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Histology - OMS 1 > Cardio > Flashcards

Cardio Flashcards

1
Q

T/F: smooth muscle has 1 nucleus

A

True

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2
Q

______capillaries have pores and are seen in liver/spleen/lymph/bone marrow/some endocrine glands

A

Sinusoidal

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3
Q

Where do we get the name “striated muscle”?

A

Highly organized arrangement of filaments within the muscle cell

(this gives a characteristic alteration of light and dark bands when viewed in longitudinal section)

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4
Q

Derivations of “sarco”, “myo”, and “mys” are generally used in relation to _____.

A

muscle

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5
Q

Define sarcolemma

A

Muscle cell membrane

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6
Q

Define sarcoplasm

A

Cytoplasm of muscle cells

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7
Q

Define sarcoplasmic reticulum

A

Highly specialized membrane system derived from the muscle endoplasmic reticulum

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8
Q

Why is smooth muscle referred to as involuntary?

A

It is regulated by the autonomic nervous system, hormones, or local physiological conditions

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9
Q

Where is smooth muscle found (7)?

A
  1. GI tract
  2. Wall of urinary tract
  3. Reproductive system
  4. Blood vessels
  5. Gland ducts
  6. Respiratory system
  7. Dermis
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10
Q

Describe the shape and the nucleus location of smooth muscle cells.

A
  • Fusiform shape
  • Single nucleus located in the thickest central portion of the cell
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11
Q

Describe the nucleus of a fusiform - shaped cell in longitudinal cross section when contracted vs. relaxed?

A

Contracted: cork screw appearance
Relaxed: round

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12
Q

Describe the histological appearance of multiple smooth muscle cells in cross section.

A
  • Packed with the narrow part of one cell lying adjacent to the thick (nucleus - containing) portion of another cell.
  • In cross-section we see a range of diameters, the thickest having a nucleus in the center
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13
Q

Which organelles are present adjacent to each pole of a smooth muscle cell nucleus?

A
  1. Polyribosomes
  2. RER
  3. Golgi
  4. Mitochondria
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14
Q

Do smooth muscle cells contain T tubules?

A

No

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15
Q

Describe the sarcoplasmic reticulum of smooth muscle cells (3).

A
  1. Continuous w/RER
  2. Rudimentary and scattered throughout the sarcoplasm
  3. Contains Calcium binding proteins (Calsequestrin)
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16
Q

Define caveolae.

A

Structures involved in calcium sequestration

(near cell surface & look like pinocytotic vesicles)

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17
Q

Why is smooth muscle “smooth” and not “striated”?

A

Myofilaments are NOT arranged in an organized manner, as striated muscle is.

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18
Q

What are the three types of filaments found in smooth muscle sarcoplasm?

A
  1. Thin filaments
  2. Intermediate filaments
  3. Thick elements
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19
Q

What are thin filaments of smooth muscle cells coposed of?

A

Actin and tropomyosin (NO TROPONIN)

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20
Q

What are intermediate filaments of smooth muscle sarcoplasm composed of?

A

Desmin

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21
Q

What are thick filaments of smooth muscle sarcoplasm composed of?

A

Myosin

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22
Q

What is unique about the arrangement of thick and thin filaments in smooth muscle?

A
  • *Thick filament**: myosin heads all along the length of the filaments
  • *Thin filaments:** longer & 3 xs more than skeletal m.

(casual intermingled association between filaments, not as structured as skeletal m.)

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23
Q

Where do the thin and intermediate filaments insert?

A
  1. dense bodies
  2. dense plaques
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24
Q

Define dense bodies

A
  • Small, poorly defined densities in the cytoplasm
  • Possess Alpha actin and other proteins
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25
Q

Define dense plaques

A
  • Similar to dense bodies. Uniform Arrangement on inner surface of sarcolemma
  • Composed of actin, vinculin, talin & other proteins
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26
Q

Which two structures of the extracellular components help to transmit & coordinate force of contraction by smooth muscle cells?

A

Basal lamina

Reticular fibers

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27
Q

Identify:

  1. Black dots
  2. Dashed lines
  3. Fine black lines
  4. Blue lines
A
  1. Black dots = plaques and dense bodies
  2. Dashed lines = thick and thin filaments (blue & black lines)
  3. Black lines = Thin filaments
  4. Blue lines = Thick filaments
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28
Q

List the components of the endocardium (6)

A
  1. Endothelium
  2. Subendothelial connective tissue
  3. Collagen
  4. Elastic fibers
  5. Occasional smooth muscle cells
    6.
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29
Q

The endocardium is continuous with _____.

A

Tunica intima of vessels entering the heart

(consists of elastic fibers, collagen, endothlial cells, subendothelial CT & smooth m.)

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30
Q

Describe The myocardium

A
  • Thickest tunic
  • Cardiac muscle arranged in layered, spiral pattern around the heart chambers
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31
Q

Describe the epicardium

A
  • Covered by simple squamous epithelium (mesothelium) & Loose CT (under mesothelium)
  • adipose cells and coronary vessels are seen in this layer
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32
Q

How are cardiac myocytes different from skeletal muscle fibers?

A
  • long and branched
  • One centrally located nucleus (sometimes 2)
  • Lipofuscin granules (in older cells)
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33
Q

How does the t tubule system of atrial myocytes differ from ventricular myocytes?

A

atria has smaller and poorly developed T tubules system

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34
Q

Cardiac myocytes undergo 60 contractions per minute on average. How does it meet the energy demands for this?

A
  • mitochodria: immediately adjacent to the sarcolemma, wedged between myofibrils and perinuclear space
  • Lipid droplets store triglycerides used by mitochondria

(mitochondria make up to 40% of the sarcoplasm compared to 2% and skeletal m.)

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35
Q

How do the T tubules systems differ between skeletal m. & cardiac m.?

A

In cardiac myocytes:

  • T tubules of cardiac myocytes or larger in diameter
  • Sarcoplasmic reticulum is less expensive
  • diads instead of triads
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36
Q

What are the three important specializations of intercalated discs?

A
  1. fascia adherens
  2. desmosomes (macula adherens)
  3. gap (nexus) jxns

(yellow arrows in photo)

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37
Q

What is the function and location of fascia adherens?

A

Function: Attachment site for actin filaments of the terminal sarcomeres

Location: transverse portion of disc (accounts for density of disc; similar to z-disc)

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38
Q

What is the function, location, and composition of desmosomes (macula adherens)?

A
  • *Location**: transverse portion of disc
  • *Function**: holding myocyte ends together
  • *Composition**: intermediate filament proteins
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39
Q

What is the location and function of gap (nexus) junctions?

A
  • *Location**: lateral portion of intercalated discs
  • *Function**: contains connexons (connection channels between myocytes) which allow passage of molecules (1,500 Da)
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40
Q

What is one of the most important factors that allows a wave of contraction to spread throughout the heart wall?

A

The ability of ions to freely pass through Gap Junctions

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41
Q

What components comprise the fibrous skeleton of the heart? Where are they found?

A
  • Dense irregular collagenous connective tissue with collagen bundles.
  • Basis of aorta, pulmonary artery, atrioventricular orifices (annuli fibrosi), aortic valve cusps (trigonum fibrosum), upper atrioventricular septum (septum membranaceum)
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42
Q

fibrous skeleton functions

A
  • Structural support
  • Attachment for cardiac muscle
  • Structural discontinuity between atria and ventricles (prevents simultaneous contraction)
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43
Q

Constituents of cardiac valves

A
  • Core of fibrous connective tissue
  • Endothelial covering
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44
Q

Inflamed cardiac valves can lead to _____ (3).

A
  • Blood regurgitation
  • Volume overload
  • Heart failure
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45
Q

Atrial contraction must finish before _____

A

the initiation of ventricular contraction (accomplished by conducting system of heart)

46
Q

List the highly specialized cardiac myocytes involved in the impulse conduction system of the heart.

A
  • Sinoatrial node
  • Atrioventricular node
  • AV Bundle/Bundle of His
47
Q

Where is the sinoatrial node located?

A

Right atrium, near its Junction with the superior vena cava

48
Q

Where is the site of initiation of excitation of the cardiac conduction system?

49
Q

Describe the histological features of the SA node of the heart

A
  • Cells are pale with few myofilaments
  • Gap Junctions
  • No intercalated discs
50
Q

The SA node depolarizes spontaneously at ____ beats per minute.

A

70

(pacemaker of the heart, but ANS can modify)

51
Q

Define internodal tract

A

Cells that carry impulses from the SA node to the AV node

52
Q

Where is the AV node located?

A

Lower right side of the interatrial septum

(continuous with the bundle of His)

53
Q

Purkinje fibers are prominent in the _____ and continue into the _____.

A
  • distal portions of the AV node
  • right and left bundle branches
54
Q

How are purkinje fibers morphologically different from cardiac myocytes ?

A
  • Shorter and wider,
  • No intercalated discs
  • Pale cytoplasm
  • small population of myofilaments (arranged in poorly to find vestigial sarcomeres)
58
Q

Chronic hypertension can lead to which morphological changes which eventually lead to impaired contractile function?

A

Thickening or hypertrophy of The ventricle wall

59
Q

Define calcium paradox

A

Rapid return of blood flow to ischemic tissue can cause mycordial cell death due to massive influx of calcium into cardiac myocytes.

60
Q

Endothelium of Tunica intima

A

Simple squamous

61
Q

How are endothelial cells held together in the Tunica intima?

A

Tight junctions and occasional gap junctions

62
Q

Describe tunica intima connective tissue

A

Subendothelial connective tissue and smooth muscle cells

63
Q

Describe Tunica Media

A
  • Middle layer
  • Circumferencially arranged smooth muscle cells
  • Extracellular Matrix
64
Q

Describe the Tunica adventitia

A
  • Outer surface of vessels
  • Collagen (type 1)
  • Elastic fibers
  • Fibroblast
65
Q

What are the classifications of arteries?

A
  1. Large elastic
  2. Muscular
  3. Arterioles
66
Q

Describe the Tunica intima of large elastic arteries

A
  • Endothelium
  • subendothelial layer of loose connective tissue
  • Occasional smooth muscle cells
  • Internal elastic lamina (elastin and fenestrations)
67
Q

Describe the Tunica Media of large elastic arteries

A
  • 70 fenestrated elastic lamellae (ECM separates each layer)
  • concentric arrangement
  • SM cells (secrete collagen, reticular fibers, elastin, ground substance)

NO FIBROBLASTS IN THIS LAYER

68
Q

Describe the Tunica adventitia of large elastic arteries

A
  • Loose irregular connective tissue
  • Fibroblasts (UNLIKE THE TUNICA MEDIA)
  • Vasa vasorum
70
Q

Most arteries are of which classification?

A

Muscular

(aka distributing arteries: control blood distribution to organs)

71
Q

Define Vasa vasorum

A

Vessels of the tunica adventitia of thick-walled arteries and veins that provide nutrients to cells that lie in the outer tunics

72
Q

Large elastic arteries are also known as

A

Conducting arteries: provide continuous blood flow through vascular system w/reduced fluctuation in blood pressure.

73
Q

Function of elastic arteries

A

prevent excessive BP: elastic lamellae of tunica media stretch during systole & relax during diastole

74
Q

Describe the tunica intima of muscular arteries

A

Endothelium plus thin subendothelial layer with few smooth muscle fibers

Internal elastic lamina: outermost boundary; causes undulations in tunica intima

75
Q

Describe the Tunica Media of muscular arteries

A
  • Up to 40 layers of smooth muscle cells
  • concentric orientation
  • external elastic lamina (outer border)
76
Q

Describe the tunica adventitia of muscular arteries

A
  • Longitudinally oriented collagen
  • Fibroblasts synthesize the collagen and other ECM components
  • free nerve endings
  • vasa vasorum

(Generally thinner than the Tunica Media)

77
Q

Describe arterioles

A
  • One to a few smooth muscle layers in the Tunica Media
  • rarely internal elastic lamellae
  • tunica adventitia poorly defined
    *
78
Q

Describe meta arterioles

A
  • Continuous with capillary beds
  • Smooth muscle cells form a sphincter around the vessel where they join the capillary
  • Greater diameter than continuous capillaries
79
Q
A

(notice how the nucleus buldges into the lumen or the arteriole. The lumen of the venule is larger (more compliant))

80
Q

Where are pericytes located?

A

Outside of capillaries and small venules

81
Q

Describe pericytes

A
  • numerous cytoplasmic extensions wrapping around the capillary
  • share gap junctions & basal lamina w/endothelial cells
82
Q

Function of pericytes

A
  • Regulate blood flow through capillaries
  • Division and formation of new vessels and connective tissue is damaged
83
Q

Most common subtype of capillaries found in connective tissue, muscles, nervs & exocrine glands

A

Continuous capillaries

84
Q

Describe continuous capillaries

A
  • No fenestrations
  • Tight junctions
  • Carrier - mediated transport
85
Q

Where are fenestrated capillaries found?

A
  1. Intestine
  2. Endocrine glands
  3. Kidneys

(rapid exchange occures between blood and these tissues)

86
Q

Describe fenestrated capillaries

A
  • Continuous basal lamina
  • Thin diaphragm, non-membranous covering
87
Q

The endothelium of _____ is more permeable than that of capillaries

A

postcapillary venules

88
Q

Leukocytes tend to exit the bloodstream at ______.

A

postcapillary venules

89
Q

Describe postcapillary venules

A
  • Blood enters immediately after exiting capillary beds
  • Structure is comparable to capillaries (endothelium surrounded by reticular fibers and pericytes)
90
Q
A

medium-sized vein

91
Q

Valves are thin leaflets formed from ____ and are most common in ______.

A
  • Tunica intima projections
  • medium veins
92
Q

Describe the Tunica Media of medium veins

A
  • Loose circular arrangement of smooth muscle cells
  • some collagen
  • occasional fibroblast
93
Q

Describe the Tunica adventitia of medium veins

A
  • Thickest tunic
  • Elastic fibers
  • Collagen bundles
  • Some smooth muscles
  • Longitudinal arrangement
94
Q
A

Large vein (ex: vena cava, pulmonary veins)

95
Q

Describe the Tunica intima of large veins

A

Thicker subendothelial connective tissue (than medium veins)

96
Q

Describe the Tunica Media in large veins

A

Poorly defined in most large veins, but pulmonary veins have a developed circular smooth muscle layer

97
Q

Describe the Tunica adventitia enlarged veins

A
  1. Thick and well-developed
  2. Elastic fibers
  3. Longitudinal collagen
  4. Vasa vasorum

(large veins lying below the heart have prevalent smooth muscle to move blood against gravity)

98
Q

Weibel-Palade bodies

A

Membrane-bound inclusions of arterial endothelial cells that contain glycoprotein coagulating factor

(aka von willebrand factor)

99
Q

Define arteriosclerosis

A

Hardening/thickening of arteries and a reduction in elasticity

(mostly pathological but does occur as part of the natural aging)

100
Q

Secondary hypertension can result from _____.

A

Arteriosclerosis

101
Q

Define atherosclerosis

A
  • Atherosclerosis plaque of fibrous and fatty tissue forms in the wall of an artery, reducing lumen size
  • Thrombus may form if endothelium is damaged leading to thrombus or embolis

(most common pathological form of arteriosclerosis & leading cause of death in industrialized countries)

102
Q

Define thrombus

A

Clot forms when endothelium is damaged and blocks vessel

103
Q

Define embolus

A

Clot forms if the end of the alarm is damaged and breaks off into circulation

(eventually lodging in a vessel lumen causing ischemia)

104
Q

What are the three major functions of capillaries?

A
  1. Selective permeability
  2. Synthetic / metabolic activity
  3. Auntie thrombogenic function
105
Q

Describe the synthetic/metabolic activities of capillaries

A
  • Production of growth factors coagulation factors
  • Activat a wide range of circulating molecules
106
Q

Describe the anti thrombotic function of capillaries

A
  • Capillary endothelial cells produce anti-coagulants and inhibitors of platelet aggregation
  • Barriers between platelets and subendothelial tissue
107
Q

Describe lymphatic capillaries

A
  • Drains for lymph
  • Located in subepithelial loose connective tissue
  • No pores
  • No tight junctions

(not distinguishable under a standard light microscope preparation)

108
Q

Describe lymphatic vessels

A
  • Closely spaced valves
  • Vessels drain into progressively larger vessels
  • Some have elastic fibers and smooth muscle cells

(comparable to venules, but NO RBCs)

109
Q

Describe the tunica intima of lymphatic duct

A

Endothelium and layers of collagen and elastic fibers and subendothelial space

Internal elastic lamina (where TI meets TM)

110
Q

Describe the tunica media of lymphatic ducts

A

Longitudinal and circular smooth muscle

111
Q

Describe the tunica adventitia of the lymphatic ducts

A
  • Longitudinal smooth muscle and collagen fibers
  • Continuous with surrounding connective tissue

Histology - OMS 1 (16 decks)

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