Material until Midterms

Question 1

Biologically active amines

Answer 1

GABA - neurotransmitter

Histamine - mediates allergic and inflammatory responses, gastric secretion and neurotransmission

Question 2

Catecholamines (biologically active amines)

Answer 2

Dopamine, norepinephrine and epinephrine are formed from tyrosine

Question 3

ECF & ICF electrolytes

Answer 3

ECF - Sodium & chlorine

ICF - potassium & HPO4 2-

Question 4

Clinical Relevance of Osmolality

Answer 4

high glucose results in fluid moving from ICF to ECF which causes neuronal dehydration that can manifest as a coma

Question 5

Colloidal osmotic pressure

Answer 5

Low levels of albumin induced increased water in interstitial space (edema)

Question 6

Scurvy

Answer 6

Vitamin C deficiency - leads to bleeding gums, haemorrhages, poor wound healing
Vitamin C is necessary to catalyse hydroxylation step of collagen modification (hydrolyses proline and leucine)

Question 7

Ehlers-Danlos Syndromes (EDS)

Answer 7

Can result from mutation of a gene for pro-alpha chains of collagen (Type I, III, or V collagen)

Can result from a hereditary defect related to one of the enzymes needed for correct collagen synthesis - propyl hydroxyls, lysyl hydroxyls, lysyl oxidase, pro collagen peptidase

Show hyper mobility of joints, hyper extensibility of skin, fragility of skin vascular vessel walls

Question 8

Osteogenesis imperfecta

Answer 8

brittle bone syndrome

Bones bend or fracture easily, defective collagen synthesis can result in less collagen or in abnormal collagen

Type I is the mildest form, Type II is the most severe form

Type III is severe, and type IV is most common - deforming but with normal sclerae

Clinical signs - weak bones, loose joints, low muscle mass, blue sclerae, short stature, hearing loss, respiratory problems, dentiogenesis imperfecta

Question 9

Osteogenesis Imperfecta Tarda (Type I)

Answer 9

In early infancy - long bone fractures after minor trauma
in adulthood - less fractures
blue sclerae - results from think sclera and appearance of uveal tissue (pigmented layer)
normal or near normal height
possibility of hearing loss in adulthood

Question 10

Osteogenesis Imperfecta Congenita

Answer 10

Leads to death in utero or neonatal due to respiratory problems

Can include underdeveloped lungs and an abnormal small and fragile rib cage

Question 11

Marfan syndrome

Answer 11

Results from an autosomal dominant hereditary defect in the gene that encodes fibrillin-1
Gene for elastin is normal

Characteristics - long limns, arachnodactyly, lens dislocation, aortic root dilation, pectus excavatum (abnormal formation of rib cage)

Question 12

Systemic Lupus Erythematosis

Answer 12

antibodies react with U1 RNA component of spliceosome, prevents normal splicing of mRNAs

Question 13

Beta-thalassemia

Answer 13

have mutations on beta-globin gene that generates additional splice sites within mRNA and results in frame shifts of premature stop codons as well as abnormal beta-globin protein

Question 14

Limb Girdle Muscular Dystrophy

Answer 14

mutation in calpain-3 gene that generates new splice site within exon 16 so a shorter mRNA is produced that is missing these codons so the protein is defective

Question 15

apo-b gene mutation

Answer 15

mRNA edited so premature stop codon is produced (UAA) leading to synthesis of shorter Apo-B48
editing is accomplished by cytidine deaminse enzyme

Question 16

A-I glutamate receptor editing in brain

Answer 16

base change results in codon change from glutamate to arginine which alters calcium permeability and impairs brain function

Enzyme involved - adenosine deaminase

Question 17

Trypanosome & Leshmania RNA editing

Answer 17

edit RNA by clueing with endonuclease, terminal uridyltransferase (add U) and RNA ligase

Question 18

Metabolic acidosis

Answer 18

Characterized by low bicarbonate and low pH
PCO2 is almost normal

Causes - increased production of non-volatile acids, increased loss of bicarbonate

Question 19

Metabolic alkalosis

Answer 19

Increased bicarbonate, pH is elevated, can ultimately increase PCO2 (compensatory mechanism)

Causes - vomiting, nasogastric suction, excessive consumption of antacids

Question 20

Respiratory acidosis

Answer 20

decreased pH and increase PCO2

decreased rate of respiration

Question 21

Steroid Receptor

Answer 21

Signal transduction by hormones that penetrate the cell membrane to gain access to their specific intracellular receptors

Example - testosterone, oestrogen, cortisol, vitamin D and vitamin A, thyroid hormone

Mechanism - up-regulating gene expression at level of DNA transcription

Question 22

Hormones that work via intracellular receptors

Answer 22

Cortisol, aldosterone, thyroid hormone, vitamin D3, retinoids

Question 23

Gated-ion channels

Answer 23

Mechanism - receptor linked to ligand ion channel - binding causes channel to open and allows rush of ions

Cell surface receptor

Examples - nicotinic Ach receptors of muscle or nerve, GABA, glycine receptors in CNS

Question 24

Receptor Tyrosine Kinase (Catalytic receptor)

Answer 24

Mechanism - receptor is the enzyme with kinase activity and it’s specific for tyrosine residues; able to phosphorylate specific residues and convert them to phospho-tyrosine

Cell surface receptor

Examples - insulin

Insulin receptor - tyrosine kinase - Intracellular effectors - IRS, adaptors, enzyme effectors
Cellular responses - increased glucose uptake, regulation of transcription, activation of enzyme: covalent modification and up regulation

Question 25

G protein coupled receptors (GPCR)

Answer 25

External ligand binding to receptors (R ) activates intracellular GTP-binding protein (G) which regulates an enzyme (Enz) that generates an intracellular messenger, X.