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Human Body_TP > Cardio Histology > Flashcards

Cardio Histology Flashcards

1
Q

arteries

A

-carry blood away from the heart
-thick, multi-layered walls which form the lumen for blood to flow

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2
Q

what are the three main layers of arteries?

A
  1. tunica interna (endothelium)
  2. tunica media
  3. tunica externa
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3
Q

what is the function of the arteries?

A

-carries blood away from the heart
-systemic arteries provide blood rich in oxygen to the body’s tissues
-pulmonary arteries carry blood low in oxygen exclusively to the lungs for gas exchange

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4
Q

what is the structure of the arteries?

A

-arterial walls: thick structures that are generally round in appearance, and experience higher blood pressure than other types of blood vessels
-lumen: inner passage where blood flows and small lumen maintain higher pressure

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5
Q

tunica interna structure

A

-endothelium usually appears wavy due to the constriction of smooth muscle
-internal elastic membrane present in larger vessels

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6
Q

tunica media structure

A

-normally the thickest layer in the arteries
-smooth muscle cells and elastic fibers predominate (the proportions of these vary with distance from the heart)
-external elastic membrane present in larger vessels

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7
Q

tunica externa (adventitia) structure

A

-normally thinner than the tunica media in all but the largest arteries
-collagenous and elastic fibers
-nervi vasorum and vasa vasorum present

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8
Q

tunica interna (media)

A

-composed of epithelial and connective tissue layers
-simple squamous endothelial lining
-basement membrane: provides strength and flexibility and binds the endothelium to connective tissue
-internal elastic membrane: present in large arteries, thick elastic fibers, and provides structure while allowing the artery to stretch

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9
Q

tunica media

A

-normally the thickest layer in the arteries
-smooth muscle cells and elastic fibers predominate (the proportions of these vary with distance from the heart)
-external elastic membrane present in larger vessels
-composes the middle layer of the artery wall
-consists of layers of smooth muscle and connective tissues arranged in circular sheets
-contraction and relaxation of these muscles lead to changes in blood flow and pressure

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10
Q

tunica externa

A

-normally thinner than the tunica media in all but the largest arteries
-sheath of connective tissue, primarily collagenous fibers
-edges are interlaced with surrounding connective tissue, maintaining vessel in the same relative position

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11
Q

elastic arteries

A

-vessels larger than 10 mm
-closest to the heart with the thickest walls
-contain the largest percentage of elastic fibers —> allows them to expand with the increased pressure as blood is pumped and rushes through them
-without the elastic fibers, these walls would be rigid and the blood pressure would greatly increase to very high levels and the heart would not pump efficiently
-elastic recoil helps maintain the pressure gradient that drives blood flow through the body

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12
Q

what happens to the amount of elastic fibers in the arteries as you move further from the heart?

A

decreases

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13
Q

tunica media of the elastic arteries

A

-middle layer composed of alternating layers of circumferentially arranged smooth muscle and sheets of elastic tissue
-thickest of the three layers in elastic arteries

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14
Q

muscular arteries

A

-distribute blood to various parts of organs and tissues like radial and femoral arteries
-well-defined elastic lamina- layer of undulating elastic fibers separating tunica intima from the tunica media
-tunica intima is thinner compared to elastic arteries
-walls have a greater number of smooth muscles
-has a companion vein, medium vein: thinner tunica media than muscular artery and adventitia is the thickest layer compared to tunica media

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15
Q

veins structure

A

-same three layers of arteries
-differences: lacks elastic lamina, thinner tunica media, larger lumens, and smooth muscle is more loosely arranged
-contains one-way valves that are outfoldings of the tunica intima

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16
Q

what is the function of veins

A

-return blood to the heart —> carry oxygen-poor blood from body to heart and carry oxygen-rich blood from lung to the heart
-venous system is low pressure —> one-way valves prevent backflow and muscle contractions in leg aid blood flow from lower extremities

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17
Q

what is the structure of capillaries?

A

-one layer of endothelial cells
-epithelial cells form a protective layer (basal lamina)
-three types of capillaries: continuous, fenestrated, and discontinuous

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18
Q

what is the function of capillaries?

A

-exchange materials between blood and tissue —> provides nutrients and oxygen to surrounding tissue and removes CO2 and other waste
-there are multiple mechanisms for exchange: simple diffusion, membrane transport carriers, and transcytosis through large molecules and endocytosis/exocytosis

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19
Q

continuous capillaries

A

-most common type
-found in brain, muscle, connective tissue
-endothelial cells are joined by a tight junction to form a continuous tube
-basal lamina is continuous
-less permeable —> only allows small molecules to pass through and can have a barrier function

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20
Q

fenestrated capillaries

A

-found in kidney, choroid plexus, endocrine organs, and gut
-endothelial cells contain pores (fenestrae) that are covered by thin layer of diaphragm
-basal lamina is continuous
-more permeable —> fenestrae allow larger molecules to pass through like proteins and facilitate absorption

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21
Q

discontinuous (sinusoidal) capillaries

A

-found in liver, bone marrow, and spleen
-endothelium has large openings which lack diaphragms
-basal lamina is thin and discontinuous over openings
-most permeable —> allow large proteins and cells can pass through these openings to allow trafficking of blood cells

22
Q

properties of endothelial cells

A

-single cell layer
-line entire vascular system from the heart to the smallest capillary
-component of tunica intima
-selectively permeable
-phenotypically heterogeneous depending on localization so varying permeability

23
Q

what are the functions of endothelial cells?

A

-regulate gas and nutrient exchanges between the bloodstream and surrounding tissues
-regulate immune responses and inflammation through the BBB, platelet adhesion, and leukocyte activation
-angiogenesis to form new vessels and capillaries
-vascular homeostasis- enable the blood vessel to adapt diameter and wall thickness plus release endogenous vasodilators like nitric oxide

24
Q

arteriosclerosis

A

blood vessels that carry oxygen from heart to other parts of the body become thick and stiff —> restricts blood flow to organs and tissues

25
Q

what causes atherosclerosis?

A

-buildup of fats, cholesterol, and other substances in and on artery walls called plaque
-plaque narrows the arteries, blocks blood flow, bursts, and blood clots

26
Q

epidemiology of atherosclerosis

A

-less prevalent in central and south america, africa, and asia
-more prevalent in US and japan
-in the US, coronary artery disease causes approx. 1 of every 6 deaths
-account for more than 400,000 deaths annually

27
Q

what are some risk factors of atherosclerosis plaque buildup?

A

-high blood pressure
-high cholesterol (high LDL cholesterol)
-irritant like tobacco or nicotine
-diseases like obesity and diabetes
-elderly people
-lack of physical activity

28
Q

what are treatments for atherosclerosis plaques?

A

-lifestyle changes
-medications
-surgeries for severe blockages or high-risk complications

29
Q

what are some symptoms of atherosclerosis plaques?

A

-most symptoms do not show until a blockage occurs
-chest pain or pressure (angina)
-pain in the leg or arm
-shortness of breath
-fatigue
-confusion, dementia (if blood flow is blocked to the brain)
-muscle weakness
-high blood pressure or kidney failure (if blood flow is blocked)

30
Q

how does atherosclerosis develop?

A

-high LDL proteins enter the arterial intima
-if there are high levels, the LDL accumulate
-oxidation of the LDL into pro-inflammatory particle invokes an inflammatory response in the intima —> causes damage to the endothelium
-accumulation of macrophages form cells that cause cell necrosis (fatty streak)
-dead foam cells and other debris widen the fatty streak into a large piece of plaque
-fibrous tissue from the smooth muscle cells form a fibrous cap over the plaque and prevent it from breaking off
-prevents blood flow and eventually the plaque ruptures and leads to formation of a blood clot

31
Q

angiogenesis

A

-formation of new blood vessels from pre-existing ones induced by angiogenesis factors (vascular endothelial growth factor or VEGF)
-endothelial cells differentiate, divide, and migrate within the lining of blood vessel walls
-occurs during embryonic development, postnatal growth, and wound repair

32
Q

angiogenesis —> tumorigenesis

A

-tumorigenesis involves a multistep process in which the normal cells progress into cancerous cells through oncogenic mutations and clonal expansion
-initial solid tumors remain in an avascular state and absorb oxygen and nutrients from surrounding tissue
-blood vessel expression and movement to tumor increases its ability to access oxygen as well as nutrients

33
Q

myocardial infarction (heart attack)

A

-decrease/cessation of blood flow to the myocardium (coronal arteries) results in ischemia and cell death
-ischemia initially presents as retrosternal chest/upper extremity pain (quick or gradual)
-often the result of plaque buildup/rupture or artery occlusion
-trigger cell death in cardiomyocytes through apoptosis and necrosis —> cardiomyocytes are thought not to proliferate so damage will be permanent and leads to scarring

34
Q

how is a heart attack diagnosed?

A

-EKG
-imaging through MRI
-cardiac troponins in serum samples —> cardiac troponin T (cTnT) and cardiac troponin I (cTnI) and can differentiate between acute and chronic MI

35
Q

how is a heart attack treated?

A

-less than 2 hours —> PCI (balloon angioplasty + stent placement)
-more than 2 hours —> fibrinolysis

36
Q

histopathology of myocardial infarction

A

necrosis will trigger pro-inflammation signals and macrophages —> you will see lots of cell nuclei/cell waste as well as immune cells like neutrophils and macophrages plus scar tissue

37
Q

pericardium

A

fibrous encasement of the heart and vessels

38
Q

functions of the pericardium

A
  1. positions heart in the mediastinum and separates it from other organs
  2. allows for movement of the heart
  3. restricts the movements o the heart
  4. protects by providing cushioning
39
Q

what are the layers of the pericardium?

A

fibrous and serous (subdivides to parietal and visceral layers)

40
Q

fibrous pericardium

A

-strong connective tissue of collagen fibers and elastic lamellae
-restricts movement of the heart
-runs from the great vessels to diaphragm

41
Q

serous pericardium

A

-parietal layer is attached to the fibrous layer and is composd of a serosal lining as well as a fibrous sac
-visceral layer is attached to the surface of the heart and forms the epicardium

42
Q

epicardium

A

-innermost layer of the pericardium formed by mesothelial cells
-attached to the surface of the heart
-release a lubricating fluid
-contains blood vessels and is thicker in the ventricles but thinner in the atria

43
Q

myocardium

A

-layer of muscle cells connected through intercalated discs
-they are near capillaries
-their helical arrangement allows for blood release upon contractions
-thicker in ventricle and thinner in atria
-cells can separate during the histo staining

44
Q

endocardium

A

-layer of epithelial cells lining the heart and blood vessels
-connected to loose connective tissue (subendocardial layer)
-prevent blood from clotting (antithrombotic)
-thinner in ventricle and thicker in atria
-large purkinje cells are found in the subendocardial space below connective tissue

45
Q

purkinje fibers

A

-specialized nerve cells that relay electrical signals between ventricles
-located in the subendocardial wall of ventricles
-3D mesh-like network
-paler cytoplasm than cardiomyocytes

46
Q

intercalated disks or unique junction

A

-hold adjacent cells together and mediate intercellular signalling
-located between adjacent cardiac muscle cells at ends
-composed of gap junctions (allow propagation of action potentials) and desmosomes (anchor cardiac muscle fibers together so the cells do not move apart during individual contraction)

47
Q

cardiomyocyte

A

-singular cardiac muscle cell
-rhythmic contractility
-located in the myocardium
-rectangular branching cells with central nucleus
-within the cardiomyocytes are myofibrils that contain myosin-actin filaments that cause the heart to contract

48
Q

cardiac muscle

A

-located in the heart, specifically the myocardium
-involuntary contractions to pump blood
-structures are branched, striated (sarcomeres), mainly one central nucleus but sometimes two nuclei, and intercalated discs that join cells with adherent and gap junctions

49
Q

skeletal muscle

A

-attached to skeleton
-voluntary movements like moving limbs
-large, elongated
-striated
-mutinucleated, on periphery
-sarcomeres

50
Q

smooth muscle

A

-located in blood vessels and internal organs
-involuntary movements like blood pressure in vessels and moves food in digestive tract
-fibers are grouped fusiform cells, closely packed
-not striated
-central nucleus and the widest part of the cell
-contains gap junctions

Human Body_TP (25 decks)

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