Transport Of Substances Through Cell Membrane

Front 1

Concentration of different substances in a normal cell

Back 1

Extra cellular rich in sodium and chlorides while the intracellular is rich in potassium phosphates and proteins

Front 2

Basic structure of cell membrane

Back 2

Bi lipid layers with transport proteins piercing through them

Front 3

Different types of transport proteins

Back 3

Channel proteins that have watery spaces all the way through the membrane and allow transport of water and selected ions. Carrier proteins that actively transport the proteins.

Front 4

What is diffusion?

Back 4

Natural movement of substances according to concentration gradient

Front 5

What are the different types of diffusion?

Back 5

Simple diffusion - kinetic movement of an ion or molecule through a cell membrane through inter molecular spaces or openings without the help of carrier proteins

Facilitated diffusion - diffusion that needs and is facilitated by a carrier protein that shuttles the molecule by carrying it through the cell membrane by binding chemically with them.

Front 6

Simple diffusion pathways

Back 6

If lipid soluble, through the lipid membrane

Or through watery channels through the transport proteins

Front 7

Substances with high lipid solubility

Back 7

Oxygen, nitrogen, carbon dioxide, alcohols

Front 8

What are aquaporins?

Back 8

Protein pores that selectively permit rapid diffusion of water through the membrane

Front 9

What are the special characteristics of protein channels?

Back 9

They are selectively permeable to certain substances and they can be closed by gates known as voltic gates regulated by electrical signals or chemicals that bind to the proteins called ligand-gated channels.

Front 10

What is voltage gating?

Back 10

In this gate changes in the molecular shape or the chemical bonds of sodium or potassium gate respond to changes in the voltage potential across the cell membrane.

For example strong negative charge in the inside of the membrane can cause outside of the sodium pump to remain tightly closed

And a loss of negative potential inside the membrane, causes the sodium pumps to open and sodium ions to rush in.

This is the basis for eliciting an action potential

Front 11

How does voltage effect potassium gates?

Back 11

When the in side of the membrane becomes positively charged, this stimulates the potassium gate to open and the potassium Ions to go out of the cell. This terminates the action potential

Front 12

What is chemical ligand gating?

Back 12

Some protein channel Gates are opened by the the chemical binding (liganding) of a substance with the protein which causes a shape change or chemical bonding at the gate. Eg. Acetylcholine effect on the acetylcholine channel. Acetylcholine opens this channel that allows positive charged ions to pass through. Important in nerve signal transmission from one nerve cell to another and from nerve cell to muscle cell.

Front 13

examples for facilitated diffusion

Back 13

Glucose and most of the amino acids

Front 14

Name of the membrane protein group that helps in transport of glucose

Back 14

Glut or glucose transporter , there are 14 in number. glut 4 is especially sensitive to insulin and can increase the intake of glucose by 10 to 20 fold

Front 15

Factors that affect net rate of diffusion

Back 15

Difference in concentration gradient

If the concentrations are equal there can still be a flow of diffusion due to voltage difference

Difference in pressure, substances move from high pressure to low pressure, example in capillaries

Front 16

Osmosis movement of water across the membrane

Back 16

Normal water movement is free flowing through the membrane. But due to Osmosis if there is a concentration of sodium chloride ions outside the membrane, water tends to move out words, towards the sodium chloride. this is called osmosis

Front 17

What is osmotic pressure

Back 17

The pressure used to stop Osmosis is called osmotic pressure

Front 18

What is osmolality

Back 18

The osmotic pressure of a solution is dependent on the concentration or number of particles in the the solution. It is not dependent on the mass of the particles.

To express the number of particles in a solution the term osmole is used instead of grams and it is referred to as the osmolality of a solution.

Front 19

Difference between osmomolality and osmomolarity

Back 19

Osmolality - Osmoles per kilogram of water osmolarity - osmoles per litre of solution

Front 20

Difference between primary active transport and secondary active transport

Back 20

Primary active transport derives its energy from adenosine triphosphate breakdown. The secondary active transport derives its energy from the Stored energy due to the ionic concentration difference between the two sides of the cell membrane

Front 21

Primary active transport examples

Back 21

Sodium, Potassium, calcium, hydrogen, chloride

Front 22

Normal mechanism of na k pump

Back 22

Pumps sodium outwards while pumping potassium inwards

Front 23

Importance of na k pump in cell volume maintenance

Back 23

Due to high concentration of substances inside the cell, water flows in due to Osmosis. If this is not checked, the cell will swell indefinitely and burst. The nak pump pushes na outwards and k inwards, maintaining a concentration gradient that allows water to flow in both directions thus maintaining cell volume

Front 24

electrogenic nature of the Sodium Potassium pump

Back 24

Because the Sodium Potassium pump pushes out 3 sodium ions while pushing two potassium ions there is a net discharge of one positive Ion towards the outside of the membrane which causes positive charge on the outside of the membrane while there is a negative charge on the inside of the membrane this difference and electric potential caused by the Sodium Potassium pump is called the electrogenic nature of the pump

Front 25

Role of calcium pump

Back 25

By primary active transport, concentration gradient of less than 10000 times the concentration outside in the extracellular fluid is maintained by the calcium pump in the cell.

Front 26

Primary active transport of hydrogen ions

Back 26

At the secretary end of the gastric parietal cells, hydrogen ion concentration inside the cell is about a million to one, this is needed for secreting the hydrochloric acid digestive juice

Special intercalatal cells of the late distal tubules of the kidney, hydrogen ion concentration is increased so that excess hydrogen ions can be excreted from the body through the urine

Front 27

What is co transport or secondary active transport

Back 27

Due to the high difference in the concentration of sodium diffusion, energy created helps in the transport of other substances along with the sodium into the cell. This is called ko transport which is type of secondary active transport.

In counter transport The Other substance tries to go out of the cell using the energy of the sodium which tries to go inside the cell

Front 28

Examples of sodium co transport

Back 28

Sodium co transport of glucose happens in the renal and intestinal epithelial cells

Sodium ko transport of amino acids also happens in the same sites