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Physiology > Cellular Physiology > Flashcards

Cellular Physiology Flashcards

1
Q

What are the four parts of the cell theory

A

Cells are the basic unit of an organism
Activity of organisms depends on their cells activity
Cell function in dictated by cell shape (form=function)
Cells can only come from other cells

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2
Q

What is an integral protein

A

Firmly inserted in the plasma membrane and is usually a transmembrane

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3
Q

What are peripheral proteins

A

Not embedded in the bilayer but attached loosely to integral proteins

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4
Q

What are the functions of membrane proteins

A

Transport
Receptors
Support
Enzymes
Cellular adhesion
Cell communication

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5
Q

What is the difference between passive and active transport

A

Passive transport doesn’t require energy but active transport does

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6
Q

What does a cell membrane being selectively permeable mean

A

It is selective of what can pass through the membrane and allows most things only with a channel

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7
Q

What utilizes passive transport, what utilizes active transport, and what utilizes both

A

Diffusion uses passive
Active uses vesicular transport
Both use carrier mediated transport

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8
Q

What is diffusion

A

Molecular or ions moving from one area to another using a gradient
Usually occurs from high to low concentration
Passive process
Distance and molecular weight slow it down
Temperature “speeds up” diffusion
Can take place in open or compartmentalized system

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9
Q

What things can move through the lipid bilayer using simple diffusion

A

Non polar molecules and lipid soluble substances
Examples include oxygen, carbon dioxide, fat soluble vitamins

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10
Q

What is carrier mediated facilitated diffusion

A

Can only work using a carrier and transmembrane integral protein

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11
Q

What is channel mediated facilitated diffusion

A

Fluid filled transmembrane channel that allows ions to to pass through

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12
Q

How are membrane channels specific to ions and molecules

A

Their structural composition

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13
Q

What is a transport maximum

A

When all the membrane channels are saturated and there are no more carrier binding sites

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14
Q

How can competitors reduce the transport maximum

A

They looks and act like another substance so they compete for spots in the channel

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15
Q

What kind of transmembrane integral protein does water move through

A

An aquaporin which will move water until osmotic pressure and hydrostatic pressure reaches equilibrium
Water needs aquaporins to move through the membrane since polar substances can’t really move through the membrane easily

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16
Q

How will water move to try and make hydrostatic pressure equal

A

From high to low

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17
Q

What is hydrostatic pressure

A

A force generated by fluid volume so as volume increases hydrostatic pressure also increases

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18
Q

What is osmotic pressure

A

A force generated by osmolarity

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19
Q

What is osmolarity

A

Total concentration of all solute particles in a solution

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20
Q

What is Tonicity

A

When a solution changes the shape of a cell by changing how much water can enter or exit

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21
Q

What is isotonic

A

A solution that will not change the cell shape

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22
Q

What is hypertonic

A

A solution that causes a water efflux (leaves the cell) and causes the cell to shrink

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23
Q

What is hypotonic

A

A solution that causes a water influx (water enters the cell) and causes the cell to swell

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24
Q

How does active transport carry substances and does it utilize anything important

A

Active transport requires a carrier protein that carries substances against the concentration gradient and also utilizes atp or energy input

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25
Q

What is primary active transport

A

Breaks down atp which causes phosphorylation of the transport system which then causes the transporter to change shape

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26
Q

What is secondary active transport

A

Uses an electrochemical gradient which was set up by diffusion and the primary active transport
It uses energy but not from atp directly
It uses the energy from Na diffusing across the membrane and pushing glucose across its concentration gradient

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27
Q

What is the electrochemical gradient

A

When ions move so the charges balance out
When an ion moves across a membrane the charge follows
Usually made up of concentration and electrical gradient since ions and molecules want to move along their gradients

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28
Q

How can you find the membrane potential

A

Charge inside the cell minus the charge outside the cell

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29
Q

What is equilibrium potential

A

When the electrical gradient is equal to the chemical gradient

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30
Q

Should the membrane potential equal the equilibrium potential for ions?

A

Yes and it can be found using the Nernst equation

31
Q

If the Nernst equation tells us the equilibrium potential of an ion and these ions are trying to reach their own equilibrium potential, how can this be calculated

A

The Goldman Hodgkin Katz equation can find the average equilibrium potential while also factoring in permeability

32
Q

When there is an unequal distribution of ions between the ECF and ICF what does that create

A

The membrane potential which is essentially a charge difference across the cell membrane

33
Q

What is endocytosis

A

Bringing large molecules into the cell

34
Q

What is exocytosis

A

Taking large molecules out of the cell

35
Q

What is contact signaling

A

When cells contact each other by touching

36
Q

What is chemical signaling

A

When ligands bind to receptors to change their shape

37
Q

What is a G protein linked receptor

A

Secondary messengers that change the shape of a different membrane protein

38
Q

How do nexus junctions work in order to signal to other cells

A

They use direct cell to cell communication
Signal across gap junctions

39
Q

What are the three ways for chemical signaling in the endocrine system

A

Autocrine which is when a signal molecule targets itself
Paracrine which is when a signal molecule targets a cell of the same tissue
Endocrine which is when a signal molecule targets a distant cell using the blood stream

40
Q

What do chemical messengers have and what do they do

A

They must have a receptor otherwise they can’t accept and send signals
They activate signal transduction pathways

41
Q

How can amino acid based hormones be classified

A

Usually variable in size
Usually as peptides, water soluble, and can’t cross the plasma membrane

42
Q

How can steroids be classified

A

Made from cholesterol
Include gonadal and adrenocortical hormones
Lipid soluble and can cross the plasma membrane

43
Q

How can eicosanoids be classified

A

Lipid based that usually act as Paracrine and Autocrine hormones

44
Q

Explain how peptide messengers are eventually made to signal to the body

A

They are synthesized as preprohormones that contain signal sequences for secretion
That secretin signal is then cleaved before vesicular formation in the golgi
In the golgi the hormone is broken down so the only thing left is the prohormone which is inactive
The secretory Vesicles contain enzymes that then cleave the pro hormone to activate the hormone and send a signal to the body

45
Q

What are the three major classes of steroid hormones

A

Mineralcorticoids which regulate sodium intake by the kidney
Glucocorticoids which are the stress hormones
Reproductive hormones which regulate sex specific characteristics and reproductions

46
Q

How do steroid hormones usually cross the cell membrane

A

They bind to a carrier protein for transport such as albumin
Once in the cell they bind to transmembrane receptors or intracellular receptors

47
Q

What are biogenic amines

A

They have an amine group and are synthesized from amino acids

48
Q

What is the structure of an eicosanoid and where does it come from? What other characteristics can you name

A

20 carbons
Derived from arachidonic acid
Act as neurotransmitters and Paracrine hormones
Degrade quickly in the ECF
Prostaglandins are most common type

49
Q

What happens when there is a higher affinity for a messenger? What about a low affinity?

A

Higher affinity means lower concentration and lower affinity means higher concentration of messenger

50
Q

How can you stop a ligand receptor signal

A

Remove it using distant tissues
Have adjacent cells take the ligand
Degrade it by Extracellular enzymes
Remove the ligand receptor complex using endocytosis
Inactivate a signal transduction pathway

51
Q

What can signal transduction pathways lead to

A

Amplification of a signal (stronger signal)

52
Q

With intracellular receptors being inside the cell what can they do

A

Increase transcription

53
Q

What are G protein linked receptors considered and what some examples

A

They are second messengers such as cAMP, cGMP, IP3/DAG
Can act through calmodulin and interact with amplifier enzymes which can change the speed of second messengers

54
Q

What do receptor enzymes involve and what are the three types

A

Involve phosphorylation cascades
Guanylate Cyclase makes cGMP
Tyrosine kinase phosphorylates tyrosine and uses RAS to change GDP to GTP and visa versa
Serine/ threonine kinase phosphorylates but doesn’t use RAS proteins

55
Q

Explain the cAMP pathway

A

Protein binds to receptor which then activates G protein
G protein activates adenylyl Cyclase which converts ATP into cAMP
cAMP activates protein kinases which phosphorylate a protein and the proteins generate a cellular response

56
Q

Explain the PIP2 and IP3 pathway

A

A ligand binds to the G protein coupled receptor
GDP exchanged for GTP on the G protein then the G protein dissociates from the receptor
G protein then activates phospholipase and phospholipase splits PIP2 into DAG and IP3

57
Q

When PIP2 is split into DAG what happens

A

DAG activates protein kinase C and protein kinase C phosphorylates the protein

58
Q

What happens when PIP2 is made into IP3

A

IP3 caused the ER to release Ca2+ which binds to calmodulin which then causes a cellular response

59
Q

What is a negative feedback loop

A

When A deviation from the set point is decreased and the regulated variable returns to its original value

60
Q

What is a positive feedback loop

A

When there is an increased deviation from the set point that tends to cause the regulated variable to move further away from its original value

61
Q

Explain the MAP K pathway

A

Ligand binds to the RTK and RTK phosphorylate itself
The phosphorylated RTK then binds to GRB2 and SOS binds to GRB2
RAS and GDP binds to SOS and GDP is exchanged for GTP
GTP and RAS dissociate from SOS and MAP K is activated when protein kinase binds to RAS and GTP complex
MAP K then activates transcription factors and cell proliferation occurs

62
Q

When blood glucose levels rise and and insulin is secreted what happens

A

An increase in intracellular atp levels which sends a signal to the ATP dependent K+ channel which causes it to close
The closed channel then causes the cell membrane potential to rise which causes the gated Ca2+ channel to open
Ca2+ enters the cell causing exocytosis of insulin containing vesicles and insulin then travels to the liver and binds to tyrosine kinase
Glucose transporters are then activated and glucose is taken up by the liver
Blood glucose levels drops and a decrease in blood glucose causes a decrease in intracellular ATP levels

63
Q

What happens when a fetus puts pressure on the cervix

A

Stretch receptors send signals to the brain to release oxytocin
Oxytocin then binds to receptors on smooth muscle causing contraction
Contractions push the fetus against the cervix which increases stimulus on the stretch receptors
This increase in stimulus then causes an increase in oxytocin release

64
Q

What is the cytoskeleton and motor proteins responsible for and what are they made of

A

Responsible for intracellular trafficking
Made of microtubules, MAPs, kinesin, dynein, actin, myosin

65
Q

What is an example of a microtubule organizing center and what are microtubules used for

A

The centrosome is a MTOC and microtubules are used to control the movement of subcellular components

66
Q

What is tubulin a dimer of and what is attached to the tubulin prior to dimerization

A

Alpha and beta tubulin and GTP is attached

67
Q

How is a protofilament formed and what do they make

A

Dimer merge together to make the protofilament and then the protofilament sheets rile together to form a microtubule

68
Q

What does a beta dimer correspond with and what does an alpha dimer correspond with in regards to charge

A

Beta is positive
Alpha is negative

69
Q

What happens when you have a high concentration of tubulin? Low concentration?

A

High concentration means growth and low concentration means shrinking

70
Q

What is treadmilling

A

When growth and shrinkage from tubulin occurs at the same rate

71
Q

How fast the dimmers add depends on what and how do tubulin dimers add

A

Depends on the concentration of tubulin which follows law of mass action and tubulin dimers fall off on negative end and add on positive end

72
Q

What helps stabilize and destabilize microtubule structure

A

MAPs which are controlled by protein kinases and phosphatases

73
Q

When are stable tubule only peptides (STOPs) used

A

When cells need long stable microtubules

74
Q

What can dynein and kinesin do

A

Walk along a microtubule
Dynein moves toward the negative charge (alpha) and kind in moves toward the positive (beta) charge
Dynein moves in a retrograde (towards the nucleus) and kinein moves anterograde (away from the nucleus)

Physiology (13 decks)

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