Circulatory System Flashcards
Function of the cardiovascular system
- transport blood from heart to tissues
- two vascular circuits: pulmonary and systemic
- distribute gases, nutrients, wastes & hormones
Function of the lymphatic vascular system
- collect, filter lymph and return to the cardiovascular system
pericardium
- it provides mechanical protective covering for the heart
- fibrous pericardium forms outer wall of sac made of fibroelastic CT
- parietal layer of serous pericardium
- visceral layer of serous pericardium (epicardium)
- serous pericardium is lined by mesothelium (simple sqaumous epithelium)
heart wall
- visceral layer of serous pericardium (epicardium)
- myocardium
- endocardium
pericarditis
- inflammation and thickening of the pericardial layers
- decreased space in the pericardial cavity causes friction between layers and the heart
epicardium
- outermost layer of heart wall & relatively thin in comparison to the myocardium
- two layers: mesothelium & subepicardial CT
- meso-simple squamous epithelia (visceral pericardium
- loose CT-contains adipose tissue, coronary bv, nerves and ganglia
myocardium
- thick middle layer made of:
- cardiomyoctes arranged in spiral layers around heart to apex
- contractile, conducting, & endocrine myocytes
- endomysium & perimysium
endomysium
connective tissue surrounding each muscle fiber
perimysium
CT between the layers of muscle bundles, blood vessels, & nerves (wrap fascicles)
intercalated disc
- allow organ (heart) to work as single functional unit; as syncytium
- mechanically (desmosomes a.k.a macula adherens)
- chemically (gap junctions)
myocardial infarction
- necrosis: death of cardiac muscle cells due to ischemia
- neutrophil infiltration to repair leads to scarring of heart wall
- hypertrophy of heart cells (dead myocytes are not replaced)
- dense irregular CT structures hold valves open and maintain shape
- scaffold for myocytes to work against (point of insertion)
- Electrical insulation (atria from ventricles) prevents singular contraction
- tissue is chondriod w/ large round cells that make up:
- annulus fibrosus
- fibrous trigones
- septum membranaceum
annulus fibrosus
- rings of CT around the openings of each valve in the heart:
- 2 A-V valves
- 2 semilunar valves
- holds valves open & maintains their shape
fibrous trigones
- triangular-shaped CT area between the valves
- R & L trigones
- Right trigone pierced by A-V bundle
septum membraneceum
CT extending downward from trigone into top of interventricular septum
cardiac conducting system
- a system of specialized cardiac cells that coordinate and distribute the contraction impulse (SAARS)
- SA node
- AV node
- AV Bundle of His
- R & L branch bundle
- Subendocardial Plexus
SA node
- pacemaker cells initiate contraction that intrinsincally beat (70/min)
- under sympathetic and parasympathetic autonomic invervation
AV Node
- made of “Follower cells” located at lower RA in atrial septum by tricuspid valve
- can take over role of pacemaker
Bundle of His
- leaves AV node pierces right trigone and enters ventricular septum
- divides into R & L bundle branches at superior septum
R & L bundle branches
- travels down interventricular septum to supply impulse to respective ventricle
- houses purkinje fibers (specialized cardiac muscle cells)
- located in subendocardial connective tissue of endocardium
- large, multinucleated cells; large perinuclear space; no contractile filaments
- impulse starts at apex and spreds up towards base
endocardium
- lines heart chamber and separates the blood from the heart wall
- made up of endothelium (simple sqaumous epithelium with basal lamina)
- subendocardial loose connective tissue: contains purkinje fibers and contractile myocytes
arteries
carry blood away from heart (high pressure)
veins
carry blood towards heart (low pressure)
capillaries
microvasculature mediating exchange of materials between blood and parenchyma (functional tissue not CT)
what are the tissue layers of a vessel wall
- tunica intima
- tunica media
- tunica adventia
elastic arteries
- largest type of arteries; they are conducting vessels; elastic lamellae
- maintain blood pressure within vessels during diastole
- eg. aorta, pulmonary, brachiocephalic, subclavian, common carotid & illiac
musclar arteries
- they are typically 1cm-0.3 mm and known as distributing arteries; thick muscular wall
- regulate flow to different regions of the body as needed
- prominent IEL and thick T.media
- eg. brachial, radial, ulnar, tibial, femoral arteries
arterioles
- small, less than 100 um, 1-3 smooth muscle cells (t. media)
- regulate blood flow into capillary bed
large veins
- large low pressure, thin-walled vessels; return blood to heart
- adventia is thickest
arteriovenous anastomosis
- shunt that regulates blood flow through arteriole and venule to conserve heat
- ex: fingertips during the winter
capillary endothelial cell functions
- permeability (small/large: intercellular junctions:fenestrae)
- activate angiotensin II/inactivate BK, amines, prostaglandin
- lipolysis (ectoesterases)
- vasoactive factors (ET& NO)
- prevent contact between subendothelial CT & platelets (antithrombogenic)
- contain Weibel-Palade bodies (VWF)
types of capillaries
- continuous
- fenestrated
- discontinuous (sinusoids)
Tunica Intima
- endothelium (simple squamous epithelium)
- variable basal lamina
- subendothelial CT
- loose CT (type II, IV, & V) & scattered smc
- Internal Elastic lamina (IEL) (intima from media)
***clinical correlation: atherosclerosis
tunica media
- made of smc, functions to reduce caliber or size of lumen
- elastic & collagen type III fibers, proteoglycan
- external elastic lamina (separate media from adventitia)
Tunica Adventitia
- consists of dense irregular CT (fibroblasts, type 1 collagen)
- continuous with CT covering
- contains vaso vasorum: small vessels that supply the wall of large vessels
- ARTERIES: demarcated by EEL
- VEINS: most prominent layer
atherosclerosis
- fatty streaks and plaques
- lesions of thickened T. intima
- proliferation of smc, extracellular CT, & cholesterol in smc and macrophages (foam cells)
T. Media of Elastic fibers
- 40-70 layers of elastic sheetes (diagnostic)
- separated by smc and collagen
- part that maintains BP within vessel during diastole due to passive constaction of elastic lamellae
T. intima of muscular arteries
- have a prominent scalloped IEL (diagnostic)
T. media of muscular arteries
- thick, 5-20 layers of smc (diagnostic)
what is the order of organization of a microvascular bed?
- terminal arteriole (many single smc forms T. media)
- metarteriole (scattered smc): controles blood flow into true capillaries/opens into true capillaries
- central channel: slightly larger than true capillaries
- thoroughfare channel: distal end of central channel that lacks smc
- venule: where capillaries and central channel drain into
arteriovenous anastamosis/shunt
alternative channel directly between artierole and venule that bypasses capillaries; conserve heat
what is the general structure of a capillary
- simple squamous endotheilum with basal lamina, some areolar CT and no media
- cells are joint by occludens (tight junctions)
- 3 classes: continuous, fenestrated, & sinusoid
pericytes
- outside of capillaries and venules
- form a gap junction with the endothelium
- myoepithelial cells that aid in contraction (blood flow control)
small veins
thin, irregular walls; no media
medium veins
poorly defined IEL, no EEL, few smc, valves, and thick adv.
varicose veins
incompetent venous valve, blood flowing back causes venous congestion
large veins
large tunica adventitia with longitudinal smc (diagnostic)
lymphatic system
- part to of circulatory system, functions in conjunction with the CV system
- removes, filters, and returns excess interstitial fluid from teh EC space to CV system
lymphatic capillaries
- patency maintained by collagenous anchoring filaments
- contains valves to direct lypmh back to heart
- lymph filtered in lymph nodes prior to return to blood
small and medium lymph vessels
- don’t contain RBC have valves and patency supported by smc and elastic fibers
