A Intima
Intima: Endothelium, connective tissue with smooth muscle,
| internal elastic lamina is prominent
60
External elastic lamina present only in larger muscular arteries
External elastic lamina present only in larger muscular arteries
61
Muscular A Media
Media: Many (up to 40) smooth muscle layers with variable,
| decreasing elastic material
62
Muscular A Adventitia
Adventitia: Connective tissue, thinner than media, vasa vasorum maybe present
63
Muscular A Role in Circulation
in circulation: Called distributing arteries because they
distribute blood to all organs and maintain steady blood
pressure and flow with vasodilation and constriction
64
Small A diameter
0.1-1 mm
65
Small A Intima
Intima: Endothelium, connective tissue with less smooth
| muscle
66
Small A Media
Media: 3 to 10 layers of smooth muscle
67
Small A Adventitia
Adventitia: Connective tissue, thinner than media, NO vasa
| vasorum
68
Small A Role in circulation
Role in circulation: Distribute blood to arterioles, adjusting flow
with vasodilation and constriction
69
Microvasculature permeates
most organs
70
why are Microvasculature vessels unnamed
and too small for surgical manipulation
71
Arterioles
one to three smooth muscle layers
72
Capillaries
consisting only of an intima endothelial layer
73
Venules
large lumens and thin walls, which drain capillaries
74
Terminal arterioles branch into ---
metarterioles
75
metarterioles
smooth muscle
sphincters contract to resist blood flow and relax cyclically to allow
pulsatile flow of blood into an anastomosing capillary bed, where
metabolic exchange with surrounding cells occurs
76
Arterioles diameter
10-100 um
77
Arterioles Intima
Intima: Endothelium only, NO connective tissue, NO smooth
| muscle
78
Arterioles Media
Media: 1 to 3 layers of circumferential smooth muscle cells
79
Arterioles Adventitia
Adventitia: Very thin connective tissue layer
80
Arterioles Role in Circulation
Role in circulation: Resist and control blood flow to capillaries;
major determinant of systemic blood pressure
81
First vessel in microvascular
Arterioles
82
Capillaries Diameter and length
4-10 um length < 50 um
83
Capillaries Intima
simple layer of endothelial cells rolled as a tube,
| surrounded by basement membrane
84
Allow transit of blood one at a time
Capillaries
85
Capillaries Role in Circulation
in circulation: Exchange of metabolites by between blood
| and tissues
86
Associated with pericytes
Capillaries
87
pericytes
perivascular contractile cells with a
| variety of functions
88
Capillaries always function in networks called
capillary beds
89
Size, shape and density of capillary beds depends on t
Size, shape and density of capillary beds depends on the size
and metabolic activity of the tissue being perfused
90
what makes up 90% of vasculature
Capillaries
91
Capillary beds are supplied by
metarterioles
92
metarterioles
continuous with thoroughfare channels and postcapillary venules
93
Continuous capillaries
most common, many tight junctions so that all exchange must occur through the cells by
diffusion or transcytosis
94
Fenestrated capillaries
also have tight junctions but perforations (fenestrations) through the endothelial cells allow
greater exchange across the endothelium. Both continuous and fenestrated have continuous basement membrane.
Found in organs where molecular exchange with the blood is important (
95
Discontinuous capillaries or sinusoids
larger lumens, large spaces between the endothelial cells, discontinuous
basal lamina. Found in organs where exchange of macromolecules and cells occurs readily between tissue and blood
96
Fenestrated capillaries ex
kidneys, endocrine organs, intestinal walls,
| choroid plexus)
97
Discontinuous capillaries or sinusoids ex
bone marrow, liver, spleen)
98
Venules Diameter
10-100um
99
Venules Intima
Endothelium; no valves
100
Venules Media
Media: Pericytes and scattered smooth muscle cells
101
Venules Adventitia
none
102
Venules Role in circulation
Role in circulation: Drain capillary beds; site of leukocyte exit
from vasculature into damaged or infected tissue
103
last segment of microvasculature
Venules
104
Veins size
small
med
large
Small (0.1 1 mm), medium (1 10mm) and large (>10 mm)
105
--- that prevent backflow are found in medium and large veins
Intimal valves that prevent backflow are found in medium and large veins
106
Veins Intima
thin
107
Veins Media
small bundles of SMCs and Connective tissue
108
Veins Adventitia
collagenous, thick and well developed
109
--- become increasingly well developed as vein increases in diameter
Tunics become increasingly well developed as vein increases in diameter
110
Small and medium veins usually travel with ---
Small and medium veins usually travel with muscular arteries
111
Arteriovenous anastomoses (AV
```
Arteriovenous anastomoses (AV
shunts) arterioles can bypass a
capillary bed (skin)
```
112
Venous portal system
```
venules
draining a capillary bed quickly
branch again to form another
capillary bed (anterior pituitary,
liver)
```
113
Arterial portal system
afferent
arteriole → capillaries → efferent
arteriole (kidney glomerulus)
114
Carotid sinuses located
Located in the internal carotid arteries just after the bifurcations
of the common carotids
115
Carotid sinuses Act as --- to monitor --- blood pressure
Carotid sinuses Act as baroreceptors to monitor arterial blood pressure
116
--- is thinner in carotid sinuses and allows for greater --- when blood pressure rises
Tunica Media; distension
117
Carotid Sinuses Adventitia
Adventitia contains many sensory nerve endings from CN IX
| (glossopharyngeal
118
--- centers in the brain process impulses from the --- and adjust vasoconstriction to maintain normal blood pressure
Vasomotor centers in the brain process impulses from the carotid sinuses and adjust vasoconstriction to maintain normal blood pressure
119
Carotid and aortic bodies (glomus bodies) are --- that monitor ---
Complex chemoreceptors that monitor CO 2 , O 2 and pH
120
Carotid bodies found in the
the walls of the carotid sinuses
121
Aortic bodies found in the arch of the aorta
arch of the aorta
122
Carotid and aortic bodies (glomus bodies) are part of the --- known as ---
Part of the autonomic nervous system known as paraganglia
123
paraganglia contain
Contain rich capillary networks
124
paraganglia capillaries are surrounded by
glomus cells
125
glomus cells contain
neurotransmitters
| ACh and dopamine
126
paraganglia supported by
satellite cells
127
Glomus cell membranes respond to ---, --- and --- by releasing neurotransmitters
Glomus cell membranes respond to hypoxia, hypercapnia and acidosis by releasing neurotransmitters
128
Sensory fibers from CN --- synapse with glomus cells, signal brain centers to initiate cardiovascular and respiratory adjustments to correct the condition
Sensory fibers from CN IX synapse with glomus cells, signal brain centers to initiate cardiovascular and respiratory adjustments to correct the condition
129
Interstitial fluid that is not pulled into venules by colloidal osmotic
pressure drains as lymph into --- --- called lymphatics
Interstitial fluid that is not pulled into venules by colloidal osmotic
pressure drains as lymph into blind vessels called lymphatics
130
lymphatic capillaries have
very think endothelial cell walls with spaces between cells
131
Lymphatics converge into larger, thin walled lymphatic vessels in
which lymph is propelled by movements of surrounding muscles and organs, with --- --- keeping the flow unidirectional
Lymphatics converge into larger, thin walled lymphatic vessels in
which lymph is propelled by movements of surrounding muscles and organs, with intimal valves keeping the flow unidirectional
132
largest lymphatic vessel
thoracic duct and right lymphatic duct
133
The largest lymphatic vessels, the thoracic duct and right lymphatic
duct, both with walls having --- return lymph to the circulatory system by joining veins near the ---
The largest lymphatic vessels, the thoracic duct and right lymphatic
duct, both with walls having tunics return lymph to the circulatory system by joining veins near the heart
