Cirulatory System Flashcards
Components of tunica intima
. Endothelial cells
. Basal lamina
. Subendothelial layer (Loose CT w/ or w/o smooth muscle)
What separates tunica intima from media in arteries and why?
. Inner elastic lamina w/ elastic fibers
. Allows for nutrient diffusion from intima to media
Tunica media
. Smooth muscles helical around long axis
. Extends from internal to external elastic lamina
. Can include fenestrated elastic lamellae, reticular fibers, and proteoglycans
. All ECM components produced by smooth muscle cells
Tunica adventitia
. CT that becomes continuous w/ CT surrounding the vessels
. Thin in arteries
. Thick in veins when it constitutes main component of Essex wall
Vasa vorum
. Small blood vessels in walls of large arteries/veins
. Provide wall of adventitia and outer part of media w/ nutrients
. More in veins bc less diffusion of oxygen and nutrients from depleted blood in vein lumen
Nervous system components in vessels and where are they found
. Unmyelinated sympathetic fibers using NE
. NE causes vasoconstriction
. Artery nerve endings in adventitia
. Vein’s found in adventitia and media
Endothelium
. Simple squamous, in all blood and lymph vessels
. Forms selectively permeable barrier btw blood and tissues
. Allows diffusion of small molecules and restricts some macromolecules
. Have Weibel-Palade bodies in cytoplasm
. Weibel-Palade bodies
. Contain von Willebrand (VW) factor and P-selectins
. Compounds Released from granules at site of injury during inflammation
VW factor
Part of blood coagulation, absence causes hemophilia
P-selectins
. Expressed as adhesion molecule
. Play role in recruitment of leukocytes to inflammation site
Endothelium participates in _____
. Maintenance of nonthrombogenic barrier btw blood and subendothelial tissue
. Repair of damaged blood vessels (production of agents that promote platelet aggregation and clots)
. Modulation of immune responses (Cleese’s cytokines, cell interactions)
. Modulation of metabolic activities (synthesis/modification of various hormones and growth factors)
Large arteries
. Conducting vessels
. Aorta and branches
. Large amts of elastic fibers for more uniform blood flux
. Elastic laminae stretch during systole (ventricular contraction) to reduce pressure change
. Elastic rebound during diastole when ventricular pressure lowers to prevent change in arterial pressure
Large arteries tunica intima
. Endothelium
. Thick w/ subendothelial layer
. CT made of collagen and elastin
. Internal elastic lamina present but hard to see
Tunica media in large arteries
. 50-70 concentric fenestrated sheets of elastic laminae
. Each sheet 2-3 um thick and is 5-10 um from its neighbor
. External elastic lamina lacking
. Smooth muscle cells and collagen fibrils found btw successive lamellae
. Smooth muscle synthesize and maintain elastic lamellae
Tunica adventitia in large arteries
. Thin
. Elastic and collagen fibers
. Vasa vorum
Medium sized arteries
. Muscular/distributing
. Includes most named arteries in body
Medium arteries tunica intima
. Endothelium, subendothelial layer, internal elastic lamina
. Subendothelial layer size dec. as artery diameter dec.
. Subendothelial layer: collagen, few elastic fibers, some scattered longitudinal smooth muscle
. Internal elastic lamina prominent (scalloped line)
Tunica media in medium arteries
. Thickest layer
. Up to 40 layers smooth muscle
. Layers dec. as diameter dec. (3-4 layers in smallest)
. Scattered elastic laminae but not as prominent as large arteries
. External elastic lamina present
Tunica adventitia in medium arteries
. Prominent, thick as tunica media
. Longitudinally oriented CT and elastic fibers
. Vasa vasorum and lymph capillaries present
Small arteries
. 1-0.1 mm
. Distribute blood to arterioles
Arterioles
. 0.1-10um
. Resistance vessels
. Regulate arterial blood pressure and blood flow w/in organ
. Highly innervated, dilate/constrict in response to different stimuli
Arterioles tunica intima
. Only endothelium
. Internal elastic lamina absent
. Subendothelial CT very thin
Arteriole tunica media and adventitia
. 1-2 layers of circularly arranged smooth muscle
. No external elastic lamina
. Adventitia thin
Metarterioles
. Branch of arterioles
. Branch into capillaries
. Precapillary sphincter (ring of smooth muscle) that controls blood flow into capillary bed at point of branching
Capillary functions
. Exchange of nutrients, H2O, CO2, and O2 btw tissue and blood
. Metabolism of substances by endothelial cells themselves
. Production of vasoactive factors
. Prevention of formation of thrombus
Capillary structure
. Single layer endothelium forming tube w/ cells oriented w/ long axis parallel to flow of blood
. 7-9 um diameter, 0.25-1 mm in length (some up to 50 mm)
. Basal lamina form by endothelial cells
. Nucleus of endothelial cell bulges into lumen
. Cytoplasm has few organelles and tons microfilaments
. Cells joined by zonula occludentes and gap junctions
Pericytes
. Mesenchymal origin
. Long processes that partly surround endothelial cells in capillaries
. Contractile cells that modulate blood flow downstream of arterioles
. Has own basal lamina fused w/ basal lamina of epithelial cells
Continuous/somatic capillaries
. Type I
. Endothelial cells have many pinocytotic vesicles but no fenestrae (less vesicles in nervous system)
. Basal lamina continuous
. Found in muscle, CY, exocrine glands, and nervous tissue
Fenestrated/visceral capillaries w/ diaphragm
. Type II
. Fenestrae (large openings 60-80 nm) in cytoplasm
. Covered by thin diaphragm thinner than cell membrane
. Basal lamina continuous around capillary
. Found in kidney, intestine, and endocrine glands (rapid exchange of molecule locations)
Fenestrated capillary w/o diaphragm
. Type II
. Thick continous basal lamina separates endothelial cells from adjacent structures
. Found in glomerulus of kidney
Sinusoid capillary
. Greatly dilated lumen (30-40 um)
. Sometimes cells not connected by cell junctions and spaces are present
. Basal lamina discontinuous
. Phagocytic cells found in tissue adjacent to sinusoid
. Found in liver, bone marrow, and spleen
. Structure facilitates passage of blood cells into and out of vessel
Arteriovenous anastomoses
. Arterioles w/ thick, innervated tunica media communicate w/ venules
. normally Smooth muscle contraction closes off lumen of anastomoses to direct blood into capillary bed
. Relaxation opens up lumen so blood flows directly into venule
.thermoregulation
. Found in fingertips, lips, nose, toes
. Responsible for cold induced sympathetic Adrenalin vasoconstriction in fingers
Venules
. Smallest postcapillary venules (10-50 um)
. Largest are muscular venules (50-100 um)
Venule tunica intima
. Thin, poorly joined cells
. No internal elastic lamina
Venule tunica media
. Postcapillary contains pericytes
. Muscular contained 2-3 layers smooth muscle cells circularly arranged
Venule tunica adventitia
. Thick compared to arterioles
. Collagen fibers and fibroblasts
Medium sized veins
. Up to 10 mm
. Tunica intima: thin, narrow subendothelial layer containing collagen and elastic fibers, poorly developed elastic lamina
. Tunica media: circular arranged smooth muscle, thinner than artery, reticular and elasticfibers
. Tunica adventitia: contains collagen fibers, well developed, bulk of wall thickness, may have some smooth muscle fibers
Valves
. Seen in lumen of medium-sized veins
. Semi-Lunar shaped folds in tunica intima made of CT core on both sides by endothelium w/ elastic tissue
. Numerous in vessels of limbs to prevent backflow
Large veins
. >10mm (sup./inf vena canvas, renal veins)
. Tunica intima well developed, fragmented internal elastic lamina
. Media: thin, few layers smooth muscle in abundant collagen fibers
. Adventitia: thickest, loosely know CT w/ thick longitudinal bundles of collagen and elastic, longitudinally oriented smooth muscle bundles (well developed in inf. Vena cava)
. Cardiac fibers may be present in sup./inf. Vena cava, pulmonary vessels close to heart
Hepatic portal system
. Portal hepatic vein connects intestinal capillaries to sinusoids in liver
. Blood flows from sinusoids into hepatic veins
Hypothalamic-hypophyseal portal system
. Large capillaries connect capillaries of hypothalamus w/ papillary plexus of pituitary gland (hypophysis)
Carotid and aortic bodies
. Arterial sensory structures
. Small, chemoreceptors for O2 tension, CO2 levels, and blood pH
. Found at bifurcation of common carotid arteries and aortic arch
. Rich capillary networks by neural-crest-derived glomus cells ( contain neurotransmitters)
. Afferent nerve fibers from synapsis w/ glomuand signal brain cardiorespiratory centers
Layers of heart
. Endocardium
. Myocardium
. Epicardium
Endocardium
. Homologous to tunica intima
. Single layer endothelial cells, subendothelial layer, and subendocardial layer
. Cells joined by jap and tight junctions
. Subendothelial: CT w/ elastic and collagen and some smooth muscle
. Subendocardial: deep to endothelial layer, dense CT binds that endocardium to myocardium, contains collagen and elastic, nerves, and purkinje cells in ventricles
Purkinje cells
. Modified muscle fibers
. Larger w/ more sarcophagi than typical cardiac cells
. Cytoplasm appears vacuolated from large amts glycogen
Myocardium
. Thickest layer
. Cardiac muscle cells
. Thicker in ventricle than atria
. Arranged in spirals that insert into fibrous skeleton of heart
Epicardium
. Covers outer surface of heart
. Surface layer to mesothelioma cells (visceral layer of serous pericardium), layer of thin CT underlying mesothelioma, and subepicardium
Subepicardium
. Loose CT contains nerve, ganglia, and fair amt adipose
. Coronary vessels course w/in subepicardial layer
Fibrous skeleton of heart
. Dense CT found around valves and upper portion of interventricular septum
. Attachment site for cardiac muscle fibers
Valves in heart
. Core of dense CT covered on both sides w/ endocardium
. Attached to fibrous skeleton
Lymph is drained from interstitium via ___
. Blind-ending lymphatic capillaries
Collecting lymphatic vessels unite to form ___
Thoracic duct and right lymphatic duct
Intrinsic contraction of lymph flow
. Smooth muscle of wall contracts when collecting lymphatics become extended w/ lymph
. Each section btw valves is like automatic pump
. Segment filled, wall contracts, valve opens, and lymph flows to next segment
Extrinsic contraction of lymph
. Contraction of surrounding uncles, arterial pulsations, and compression of tissues by forces outside the body compress lymph vessels causing pumping
Lymph vessel structure
. Similar to veins w/ thinner walls and no separation into intima, media, and. Adventitia
. Large number valves
Lymphatic capillaries
. Thin-walled
. Thin continuous endothelium w/ discontinuous basal lamina
. Junctional complexes rare, clefts btw cells
. Leaky
. Anchoring microfilaments from capillary to adjacent CT help keep capillary open
. Big in dermis of skin and mucous membranes of digestive and respiratory system s
. NOT present in avascular structures, brain, eyeball, inner ear, and spleen
Lymphedema
. Accumulation of interstitial fluid
. Common problem in radical mastectomy when all axillary lymph nodes are removed
Lymph collecting vessels
. Poorly defined layers
. Valves
. Largest is thoracic duct, resembles Small veins w/ larger lumen and prominent valves
. 25-50% lymph flows into thoracic duct produced by liver
T/F disease of circulatory system are largest cause of morbidity and mortality in western society
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