Lecture 1: Histo Flashcards
What are the layers of vessels in the heart?
1) Epicardium (tunica adventitia)
- Outer most layer (DICT)
2) Myocardium (tunica media
- Middle layer
- Muscle of heart
3) Endocardium (tunica intima)
- Inner layer
Characteristics and functions
of Epicardium?
Characteristics:
1) Visceral layer of serous pericardium
2) Single layer of mesothelial cells underlying connective/adipose tissue
Functions:
1) Contains the blood vessels and nerves that supply the heart
2) Prevents excessive expansion of the vessel
Describe the importance of the pericardial cavity-potential space
- Space created when epicardium folds over and lines inside pericardium
- Space allows heart to contract
Characteristics of Endocardium
- Inner layer of endothelium and subendothelial connective tissue
- Purkinje fibers = large, round nuclei, pale (bc high glycogen), less myofibrils
Components of Valves
1) Fibrosa:
- core
- structure of valve
2) Spongiosa:
- loose connective tissue
- collagen and elastic fibers
- shock absorber
3) Ventriularis:
- Dense connective tissue
- Elastic fibers
Functions endothelial cells
(Squamos cells)
1) Permeability barrier (intestinal tissue fluid control)
2) Allows for movement of inflammatory cell into tissues
3) Vascular endothelial Growth Factor (New blood vessels formed in embryogensis/injury)
4) Helps Control BP w vasocontriction/dilation
5) Anticoagulant = prevents blood clots, regular flow
6) Antithrombogenics = creates blood clots
- Weibel Palade bodies bind clotting factor VIII during injury
Functions and Components of Elastic fibers
Functions:
1) Maintain intra vascular pressure
2) Expands vessel wall to accommodate large amounts of blood let in during systole (heart contraction)
Components:
1) Imbricated
- Arranged in concentric layers
2) Fenestration
- Permitting diffusion of nutrients
3) Vascular smooth muscle between fiber layers
Characteristics and functions
of Myocardium
Characteristics:
1) 40-70 layers of elastic lamellae
2) Smooth muscle cells
3) Type III collagen
Function:
-Helps with heart contraction
Characteristic of Muscular Arteries in different layers of vessels
Layers:
1) Tunica Intima
- Internal elastic lamina
2) Tunica Media
- 8-14 layers smooth muscle
- Smooth muscle cells > elastic fibers
- External elastic laminae
3) Tunica Adventitia
- DCT, collagen, elastic fibers
- vasa vasorum and nerves
Functions:
1) Distributes blood from elastic vessels –> smaller vessels
Characteristics of Small Arteries in different layers of vessels
Layers:
1) Tunica Intima
- Endothelial cells
- Internal elastic lamina
2) Tunica Media
- 3-8 layers of smooth muscle cells
- Circular fashion arrangement
3) Tunica adventitia
- Connective tissue
- Type I and III collagen
Arterioles
- Smallest arteries
- Small radius increases resistance to flow of blood, regulating BP
Continuous Somatice capillary
Characteristics:
- Continuous basal lamina
- Uninterrupted endothelium
- Tight junctions between cells
Functions:
- Complete control of diffusion (endocytosis and exocytosis)
- vessels form barrier in organs
Locations: -Connective tissue -Muscle tissue -Nerve tissue -Exocrine glands Cerebral cortex
Fenestrated/ Visceral Capillary
Characteristics:
- Continuous basal lamina
- Tight junctions present between endothelial cells
- Numerous pinocytotis vesicles
Function:
(Some openings) to let things pass through
Locations:
- Peptide-secreting endocrine organs
- Ciliary processes (eye)
- Choroid plexus (Ventricles)
- Kidney-glomeruli
- Lamina propria of Gastral intestine tract
Discontinuous/Sinusoidal
Characteristics:
- DISCONTINUED basal lamina
- Absence of tight junctions between the cells
- Presence of large fenestration
- Separated by wide irregular intercellular gaps
Functions:
-Allows passage of macromolecules
Locations:
- Liver
- Spleen
- Bone marrow
Post capillary Venules
- Also called High endothelial vessels: Port of entry for lymphocytes into lymphatics organs, recruit lymphocytes
- Collect blood from the capillary network
- Contains histamine
