Physiology Flashcards
(21 cards)
Immunoglobulins – what are they?
- Bind to antigens (toxins, proteins on pathogen surfaces)
- They’re basically antibodies
- Label for destruction by immune system
- Specificity determined by variable regions
- Diff types: IgG, IgM, IgA, etc
Function of DNA polymerase
• Reads template strand from 3’ to 5’ (daughter strand from 5’ to 3’)
DNA replication
• Topoisomerase unwinds DNA slightly
• DNA helicase can break hydrogen bonds and separate strands
• Single strand binding protein coat single DNA strands to prevent re-annealing
• DNA primase synthesises short RNA primer to get DNA polymerase started
• DNA polymerase reads 3’ to 5’ strand to create daughter cell 5’ to 3’
• On the 5’ to 3’ strand, synthesis can’t occur the same way:
o DNA primase adds RNA primers, allow nucleotides to be added in fragments by DNA polymerase (OKAZAKI FRAGMENTS)
o DNA polymerase can then add these together into a continuous strand
Autocrine communication
• Chemical released from cell to extracellular fluid – goes back to same cell
Paracrine communication
- Chemical messengers between cells
- Local communication
- E.g Acetylcholine
Endocrine communication
- Produce and secrete hormones
- Into BLOOD
- Hypothalamus => dopamine
- Anterior Pituitary => FSH, LH, TSH
- Posterior pituitary => oxytocin, ADH/vasopressin
Exocrine communication
• Secretion into ducts then organ
Positive Feedback Loop
- Signal amplification
* E.g. clotting cascade, oxytocin during childbirth
Negative Feedback Loop
- Main way endocrine hormones controlled
* E.g. blood sugar, temperature, blood pressure, thyroid regulation
Thyroxin regulation
• Thyroxin sensed by pituitary – if too much thyroxine => pituitary stops producing TSH
Primary hypothyroidism
- Thyroid producing too little thyroxine
- Not enough to induce negative feedback in pituitary
- Pituitary continues producing TSH
- Blood test: high TSH, low T4
Secondary hypothyroidism
- Pituitary not producing enough TSH
- Thyroid not stimulated to produce thyroxin
- Blood test: low TSH, low thyroxin
Water distribution in the body
60% of 70kg man is water - 42L • Intracellular fluid 40% 28L • Extracellular fluid 20% 14L o Intravascular 3L (plasma) o Interstitial 11L (around cells)
Water regulating hormones
- ADH
- Aldosterone
- Atrial natriuretic peptide
Osmolality vs. Osmolarity
- Osmolality - No. of dissolved particles per kg
* Osmolarity – no. of dissolved particles per Litre
Water lost from ECF (water deprivation or increase in solute) results in…
- Increase in osmolality in ECF
- Change detected by osmoreceptors in hypothalamus
- Stimulate thirst centres in hypothalamus - elderly get reduction
- Released ADH (anti-diuretic hormone) from posterior pituitary
- ADH increases water reabsorption in collecting ducts in kidney to dilute solute
Renin-Angiotensin-Aldosterone System
leads to reduction in renal perfusion, increase in BP
Stimulates release of renin (enzyme) from kidneys
Renin catalyses angiotensinogen (liver) into angiotensin I
ACE hormone produced mostly by lungs converts Angiotensin I to II
- Stimulates Na+ and water retention, K+ loss
- Indirectly stimulate release of ADH
- Arteriolar vasoconstriction - increase blood pressure
Negative feedback mechanism => renin secretion decreases
Types of Oedema
• Inflammatory
§ Large albumin able to move out of cell => lose oncotic pressure and water not drawn back into venous end
• Venous
§ Congestive cardiac failure - increased pressure at venous end
§ Water being pushed out - hydrostatic > oncotic
• Lymphatic
§ Disease of lymph node or removal - impaired water reabsorption into lymphatics
•Hypoalbuminaemic
§ Albumin low bc of sever malnutrition
§ Sever diarrhoea - protein losing enteropathy?
§ Liver problems which makes protein
§ Lose oncotic pressure so water not reabsorbed - moves into interstitial space
Difference between transudate and exudate pleural effusion
Pleural effusions - diff fluids enter pleural cavity
Transudate
• Change hydrostatic pressure (e.g. congestive heart failure)
• Protein conc is lower than norm, intravascular fluid moves out of vessel
• Venous effusion, fluid leaks to pleural space
Exudate
• Inflammatory e.g. Pneumonia, lupus
• Vessels dilate, endothelial cells more spaced out so fluid and protein in the effusion
Test?
• Light’s criteria, look for presence of protein, cholesterol, glycerol (large protein) know its exudate
Dietary energy sources
Carbohydrates - 4kcal/g
Proteins - 4kcal/g
Alcohol - 7kcal/g
Lipid - 9kcal/g
Methods of generating ATP
glycolysis Kreb's cycle Oxidative phosphorylation Substrate level phosphorylation Electron Transport chain Beta oxidation
