Physiology Flashcards
What does Starlings law state?
The more the ventricles of the heart fill, the more it pumps out and with greater force.
Describe the key constituents of the a) plasma b) intercellular environment c)intracellular environment.
What is the Transcellular environment?
a) Na+ based. Negative in comparison to extracellular fluid
b) Similar to plasma, lacks proteins
c) K+ fortified. Most negative environment
Tubes of lumen and other organs.
State the 6 states ions are found within the body.
- Free
- Sequestered (behind a membranes in sarcoplasmic reticulum)
- Chelated
- Tightly bound
- In teeth & bones
- Buffered (non-specifically bound)
State the 5 ways ions can travel through a membrane.
- Channels
- Chloride-carbonate exchangers
- Pump
- Leak
- Co-transporters
State 9 roles ions play
- move water (Cl-)
- exocytosis
- fertilisation
- initiating cellular processes
- activating enzymes (P)
- energy generation (Pi)
- secondary messengers (Ca+)
- control transmembrane voltage (Na+)
- muscle contraction (Ca+)
State 5 causes of ionic imbalance.
- diabetes
- trauma/ haemorrhage
- hormonal imbalance
- kidney dysfunction
- dehydration
State 5 effects of ionic imbalance.
- ticks and nervous dysfunction
- cardiac arrhythmia
- seizures
- oedema
- bone abnormalities
What is voltage and what is its formula?
How does it relate to conductance?
The potential difference between two distinct points in an electric field.
V= I x R
g= I/R
Describe the electric force and chemical force involved in an AP.
Na+ move into the axon (movement of ions)
Generates an electric current (positive electric force inwards)
However, concentration of ions intracellularly and intercellular remain the samosa no chemical force .
Describe net force and its value at equilibrium.
Net force = chem force + electrical force
At equilibrium =0
State 2 effects of hypocalcaemia.
What physical sign is a tell-tale sign of hypocalcaemia?
Overactive tendon abnormalities
ECG abnormalities
Chvosteks sign
What does the fertilisation enveloped prevent?
How is the cytosolic concentration of calcium different during fertilisation?
Prevents multiple sperm fertilising egg.
High cytosolic calcium concentration
Describe the relative ionic gradients of calcium, hydrogen and potassium ions across the cell.
Calcium has the greatest concentration gradient. 10000x more outside cell
H+ 60% more outside cell
K+ 30000x more in cell
Define excitable and non-excitable cells. Give examples
Excitable : cells that generate/propagate action potentials e.g. cardiac muscle, nerves
Non-excitable: unable to propagate AP e.g. skin, liver and epithelial cells.
Produce a schematic of the role of calcium concentration in AP.
AP-> HIGH calcium concentration in cytosol -> synaptic transmission/ muscle contraction
State the 3 rules of ionic balance.
- The positive and negative charges must balance
- Energy used to reestablish gradients
- Replacement of ions
State the normal pH inside and outside the cell.
inside : 7.2, outside: 7.4
State the reversible equation catalysed by carbonic anhydrase.
How does the transport intermediate make this efficient?
What happens to the excess H+?
How are pH changes regulated by the kidneys and lungs?
CO2+ H2OH2CO3HCO3(-) + H+
H+ ions are charged so cannot pass through membrane and CO2 is poorly soluble in blood.
RBC: “Cl- shift” for removal of h+ from muscle
Pancreas: secretes bicarbonate
Kidneys secrete H+ that increases acidity
Lungs blow off CO2 which removes acidity
How does the location of parietal cell said in their function?
Which ion transporters are present on the basolateral membrane of a parietal cell?
Which ion transporters are present on the apical membrane of a parietal cell?
Protected from friction and secretions.
Chloride-carbonate exchangers
Cl- channels (get rid of Cl- build up in cell)
Na+/K+ pump (if K+ conc. decreases, pumps K+ to maintain conc)
H+ channel
Cl-channel (mix with H+ in stomach to form HCL)
K+ channel(get rid ofK+ build up in cell and to maintain K+ intercellular conc. for pump)
H+/K+ pump using H+/K+ ATPase
Describe three features of transmembranal potential.
- depends on relative electric currents
- conductance of ions across membrane
- membrane with complete permeability have Vm=0
What is the effect of the extracellular space of all cells being electronically joined ?
Same voltage everywhere
What voltage do Na+ voltage gated channels open?
> -50mv
Describe what an equilibrium potential is.
An ions favourite voltage.
The greater the permeability for an ion, the more the membrane potential is driven towards the equilibrium potential for that particular ion.
State the equilibrium potential for
a) eNa
b) eK
c) eCa
d) eCl
a) +60mv
b) -90mv
c) +123mv
d) -40mv
