CVPR Week 1: Heart, Lungs and Vessels Histology Flashcards
The wall of all 4 heart chambers consists of
3 layers
- Endocardium
- myocardium
- epicardium
Layers of the heart
3 listed
superficial to deep
- epicardium
- myocardium
- endocardium
Epicardium description
Thin layer of flat to cuboidal mesothelial cells covering fibrous and adipose connective tissue (also called the visceral layer of the pericardium)
Epicardium AKA
Visceral layer of the pericardium
Identify
The bulk of heart tissue is?
striated involuntary cardiac muscle
Heart tissue can undergo
4 listed
- Hypertrophy
- atrophy
- necrosis
- apoptosis
Epicardium contains
- nerves
- blood vessels
that supply the heart
Identify
Identify
Myocardium description
- 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
The thickest layer of the heart
myocardium
How to distinguish cardiac muscle cells
striations
intercalated discs
branched fibers
centrally located nuclei
How to distinguish myocardium
- cardiac muscle cells
- strands of connective tissue and vascular elements course through the myocardium between the fascicles
Cardiac muscle cells contents
- contractile proteins
- Sarcoplasmic reticulum
- T-tubules
- High density of mitochondria (40% of cytoplasmic volume)
The density of mitochondria in skeletal muscle
2% of cytoplasmic volume in skeletal muscle
Endocardium description
Simple squamous epithelium over a layer of variable thickness connective tissue called the subendocardium
Where are the Purkinje fibers found?
In the subendocardium
Identify
Things necessary for Cardiac muscle cell contraction
rely on a large influx of extracellular Ca2+
When asked to work harder, cardiac muscle cells undergo
hypertrophy like other muscle cells
Identify muscle types
Cardiac muscle cells have specialized junctions called
intercalated discs
Intercalated discs functional components
3 listed
- 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
Neuromuscular junctions in cardiac muscle
There are no neuromuscular junctions in cardiac muscle unlike in skeletal muscle
Identify
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
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
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
SA Node AKA
Pacemaker
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
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
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
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
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
Identify
Identify
Purkinje fibers description
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
Properties of arteries
3 listed
- Elastic (conducting)
- Muscular (distributing)
- Small
Properties of veins
3 listed
- Large
- medium
- small
Identify
&
Arteries vs veins
Blood vessel layers
3 listed
- tunica intima
- Tunica media
- tunica adventitia
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)