Histo Midterm 2 - Circulatory System Flashcards
What are the 3 tissue types in the walls of blood vessels?
Endothelium (simple squamous epithelium) Muscle tissue (smooth muscle in all but capillaries) CT (collagen and elastic fibers)
What is the general plan of the circulatory system?
Heart -> Artery -> Arteriole -> Capillary -> Venule -> Vein -> Heart
What is the structural plan of blood vessels?
Tunica intima
Tunica media
Tunic adventitia
What are the 3 different types of vessels and their functions?
Artery - transport oxygenated blood to tissue
Vein - transport deoxygenated blood back to lungs
Capillary - moves oxygenated blood to tissue and deoxygenated blood into veins
How do the 3 layers of the wall differ between classes
Tunic intima
-Internal elastic lamina (arteries/not veins)
Tunica media
-External elastic lamina (arteries/not veins)
Tunic Adventitia
-Layers of collagen 1 and elastic fibers
-Lager vessels have vasa vasorum
What are the major characteristics of each class of artery?
Conducting arteries -Large/Elastic Distributing arteries -Medium/muscular Arterioles -Small arteries
Capillaries
Small Veins
-Venules
Medium Veins
Large Veins
What are the features of large/elastic artery?
Locations: Aorta, Brachiocephalic, Subclavian
Tunica intima: thicker due to presence of elastic laminas
Tunica media: thick with smooth muscle, collagen, and elastic fibers
What are the features of Medium/muscular artery?
Location: muscles
Tunica intima: prominent internal elastic lamina
Tunic media: 20-40 layers of smooth muscle; may have external elastic lamina
Tunica adventitia: may find lymphatics, vasa vasorum, and nerves
What are the features of arterioles?
Tunica intima: thin layer; prominent internal elastic lamina
Tunic media: 10 or less layers of smooth muscle
Tunica adventitia: thin layer
Function: Regulate blood pressure and determine blood flow to tissues
What are the features of Capillaries?
Function: exchange vessels (where diffusion takes place)
Tunica intima: single layer
8 micron diameter (size of RBC)
Basal lamina determines type of capillaries
What are the variations of capillaries?
Continuous/somatic - typical capillary - 2-3 endothelial cells attached via tight junctions Fenestrated/visceral -opening between endothelial cells -diaphragm connections -basal lamina continuous -Found in: Kidneys, other viscera Discontinuous/sinusoidal -enlarged diameter -endothelial cells separated by spaces (no diaphragm) -Basal lamina discontinuous -found in: liver, hematopoetic tissue
What are pericytes?
Specialized cells found around capillaries
In place of smooth muscle to help regulate flow
help form new blood vessels
What are the features of Venules?
Tunica intima
Tunica media - pericytes
What are the features of medium veins?
Irregular lumen
Tunica intima
Tunica Media
Tunica adventitia - thickest layer
What are the features of large veins?
Found in: subclavian, brachiocephalic, internal jugular, vena cada
Tunica intima - well developed
Tunica media - thin
Tunica adventitia - thickest layer
May have longitudinal smooth muscle and valves (endothelium + CT)
What is the histology of lymphatic vessels?
Return extracellular fluid to the bloodstream (lymph)
Circulation is one direction only (valves)
Made of: single layer endothelial cells and incomplete basal lamina
Found in: all tissue except CNS and Bone Marrow
What are the 3 layers of the heart?
Endocardium
-Endothelial cells, subendothelial layer, subendocardial layer (purkinje fibers)
Myocardium
-cardiac muscle
Epicardium/visceral pericardium
-mesothelium, subepicardial layer loose CT (veins, nerves, ganglia, and adipose)
How does cardiac muscle originate and insert?
Fibrous skeleton (dense CT) has distinct regions that separate artrial from ventricles
Trigone fibrosa - between aorta and atrioventricular orifices; serve as origin and insertion points for cardiac muscles
Annuli fibrosi - attachment site for atrioventricular valves
What is the difference between macrovasculature and microvasculature?
Macrovasculature can be seen with the unaided eye
Microvasculature need a microscope to be seen
