EOS Flashcards
What are the main functions of epithelium?
Protection - selective barrier Absorption Excretion/Secretion Containment Receptors for special senses
What is the function of simple squamous epithelium?
Weak barrier - allows some exchange.
What is the function of endothelium and mesothelium?
Endothelium - exchange and barrier.
Mesothelium - exchange and lubrication.
What are hepatocytes?
Simple cuboidal epithelium.
Secrete bile.
What are enterocytes?
Simple columnar epithelium within SI, caecum, colon.
Absorption and secretion.
What are the two modes of secretion of sweat glands?
Merocrine - exocytosis of vesicles, only in hairless skin, secretes water and electrolytes.
Apocrine - exocytosis of part of cell with lipid droplet, secrete serous fluid (mostly water).
Simple cuboidal/columnar secretory portion, stratified cuboidal ducts.
What is the mode of secretion of sebaceous glands?
Holocrine - programmed cell death and lysis.
Same epithelium as sweat glands.
What kind of glands are sweat glands?
Simple coiled tubular.
What kind of glands are sebaceous glands?
Branched acinar.
Cuboidal cells for secretory portion, stratified squamous duct.
Where will you find myoepithelial cells? What do they do?
Around alveoli/acinus and ducts - facilitate secretion by contracting.
Sweat glands.
What are the functions of integument?
Barrier Regulate temperature and hydration Mechanical support Immunity Neurosensory reception Endocrine Metabolism
What is the epidermis?
Skin consisting of stratified squamous epithelium (layers).
Keratinised - keratinocytes.
What is a primary hair follicle?
Deep in dermis, larger.
Arrector pilli muscle
Sebaceous and sweat glands empty into follicle.
What is a secondary hair follicle?
Small, root near surface.
No glands or muscle.
What are the 4 main tissue types?
Connective
Muscle
Nervous
Epithelium
Connective tissue is a matrix of….
Fibres
Ground substance
Cells - fibrocytes/blasts, adipocytes, mast cells, macrophages, immune cells.
What is the function of collagenous fibres?
Provide stiffness and rigidity
What is the function of irregular connective tissue?
Decreased stretching, maintains shape.
Describe the matrix of hyaline cartilage.
Thin peri cellular matrix, adjacent territorial matrix (fine collagen II - directly surrounds lacunae, dark), interterritorial matrix (coarse collagen II).
What is the function of hyaline cartilage?
Cushioning
Foetal skeleton, growth plates, articular cartilage, airways.
What is the function of bone?
Support Protection of vital organs Facilitates locomotion Stores Ca Harbours Haematopoietic tissue
What do osteoblasts do?
Secrete bone matrix
What do osteocytes do?
Maintain bone matrix
Describe the process of endochondral ossification.
Bone develops from cartilaginous model.
1) chondrocytes proliferate in columns
2) cartilage matrix mineralises
3) chondrocytes die - apoptosis
4) blood vessels invade. Also osteoprogenitor cells.
5) osteoblasts deposit bone on cartilage matrix - primary trabeculae.
6) osteoclasts and blasts remodel primary trabeculae to secondary.
What are the different cells present within blood?
Erythrocytes
Leukocytes - granulocytes (neutrophils, basophils, eosinophils), monocytes, lymphocytes.
Plasma cells
What is the function of neutrophils?
Phagocytose foreign matter, kill bacteria.
What is the function of eosinophils?
Kill metazoan parasites, modulate hypersensitivity reactions.
What is the function of basophils?
Anti-coagulant
Vasodilatory and chemotactic.
What is the function of monocytes?
Macrophages en route to tissues.
Phagocytosis.
What is the function of lymphocytes?
Adaptive immunity (effect and regulate).
What is the function of platelets?
Facilitate haemostasis - contain clotting factors.
What are the functions of lymph nodes?
Filter antigens from lymph.
Produce lymphocytes.
What is the function of trabeculae?
Structural support
What is the function of stroma?
Support parenchyma
What is the function of primary and secondary lymphatic nodules?
B cell area
What is the function of diffuse lymphatic tissue?
T cell area
What does a lymph node cortex contain?
Lymphatic nodules
Diffuse lymphatic tissue
What can be found in lymph node medulla?
Lymphocytes Plasma cells Macrophages All within reticular fibres. Cords between sinuses (lined by endothelium like reticular cells).
Describe the flow of lymph through a lymph node.
Afferent lymphatics (capsule) - subcapsular - trabecular - medullary sinuses - efferent lymphatics (hilus) Opposite flow in pigs.
What are the functions of lymphatic nodules?
Primary - no germinal centre - contain naive B cells.
Secondary - germinal centre (follicular dendritic cells, lymphoblasts, macrophages) - mature B cells
What is the function of the spleen?
Filters, removes and breaks down old erythrocytes Secondary lymphatic organ Produces T and B lymphocytes Stores erythrocytes, platelets and iron Removes blood parasites
Why would the spleen have smooth muscle within its capsule?
Splenic contraction during exercise
What is the parenchyma of the spleen?
White pulp - produces immune cells
Red pulp - surrounds white pulp
What are the components of splenic white pulp?
Peri arteriolar lymphatic sheaths - arteries surrounded by T and B lymphocytes.
Lymphatic nodules
Marginal zone - between red and white pulp, macrophages and B cells.
What are the components of red pulp?
Cords - erythrocytes, macrophages, lymphocytes, plasma cells within reticular connective tissue. Sheathed capillaries (macrophages surrounding dead end capillaries).
Sinuses - discontinuous endothelium and basal lamina supported by reticular fibres.
What is the order of flow of blood through the spleen?
Splenic artery - trabecular arteries - artery of white pulp (PALS) - nodular artery - pulp arteriole (red pulp) - sheathed capillary - splenic sinus - trabecular vein
What is the functional unit of the nervous system?
Neuron
What is the function of dendrites?
Carry nerve impulses to cell body
What is the function of an axon?
Transmit impulses from cell body
What are the functions of astrocytes?
Structural support, energy source (store glycogen), regulate water and ions, scavenge waste and NTs, present antigens, tissue repair, BBB.
What are oligodendrocytes known as in grey matter?
Satellite Cells
What is the function of microglia?
CNS macrophages
What is the function of ependymal cells?
Regulate movement of fluid, ions and micromolecules between CSF and neuropil.
Line ventricles and central canal of spinal cord.
Simple cuboidal/columnar
What comprises peripheral grey matter?
Cell bodies of neurons and glial cells, neuropil (axons, dendrites, processes of glial cells).
What comprises central white matter?
Dense tracts of myelinated axons and glial cells.
What comprises the 3 layers of the cerebellum?
Molecular - mostly neuropil
Purkinje - major input/output neurons
Granular - densely packed small neurons.
What are the 3 meninges?
Dura mater - DICT, vessels and nerves (barrier and protection).
Arachnoid - fibrocytes and collagen. Space between here and Pia mater filled with CSF.
Pia mater - thin, highly vascular LCT.
What are the functions of the tunica mucosa?
Protection, absorption, propulsion, lubricant.
Consists of epithelium, lamina propria (LCT, immune cells, mucous glands, vessels, nerves), muscularis (not always present).
What are the functions of the tunica submucosa?
Connection, nutrient supply, exchange, immunity.
Contains LCT, vessels, meissners plexus, submucosa glands, lymph nodes.
What are the functions of tunica serosa/adventitia?
Structure
Serosa produces lubricant (mesothelium-simple squamous).
Describe the characteristics of the 4 layers of the oesophagus?
Mucosa - stratified squamous, keratinised in some species, thin smooth muscle.
Submucosa - LCT, submucosal glands.
Muscularis - smooth, skeletal in dogs and ruminants.
Outer surface - adventitia, serosa (distally).
Describe the 4 layers of the stomach.
Mucosa - simple columnar, chief, parietal, goblet cells, gastric pits and glands (lamina propria).
Submucosa - thin LCT.
Muscularis - smooth inner, outer and middle oblique.
Serosa
Describe the 4 layers of the SI?
Mucosa - simple columnar (enterocytes), goblet cells, brush border (micro villi), crypts and villi.
Submucosa - brunners glands (mucous), GALT, ganglions.
Muscle - smooth m. Inner and outer, myenteric ganglia.
Serosa
What are the four layers of the LI?
Mucosa - simple columnar, immune cells
Submucosa - peyer’s patches (lymph nodules).
Muscle - smooth inner and outer.
Serosa, adventitia in rectum.
What is the function of the stomach?
Protein digestion
What are the functions of each of the glandular stomach regions?
Cardiac - produces mucous
Fundic - produces HCl and pepsin.
Pyloric - produces mucous
Describe gastric glands, cardiac and pyloric glands.
Short, simple, branched, coiled and tubular.
Simple cuboidal epithelium.
Goblet cells secrete mucous.
Describe the gastric glands of the fundic portion of the stomach?
Simple, branched, straight, tubular.
Mucous neck cells - columnar
Chief cells - cuboidal/pyramidal, zymogen granules, secrete pepsinogen.
Parietal cells - less, larger, eosinophilic cytoplasm, secrete HCL
What is the function of the rumen?
Absorption of VFAs
Are their glands present in the rumen submucosa?
No
What are the roles of enterocytes?
Absorption.
What is the role of intestinal glands?
Simple, tubular, secrete Na into base of villi, columnar.
Cl and water follow Na.
They are an invagination of epithelium.
What is the function of lacteals?
Transport of absorbed fats via lymphatics.
What are paneth cells?
Ruminants, horses, rodents, primates.
Pyramidal, eosinophilic granules that secrete peptidases and lysozymes. Present within intestinal glands.
What is the role of the LI?
Absorption of water, electrolytes, vitamins.
Secretion of mucous.
What are the functions of the liver?
Synthesis and secretion - glucose, bile, albumin.
Storage - lipids, glycogen, vitamins A and B.
Transformation - oxidation, hydrolysis, conjugation of toxic compounds.
Excretion - bile, bile pigments.
Haematopoiesis - prenatal
What is the function of hepatocytes?
Modify elements in blood.
Secrete bile.
What is the order of blood flow in the liver?
Portal vein (75%) - interlobar portal venules - distributing venules - sinusoids - terminal hepatic venules (central vein) - hepatic vein Hepatic artery (25%) - interlobar hepatic arterioles - interlobar capillaries - sinusoids - terminal hepatic venule - hepatic vein
Flows towards centre
Describe the flow of bile through the liver.
Hepatocytes - canaliculus - bile duct - interlobar duct - intrahepatic duct - extra hepatic duct - gall bladder/duodenum
Away from centre
Discuss hepatic sinusoids.
Carry blood from interlobar septa to terminal hepatic venule.
Discontinuous fenestrated endothelium - allows movement of large molecules.
Kuppfer cells - sinusoidal macrophages (filter pathogens from blood).
What is the functional unit of the liver? Other than hepatocytes.
Acinus.
Centri-acinar zone - gluconeogenesis
Mid zone
Periacinar zone - glycolysis, lipogenesis.
What is the function of the pancreas?
Secrete digestive enzymes.
What kind of glands is the exocrine pancreas?
Compound acinar.
What is the flow of enzymes through the pancreas?
Intercalated - intralobar - inter lobular - pancreatic ducts.
What do Centro-acinar and intercalated duct cells secrete in the pancreas?
HCO3, water - increase pH of duodenum
Simple squamous epithelium
What is the function of the endocrine pancreas?
Islets if Langerhans
Regulate blood glucose
Secrete somatostatin
What are the layers of the Adrenal cortex? What is their function?
Zona glomerulosa/arcuata - secretes mineralocorticoids.
Zona fasciculata - cords of cuboidal/columnar cells, lipid droplets, produces cortisol.
Zona reticularis - lipofuscin, produces androgens (testosterone, oestrogen).
What is the role of the adrenal medulla?
Endocrine cells (chromaffin cells-modified postganglionic sympathetic neurons) that produce adrenaline and noradrenaline. Cells are in cords separated by sinusoidal capillaries.
What are parafollicular cells and what is their function?
Modified neurons in basal lamina of thyroid follicle. Light cytoplasm and secretory granules, secrete calcitonin (regulates Ca in blood).
What are the stages of T3 and T4 production by the thyroid cell?
- Iodine absorbed on basal side from capillary, moves through cell to colloid.
- Thyroglobulin blebs off apical cell surface into colloid and gets iodinated.
- Thyroglobulin reabsorbed by apical surface of follicular cell.
- Converted to thyroxine (T4) and triiodothyronine (T3) in presence of TSH. Secreted into capillary.
What is the role of the thyroid?
Regulates metabolism.
What are the functions of the kidney?
Remove metabolic waste.
Regulate fluid/water balance and acid/base balance.
Blood pressure regulation.
Secretes/activates hormones (peritubular capillary endothelium=erythropoietin for haematopoiesis, juxtaglomerular apparatus=renin; increases blood pressure, PCT=vitamin D activation; increases Ca absorption).
What is the functional unit of the kidney? What are its components?
Nephron.
Corpuscle, PCT, DCT, loop of hence, collecting duct.
What does the filtration membrane in the kidney comprise of?
Endothelial cells of glomerular capillary and foot processes of podocytes.
Describe the proximal convoluted tubule and its location.
Located in cortical labyrinth.
Simple cuboidal with brush border.
Reabsorption - water, Na, Cl, AA, glucose, HCO3.
Describe the proximal straight tubule and its location.
Medullary rays and outer medulla.
Simple cuboidal with minimal brush border.
Reabsorption - water, Na, Cl, AA, glucose, HCO3 (same as PCT).
Describe the loop of henle and its location.
Thin segment in inner medulla.
Simple squamous
Absorbs water (descending), Na and Cl (ascending).
Describe the distal straight tubule and its location.
Medullary rays and outer medulla.
Simple cuboidal
Forms macula densa
Absorbs salts.
Describe the distal convoluted tubule and its location.
Cortical labyrinth
Simple cuboidal, no brush border.
In presence of aldosterone it reabsorbs salts.
In presence of ADH is reabsorbs water.
Describe the collecting duct and its location.
Tubules in cortical labyrinth, ducts in medulla.
Simple cuboidal.
Light and dark cells.
Reabsorbs water in presence of ADH.
What are the components of the renal stroma?
LCT - collagen, fibrocytes. Interstitial cells - stellate (secrete PGE2 - vasodilation) Blood vessels. Lymphatics Nerves
Outline blood flow through the kidney.
Renal artery - interloper artery - arcuate artery - interlobular artery - afferent arteriole - glomerular capillary - efferent arteriole - peritubular network - interloper vein - arcuate vein
Where will you find urothelium and what is it?
Pseudostratified epithelium where every cell touches the basement membrane.
Renal pelvis, ureters, bladder, urethra.
What are the functions of the respiratory system?
Conduction of air
Filtration/humidification of air
Exchange of gas
Removal of xenobiotics
Describe the trachea.
Respiratory epithelium - psuedostratified columnar.
Cilia
Goblet cells
Migratory cells - lymphocytes, leukocytes, mast cells.
Clara cells - protection, detoxification and regeneration.
Submucosa - LCT, migratory cells, fibrocytes, seromucous tubuloacinar glands.
Cartilage joined by tracheal muscle.
Describe the bronchi.
Pseudostratified columnar Less goblet cells, more clara cells. Less glands. Less cartilage, more smooth muscle. BALT - bronchus associated lymphatic tissue.
Describe bronchioles.
Primary, secondary, terminal, respiratory Simple columnar/cuboidal Cilia Clara cells - no cilia No cartilage or submucosal glands.
What are the four layers of the heart and some of their features?
Endocardium - endothelium, DICT, smooth m., purkinje fibres, vessels, LCT.
Myocardium - thick, myocytes inserting into cardiac skeleton (DICT or bone). Endomysium of LCT, vessels, nerves and purkinje fibres.
Epicardium - LCT, adipose, coronary arteries and veins, nerves. Mesothelium secreting pericardial fluid.
Pericardium
What are the characteristics of atrio-ventricular valves?
Stratum spongiosum (near atria) - vascular fibroelastic CT. Stratum fibrosum (near ventricles) - avascular CT, extending from cardiac skeleton.
What are the characteristics of semi-lunar valves?
Avascular fibrous CT, some fibrocartilage.
What are purkinje fibres?
Modified cardiac myoctyes.
Present in ventricle walls.
What is the function of the cardiac skeleton?
Anchors myocardium
What are the 3 layers of blood vessels?
Tunica intima - endothelium, basal lamina, sub endothelium, internal elastic membrane.
Tunica media - smooth muscle, fibroelastic CT, external elastic membrane.
Adventitia - CT, vasa vasorum and nervi vasorum (unmyelinated sympathetic nerve fibres).
What are the functions of endothelium?
Selectively permeable - O2 and CO2 Clot inhibition - prevents clotting while alive. Secretes growth factors Vasodilation - NO, PGI2 Vasoconstriction
What are the characteristics of elastic arteries?
Maintain BP.
Very thick intima with smooth muscle.
Very thick media with fenestrated elastic fibres.
What are the characteristics of muscular arteries?
Intima - thinner sub endothelium, thick internal elastic membrane (diffusion-fenestrated).
Media - very thick smooth muscle, more collagen, less elastin.
What are the characteristics of arterioles?
Intima - fenestrated internal elastic membrane
Media - no external elastic membrane, muscle not too thick.
Adventitia is very thin.
What are the 4 types of capillaries?
Fenestrated
Porous
Sinusoids
Continuous
Describe post capillary venules?
Continuous endothelium
Junctions between cells more permeable/sensitive to chemical mediators.
Immune cells leave blood here.
What are the characteristics of veins?
Store blood volume.
Intima has semilunar valves
Internal elastic membrane in larger veins.
Media has several layers of smooth muscle and CT.
