CVPR Week 1: Heart, Lungs and Vessels Histology Flashcards
1
Q
The wall of all 4 heart chambers consists of
A
3 layers
- Endocardium
- myocardium
- epicardium
2
Q
Layers of the heart
3 listed
A
superficial to deep
- epicardium
- myocardium
- endocardium
3
Q
Epicardium description
A
Thin layer of flat to cuboidal mesothelial cells covering fibrous and adipose connective tissue (also called the visceral layer of the pericardium)
4
Q
Epicardium AKA
A
Visceral layer of the pericardium
5
Q
Identify
A
6
Q
The bulk of heart tissue is?
A
striated involuntary cardiac muscle
7
Q
Heart tissue can undergo
4 listed
A
- Hypertrophy
- atrophy
- necrosis
- apoptosis
8
Q
Epicardium contains
A
- nerves
- blood vessels
that supply the heart
9
Q
Identify
A
10
Q
Identify
A
11
Q
Myocardium description
A
- the thickest layer of the heart
- composed of bundles of cardiac muscle cells organized into spiraling fascicles that efficiently squeeze blood out of the heart chambers
12
Q
The thickest layer of the heart
A
myocardium
13
Q
How to distinguish cardiac muscle cells
A
striations
intercalated discs
branched fibers
centrally located nuclei
14
Q
How to distinguish myocardium
A
- cardiac muscle cells
- strands of connective tissue and vascular elements course through the myocardium between the fascicles
15
Q
Cardiac muscle cells contents
A
- contractile proteins
- Sarcoplasmic reticulum
- T-tubules
- High density of mitochondria (40% of cytoplasmic volume)
16
Q
The density of mitochondria in skeletal muscle
A
2% of cytoplasmic volume in skeletal muscle
17
Q
Endocardium description
A
Simple squamous epithelium over a layer of variable thickness connective tissue called the subendocardium
18
Q
Where are the Purkinje fibers found?
A
In the subendocardium
19
Q
Identify
A
20
Q
Things necessary for Cardiac muscle cell contraction
A
rely on a large influx of extracellular Ca2+
21
Q
When asked to work harder, cardiac muscle cells undergo
A
hypertrophy like other muscle cells
22
Q
Identify muscle types
A
23
Q
Cardiac muscle cells have specialized junctions called
A
intercalated discs
24
Q
Intercalated discs functional components
3 listed
A
- desmosomes - hold the cells together under the forces of contraction
- adherens junctions - hold the cells together under the forces of contraction
- gap junctions - facilitate the movement of signals to contract from one cell to another
25
Neuromuscular junctions in cardiac muscle
There are no neuromuscular junctions in cardiac muscle unlike in skeletal muscle
26
Identify
27
Briefly describe the cardiac conduction system
* A group of specialized cells are responsible for the normal electrical conduction in the heart
* The ordered stimulation of the myocardium by the conduction system allows for efficient contraction of the heart allowing blood to be pumped throughout the body
28
List the cardiac conduction system components
5 listed
* SA node
* AV node
* Bundle of His
* Left and right Bundle branches
* Purkinje fibers and Purkinje cells
29
SA Node description and function
* Under normal conditions, electrical activity is spontaneously generated by the SA node
* This electrical impulse is propagated throughout the right atrium and to the left atrium and AV node
30
SA Node AKA
Pacemaker
31
AV Node Description and Function
* An area of specialized tissue between the atria and the ventricles of the heart, specifically in the posteroinferior region of the interatrial septum near the opening of the coronary sinus (Koch's triangle)
* The AV node conducts the normal electrical impulse from the atria to the ventricles
32
Bundle of His description and function
A collection of heart muscle cells specialized for electrical conduction that transmits the electrical impulses from the AV node through the cardiac skeleton and membranous interventricular septum to a point at the apex of the muscular interventricular septum where it splits into the bundle branches
33
Left and Right bundle branches description and function
A group of Purkinje fibers that run in the subendocardial space along the interventricular septum and give rise to the Purkinje fibers that are distributed to the cardiac muscle cells of the ventricular muscle
34
Purkinje fibers and Purkinje cells description and function
Specialized cardiac muscle cells that are able to conduct cardiac action potentials more quickly and efficiently than any other cells in the heart
35
Purkinje fibers and Purkinje cells histological features
Appear as light staining cells in routing H&E sections
* Have few myofilaments
* increased glycogen content
* increased numbers of gap junctions
36
Identify
37
Identify
38
Purkinje fibers description
39
Organization and structure of the vascular system
* Oxygenated blood flows within arteries of decreasing diameter and into arterioles which lead to capillary beds
* The deoxygenated blood leaves the capillaries and flows into venules that lead into veins of increasing diameter
40
Properties of arteries
3 listed
* Elastic (conducting)
* Muscular (distributing)
* Small
41
Properties of veins
3 listed
* Large
* medium
* small
42
Identify
&
Arteries vs veins
43
Blood vessel layers
3 listed
* tunica intima
* Tunica media
* tunica adventitia
44
tunica intima description & function
* A single layer of squamous endothelial cells providing a non-thrombogenic surface to the blood
* Has a role in the physiological regulation of vascular tone (release factors that affect the contraction or relaxation of smooth muscle cells)
45
Identify
46
Identify
47
Tunica Media composition
Concentric layers of smooth muscle cells with elastic fibers, type III collagen and proteoglycans
48
Tunica Media function
smooth muscle of the tunica media is primarily responsible for the regulation of vascular tone, vessel diameter, and blood pressure
49
Tunica media histological features
* Fibers of smooth muscle are elongated, tapering and nonstriated each of which is enclosed by a thin basal lamina
* Adjacent cells are linked to one another by numerous gap junctions so that groups of cells can contract in unison
50
Tunica Media contraction
contraction is controlled by a variety of involuntary mechanisms including autonomic nerves, a variety of hormones and local physiologic conditions
51
Tunica Adventitia composition
a connective tissue layer containing fibroblasts, type I collagen and elastin fibers
52
Tunica Adventitia Function
* Small vessels called vasa vasorum are located in the adventitia of large vessels and provide blood supply to the outer layers of the vessel
* Autonomic nerve fibers (sympathetic) that control the contraction of the smooth muscle of the tunica media are also located in the adventitial layer
53
Identify
54
Arteries and veins of a similar size display unique and distinguishing histological features
Veins have a less well-developed tunica media compared to similarly sized arteries, a well-developed tunica adventitia and often contain valves to prevent backflow of blood in a low-pressure system
In the sections, the artery holds its shape as a circular tube whereas the vein is usually collapsed
55
Arterioles description
small vessels with one to three layers of smooth muscle cells in the tunica media
these vessels are important for the regulation of blood flow into tissue capillary beds
56
Capillaries description
the smallest diameter blood vessels and are the site of fluid, gas and small molecule exchange between blood and tissues
these vessels are composed of a single layer of endothelial cells and a basement membrane
In some tissues, a smooth muscle-like cell called a **pericyte** associated with the outer wall of the capillary
57
Pericyte description
In some tissues, a smooth muscle-like cell called a pericyte associated with the outer wall of the capillary
58
Identify
59
Types of capillaries
3 listed
* Continuous capillary
* Fenestrated capillary
* Sinusoidal capillary
60
Continuous capillary description and location
* found in muscle nerve and connective tissue
* have tight intercellular junctions to restrict leakage and utilize pinocytotic vesicles in transport functions
61
Fenestrated capillary description and location
* Found in GI and endocrine systems
* contain permanent channels or fenestrations across the endothelial cells
62
sinusoidal capillary description and location
* Found in marrow, liver, spleen and lymph nodes
* contain large discontinuities between the endothelial cells
63
Identify & capillary type
Continuous capillary
64
Identify & capillary type
Fenestrated capillary
65
Identify & capillary type
Sinusoidal capillary
66
angiogenesis description
* The formation of new capillaries from existing capillaries
* The process of angiogenesis follows a consistent series of steps in all tissues and can be part of normal tissue growth and repair or can be part of a pathological condition (i.e. excessive and abnormal angiogenesis in diabetic retinopathy)
67
Angiogenesis steps
1. Stimulation of endothelial cells by angiogenic factors such as vascular endothelial growth factor (VEGF)
2. Degradation of the vessel basement membrane by activated endothelial cells and the formation of endothelial sprouts
3. The proliferation of endothelial cells and formation of new capillary tubes
4. New vessel stabilization/maturation (new basement membrane formation and association of pericytes)
68
Identify
69
The respiratory system overview
The respiratory system is a series of branching tubes of gradually decreasing diameter organized into a conducting m
70
Blood flow of the lungs
A branch of the pulmonary artery (carrying deoxygenated blood) follows the branching pattern of the conducting and respiratory portions of the airway
while
branches of the pulmonary veins (carrying oxygenated blood) are restricted to the boundaries of a segment of the lung
71
Identify
72
Conducting portion of the respiratory system function
provides tubular conduits through which air can travel to and from the lungs and plays an important role in conditioning the inspired air (i.e. trapping particulates and humidifying the air)
73
Conducting portion of the respiratory system consists of
* trachea
* bronchi
* bronchioles
74
Conducting portion of the respiratory system histology
4 listed
similar to other tubular organs and contains
* mucosa
* lamina propria
* submucosa
* adventitia
75
Identify
76
Respiratory Mucosa function
respiratory epithelium functions to cleanse, moisten and warm the inspired air before it enters the lungs
Goblet cells produce a rich mucous secretion which is abundant in the upper portions of the conducting tubes and gradually decrease in the respiratory portion
77
Respiratory Mucosa histology
* consists of a layer of ciliated pseudostratified columnar epithelium with goblet cells referred to as the respiratory epithelium
* the ciliated pseudostratified columnar epithelium transitions to simple columnar and cuboidal epithelium deeper in the respiratory portion from the collecting tubes
78
Lamina propria description
the lamina propria is a thick, loosely organized vascularized connective tissue that supports the mucosa
79
Submucosa description
forms the thickness of the wall and contains three main components of varying amounts depending upon the level of the bronchial tree; smooth muscle cells, hyaline cartilage and seromucous glands
80
Submucosa histological features
* The smooth muscle cells are organized into bundles of cells that increase in quantity as the diameter of the tubes decreases
* The smooth muscle contracts and restricts/regulates the amount of airflow through the conducting tubes
* The hyaline cartilage can form C-shaped rings, irregular rings and small plates
* The cartilage is important in preventing the collapse of the tubular walls
* The cartilage tends to decrease in quantity and the diameter of the tubes decreases
81
Identify
82
Structure of the trachea
* The trachea is a thin-walled tube approximately 10cm long extending from the larynx to the point at which it divides into the two main bronchi
* It is lined with ciliated pseudostratified columnar epithelium with goblet cells
* There are 16-20 C-shaped rings of hyaline cartilage in the submucosa that help to keep the tube from collapsing
* the rings are incomplete posteriorly and there is fibroelastic cartilage and smooth muscle (trachealis muscle) that supports this portion of the tube
83
Identify
84
Gross structure of the bronchi
* The trachea divides into two primary bronchi, one to each lung
* the primary bronchi further divide into secondary or lobar bronchi of smaller diameter that each supply a lobe of the lung (three on the right and two on the left)
* The secondary bronchi divide further into smaller diameter tertiary or segmental bronchi that supply segments of the lung and give rise to the bronchioles
85
Bronchi histological features
The bronchi histologically resemble the trachea however as one proceeds towards the bronchioles the epithelium becomes more simplified, the seromucous glands decrease in quantity, the amount of cartilage decreases and the bundles of smooth muscle and elastic connective tissue increase
86
Identify
87
Identify
bronchioles
88
Structure of the bronchioles
* The bronchioles are the last and simplest part of the conducting portion of the respiratory system
* The bronchioles consist of airways with diameters of 5mm or less
* The mucosa contains no glands or cartilage
* The epithelium decreases in height to become cuboidal epithelium
* The submucosa contains mainly smooth muscle and elastic fibers
89
The respiratory portion of the lung is composed of? And function?
consists of respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli and is the site of gas exchange in the lung
90
Structure of the respiratory bronchioles
* Each terminal bronchiole divides into two or more respiratory bronchioles
* The mucosa of the respiratory bronchioles resembles that of terminal bronchioles except the walls are interrupted by numerous saccular alveoli where gas exchange can take place
91
Structure of the alveoli
* The individual alveoli are sac-like structures about 200 um in diameter that are organized into larger structures called acini
* Approximately 300 million alveoli with a surface area of 140m2
* Form the parenchymal structure of the lungs
* Within these specialized structures, oxygen and carbon dioxide are exchanged between the air and blood
* The alveoli are covered by a rich capillary network, fibroblasts and elastic and reticular fibers
92
Identify
93
The alveolar wall consits of _______ main cell types
2 main cell types
94
The alveolar wall cell types
* Type I alveolar cells / Type I pneumocytes
* Type II alveolar cells / Type II pneumocytes
95
Type I alveolar cells AKA
Type I pneumocytes
96
Type II alveolar cells AKA
Type II pneumocytes
97
Type I alveolar cells description
* Squamous cells that make up 97% of the alveolar surface
* All desmosomes and tight occluding junction and form a gas permeable barrier of minimal thickness
98
Type II alveolar cells description
* Interspersed among the type I cells
* Cuboidal in shape
* Resemble secretory cells with a foamy cytoplasm caused by the presence of lamellar bodies containing lipid, glycosaminoglycans and protein
* These lamellar bodies are continuously synthesized and released from the apical surface providing a coating of pulmonary surfactant that lowers alveolar surface tension
99
The third cell found within the alveolus
Dust cells or alveolar macrophages
100
Alveolar macrophage AKA
Dust cell
101
Dust cells derived from?
monocytes
102
Dust cells location
can be found in the interior of the alveolus or on its outer surface
103
Dust cells function
they can often contain large amounts of carbon and dust which they phagocytose from the alveolar lumen
104
Identify alveolar cell type
105
Identify alveolar structures
106
Identify
107
Air in the alveoli is separated from the blood in the capillary by?
Three components called the blood-air barrier
108
Components of the blood-air barrier
1. surface and cytoplasm of the Type I alveolar cells
2. Fused basal laminae of the alveolar cells and the capillary endothelial cells
3. The cytoplasm of the endothelial cells
109
Identify components of the blood-air barrier
110
Thickness of the blood-air barrier
varies from .1 - 1.5um
111
Blood-air barrier gas exchange
Oxygen from the alveolar air diffuses through the layers of the alveolar wall toward the capillary while carbon dioxide diffuses in the opposite direction
