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258 - physiology > Lecture 1: Intro Cell Membrane Transport > Flashcards

Lecture 1: Intro Cell Membrane Transport Flashcards

1
Q

Name the parts of a neuron and be able to locate them

A

Dendrites
Cell body (soma)
Axon

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2
Q

How many neurons are present in the human brain?

A

86 billion

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3
Q

Put the following in order from highest to lowest amount of neurons

1) Chimpanzee
2) Gorilla
3) Human
4) Elephant

A

4,3,2,1

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4
Q

What is the order of the neurological system?

A

Reception
Treatment
transmission

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5
Q

Where is treatment done? Reception? Transmission?

A

Treatment is done in the soma (intergrate all the signals from the adjacent neurons
Reception: dendrites
Transmission: done at the axon level

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6
Q

What is another name for the cell?

A

NEURON

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7
Q

Explain the structure of the cell membrane and its size

A

A thin, elastic structure, 7 to 10 nanometers thick

Composed of:
lipid bilayer
proteins
carbs

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8
Q

What is the purpose of the lipid bilayer and what is it impermeanle/permeable to?

A

Form a barrier,

Impermeable to water and the usual water-soluble substances (e.g., ions, glucose, urea…)

Permeable to lipid-soluble substances (e.g., oxygen, nitrogen, carbon dioxide, alcohol)

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9
Q

What is the fucntion of membrane proteins?

A

Membrane proteins transport water-soluble substances across the cell membrane.

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10
Q

Where are integral proteins located and what do they act as

A

Protrude through membrane

Act as
Pores and channels
Substance carriers

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11
Q

Where are peripheral proteins located and what do they act as?

A

Attached to only one surface of the membrane (often attached to integral proteins)

Act as
enzymes
Controller of transport through channels

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12
Q

What are the 2 basic processes of transport?

A

Diffusion (passive)

Active transport

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13
Q

What is the difference between passive and active transport?

A

PASSIVE= NO ENERGY

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14
Q

What are the 2 subcategories of diffusion?

A

Simple and faciliated

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15
Q

Give a quick description of diffusion vs active transport

A

Diffusion: ions and substances can travel freely through the membrane (either straight through the bilayer or by using channel proteins or by binding doing facilitated diffusion)

Active transport: Going against the electric gradient so a pump is needed to redistribute the ions./substances

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16
Q

In simple diffusion, what are the 2 ways molecules move through and what molecules move through them

A

1) Interstices of lipid bilayer (lipid-soluble substances: oxygen, nitrogen, carbon dioxide, alcohol)
2) Protein channels (water and lipid-insoluble molecules (e.g., ions, urea…)

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17
Q

What are the 2 chracteristics of simple diffusion

A

1) selective permeability

2) GATES

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18
Q

What are the 4 factors that affect permeability

A

1) Diameter of channel
2) Diameter of substance
3) Shape of channel
4) Nature of electrical charges along the surface of the channel

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19
Q

How can channels be open?

A

BY GATES

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20
Q

What are the 2 gates that open channels

A

Channels can be opened or closed by gates
Voltage gating channels:

Chemical gating (ligand-gated) channels:

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21
Q

Explain voltage gating channels

A

gate responds to electrical potential

Participate in the generation of action potential

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22
Q

Explain chemical gating (ligand gating) channels

A

Gate responds to binding of another molecule with the channel (changes conformation)

Participate in synaptic transmission (receptors)

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23
Q

What is the role of facilitated diffusion?

A

Transporting large molecules (ex gluc)

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24
Q

What are the steps of facilitated diffusion

A

1) Molecule diffuses by using a specific carrier protein
2) Molecule enters the pore and binds to the binding point of protein
3) A conformational change occurs so that the pore opens to the opposite side

4) At this position:
Molecule is released

25
Q

True or false: In simple diffusion, the diffusion rate is proportional to the concentration of the transported surface?

A

true

26
Q

True or false: Diffusion rate for facilitated diffusion is proportional and explain

A

FALSE:
Diffusion rate is not proportional to the concentration of the transported substance (i.e. diffusion rate approaches a max as the concentration of the diffusing substance increases)

27
Q

KNow the graph of the facilitated vs simple diffusion rate

A

.

28
Q

Why does faciliated diffusion speed reach a max?

A

Because speed of diffusion is limited by the speed of change of conformation of the protein

29
Q

What are the 2 factors that affect net rate of diffusion?

A

1) concentration difference

2) electrical potential difference

30
Q

Explain diffusion through concentration difference and what does it create

A

Net movement of molecules from high conc side to low concentration side

CONCENTRATION GRADIENT

31
Q

Explain diffusion through electrical potential difference and what does it create?

A

Electrical charges of ions cause them to move through the membrane even though no concentration difference exists to cause movement.

A concentration difference of the ions will be developed in the direction opposite to the electrical potential.

=ELECTROCHEMICAL GRADIENT

32
Q

What is required to move substances across a gradient

A

An additional source of energy (ATP)

33
Q

How do molecules move in active transport

A

move across the membrane through a carrier protein against conc and/or electrical gradient

34
Q

What are some examples of molecules that use active transport to get across membrane?

A

Na+, K+, Ca2+, Fe2+, H+, Cl-, urate ions, sugars and amino acids

35
Q

True or false: the molecules transported by active transport can ONLY be moved by active?

A

False, they can move through simple diffusion

36
Q

What are the 2 types of active transport

A

PRIMARY ACTIVITY TRANSPORT

SECONDARY ACTIVE TRANSPORT

37
Q

Explain primary active transport

A

Energy is directly driven from adenosine triphosphate (ATP)

38
Q

explain secondary active transport

A

2 different substances are transported

Energy is driven from concentration gradient of one of the transported substances

39
Q

What is the purpose of the Na+/K+ pump?

A

to transport Na+ & K+ ions against their concentration gradient

40
Q

the na/k pump establishes a negative or positive electrical potential inside the cell

A

negative

41
Q

Explain the process of the sodium potassium pump

A

3 Na+ ions transported from inside to outside of the cell,

2 K+ ions transported from outside to inside of the cell,

Enzymatic ATPase activity causes conformational change.

42
Q

Define electrogenic

A

ELECTROGENIC: TRANSFER OF ONE NET POSITION CHARGE OUT OF THE CELL

43
Q

True or false: the sodium/potassium pump is not a electrogenic pump

A

FALSE (it has a net charge charge of 1 outside)

44
Q

What are the 2 substances transported in symport secondary active trasport

A

Principal & co-transported

45
Q

Where is the energy obtained for secondary active transport?

A

Energy is from the concentration gradient of the principal transported substance (e.g. Na+):
GRADIENT ENERGY

46
Q

What are the 2 forms of secondary active transport and what are they dependant on?

A

Symport (co transport)
Antiport (counter transport)

according to the direction of diffusion of the two substances:

47
Q

What is the main goal of secondary active transport?

A

to maintain homeostasis in the cell

48
Q

What is an example of symport secondary transport?

A

Glucose & Sodium

49
Q

What molecule is the principal substance and co transported substance of the glucose and sodium symport pump

A

Na +: principal substance

glucose: the co-transported substance

50
Q

Explain the process of the glucose/sodium symport pump?

A

1) Na+ is principal, glucose is co transported
2) Carrier protein in the cell membrane = binding site for both glucose and Na+
3) Once both are attached a conformational change occurs in the carrier protein.
4) The energy gradient of Na+ causes both Na+ and the glucose to move together to the interior of the cell

51
Q

Why does Na+ want to diffusion from the cell in symport pump with glucose?

A

Wants to move down the energy gradient (less Na+ outside)

52
Q

What are the 2 substances transported in antiport secondary active transport

A

The principal substance and the counter-transported substance

53
Q

Are the principal and counter transported substance on the same or opposite sides of the membrane?

A

OPPOSITE

54
Q

What are 2 examples of secondary antiport transport>

A

sodium and hydrogen

sodium and calcium

55
Q

Explain the process of antiport secondary transport

A

1) the principal substance (Na+) binds on the exterior side of the carrier protein and the counter-transported substance (e.g. Ca2+, H+) binds on the interior side
2) A conformational change occurs

3) With the gradient energy, Na+ is transported from outside to inside and the counter-transported substance is transported from inside to outside

56
Q

True or false: molecules are kept in unequal concentrations inside and outside of the cell ?

A

TRUE

57
Q

What molecules are found in the extra and intra cellular fluids and the main charge

A

Extracellular fluid :
High in Na+, Ca2+ and Cl-.
Positively charged

Intracellular fluid :
High in K+, Mg2+, proteins
Negatively charged

58
Q

Where can you find the Na+ Ca2+ counter transport

A

occurs through almost all cell membranes

59
Q

Where can you find the Na+ H+ counter transport pump?

A

Especially important in the proximal tubules of the kidneys

258 - physiology (21 decks)

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