Unit 4 - Histology

Roles of blood vessels

transport blood (hormones, oxygen, nutrients), circulation of white blood cells, removal of waste

tunica intima

internal layer of blood vessels consisting of endothelium and connective tissue

tunica media

middle layer of blood vessels consisting of smooth muscle cells

tunica externa (adventitia)

outer layer of blood vessels consisting of connective tissue

tunica intima

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tunica media

what is this (black arrow)

tunica externa

what is this (blue arrow)

elastic lamina

elastic sheets that may be present in blood vessels, situated between the three layers; role of support and barrier

capillaries

transport blood between arteries and veins, and distribute nutrients to organs

elastic arteries

receive blood from heart; consist of lots of elastic fibers; expand and recoil to allow for uniform blood flow

elastic arteries

what is this (wrinkles)

pericytes

supportive cells of capillaries

pericyte

what is this

continuous capillary

endothelial cells with tight junctions and basement membrane; only allows for passage of small, select molecules (nervous system, skin, and lungs)

fenestrated capillary

endothelial cells with fenestrations within the membrane allowing for more molecules to pass (kidneys, intestine)

sinusoid capillary

fenestrations without membranes between endothelial cells to allow proteins and blood cells to pass through (liver, bone marrow, spleen)

capillary bed

interwoven network of capillaries that supplies an organ

baroreceptors

monitor blood pressure in arteries

chemoreceptors

monitor changes in blood composition of O2, CO2, pH in arteries

blood components

erythrocytes, leukocytes, plasma

plasma components

water, ions, metabolites, albumin, clotting factors

myeloid cells

precursor cell for blood cells, found in bone marrow

erythrocytes (red blood cells)

no nucleus and very little organelles; filled with hemoglobin. shape maximizes gas exchange and provides flexibility to pass through capillaries. life span of 120 days

hemoglobin

iron-containing protein that carries oxygen

platelets (thrombocytes)

small, non-nucleated cells that promote blood clotting and wound repair to prevent blood loss. contain granules and have a life span of 10 days

alpha granules

contain a clotting agent and growth factors

delta (dense) granules

contain serotonin and calcium

pseudopodia

extended by activated platelets; enable adherence to neighboring platelets and other cells, and increases plasma membrane surface area

antiplatelet

decrease platelet aggregation

anticoagulant

decrease fibrin production

leukocytes (white blood cells)

cells of the immune system; destroy pathogens by phagocytosis; contain granules that contain digestive enzymes and cytokines (hormones)

antigen

molecule that stimulates the immune system (pathogen, part of a pathogen, dead cell…)

antibody

receptor on a leukocyte from adaptive immunity that binds to an antigen

granulocytes

abundant granules in their cytoplasm, often involved in innate response

agranulocytes

fewer or no granules in their cytoplasm, mostly involved in adaptive response

neutrophils

short lived cells that are part of the non-specific immune response. first type of leukocytes to arrive at sites of infection during the inflammatory response. they are involved in bacterial infection and immune disease

neutrophils

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eosinophils

small percentage of leukocytes that live days to weeks in tissues and are part of the nonspecific response; involved in allergic reactions and destructions of large parasites

eosinophils

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basophils

less than 1% of leukocytes with a short life span, involved in the non specific immune response; involved in allergic reactions

basophils

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monocytes (agranolocytes)

largest white blood cells that live multiple days in blood until they enter tissues and become active; phagocytosis and antigen presentation; may develop into macrophages or dendritic cells, which activate the adaptive immune response

monocyte

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macrophage

respond to viral, microbial, and fungal contamination as well as cancer cell propagation; contain secretory granules used for phagocytosis

lymphocytes

30 percent of immune cells, involved in adaptive immunity; vary in life span from a few days to many years

b lymphocytes

humoral response; mature in bone marrow, respond to extracellular pathogen; may mature further into plasma cells

t lymphocytes

cell mediated immunity; mature in thymus, respond to intracellular pathogens

NK cells

mature in all lymphoid tissues, non-specific

hematopoiesis

production of all blood cells

hematopoietic stem cell

precursor of all blood cells

erythropoiesis

production of red blood cells

leukopoiesis

production of white blood cells

thrombopoiesis

production of platelets

bone marrow

the site of synthesis of all formed elements of the blood

red bone marrow

produces all blood cells; also contains some adipose cells and connective tissue

yellow bone marrow

stores adipose tissue, but can produce red blood cells in emergencies

sinusoids

allow newly formed blood cells to pass through them and enter the circulation

thymus

primary lymphoid organ developed from epithelial cells; site of T cell maturation

capsule

connective tissue that surrounds the thymus

trabeculae

extensions of the capsule that partition the thymus into lobules

cortex

darked outer portion of each lobule, contains immature T cells

medulla

central area of lobules containing mature T cells

epithelial reticular cells

present in the medulla; protect and favorize maturation; over time, come together and condense to form larger Hassall’s corpuscles

Role of kidneys

filter the blood to remove excess water, ions, molecules, and cellular waste through formation of urine; also secretion

renin

enzyme important for regulation of blood pressure

erythropoietin

glycoprotein that stimulates erythrocyte production

role of urinary system

transport, store, and remove urine from the body

renal cortex

outer region of the kidney

medulla

central region of the kidney containing renal pyramids

minor calyx

pyramids drain into this structure

major calyx

when two or more minor calyces join

renal pelvis

joining of major calyces; forms the ureter

renal capsule

thin connective tissue that covers the kidney

renal lobes

multiple lobes that make up the kidneys; each lobe contains a renal pyramid and associated cortex

nephron

functional unit of the kidney; produces urine in a renal lobe and drains into the minor calyx of that lobe

cortical nephrons

almost entirely in the cortex with a short loop of Henle; general urine production and solute reabsorption

juxtamedullary nephrons

renal corpuscle is in the cortex, but loops of Henle are long and extend into deeper portions of the medulla; critical role in urine concentration

secondary capillary beds

pertitubular cappillaries and vasa recta; role in reabsorption and secretion

medullary ray

straight portions of the nephron (limb loops of Henle, collecting ducts)

pars convoluta

coiled parts of the nephron (corpuscle, PCT, DCT)

podocytes

epithelial cells that surround the capillaries of the corpuscles

mesangium

connective tissue that connects the capillaries of the glomerus

capsular space

space between the glomerulus and parietal cells

pedicels

extensions of podocytes; allows them to interlock, with filtration slits in between

juxtaglomerular apparatus

made of macula densa and juxtaglomerular cells; regulates blood volume by releasing hormones

erythropoietin

increases the rate of production of red blood cells in response to falling levels of oxygen in the tissues

when renin is released

blood pressure drops or there is not enough sodium in the blood

Renin-angiotensin process

renin converts angiotensin into angiotensin I. becomes active when converted to ang. II by ACE from the lungs; ang II increases blood pressure to stimulate release of aldosterone from the adrenal cortex; aldosterone stimulates Na+ reabsorption

medullary rays

what is this (yellow outline)

pars convoluta

what is this (in between outlines)

proximal convoluted tubules

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distal convoluted tubules

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descending loop of henle

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ascending loop of henle

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collecting ducts

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collecting duct

what is this (green)

thin loop of henle tubule

what is this (yellow)

vasa recta

what is this (black)

corpuscle

what is this

podocytes

what is this (blue)