Cardio Pt.2 Flashcards
What are the functions of the CVS?
-maintain adequate blood flow (cardiac output)
-delivery O2, nutrients, hormones, electrolytes, H2O to tissues
-remove CO2 & other metabolic waste products
-maintain normal thermoregulation
-maintain normal glomerular filtration rate & urine output
Describe the normal vascular pattern.
Artery -> Arteriole -> metarteriole -> capillaries -> venue -> vein
Describe the 3 heart layers.
(In to out)
1. Endocardium (valves)
2. Myocardium (muscle)
3. Epicardium (visceral pericardium = sac)
Describe the endocardium. (Tunica intima)
-forms inner lining & valves
-similar to tunica intima of BV
-endothelial cells
-contact w blood
-imp for hemostasis
3 layers:
1. Endothelium
2. Basal lamina
3. Subendothelial CT
contain part of conductive system & Purkinje fibers
Describe purkinje fibers.
-located between endocardium & myocardium
-subendocardial layer
-contains small nerves
-cardiac cells joined by intercalated disks
-specialized for impulse conduction (rather than contraction)
-larger than contractile cardiac muscle fibers
-lg amounts of glycogen filling most of cytoplasm & displacing sparse myofibrils to periphery
Describe the micro anatomy of the valve & fibrous skeleton.
-fibrous skeleton = dense CT in endocardium
-valve = dense CT covered with thin layer of endothelium
>collagen rich CT = pale green
Describe cardiomyocytes.
-cross striated
-central single nucleus
-intercalated disks (gap junction + anchoring junctions)
-lipofuscin
-SR
-mitochondria
>20% cell volume
>requires O2
-low mitosis capacity (regen)
Describe myocardium. (Tunica media)
-LV myocardial thickness is thicker than right due to higher pressure on L side
-involuntary striated muscle
-sarcomere
-branched & connect via intercalated disks
-contain lg # mitochondria
-purkinje cells = modified cardiomyocyte that function in conduction
-regulates diameter & tone (vasodilation & vasoconstriction)
Describe the epicardium. (Tunica adventitia)
-outer surface (visceral pericardium)
-covered by mesothelium (simple squamous epithelium)
>mesothelial layer lines opposing parietal surface of pericardial sac
>secrete serous fluid that lubes movement of epicardium on opposite parietal pericardium
-thin layer of dense CT
-thick layer of adipose with blood vessels (coronary arteries & veins)
-continuous with endocardium at level of endocardial cushion
Describe the cardiac skeleton.
-4 dense bands of fibrous CT encircle base of pulmonary trunk, aorta & AV valves = structural support
-triangular mass of fibrous CT “fibrous trigon” = connects aortic a. Ring & L & R atrioventricular rings.
>undergoes osseous differentiation & forms the “Os cordis” = seen in cattle
Describe the classifications of vessels.
- Arteries
-elastic, muscular, arterioles - Capillaries
-continuous, fenestrated, discontinuous/sinusoids - Veins
-venules - Lymphatic vessels
Describe the layers of vessels.
INNERMOST: tunica intima
-endothelium, internal elastic membrane, subendothelial CT
MIDDLE: tunica media
-smooth muscle & elastic fibers
OUTERMOST: tunica adventitia/externa
-collagen, BV, nerves, capillaries
Describe the function of the vascular endothelium.
-role in hemostasis
-modulates perfusion
-role in inflammation
What is hemostasis?
-physiological response to vascular damage
-seal injured vessel to prevent blood loss
-maintains blood flow
Describe the elastic artery (ex. Aorta)
-tunica intima (endothelium + loose CT)
-tunica media (elastic lamellae)
-tunica adventitia (vasa vasorum = supply nutrition to tunica media)
Describe muscular arteries. (Ex. Femoral artery)
-tunica media = smooth muscle (THICKEST)
-round appearance
Describe arterioles.
-1 to 3 layers of smooth muscle
-effect on BP
-nuclei bulge into lumen
-round appearance
-no internal elastic membrane in small arterioles with one smooth muscle cell
-metarteriole = terminal vessel w precapillary sphincters that regulate flow to capillary bed
Describe capillaries.
- Thin walled tubules of mesenchymal origin (one endothelial cell rolled into a tube form) simple squamous cells
- Site of exchange between blood & surrounding tissue
- Diameter 7-9 Um & length 0.25-1mm
adrenal cortex, kidney medulla = 5-10 cm long
Capillary wall impermeable to proteins & blood cells, but permeable to: O2, CO2, ions, water, glucose, amino acids, fatty acids, vitamins, hormones.
Describe pericytes (Roujet Cells)
-mesenchymal-like cells that wrap around endothelium of capillaries & venules
-communicate with endothelial cells by contact & paracrine signaling
-maintain homeostatic & BBB
-proliferate after injury
-stem cell source
-imp in angiogenesis -> new formation of vessels
Describe the classification of capillaries.
- Continuous =
-most common
-found in muscle, bone, brain, lung (BBB & BTB) - Fenestrated =
-tissues w fluid exchange
-intestinal villi, choroid plexus, ciliary process, glomerular capillaries - Discontinuous (sinusoidal) =
-hepatic & splenic sinusoids
-lg molecules can exit (RBC in spleen)
-bone marrow & lymph nodes
Describe the structure of continuous capillaries.
- Nucleus of endothelial cell
- Pinocyototic vesicles
- Tight junctions
- Basement membrane
Describe renal corpuscle (glomerulus).
-tight coiled network of fenestrated capillaries
-filtration of plasma
-RBC stained orange
Describe podocytes.
lining bowman’s capsules (nephrons)
-prevent protein & other lg molecules from being filtered
-foot processes (pedicels) extend & wrap around capillaries of glomerulus to form filtration slits
-pedicels increase the area of cells = ultrafiltration
Describe discontinued capillaries (sinusoids).
-lg and irregular lumen
-lining endothelium is discontinued & fenestrated
-basal lamina absent (discontinuous)
Describe venules.
-“postcapillary venules”
-leaky vessels
-no smooth muscle
-leukocyte diapedesis possible
-5 mm Hg pressure
Describe vein VS artery.
-lg, wide lumen, thin walls compared to arteries
-valves
-thin tunica media in veins
-tunica adventitia = thickest tunica
-lg veins may have vasa vasorum
Describe lymphatic vessels.
-complementary to CVS
-transport lymph throughout lymphatic system
-valves
-freely anastomose
-lined by endothelial cells
-thin layer of smooth muscles
-adventitia bind the lymph vessel to surrounding tissue
-low pressure
-no RBS = clear
