Histology of the Cardiovascular System Flashcards
Microcirculation (cascade)
Microcirculation blood goes…
artery—>arteriole—>metarteriole—>capillaries—>venule—>vein
Heart: layers
Heart:layers
Endocardium: lining of the heart chambers surface. also surface of valves.
Myocardium: cardiac muscle mass. composed of cardiomyocytes.
Epicardium: formed by mesothelium. cells secrete a small ammount of serous fluid (lubricates movement of epicardium on parietal pericardium). (Epicardium= visceral layer of pericardial sac)
Lable: purkinje fibers, epicardium, endocardium, myocardium
Perkinje fibers are a specialized type of endocardial cell. transmit impulses
Cardiomyocytes
Cardiomyocytes=cell that make up myocardium= muscle mass
- different from skeletal muscle because…
- lots of mitochondria
- interwoven pattern (not just long strait fibers)
- intercalated discs where cells meet
- centrally located single nucleus
- cannot regenerate!!!
Epicardium
Heart: Epicardium
Epicardium: outer surface of the heart (visceral paricardium)
- covered by thin layer of mesothelium on surface
- contiguous with the endocardium at the level of the endocardial cushion
Cardiac skeleton
Cardiac skeleton: 4 dense bands of fibrous connective tissue that provides structural support to the heart. encircles…
- pulmonary trunk
- aorta
- AV valves
Fibrous trigon: triangular mass of fibrous connective tissue.
- connects aortic arterial ring and left/right atrioventricular ring.
- Os Cordis occurs when this area undergoes osseous differentiation in cattle.
Not an Objective!!
Tunics of Vessels
Tunics of Vessels
- Tunica Externa= Outermost layer of vessels
- principly COLLAGEN
- can contain blood vessels, nerves and capillaries
- Tunica Media= middle layer
- smooth muscle and elastic fibers
- ** thickest layer in arteries**
- Tunica Intima= innermost layer
- endothelium
- internal elastic membrane
- subendothelial connective tissue
- **thickest layer in veins**
Veins vs. Arteries
Veins vs. Arteries
Veins
- thickest tunica is tunica externa
- vaulves
- larger lumen
Arteries
- thickest tunica is tunica media
- smaller lumen
Arteries: structure and function
Arteries: structure and function
Arteries: cary oxygenated blood from heart
- tunica intima
- internal elastic lamina
- subendothelial layer
- endothelium
- tunica media
- smooth muscle cells producing all kinds of fibers
- tunica externa
- loose ct
- blood vessels, lymphatics and nerves
Veins: Structure and Function
Veins: Structure and Function
Veins: carry deoxyganeted blood to lungs/heart
- tunica intima
- no prominent elastic lamina
- subendothelial layer
- endothelium
- tunica media
- thinner than in arteries
- tunica externa
- loose ct few nerve fibers
*
- loose ct few nerve fibers
Example of Muscular Artery
Identify
vein is irregular thin lumen
artery has thick constant lumen
Arteriole
Arteriole: smaller vessel
- 1-3 layers of smooth muscle
- greatest effect on blood pressure
- round appearance
- red blood cells in center…
Identify
Pericytes
Pericytes: mesencymal-ish contractile cells. wrap around capilaries and veins and communicate with endothelial cells by contact and signaling
important in formation of new vessles
Capillaries
Capillaries: tiny
- thin walled tubules of mesenchymal origin
- site of exchange b/t blood and tissue
- three types:
- Continuous- most common
- Fenestrated- in tissues with lots of fluid exchange
- ex. intestinal villi, ciliary process, choroid plexus
- Discontinuous- hepatic and splenic sinusoids
- large molecule passage
Sinusoids
Sinusoids= discontinued/sinusoidal capillaries
- enlarged irregular lumen
- no basal lamina
- ex. bone marrow
Venules
Venules= small veins
- leaky vessles
- no smooth muscle
- leukocytes possible
Lymphatic Vessels
Lymphatic Vessels:
- very thin wall
- low pressure
- may contain valves
- no RBC (will appear clear)
list all different types of vessels: (6)
Vessels
Veins
- Vein
- Venule
Arterys
- Elastic artery
- muscular artery
- arteriole
Capillary
