CV Histology

Question 1

Answer 1

CARDIAC MUSCLE (MYOCARDIUM)

• branching chains of cardiac myocytes
• striations (myofibrils and repeat sarcolemmas)
• dark intercalated discks (myocyte junctions)

differ from skeletal -

1. structural - branched, mononuclear (central), no stem cells
2. physiological - contract/relax without rest, secrete hormones (ANP- when stretched excessibely, increases water/Na+/K+ excretion, inhibits RAAS)

Question 2

Answer 2

INTERCALATED DISC

• w/ desmosomes + adherent junctions (stick)
• w/ gap junctions (electrical coupling)

disc = black

myofibrial = blue/black

function:

desmosome - anchor one cardiac muscle to next by immediate cytoskeleton filaments

gap junctions - allow ion transfer between cardiac smooth muscle

electrochemical coupling - not cardiac conduction

Question 3

Answer 3

PURKINJE FIBRES (WITH PAS PROCEDURE - MAGENTA)

• large modified muscles
• large vacuoles
• few myofibrils therefore pale H&E
• stores of GLYCOGEN (PAS)

CARDIAC CONDUCTION

Question 4

Answer 4

ARTERY - LEFT, VEIN - RIGHT

• 3 layers

1. intima (innermost) - endothelial cells on loose connective tissue w/ occasional myo-intimal cells (contractile potential)
2. media (middle) - thicker in arteries than in veins - smooth muscle, elastic, collagen
3. adventitia (outermost) - dense collagen and elastic

Question 5

Answer 5

MUSCULAR ARTERY

• well defined medial layer (smooth muscle in concentric rings)
• medial layer interspersed with elastic
• media-intima divide = wavy internal elastic lamina (condensed perforated elastic)
• adventitia-media divie = external elastic lamina only in large muscular

Question 6

Answer 6

ARTERY WITH PLAQUE AND THROMBUS (WITH IRON HAEMATOXYLIN)

• elastic/nucleus = black

Question 7

Answer 7

ELASTIC ARTERY (WITH MALLORY’S STAIN)

• elastic - red / collagen & muscle - blue
• = aorta and GT vessels close to heart
• medial layer thick w/concentric sheets of elastic interspersed w/smooth muscle
• as vessels large - contain own blood supply vasa vasorum

at top = intima then internal elastic lamina, then vascular endothelial cells on BM

Question 8

Answer 8

ARTERIOLES

• 3 layers or fewer of muscle @ media
• no internal elastic lamina - therefore amy completely close when muscle contracts
• poor adventitia - mainly collagen and elastin

function: highly responsive to vasoactive stimuli - regulation of TPR

Question 9

Answer 9

CAPILLARIES

• sometimes have contractile pericytes along bed
• continuous or fenestrated (gut, kidney glomerulus, endocrine glands)
• diameter is size of RBC

this slide - mature adipose

Question 10

Answer 10

ENDOTHELIAL CELLS (EM)

• specialised - release vasoactive substances
• capillary @ centre

function:

1. active transport of molecules across cytoplasm
2. influence muscle tone
3. coagulation
4. produce cell adhesion molecules - influsence lymphocyte/neutrophil migration

Question 11

Answer 11

VENULES

• thin walled
• pericytes alongside them
• pericytes become continuous as vessel gets bigger
• in veins no pericytes, replaced by smooth muscle
• irregular outline

Question 12

Answer 12

VEINS (TOP LEFT x2)

• same layers as arteries, but thinner and poor boundaries
• irregular outline, large lumne (therefore same blood at lower pressure)
• wider lumen than arterioles (but slower flow) therefore same volume/sec

Question 13

Answer 13

LARGE VEINS

• thick wall
• distince intima/media and internal elastic lamina
• medial layer w/ longitudinal smooth muscle
• adventitia - thick w/ longitudinally arranged muscle fibres

Question 14

Answer 14

LYMPH VESSELS

• w/ pink staining blood plasma and valves
• small = like capillaries
• large = like veins
• walls = connective tissue with some muscle
• less pressure than venules
• sometimes lymphocytes
• transports antigens and activated lymphocytes from tissue to lymph nodes (and resident macrophage)
• drains excess fluid fro tissue (hydrostatic/oncotic pressure imbalance)
• no blood

Question 15

Answer 15

RBC (LEISHMAN’S STAIN - TYPE OF ROMANOVSKY SMEARS)

• 44% of blood
• anucleate - leads to biconcavity
• 120 day lifespan

Question 16

Answer 16

RETICULOCYTES

• mature RBC loses cytoplasm and nucleus
• reticulocytes = immature RBC w/ some visible ribosomes, ie. some dark staining granules
• increased number with increased RBC produciton

Question 17

Answer 17

EOSINOPHILS (ROMANOVSKY/LEISHMAN’S)

• 2-3 lobe nucleus
• bright pink granules
• acidophils
• circulate for a few hours
• diurnal - highest in morning
• phagocytose antigen/antibody complexes, associated w/ parasitic infection
• neutralise histamine

GRANULOCYTES

Question 18

Answer 18

NEUTROPHILS - POLYMORPHONUCLEAR LEUKOCYTES (LEISHMAN’S STAIN)

• multi-lobar nucleus
• most numerous
• phagocytic
• engulf and destroy bacteria
• leave blood stream to enter tissue @ infection site

fine granules = GRANULOCYTES

1. primary - lysosomes, acid hydrolases, antibac and digest
2. secondary - neutrophil specific, regulation of inflammation response
3. tertiary - facilitate insertion of proteis to cell membrane

lobes = 2-4, number increases with age

Question 19

Answer 19

BASOPHILS - BASOPHILIC LEUKOCYTES

• not multi-lobar
• dark blue granules which appear to fill cell
• least common
• similar role to MAST cells
• secrete HISTAMINE and other vasoactive substances - increased blood flow locally

Question 20

Answer 20

LYMPHOCYTES

• small cells with dark stained nucleus and little cytoplasm
• B and T are indistinguishable
• immature are bigger than RBC, smaller than granulocytes
• mature roughly equal size to granulocyte

Question 21

Answer 21

MONOCYTES

• kidney-shaped nucleus
• no granules
• pale blue cytoplasm
• immature cells which differentiate to one of various forms when leave blood and enter connective tissue
• many to macrophages (fixed marcophage @ liver = Kupffer, and @ spleen)

in blood and alveolar air spaces

macrophage phagocytotic, actute inflammation, arrive after neutrophils

Question 22

Answer 22

PLATELETS

• smaller than red cell
• anucleate
• fragements
• from multinuclear megakaryocytes
• blue
• 4 types of granules:

1. alpha - clotting
2. dense
3. lysosomes
4. peroxisomes - elimination of oxygen radicals

Question 23

Answer 23

MUSCULAR ARTERY 2

• circumferential sm @ media
• when this contracts reduces diameter of vessel

Question 24

Answer 24

ELASTIC TISSUE (ELASTIC VAN GIESON’S WITH IRON HAEMATOXYLIN COUNTER STAIN

• elastic tissue in tube like sheets - elastic lamina
• elastic = black
• sm = mushroom
• collagen = pink