Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

physiology for PHYSIOTHERAPY > Lecture 1 - plasma membrane and transport across membranes > Flashcards

Lecture 1 - plasma membrane and transport across membranes Flashcards

1
Q

Describe the structure of the plasma membrane

A
  • 3 layers - inner, middle and outer
  • contains a phospholipid bilayer ( hydrophobic tail and hydrophilic head)
  • contains integral and peripheral membrane proteins
  • Contains cholesterol between each phospholipid molecule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the functions of the plasma membrane?

A
  • encloses contents of the cell
  • separates cell from external environment
  • cell communication
  • import and export of molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How are proteins organized in the plasma membrane?

A
  • Integral proteins - go across membrane that serve as membrane transporters
  • peripheral proteins are loosely attached to membrane, act as enzymes shaping the cell
  • lipid anchored proteins on surface of cell membrane, the lipd anchors the protein on membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 4 mechanisms of transport across plasma membrane?

A
  1. passive diffusion
  2. facilitated diffusion
  3. active transport
  4. bulk transport
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what does the rate at which a molecule passes the membrane depend on?

A
  • size of molecule
  • solubility of molecule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is passive diffusion?

A
  • does not require energy to move molecules across the membrane
  • it relies on the concentration gradient across the membrane
  • eg 02 c02 & small molecules pass freely
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How do ions travel across the membrane?

A

ions travel across the membrane via ion channels, pumps, exchangers or co-transporters (eg sec active transport)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is osmosis facilitated in the membrane ?

A
  • by a family of membrane proteins called aquaporins that form a channel for water to flow through
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the 4 types of ion channels present in the membrane?

A
  1. gated channels (open or closed)
  2. voltage gated channels (conformational change depends on difference of charge on both sides of membrane)
  3. Ligand gated channels ( depends on binding of ligand molecule)
  4. mechanically gated (physically stretching the membrane may cause it to open eg)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is facilitated diffusion?

A
  • concentration gradient dependent
  • requires gated channels /transmembrane integral proteins
  • eg glucose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is active transport?

A
  • Movement of molecules across a membrane from low- high conc against the concentration gradient
  • requires energy - ATP
  • occurs through transport protein pumps
  • Eg) Na-K+ - ATPase pump
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does Na-K+ ATPase pump work?

A
  • A transmembrane protein that pumps k+ into cells while also pumping Na+ out of cells
  • Against both of their conc gradients
  • ATP converted to ADP
  • 3 Na3+ out and 2 K+ in
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe bulk transport

A
  • Transport of large molecules or small particles into cell, requires energy
  1. Phagocytosis
  2. endocytosis
  3. exocytosis/secretion out of cell
  4. Pinocytosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are gap junctions?

A

Sites between cells that are specialised for intercellular communication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Give examples of gap junctions

A
  • Tight junctions
  • Adherens junctions
  • desmosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the different types of ‘channels’ on the membrane?

A
  • ion channels that are selective for specific ions eg Na+, K+, Ca2+
  • mixed cation channels - permeable to more than 1 ion - eg Na+ and K+
  • membrane transporters eg ATPase pumps, ion exchangers (egNa+Ca2+ exchanger) & co-transporters - NB THESE ARE ACTIVE - REQUIRE ENERGY
17
Q

What do the ion exchangers & cotransporters rely on?

A

they rely on ion gradients that are set up by ATPase pumps

18
Q

what are the specialized functions of ion channels?

A
  • control the release of neurotransmitters & hormones
  • initiate muscle contraction
  • mediate the generation, conduction & transmission of electrical signals in the nervous system
19
Q

what are ion channels made up of?

A
  • made up of subunits
  • if they have different subunits - hetero-oligomers
  • if they have the same subunits - homo-oligomers
  • also auxiliary subunits eg in some voltage gated ion channels
20
Q

what are the 3 basic functional properties of ion channels?

A
  1. selection - ie certain channels only allow one type of ion to pass eg Na+ or K+
  2. gating - what regulates ion channel opening/closing eg stretch or binding of neurotransmitter or change in membrane potential
  3. conduction - the channels allow ions to flow down their electro-chemical gradients
21
Q

what are the 3 main families of ‘ion channels’?

A
  1. ligand gated ion channels
  2. gap junction ion channel
  3. voltage gated ion channels
22
Q

What did the patch clamp method discover when studying Na+ channels?

A
  • Na+ has a specific threshold for opening to allow Na+ to enter the cell
  • only opens when the membrane depolarizes to approx. -50mv
  • the channel opens and closes rapidly
23
Q

What did the patch clamp method discover about K+ channels?

A
  • K+ channels open as the membrane depolarises and they stay open while the membrane is depolarised
  • they close when the when the membrane potential returns to a more negative value than at rest
  • K+ channels have delayed closing
24
Q

what is myotonia congenita?

A
  • an inherited neuromuscular disorder - difficulty in mobility
  • caused by a mutant voltage gated chloride channel CLCN
  • adrenaline makes the condition worse
25
Q

what types of stimuli control gating of ion channels?

A
  • ligand gated - eg GABA or glutamate neurotransmitters present
  • protein phosphorylation
  • changes in membrane voltage
  • stretch or pressure changes
26
Q

what are examples of voltage gated channels?

A
  • Na+ channels
  • Ca2+ channels
  • K+ channels
27
Q

what are examples of ligand gated ion channels?

A
  • neurotransmitter receptors
  • Ca2+ activated K+ channel
28
Q

what is an ‘inward rectifying’ channel?

A
  • a channel that passes positive charge more easily into the cell (inward direction) than in the outward direction (ie out of the cell)

physiology for PHYSIOTHERAPY (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions