Active Cellular Physiology Flashcards
How do soft cells keep their shape
- water
- uses a gradient concentration
Epipithelial cell ____ the _____ and the ____ (and what is their appearance)
Line
GI tract
Airway
Cubical appearance that is maintained by water
What provides structure for soft cells
Osmotic pressure
Composition of water and solids in biological males
Water = 60%
- ICF - 33%
- ECF - 21.5%
- Plasma - 4.5%
- Other bodily fluids <1%
Solids = 40%
- organic and inorganic materials
Composition of water and solids in biological females
Water = 50%
- ICF - 27%
- ECF - 18%
- Plasma - 4.5%
- Other bodily fluids <1%
Why do males have a higher water concentration
There is more water in muscles and men have a higher muscle mass
How much water is lost / absorbed into ECF
Gained:
300ml metabolic water
2200ml water absorbed across digestive epithelium (drunk)
Lost:
1150ml water Vapor lost at skin and lungs
150ml lost in feces
1200ml water lost in urine
Water secreted by sweat glands (variable
Isotonic solution
When the ECF and ICF are in balance
Why is the volume of the ICF larger then ECF
- water held within cells represents a significant reserve that can prevent sudden changes in solute and water concentrations in the ECF
Hypertonic
- water loss from ECF decreases volume and makes the solution hypertonic in respect to the ICF
- solutes stay the same therefore higher conc of solutes for a given volume = osmotic conc of EDF has increased
- water moves from low conc of solutes in ICF to restore osmotic equilibrium
- volume will decrease so the cells are shriveled
HYPOTONIC
- water moves from low concentration of solutes in ECF to ICF to restore osmotic equilibrium
- cell will swell
HYPONETREMIA
- too little NA+
Ion absorption
Occurs across the epithelial lining of the small intestine and colon
Ion reserves
Primarily in the skeleton
Ion pool in bodily fluids
ICF + ECF
Ion Excretion
Primary site of ion loss: Kidneys
Secondary site of ion loss: Sweat gland secretions
How are the concentrations of ions in the bodily fluids regulated
- ion excretion
- ion absorbtion
- ion storage
Editable tissues
- neurons and muscle - excitable membrane potential
- epithelial cells - membrane potential (not excitable)
Sizes of Na+ and K+
Na+ is smaller
Examples of cations and anions present in and out of the cell
cations:
- sodium
- potassium
- calcium
Anions:
- chloride
- proteins
Why can’t the charged particles freely flow through
Lipids bylayer is an insulator to prevent the freee flow of anions and cations
Cations and Anions and membrane movement
- balancing Na+ and K+ and Cl- is important for maintaining ionic equilibrium
- plasma membrane seperatges the inside and outside of the cell
- cations and anions can only move across the membrane through specific channels
What creates a membrane potential
The distribution of ions creates electricity
- there charge difference between the two sides
Resting membrane potential in living cells
-70mV
Why can’t ions freely pass through the membrane
- ions can not freely pass the plasma membranes because they are charged
How do ions pass through the plasma membrane
They use membrane channels or active transport mechanism
Concentration of Ka+ and Na+ on either side of the membrane and the ratio during resting membrane potential
ECF :
- High Na+
- Low K+
ICF:
- Low Na+
- High K+
3Na+ in ECF and 2K+ in ICF
How is RMP maintained
Passive forces such as chemical gradients
Active processes su h as the ATP requiring sodium-potassium pump
Sodiums and potassium’s size and direction of electrochemical gradient
Sodium:
- gradient is inwards
- Large electrochemical gradient
Potassium:
- slightly outwards
- Smaller electrochemical gradient
When membrane potential increases greater the -70 (-60,-50,-10) what is it called
Depolarisation:
- where a chemical stimulus opens sodium channels and sodium is transported INTO of the cell
(Once stimulus is removed, repolarisation occurs and RMB is restored)
When membrane potential decreases from -70mV (-80,-90) what is it called
Hyperpolarisation:
- where potassium channels open and more potassium ions leave the cell
Electrical graidient vs chemical gradient
Chemical gradient: determined by the conc of ions across memebrane
Electrical gradient: determined by the potential difference of ions across a membrane (charge difference between ICF and EFC)
