CVPR Histology Notes Flashcards
The bulk of the heart tissue is
striated involuntary cardiac muscle
Cardiac muscle can undergo what changes
hypertrophy
atrophy
necrosis
apoptosis
3 layers of the heart
epicardium
myocardium
endocardium
3 layers of the heart
Epicardium
thin layer of flat to cuboidal mesothelial cells covering fibbrous and asipose connective tissue (also called visceral layer of the pericardium
contains nerves and blood vessels that supply the heart (coronary vessels found in this connective tissue layer)
What type of cells is the epicardium made of
thin layer of flat to cuboidal mesothelial cells
Epicardium
Myocardium
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.
Cardiac muscle cells distinguished by striations, intercalated discs, branched fibers and centrally located nuclei
Strands of connective tissue and vascular elements course through the myocardium between the fascicles
Thickest layer of the heart
myocardium
myocardium
Endocardium
simple quamous epithelium over a layer of variable thickness connective tissue called the subendocardium. Purkinje fibers associated with the conduction system are found in the subendocardium
Purkinje fibers associated with the conduction system are found in the
subendocardium
Endothelium and subendothelium
Cardiac muscle cells are
striated muscle cells with a single centrally located nucleus and branching shape
contains contractile proteins, sarcoplasmic reticulum, and T tubules similar to skeletal muscle cells
Cardiac muscle cells have a ____ density of mitochondria compared to skeletal muscle
HIGHER
40% compared to 2%
Cardiac muscles rely on what to contract
large influx of calcium
Cardiac muscle cells
Cardiac muscle cells are joined together by
intercalated discs
Intercalated discs
contain desmosomes and adherens junctions that hold the cells together under the forces of contraction
gap junctions to facilitate the movement of signals to contract from one cell to another
Are ther NMJs in cardiac muslce
NO
intercalated discs
Cardiac conduction
SA node
Pacemaker
Under normal conditions, electricle activity is spontaneously generated by the SA node. Propagated through the right atrium to the L atrium and AV node
AV node
An area of speciaalized 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)
AV node conducts the normal electrical impulse from atria to ventricles
Bundle of His
A collection of heart muslce cells specialized for electrical conduction that transmits the electical impulses from AV node through cardiac skeleton and membranous interventricular septum to a point at the apex of the muscular interventricular septum where it splits into the bundle brances
Left and Right Bundle Branches
a group of purkinje fibers that run in the subendocardial space along the interventricular septum and give rise to purkinje fobers that are distributed to the cardiac muscle. cells of the ventrucular muscles
Purkinje fobers and Purkinje cells
specialized cardiac muslce cells that are able to conduct cardiac action pitentials more quickly and efficiently than any other cells in the heart
Appear as large light staining cells on H and E
Have fermyofilaments, increased glycogen content, and increased number of gap junctions
Purkinje cells
Angiogenesis
Formation of new capillaries from existing capillaries
Steps in Angiogenesis
- Stimulation of endothelial cells by angiogenic factors such as VEGF
- Degradation of the vessel membrane by activated endothelial cells and the formation of endothelial sprouts
- Proliferation of endothelial cells and formation of new capillary tubes
- New vessel stabilization/maturation (new basement membrane formation and association of pericytes)
Respiratory System- Conducting Portion
- Conditions inspired air
- consists of trachea, bronchi, bronchioles
- overall structure contains mucosa, lamina propria, submucosa, adventitia
Mucosa
- pseudostratified columnar epithelium with goblet cells = the respiratory epithelium.
- Respiratory epithelium= cleanse, moisten, warm the inspired air before it enters lungs
- Goblet cells produce mucous abundant in upper portions of the conducting tubes and decrease as conducting tubes proceed to respiratory epithelium
- Ciliated pseudostratified columnar epithelium transitions to simple columnar and cuboidal epithelium.
Oxygenated blood flows
within arteries of decreasing diameter into arterioles which lead to capillary beds
Deoxygenated blood-
leaves capillaries and flows into venules that lead into veins of increasing diameter
Vessels
Layers of vessels
Except for capillaries, blood vessels are organized into what 3 layers
Tunica intima
tinuca media
tunica adventitia
Lamina Propria
Thick, loosely organized vasculararized connective tissue that supports the mucosa
Waht type of cells make up the tunica intima
single layer of squamous endothelial cells
Tunica intima
innermost layer
sincle layer of squamous endothelium
physiologic regulation of vascular tone (release of factors that affect contraction of relaxation of smooth muscle)
nonthrombogenic surface
Submucosa
- Forms the bulk of the thickness of the wall and contains three main components of varying amounts depending upon the level of the bronchial tree; smooth muscle, hyaline cartilage and seromucous glands
- Smooth muscle organized into bundles of cells that increase in quantity as the diameter of the tube decreases. Smooth muscle contracts and regulates amount of airflow through conducting tubes.
- Hyaline cartilage can form C shaped rings, irregular rings and small plates. Prevents collapse of the tubular walls. Decreases in quantity as the diameter of the tubes decreases.
Tunica media
Concentric layers of smooth muslce cells with elastic fibers, type III collagen, and proteoglycans
Smooth muscle of the tunica media is primarily responsible for the regulation of vascular tone, vessel diameter, and blood pressure
Fibers of smooth muscle are elongated, tapering, nonstriated cells, each of which is enclosed in a thin basal lamina
adjacent cells linked with gap junctions (to contract in unison)
Changes in Structural Components of the Respiratory system (table)
Structure of the Trachea
- Thin walled tube 10 cm long extending from larynx and divides into the two main bronchi
- Lined with ciliated pseudostratified columnar epithelium with goblet cells
- 16-20 C shaped rings of hyaline cartilage in the submucosa to help keep the tube from collapsing
- fibroelastic cartilage and smooth muscle (trachealis muscle) support the portion where the rings end posteriorly
Structure of the Bronchi (primary, secondary, tertiary)
- Trachea divides into two primary bronchi, one to each lung
- Primary bronchi divide into secondary or lobar bronchi of smaller diameter that each supply a lobe of the lung (3 rt and 2 left)
- Secondary bronchi divide into tertiary (segmental) bronchi that supply segments of the lung and give rise to the bronchioles
*
Tunica Adcentitia
Connective tissue layer: contains fibroblasts, type I collagen, and elastic fibers
Autonomic nerve fibers (sympathetic) that control contraction of the smooth muscle of the tunica media are also located here
Tunica adventitia
Vasa vasorum
small vessels located in the adventitia of large vessels to provide blood supply to the outer layers of the vessel
Arteries vs veins
Artery vs vein
Artery
More developed tunica media
Holds its shape on histology
Vein
More developed tunica adventitia
Contains valves to prevent backflow
Usually colapsed on histology
Structure of the Bronchioles
- airways with 5mm or less, no glands or cartilage
- Epithelium decreases in height to become cuboidal epithelium
- Submucosa contains mainly smooth muscle and elastic fibers
Arterioles
small vessels with 1-3 layers of smooth muscle cells in the tunica media
important in regulation of blood flow into tissue capillary beds
Capillaries
smallest diameter blood vessels
site of fluid, gas, and small molecule exchange
single layer of endothelial cells and a basement membrane
some tissues have pericytes associated with outer wall of capillary
Pericyte support
Continuous Capillary
Found in muscle, nerve, and connective tissue
Have tight intercellular junctions to restrict leakage and utilize pinocytotic vesicles in transport functions
Fenestrated Capillary
Found in GI and Endocrine systems
Countain permenent channels or fenestrations across endothelial cells
Structure of Respiratory Bronchioles
- each terminal bronchiole divides into two or more respiratory bronchioles.
- mucosa of respiraotry bronchioles resembles the terminal bronchioles except walls are interrupted by numerous saccular alveoli where gas exchange can take place
Sinusoidal capillary
found in bone marrow, liver, spleen and LNs
Contin large discontinuities between the endothalial cells
Structure of the Alveoli
- Sac like structures about 200uM in diameter that are organized into larger structures called acini
- 300 million alveoli with a surface area of 140 m2 form the parenchymal structure of the lungs
- Oxygen and carbon dioxide are exchanged between air and blood here
- alveoli are covered by rich capillary network, fibroblasts, and elastic reticular fibers
Alveolar wall cell types
- Type 1 Pneumocytes- squamous cells that make up 97% of alveolar surface. All have desmosomes and tight occluding junctions and form a gas permeable barrier of minimal thickness
- Type II Pneumocytes-Interspersed among the type I cells. Cuboidal. Resemble secretory cells with a foamy cytoplasm caused by presence of lamellar bodies that contain lipid, glycoaminoglycans and protein. Lamellar bodies are continuously synthesized and realeased from the apical surface providing a coating of pulmonary surfactant that lowers the alveolar surface tension.
- Alveolar macrophage/dust cell- found within the alveolus or on outer surface. derived from monocytes. contain large amounts of carbon and dust which they phagocytose from the alveolar lumen
Blood-air barrier
separates air in the alveoli and blood in the capillar
Components of the blood-air barrier
- Surface of the cytoplasm of the type I alveolar cells
- fused basal laminae of the alveolar cells and the capillary endothelial cells
- the cytoplasm of the endothelial cells
- total thickness= .1-1.5 uM
- oxygen from the alveolar air diffused through layers of the alveolar wall toward the capillary while carbon dioxide diffuses in the opposite direction
