circulatory system histo Flashcards
Hollow organs possessing a lumen
blood vessels
Walls of blood vesselspossess three coats:
Inner coat lined by endothelium
Middle muscular coat
Outermost fibrous coat
Arteries have prominent —— coat
Veins have prominent —– coat
middle
fibrous
Diameter between 7-9 um
Found in all tissue except mucus, connective tissue, cartilage, bone and epithelium
Single layer of endothelial cells
Pericytes as perivascular cells
External surface resting on basal lamina of collagen fibers
capillaries
functions of capillaries
- Selective permeability
Intercellular junctions
Fenestrae and pinocytic vesicles
Blood brain barrier and other barriers - Metabolic
- Non-thrombogenic
types of capillaries
With uninterrupted endothelium and basal lamina
Lack fenestrae
Presence of pinocytic vesicles or caveolae intracellulares
Found in muscle tissue, CT, exocrine glands and nervous tissue
- Continuous/Somatic
types of capillaries
Large fenestrae in walls of endothelial cells and continuous basal lamina
fenestrated
type of fenestrated/visceral
– fenestrae is 60-80 nm closed by a diaphragm, thin continuous basal lamina;
found in kidney, GIT and endocrine glands
with Diaphragm
type of fenestrated/visceral
with very thick basal lamina; seen in renal glomerulus
Without Diaphragm
type of fenestrated/visceral
wide lumen; less prominent basal lamina; no intercellular gaps and macrophages; found in endocrine glands, carotid and aortic bodies
Sinusoidal
type of artery
Less than 0.5 mm in diameter
Narrow lumen
Tunica intima – endothelial cells with rod shaped granules for blood coagulation and a very thin subendothelial layer
Tunica media – 1-5 layers of smooth muscle cells
Tunica adventitia – very thin w/o external elastic lamina
arterioles
type of artery
Tunical intima – lined by endothelial cells; thicker subendothelial layer; prominent internal elastic lamina
Tunica media – up to 40 layers of smooth muscle cells with elastic collagen fibers and proteoglycans
Tunica adventitia – external elastic lamina in large muscular arteries; collagen and elastic fibers, fibroblast, adipose cells, lymphatics, vasa vasorum and nerve
muscular arteries
type of vein
Diameter of 0.2- 1 mm
Tunica intima of endothelial cells
Tunica media – 1-2 layers of smooth muscle cells
Tunica adventitia- thickest layer of CT rich in collagenous fibers
venules
type of vein
Diameter of 1-9 mm
Tunica intima – endothelial cells with thin to absent subendothelial layer; presence of valves in legs and arms
Tunica media - small bundles of smooth muscle cells mixed with collagenous, elastic and reticular fibers
Tunica adventitia – well developed; rich in collagen fibers; vaso vasorum extends in intima
medium-sized vein
kinds of veins
- Venules
- Medium sized veins
- Large veins
type of artery
Tunica intima – thicker than muscular artery; endothelial cells are folded or scalloped; subendothelial layer thick with absence of internal elastic lamina
large elastic arteries
type of artery
Tunica intima – well developed
Tunica media – thinner with few smooth muscle cells and abundant CT
Tunica adventitia – thickest and well developed
large vein
3 layers of heart
endocardium
myocardium
epicardium
layer of heart
homologous to t. intima;
made of a singly layer of squamous endothelial cells resting on a thin subendothelial layer of loose CT containing elastic and collagenous fibers and smooth muscle cells;
Endocardium
layer of heart
presence of subendocardial layer consisting of veins, nerve and branches of impulse conducting system of the heart (Purkinje fibers)
Endocardium
heart layer
thickest of the layer consisting of cardiac muscle cells arranged in spiral manner; grouped into contractive cells and impulse generating and conducting cells
- Myocardium –
heart layer
serous covering of the heart of simple squamous epithelium; with veins, nerve and nerve ganglion
- Epicardium –
