Equine Limb Flashcards
What makes up the extracellular matrix of a tendon?
Extracellular matrix which contains glucosaminoglycans (GAGs) which are negatively charged and attracts positively charged sodium ions (Na) which causes water attraction. This confers the lubricative property of GAGs.
What is desmitis?
Describle fibril formation.
- Procollagen is present in a tenocyte
- 3 pro-α chains together, forming a right handed triple helix
- Exocytosis of procollagen (collagen precursor)
- Once outside the cell, procollagen molecule has the pro-peptides cleaved from the N- and C- terminals by membrane bound enzymes to form tropocollagen
- Vitamin C (ascorbic acid) is responsible for the hydroxylation (addition of hydoxy radical) of proline and lysine to enable cross-linking of collagen molecules
- Tropocollagen polymerizes to from fibrils
Describe the arragment of a tendon fibre from smallest to largest unit.
- Tropocollagen
- Tripple helical collagen molecule
- Collagen fibril
- Collagen fibre
- Primary fibre bundle (subfascilcle)
- Secondary fibre bundle (fascicle)
- Tertiary fibre bundle (fascicle)
- Tendon unit
Why is the injury of a tendon more serious if it occurs in the region of a sheath?
The production of scar tissue will compromise the function of the synovial sheath
What is a morphological quality of a young lymphocyte as compared to a mature lymphocyte?
Being larger than a mature cell
What is e-cadherin?
- Transmembrane protein involved in the structural integrity of most epithelial cell layers
- Calcium-dependent cell-to-cell adhesion protein
- Phosphorylated intracellular domain
- Gene is a tumour suppressor gene
- Loss of expression associated with metastasis of some tumour cells
- Membranous expression in the periphery of the cells
- Can be measured using a dye
Describe the immediate physiological change that occurs in the cardiovacular system at high altitude for low altitude mammals.
- Low partial presure of atmospheric oxygen is detected in the lungs
- The lung blood vessels vasoconstrict
- The right ventricle of the heart has to pump harder to overcome the resistance of the vascoconstricted pulmonary arteries
- The right ventricle of the heart hypertrophies because of the increased muscular strain
What are central chemoreceptors and how do they function to maintain homeostasis?
- Central chemoreceptors (CCRs; medullary chemoreceptors)
- Found on the ventral surface of the medulla
- Bathed in cerebrospinal fluid and quickly respond to increases in arterial carbon dioxide by way of blood hydrogen ion concentration- blood becomes more alkaline
- Decreased pH causes CCRs to synapse directly with respiratory regulatory centres
- Depth and rate of breathing is increased (hyperventilation) to flush carbon dioxide from the blood to restore pH to homeostatic levels
What are some unique aspects of avian oxygen uptake?
- Unidirectional flow of air which moves continuously throughout the air sacs
- Birds are more efficient gas exchange
How is glucose processed in the kidneys by a normal individal?
Glucose is re-absorbed into circulation in the proximal convoluted tubule (PCT)
Should be 100% recovered during re-absorption in the PCT
Glucose is re-absorbed into blood by an apical secondary active transporter driven by sodium (sodium-glucose) ion and a basolateral uniporter into the blood
Can occur in a limited fashion- glucose will appear in the urine if there is too much glucose in the blood
Taken up by Secondary process in the tubule epithelial cell from the lumen
Sodium in flow at apical surface in symport with molecules of type A (A (amino acids or glucose) exists at the basolateral surface)
Sodium is flowing from high concentration to low concentration into the proximal tubule cell
A is co-transported into proximal tubule cell with sodium
Describe the homeostatic response to hypervolaemia.
In the case of hypervolamemia (high blood volume), stretch receptors release ANP ion from atria which suppresses sodium reabsorption in kidney (DCT) and water is lost in the urine osmotically
Atrial natriuretic peptide (ANP)
powerful vasodilator, and a protein (polypeptide) hormone secreted by heart muscle cells
Down-regulates channels of sodium and sodium-potassium ATPase in Principal cells of the distal convoluted tubule (DCT)
Suppresses sodium re-absorption which osmotically draws water
Dilates afferent arteriole and constricts efferent arteriole in the glomerulus
Increases the GFR- increases sodium filtration into the nephron
Describe the homeostatic response to hypovolaemia.
Hyperosmotic plasma detected by osmoreceptors in hypothalamus
Hypothalamus causes secretion of ADH by posterior pituitary
ADH actions
cAMP-mediated stimulation of cells of collecting duct to insert performed aquaporin-2 into apical membrane
Stimulates insertion of urea channels in the nephron collecting duct to allow urea exit and increase hypertonicity of interstitium
Water is reabsorbed into hypertonic medulla
Formation of a concentrated urine (high concentration of urea- massive increase
What side of the body is the stomach on in a dog?
Left
Describe Type IV Hypersensitivity.
CD4+ helper T cells recognize antigen in a complex with Class II major histocompatibility complex. The antigen-presenting cells in this case are macrophages that secrete IL-12, which stimulates the proliferation of further CD4+ Th1 cells. CD4+ T cells secrete IL-2 and interferon gamma, further inducing the release of other Th1 cytokines, thus mediating the immune response. Activated CD8+ T cells destroy target cells on contact, whereas activated macrophages produce hydrolytic enzymes and, on presentation with certain intracellular pathogens, transform into multinucleated giant cells.
Cell-mediated immune
Delayed cell-mediated
Mediated by antigen-specific T cells and macrophages
extension of normal T cell mediated immune responses, where infections are eliminated via T cell cytotoxic action and activation of macrophages
Slowly developing inflammatory response
24-48 hours after contact with antigen in a sensitized individual
Amyloid
