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Physiology Flashcards

Glossary terms (65 cards)

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1
Q

Apical Membrane

A

The surface of the PLASMA MEMBRANE that faces the LUMEN

Na+/glucose co-transporters or Na+/Amino acid co-transporters

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2
Q

Atrial natriuretic peptide (ANP)

A

A polypeptide hormone that causes vasodilation

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3
Q

Baroreflexes

A

A negative feedback system which buffers short-term changes in blood pressure

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4
Q

Extracellular fluid (ECF)

A

All body fluid outside of cells

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5
Q

Glomerular Filtration Rate (GFR)

A

The volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman’s capsule per unit time

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6
Q

Homeostasis

A

The body’s ability to physiologically regulate its INNER ENVIRONMENT to ensure its stability in response to fluctuations in the outside environment and the weather

Maintenance of a constant internal environment in the body

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7
Q

Intracellular fluid (ICF)

A

All body fluid inside of cells

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8
Q

Membrane potential

A

The difference in VOLTAGE ( or ELECTRICAL POTENTIAL difference) between the interior and exterior of a cell (V interior o V exterior)

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9
Q

Osmolality

A

The number of osmoles per Kg

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10
Q

Osmolarity

A

The number of osmoles per litre of solution

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11
Q

Osmole

A

1 gram molecular weight of solute

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12
Q

Osmotic Pressure

A

The pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane

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13
Q

Parasympathetic Nervous System

A

A part of nervous system that serves to SLOW the heart rate, INCREASE the intestinal and gland activity, and RELAX the sphincter muscles. The parasympathetic nervous system, together with the sympathetic nervous system (that accelerates the heart rate, constricts blood vessels, and raises blood pressure), constitutes the autonomic nervous system

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14
Q

Sympathetic Nervous System

A

A part of the nervous system that serves to ACCELERATE the heart rate, CONSTRICT blood vessels, and RAISE blood pressure. The sympathetic nervous system and the parasympathetic nervous system constitute the autonomic nervous system, the branch of the nervous system that performs involuntary functions.

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15
Q

Tonicity

A

A measure of the OSMOTIC PRESSURE (as defined by the water potential of the 2 solutions) of the 2 SOLUTIONS separated by a SEMIPERMEABLE MEMBRANE

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16
Q

Secretory Diarrhoea

A

An increase in the active secretion.

Most common cause is an exposure to the E. Coli or Cholera toxin.

Enterotoxins produced by the bacterial microorganisms raise intracellular [cAMP]

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17
Q

Osmotic Diarrhoea

A

Caused by macronutrients malabsorption retaining osmotic pressure in the lumen and therefore water is retained.

E.g: pancreatic disease (lack of proteases, lipase, and amylase), lactose intolerance, Coeliac disease.

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18
Q

Hydrogen Ion

A

A single free proton released from a hydrogen atom

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19
Q

Acids

A

Molecules containing hydrogen atoms that can release hydrogen ions in solutions

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20
Q

Base

A

An ion or a molecule that can accept an H+.
For example, HCO3- is a base because it can combine with H+ to form H2CO3.

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21
Q

Alkali

A

Is synonymously used with the term base.

A molecule formed by the combination of 1 or more of the alkaline metals-sodium, lithium, etc with a highly basic ion such as hydroxyl ion (OH-).

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22
Q

Alkalosis

A

Refers to excess removal of H+ from the body fluids.

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23
Q

Normal pH of Arterial blood is….

A

7.4

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24
Q

Acidosis

A

The excess addition of H+

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25
Diarrhoea
Means "a flowing through" >200g/day faeces, or 0.2L/day faecal water, 3 or more liquid bowel movements per day (WHO)
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Basal Membrane
The surface of the PLASMA MEMBRANE that faces the BLOOD | Na+/K+ ATPase pump
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Transcellular
solutes, across at least one memebrane is active | through the 2 apical membranes
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Paracellular
Movement passive via tight junctions | through gap juntions
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Absorption of water
* Entirely by osmosis * coupled to solute movemenbt * occurs via transcelular or pracellular routes * paracellular (through gap junctions) predominate mdoe of absorption * primarily ibn the jejunum * 'solvent drag' responsible for considerable Na+ and urea absoprtion in jejunum.
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Na+ absorption
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Active Cl- secretion
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K+ absorption
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Cl- absorption
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Mechanisims of pH control | 3
1) The chemical acid-base buffewr systems of the body fluids 2) The Respitratory center 3) The kidneys
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The chemical acid-base buffer systems
1st line of attack (within seconds) immediately removes H+ or alkaline ions being produced as a by-product of metabolic actions. | prevents excessive changes in H+ concentration
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The respiratory center
2cnd in line of attack (few seconds to a minute) regulates the removal of CO2 from ECF or decrease ventilation to retain CO2
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The kidneys
last in line fo attack (few hours to a day or so) excrete either acid or alkalaine urine or bicarbonate, or conserving, prodcuing more bi-carbonate. | stronger, robust, long-term controlled
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Henderson-Hasselbalch Eq <---- | H2CO3 -> H+ + HCO3-
pH directly proportional to [HCO3-] : so [HCO3-]>>> = HIGH pH (alkaline) pH inversely proportional to pCO2 : and pCO2 >>> = LOW pH ( acidic) | If constant (k or pK) = 6.1,
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Buffer systems | Buffer + H+ ----> H Buffer <----
Soaks up H+ ions and produces inert compond H buffer. Very QUICK, fast action, within seconds 3 buffer systems, Bicarbonate, phosphate, and proteins as intracellular buffers. | like a sponge
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Bicarbonate Buffers
Omnipresent (widespread) everywhere & WEAK buffer
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Phosphate Buffers | NaOH + NaH2PO4 ---> Na2HPO4+ H2O ## Footnote Strong alkali + Phosphate buffer -> inert cmpnd + water loss in tubule.
EXCLUSIVELY in the RENAL TUBULE. Very Localised and STRONG buffers sort out pH very quickly & robustly
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Proteins | As Intracellular bufffers
all over the place quick/fast at absorbing /buffering all the chemical reactions within the cell.
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Bicarbonate buffers | How H2CO3 buffer can exist & counterbalance ↑[H+] or ↑alkali in body.
Exists in 2 spaces, either H+ & HCO3- ions OR H+ & HCO3- w Na+ ions Basic arm = NaHCO3 --------> Na+ + HCO3- <-- Acidic arm = H2CO3 -> H+ + HCO3- <----- |_____| Na+ ↑ H+ = CO2 lost when breathing out and H2O lost in urine/blood. NaHCO3 + H2O = lost in urine.
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Titration curve | For Bicarbonate buffers
- Takes longer, thought they're everywhere, cause operating pt @ 7.4 = weak and exist in bicarbonate form. - Phosphate buffers @ ph @pk =6.1 primarily exist as bi-cabronate. - for buffer to act really well, needs to be in the zone around the pK of that buffer. - Because body pH = 7.4, ALL of our bicarbonate buffers exist in BASIC form -> to act quick/fast, need to be converted into an acidic arm.
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# IMPORTANT EXAM Q Phosphate Buffers | HCl + Na2HPO4 -->NaH2PO4 + NaCl NaOH + NaH2PO4 --> Na2HPO4 + H20
**How is the Phosphate bufffer working? What are the two forms it exists and how it acts when an acid is added and when a base is added? ** * It's a buffer, saoks up either acid/bases and produces an inert compoound and gets rid of it. * Main elements = H2PO4- and HPO4- * has pk of 6.8 -> not far from body pH(7.4) * thus, STRONG buffer (exists in both acidic and basic forms) * ESPECIALLY important in the TUBULAR fluids of the KIDNEYS!!! (EXCLUSIVELY in RENAL tubules) | NaH2PO4 = inert compound , NaCl= salts, H2O = water, NaOH = strong base
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Respiratory Regulation of Acid-Base Balance | 2cnd line of attack (Ventilation drives pH)
* Breath very fast = blow off CO2 = less [CO2] in body = less CO2 combining with water to form carbonic acid = less acid = becoming more basic. * Hold your breath = Not breathing = CO2 level goes up = mroe CO2 combining with water to form carbonic acid = become more acidic. * Both have impact on ventilation -> GREATER ventilation = More H+ ions moved out & CO2 moved out of the system.
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Ventilation and pH | Rate of Ventilation vs pH change
↑ Rate of Ventilation (breathe faster) = higher pH = blowing off CO2 = more basic. ↓ Ventilation (hold breath) = retain more CO2 & become more acidic. | normal rate of alveolar ventilation = 1
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Arterial pH & effect
Any drop in pH below 7.2 = ↑ Ventilation | pH of arterial blood is ~7.2 to 7.4
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# Michael hyperventilating and sweating case-study What's up with Michael? | Hyperventilating (breathing very fast)
* Hyperventialting = ↑ ventilation * Breathing out CO2 = less CO2 in body * Less CO2 combingn with water to produce carbonic acid = becoming more basic. * Effect on pCO2 = pCO2 will drop in the body * pH becoming mroe alkaline from 7.4 to 7.5/7.6. Cause: -possibly in a stressful situation =panic attack TREATMENT: Breathe into paper bag = breathes into his trapped respire (CO2 concetrated/rich) = re-inhale that CO2 respire = sets up/triggers cortex /respiratory centre to maintain that CO2 **=> Acute respiratory alkalosis** | pCO2 = partial pressure of CO2
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Kidneys & pH regulation (long term) | maintenence of HCO3-
* Reabsorption og HCO3- * Active secretion of H+ ions * Production of New HCO3- | small & large intestine ALWAYS trying to conserve as much bi-carbonate.
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Secretion of H+ | graph /diagram in lecture notes
* In distal tubutle -> Na+ & HCO3- filtered out into the filtrate. 1. Na+/K+ ATPase (found everywhere) in the basal lateral membrane (removes 3 Na+ and brings in 2 K+) = always Na+ deficiency within cell = Na+ through conc. gradient mnoves into cell in ecxchnage of a H+ ion. 2. H+ combines with HCO3- coming through = forms H2CO3 3. H2CO3 quickly dissocites into the lumen as CO2 & H2O 4. CO2 diffuses into cell 5. cells are rich in carbonic anhydrase = triggers reaciton to form H2CO3 6. H2CO3 moves back into cell | very convoluted way pf reabsorbing the bicarbonate.
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Active secretion of H+ ions | Acidic conditions (diabetes), body produces lots of acid .
Acidic conditions (diabetes), body produces lots of acid . through kidneys, body excretes acid -> H+ ions through active transport. 1. H+ moves out of cell using an ATP = facilitated by CO2 diffusing in 2. Co2 = Carbonic anhydrase (abundant within cell) produces H2CO3 3. H2CO3 goes out of cell & into lumen 4. H+ expelled out using ATP
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Addition of New HCO3⁻ | things NOT present in the tubule
* HCO3⁻ Na⁺/K⁺ ATPase = creates ↓Na+ environment within cell = drives Na⁺ gradient * H⁺ & Na⁺ exchange Filtrate coming through & Na⁺ & phsophate buffers. * As it comes in H⁺ conbines with NaHPO₄⁻ = forms inert compound NaH₂PO₄ * Net result = Getting rid of H⁺ & producing a new HCO3⁻ * done through phosphate buffers into the system | diagram in notes pg 65
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Addition of New HCO3⁻ | By means of GLUTAMINE (protien by-products)
* glutamine filtered wihtin cell. * within cell it dissociates into 2 NH₄⁺ (Ammonium) * Ammonium expelled out of cell & combines with chloride (Cl⁻) to form NaH₄Cl = inert compouind = removed from system. * NET RESULT = Adding 2 more bicarbonate into system. | diagram in notes
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Regulation of Renal Tubular H⁺/HCO₃⁻ | increased H⁺ Secretion and HCO₃⁻ Reabsorption
* ↑Pco₂ (holding breath) * ↑H⁺, ↓HCO₃⁻ * ↓ ECF Volume * ↑Aldosterone ( wants to reabsorb Na⁺, with Na⁺ comes water, With Na⁺ comes water, Na+ and H+ exchnage) ALL THIS leads to ↑Angiotensin II and ↑Aldosterone and Hypokalemia Reverse/opposite is true for decrease in H⁺ Secretion and HCO₃⁻ Reabsoption. | Table (pg 67) Body's response to acidic enviro =Active secretion of H+ ## Footnote Reabsorption of bicarbonates from the kidneys
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Normal acid base levels in human body
Normal body: pH = 7.4 H+ = 40mEq/L Pco2 = 40 mm Hg HCO3- = 24 mEq/L
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Respiratory Acidosis | Acid base disturbances reffered to as compensation of the body. ## Footnote to do with ventilation (Pco2)
* Drop in pH * ↑ H+ * ↑↑ Pco2 Body response to this = ↑HCO3- compensation of the body
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Respiratory Alkalosis | Acid base distrubnaves, repiratory orgin, to do with ventilation Pco2
* ↑pH * ↓H+ * Pco2 ↓↓ (compensation) * HCO3- ↓ We saw this with michael hyperventilating: blowing off CO2 kidneys removing HCO3- from cell
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Metabolic acidosis / alkalosis | to do with bicarbonates (HCO3-) levels in the body
follows the similar to respiratory EXCEPT: * Pco2 levels are opp/diff to respiratory version. * acidosis = Pco2 ↓ HCO3- = ↓↓ * alkalosis = Pco2 ↑, HCO3- = ↑↑ respiratory compensation /response is diff
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Juxtapmedullary nephron | kidney
long loop of henle
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GFR (Step One) | MAJOR way to regulate blood volume
* rate at which things get filtrated in the glomerlus * lots of this is reabsorbed in the gut * secretion of fluids * kidney is provided 20% CO of blood * NORMAL GFR = 125 ml/min/1.73 m2 * osmolarity ~ 200 mosmol/L = ECF | Ecretion = filtration - reabsorption + secretion
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Afferent Vs Efferent arteriole **diameter** defines GFR
* ↑ GFR = ↑Blood filtered = NOT the same amount reabosrbed * Contain water = ↓ GFR afferent = goes to bladder & excrete as urine. * ↑ mean arterial pressure = ↑ GFR * squeeze efferent = blood filtered fown to give GFR * = chnaging pressure difference = greater ____ and diameter * Afferent open, effeent closed = GFR
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Intrinsic mechanisms which control GFR include...
Tubulo Glomerular Feedback * Macula Densa = Na+ sensed in here ↳ afferent/efferent diameter chnages = GFR changes * classical -ve feedback * regulates * Distal tubule = filtreate interact back to afferent/efferent arteriole | modulate all the time to maintain internal consistency
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Extrinsic Mechnaisims (external to kidney) which control GFR include the......
Sympathetic nervous system * ↑ sympatheitc dirve = input squeezed more = ↑ pressure * Reverse; * ↓ symapthetic dirve = open efferent more =
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Juxtaglomerular Apparatus Factors that promote Renin secretion (3)
1. ↓ afferent arteriolar pressure (i.e ↓ bp) 2. ↑ Sympathetic activity 3. ↓ Macula densa NaCl delivery
MEDSCI 205
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