Basics Flashcards by Charlotte Underwood

3 components to the negative feedback systems

Detectors
Comparator (compare variable against set point)
Effector

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Initiation of the action potential is an example of?

Positive feedback

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Function of peroxisomes

Metabolise waste

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Function of golgi apparatus

Modify proteins

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Endoplasmic reticulum fx

Rough

Smooth

Assoc. with ribosombes to make secretary and membrane proteins

Makes lipids and store Ca2+

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Potassium concentration inside cells?

150 mmol/L

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Where is K+ filtered in the kidney?

glomerulus

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What happens to K+ in the proximal tubule?

Approx 65-70% is reabsorbed down a conc gradient / solvent drag

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How does Aldosterone regulate K+?

Increased K+ detected in the extracellular fluid of the adrenal cortex

Promotes synethesis and insertion into basolateral membrane (DCT and collecting duct) of Na+/K+ ATPase channels

Increases Na+ absorption and K+ secretion

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How does pH influence K+ excretion?

High pH (alkalosis) promotes apical K+ channels and Na/K ATPas activity -> increase K+ secretion

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Action of ADH on K+

reduces urinary flow rates but conversely stimulates apical K+ channel activity

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Action of Mg3+ on K+ ?

Intracellular Mg can bind and block K+ channels therefore inhibiting K+ secretion

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How is K+ reabsorbed in the ascending loop of henle (and how much)

20% reabsorbed by K/Cl co tranasporter

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Which bits of the kidney adjust k+ when diet varies?

DCT and collecting duct

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In DCT and collecting duct which cells secrete K+ back out of the blood into the lumen?

Principal cells

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What parameter has the biggest effect on resistance (and therefore flow) in a tube?

Radius

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Laminar vs turbulent blood flow ?

Laminar flow occurs when the flow is slowest near the vessel wall (where there is more friction) and fastest in the center of the blood vessel (where there is less friction). Turbulent flow describes a situation in which blood flows in all directions.

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How does a dilated heart obtain the same (or similar) ventricular pressure?

Has to develop more wall tensin

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Where do sympathetic preganglionic neurons originate?

Lateral horns of segement T1-L2 in the spinal cord

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Where do PARAsympathetic preganglionic neurons originate?

Brain stem, run in cranial nerves III, VII, IX and X, and from 2nd/3rd sacral segments of the spinal cord

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Parasympathetic action:

Pupils

Salvia

Constrict

Increase production

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Parasympathetic action:

Bronchi

Decrease

Constrict

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Parasympathetic action:

Digestive organs

Pancreas gall bladder

Stimulate all

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Parasympathetic action:

Urinary bladder

Genitals

Contracts

Stimulates erection

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Sympathetic action: Pupils Saliva

Dilate Inhibit

Sympathetic action: Heart Bronchi

Increase HR and contractility Dilate

Sympathetic action: Digestive organs / pancreas / gallbaldder

Inhibit all

Sympathetic action: Adrenal medulla

Stimulate to release adrenaline and noradrenaline

Sympathetic action: Urinary bladder Genitals

Relaxes Stimulates

Base excess =

Amount of strong acid that must be added to each litre of fully oxygenated bloods to the return the pH to 7.40 at the temp of 37 and a pCO2 5.3 kPA

Base deficit (negative base excess) =

Amount of strong base that must be added to each litre of fully oxygenated bloods to the return the pH to 7.40 at the temp of 37 and a pCO2 5.3 kPA

When does the base excess become more positive?

Metabolic alkalosis OR in compensation for respiratory acidosis

When does the base excess become more negative?

Metabolic acidosis OR in compensation for respiratory alkalosis

What causes a metabolic acidosis?

Gain of acid or loss of base as bicarbonte

Causes of metabolic acidosis linked to increased production of H+

Lactiacidosis Ketoacidosis - DKA / alcohol / starvation

Causes of metabolic acidosis linked to ingestion of H+ (or drugs metabolised to acids)

Salicylate overdose Ethylene glycol poisoning

Causes of metabolic acidosis linked to impaired renal excretion of H+

Acute or chronic renal failure

Cause of metabolic acidosis linked to loss of HCO3- in the urine

Renal tubular acidosis

Cause of metabolic acidosis linked to loss of HCO3- in the GI tract?

Chronic diarrhoea Ileal conduits Fistulae Small intestinal / pancreatic / biliary drains

Compensatory response to metabolic acidosis?

Hyperventilation

What happens to the blood pressure at low pH?

BP falls due to reduced peripheral resistance and impaired myocardial contractility

Metabolic alkalosis arises from?

Addition of bicarb to the blood or loss of H+ ions from the body

Cause of metabolic alkalosis linked to loss of H+ in the GI tract?

Vomiting, pyloric stenosis and NGT drainage

Cause of metabolic alkalosis linked to loss of H+ in the kidneys?

Diuretic therapy

Cause of metabolic alkalosis linked to ingestion of absorbable alkali?

e.g. Sodium bicarb / antacid overdose

Cause of metabolic alkalosis linked to increased renal bicarbonate reabsorption?

Primary hyperaldosteronism Secondary to volume depletion Secondary to hypokalaemia

Metabolic alkalosis associated with what calcium and potassium levels?

Hypocalaemia and hypokalaemia

Respiratory alkalosis usually result of?

Decrease in pCO2 due to hyperventilation

Respiratory acidosis usually caused by?

Decrease in ventilation due to depression of the respiratory centre / physical impediment to breathing

Plasma is always what charge?

NEUTRAL

The anion gap determines the presence of...?

unmeasured anions

Anion gap formula

([Na+] + [K+]) - ([Cl-] + [HCO3-])

Normal range for the anion gap

6 -16 mmol/L

In metabolic acidosis, an increased anion gap occurs if.....

New acid is added to the body. This dissociates producing free H+ (uses up bicarb) and anions which take the place of bicarb

In metabolic acidosis, a normal anion gap occurs if ...

there is simple loss of bicarbonate, compensatory rise in Cl- so the anion gap is normal

Causes of an increase anion gap metabolic acidosis MUDPILES

Methanol Ureaemia (renal failure) DKA Infection / iron overdose, isonoazid, inborn errors of metabolsim Lactic acidosis Ethylene glycol overdose Salicylate overdose

Causes of a normal anion gap metabolic acidosis FUSEDCARS

Fistula (pancreatic duodenal) Ureteroenteric conduit Saline administration Endocrine Diarrhoea Carbonic anhydrate inhibitors Renal tubular acidosis Spironolactone

Haematocrit ratio =

Ratio of RBCs to plasma

How long does the average RBC circulate?

120 days

Where do potential T lymphocytes mature?

Thymus and spleen

Where do potential B lymphocytes mature?

Lymphoid tissue of the intestines / spleen & bone marrow

Granulocyte WBC include

Neutrophils, eosinophils and basophils

Agranulocyte WBC include

Monocytes and lymphocytes

Functional unit in skeletal muscle

Sarcomere

Endomysium =

Supportive layer of protective tissue that surrounds individual muscle fibres

Perimysium =

Surrounds a bundle of muscle fibres, forming a fascicle (functional unit)

Epimysium =

Connective tissue surrounding the whole muscle

What type of neurons stimulate skeletal muscle?

Alpha motor neurons

When an action potential arrives at NMJ what ion channels open? and what is released into the synaptic cleft?

Ca2+ Acetylcholine

Sarcolemma =

plasma membrane of the muscle cell