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Flashcards in CVPR Histology Notes Deck (68):
1

The bulk of the heart tissue is 

striated involuntary cardiac muscle 

2

Cardiac muscle can undergo what changes 

hypertrophy

atrophy

necrosis

apoptosis 

3

3 layers of the heart

epicardium

myocardium

endocardium 

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3 layers of the heart 

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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) 

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What type of cells is the epicardium made of 

thin layer of flat to cuboidal mesothelial cells 

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Epicardium 

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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 

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Thickest layer of the heart 

myocardium

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myocardium 

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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 

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Purkinje fibers associated with the conduction system are found in the 

subendocardium 

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Endothelium and subendothelium 

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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 

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Cardiac muscle cells have a ____ density of mitochondria compared to skeletal muscle 

HIGHER

40% compared to 2%

16

Cardiac muscles rely on what to contract 

large influx of calcium 

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Cardiac muscle cells 

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Cardiac muscle cells are joined together by 

intercalated discs 

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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 

20

Are ther NMJs in cardiac muslce 

NO

21

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intercalated discs 

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Cardiac conduction 

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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 

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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 

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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 

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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 

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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 

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Purkinje cells 

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Angiogenesis

Formation of new capillaries from existing capillaries

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Steps in Angiogenesis

1. Stimulation of endothelial cells by angiogenic factors such as VEGF

2. Degradation of the vessel membrane by activated endothelial cells and the formation of endothelial sprouts

3. Proliferation of endothelial cells and formation of new capillary tubes

4. New vessel stabilization/maturation (new basement membrane formation and association of pericytes)

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Respiratory System- Conducting Portion

  • Conditions inspired air
  • consists of trachea, bronchi, bronchioles
  • overall structure contains mucosa, lamina propria, submucosa, adventitia

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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.

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Oxygenated blood flows 

within arteries of decreasing diameter into arterioles which lead to capillary beds 

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Deoxygenated blood- 

leaves capillaries and flows into venules that lead into veins of increasing diameter

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Vessels 

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Layers of vessels 

38

Except for capillaries, blood vessels are organized into what 3 layers 

Tunica intima 

tinuca media 

tunica adventitia

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Lamina Propria

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Thick, loosely organized vasculararized connective tissue that supports the mucosa

40

Waht type of cells make up the tunica intima 

single layer of squamous endothelial cells 

41

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 

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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.

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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) 

44

Changes in Structural Components of the Respiratory system (table)

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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

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46

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
  •  

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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 

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Tunica adventitia 

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Vasa vasorum

small vessels located in the adventitia of large vessels to provide blood supply to the outer layers of the vessel 

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Arteries vs veins

51

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

52

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

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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 

54

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 

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Pericyte support 

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Continuous Capillary 

Found in muscle, nerve, and connective tissue 

Have tight intercellular junctions to restrict leakage and utilize pinocytotic vesicles in transport functions 

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Fenestrated Capillary

Found in GI and Endocrine systems 

Countain permenent channels or fenestrations across endothelial cells 

58

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

59

Sinusoidal capillary

found in bone marrow, liver, spleen and LNs

Contin large discontinuities between the endothalial cells 

60

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

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61

Alveolar wall cell types

1. 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

2. 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.

3. 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

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62

Blood-air barrier

separates air in the alveoli and blood in the capillar

 

63

Components of the blood-air barrier

 

1. Surface of the 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

  • 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

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