Brainscape's Knowledge GenomeTM

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


See full index

BPK 205 > BPK 205 Week 2: Principles of Cellular Physiology; Membrane Transport, Membrane Potentials > Flashcards

BPK 205 Week 2: Principles of Cellular Physiology; Membrane Transport, Membrane Potentials Flashcards

1
Q

Why are ion channels unevenly distributed across the cell membrane?

A
  • ion channels and transporters in the plasma membrane move ions resulting in an unequal distribution of ions and net charge
  • necessary for biological processes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Typically: there are more ____x3 within the cell

A
  • proteins
  • K+
  • phosphate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Typically: there are more ____x3 outside the cell

A
  • Cl-
  • Na+
  • Ca2+
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why is the inside of the cell ___ charged?

A
  • negatively
  • Negatively charged proteins
  • Negatively charged phosphate
  • Sodium potassium charge kicking out an excess charge every time it cycles
    Potassium leak channels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

resting membrane potential (RMP)

A
  • net charge difference between the intracellular fluid and extracellular fluid at rest; Result of the unequal distribution of ions on each side of the membrane
  • -70mV
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Membrane potential symbol

A

Vm or Em

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

List and describe the 2 driving forces experienced by ions

A
  • Chemical driving force: movement of a substance in or out of a cell based on concentration gradient
  • Electrical driving force: attraction of a substance in or out of a cell based on charge; Net movement is based on electrochemical gradient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Equilibrium potential

A

the millivolt value at which the chemical driving force and electrical driving force are equal and opposite. results in no net ion movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the equilibrium potential of potassium?

A

-94mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Nernst equation

  • define
  • give equation
A
  • used to calculate equilibrium potential of an ion

- see google doc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Goldman-Hodgkin-Katz Equation (GHK equation)

  • define
  • give equation
A
  • predicts membrane potential that results from the contribution of all ions that can cross the membrane. Based on the combined contributions of concentration gradients and relative membrane permeability for each ion
  • see google doc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why is the cell almost always somewhat permeable to potassium?

A
  • potassium leak channels

- cells are more permeable to K+ than any other ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the primary contributor to resting membrane potential>

A

K+

- -90mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

If the cell’s permeability to an ion increases:

A
  • Get an increase in flow of that ion

- Change in Vm towards that ion’s Ex

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

Hyperpolarization:

A

more negative than resting membrane potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Depolarization

A

change in membrane potential that brings you closer to 0 is called depolarization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the 2 physiological signals

A
  • Electrical signals: changes in the membrane potential of a cell
  • Chemical signals: molecules secreted by cells into ECF; Bind to specific receptors on or in target cells (usually on)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe local cell-cell communication (3)

A
  • gap junctions: form direct cytoplasmic connections between adjacent cells
  • contact-dependent signals: require interaction between membrane molecules on two cells (example: cells that touch each other stop growing in a petridish)
  • autocrine signals: act on the same cell that secreted them. paracrine signals are secreted by one cell and diffuse to adjacent cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe long distance communication

A
  • example: action potential travelling along a neuron
  • hormones: secretions that travel through the blood
  • neurotransmitters: chemical secretions by neurons that diffuse across a small gap to the target cell (short distance)
  • neurohormones: chemicals released by neurons into the blood for action at distant targets (long distance)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Define: hormones and give an example

A
  • Hormones are secreted by endocrine glands or cells into the blood. Only target cells with receptors for the hormone will respond to the signal
  • Example: insulin secreted from the pancreatic B cells and bind the insulin receptors on cells throughout the body enabling glucose to enter these cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Define: neurotransmitters and give an example

A
  • neurotransmitters are chemicals secreted by neurons that diffuse across a small gap to the target cell (short distance)
  • Example: acetylcholine (neurotransmitter) - used to elicit skeletal muscle contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Define: neurohormones and give an example

A
  • Neurohormones: chemicals released by neurons into the blood for action at distant targets (long distance)
  • Example: oxytocin is released by neurons in the posterior pituitary gland into the blood and stimulates uterine contractions during labour
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the 4 major classes of chemical signalling molecules?

A
  • amino acids
  • amines
  • peptides or proteins
  • steroids
  • others
24
Q

List the 4 categories of membrane receptors

A
  • receptor channels/ ligand gated channels
  • Enzyme-linked receptor
  • G protein-coupled receptor
  • Integrin receptor
25
Q

Describe this membrane receptor: receptor channel/ligand gated channels

A

Ligand-gated channels: signalling molecule (ligand) binds to its receptor and the receptor is an ion channel that is gated by ligand binding (fast response)

26
Q

Describe this membrane receptor: enzyme-linked receptor

A

ligand building to a receptor-enzyme which activates an intracellular enzyme
- example: tyrosine kinase (TK) transfers phosphate group from ATP to tyrosine (an amino acid) of a protein

27
Q

Describe this membrane receptor: G protein-coupled receptor (GPCRs)

A

ligand binds to a receptor that is physically coupled to a Guanosine nucleotide-binding (G) protein. G protein activates. The type of G protein involved will determine which intracellular cascade is initiated. Some GPCRs when activated will modify the activity of an enzyme initiating or inhibiting intracellular cascade of events

  • can open an ion channel or alters enzyme activity
  • largest family of cell surface receptors
  • G protein has 3 subunits (alpha, beta, gamma)
28
Q

Describe this membrane receptor: integrin receptor

A

ligand binding to integrin receptors alters the cytoskeleton

29
Q

Provide an overview of signal transduction

A
  • see google doc
30
Q

Describe kinase

A

phosphorylate proteins

- Enzyme that uses ATP to put phosphates on target proteins, channels, or enzymes

31
Q

Describe phosphatases

A

dephosphorylate proteins

- Remove phosphate groups from target protein, channels or enzymes

32
Q

Signal amplification

A

turning up the “volume” in every step of the signal transduction pathway
- Example: one ligand may activate many second messenger systems

33
Q

Signal transduction cascade

A

ensures that cellular response only occurs when there’s a signal for it

34
Q

List two pathways related to GPCRs

A
  • adenylyl cyclase pathway

- phospholipase C pathway

35
Q

Describe the adenylyl cyclase pathway

A
  • see google doc
36
Q

Describe the phospholipase C pathway

A
  • see google doc
37
Q

State which is faster and why: receptor gated channel vs G protein coupled receptor

A
  • receptor gated channel; less intracellular signalling and response needed
38
Q

State the Ca2+ levels in the cytosol

A
  • really low

- [Ca2+]o = 1.8 mM; [Ca2+]i < 0.001 mM

39
Q

Ca2+ enters the cell via what (4)

A
  • Voltage-gated channels
  • Ligand-gated channels
  • Mechanically-gated channels
  • Can also be released from stores by second messengers
40
Q

State what Ca2+ is used for in the body

A

Released Ca2+ will bind with Ca2+ binding proteins to exert effects (example: muscle contraction)

41
Q

Define and describe hormones

A

Hormones: Cell-to-cell communication molecules

  • Chemical signals; usually v. low concentration
  • May be secreted by a cell or group of cells (gland)
  • Transported by blood to distant target tissues; may act on many tissue types, or just one
42
Q

half life

A

Half-life = time for the [hormone] in blood to reduce by 1/2
- Essentially a measure of stability of the hormone

43
Q

3 chemical classes of hormones

A
  • peptide/protein
  • steroid
  • amine
44
Q

Peptide/protein hormones

  • lipophobic hydrophilic, lipophilic/hydrophobic
  • synthesis
  • storage
  • release
  • transport in blood
  • half-life
  • receptor location
  • general cellular response
A
  • Lipophobic, hydrophilic
  • Synthesis: made in advance in endocrine cells all over the body as inactive preprohormone. Series of post-translational modifications (in the Golgi complex) convert it to prohormone then hormone. Only the final hormone in a vesicle is active
  • Storage: stored in vesicles until needed
  • Release: into ECF via exocytosis then diffuses from ECF into blood (carried away in solution)
  • Transport in blood: in solution
  • Half-life: short (seconds to minutes)
  • Receptor location: tend to bind to membrane receptors since they’re so large and bulky
  • General cellular response: alters activity of target proteins
45
Q

steroid

  • lipophobic hydrophilic, lipophilic/hydrophobic
  • synthesis
  • storage
  • release
  • transport in blood
  • half-life
  • receptor location
  • general cellular response
A
  • Synthesis: made from cholesterol and made on demand in the adrenal cortex, kidney, skin, gonads, placenta. Uses lipophobic precursors that could be stored in intracellular compartments (e.g. SER, cytoplasm)
  • Storage: cannot be stored because the final product is lipophilic (hydrophobic)
  • Release: simple diffusion into blood
  • Transport in blood: bound to carrier proteins
  • Half-life: hours
  • Receptor location and general cellular response:
    intracellular receptors → slow genomic response (=modulation/regulation of gene expression)
    Membrane receptors → fast, non-genomic response
46
Q

Amine

  • lipophobic hydrophilic, lipophilic/hydrophobic
  • synthesis
  • storage
  • release
  • transport in blood
  • half-life
  • receptor location
  • general cellular response
A
  • Synthesis: made in the pineal gland, adrenal medulla, thyroid; derived from tyrosine
  • Catecholamine are similar to peptide hormones in terms of characteristics
    ^ Lipophobic, stored for release, short half life, changes the activity of target protein, etc.
    ^ Includes adrenaline
    ^ neurohormone
  • Thyroid hormones are similar to steroid hormones
    ^ Lipophilic, made on demand from lipophobic precursors stored in the thyroid, requires carrier proteins, long half life, genomic responses, etc.
  • Storage:
  • Release:
  • Transport in blood:
  • Half-life:
  • Receptor location:
  • General cellular response:
47
Q

Gland

A

collection of secretory cells

48
Q

endocrine gland

A

Endocrine gland: secretes something that will stay within the body

49
Q

exocrine gland

A

Exocrine gland: secreting something that will leave the body

50
Q

Describe the pancreas’ endocrine and exocrine functions

A 
endocrine:
- Alpha cell: secretes glucagon
- Beta cell: secretes insulin
exocrine:
- Acinar cells and duct cells
- Pancreatic enzymes are secreted by the pancreas, dumped into the small intestine, where it assists with digestion
51
Q

list 3 cellular processes hormones regulate

A
  1. Rates of enzymatic reactions
  2. Transport of ions or molecules across cell membranes
  3. Gene expression and protein synthesis
52
Q

Q: What determines what a hormone does?

A

A: always about if the target receptor is present, where it is, and the specific signalling pathway present

53
Q

Pituitary gland:

  • location
  • structure
A
  • Location: in the brain; under the frontal cortex

- Structure: 2 glands fused together (posterior pituitary, anterior pituitary)

54
Q

Describe the posterior pituitary and the secretion of hormones from it

A
  • Posterior pituitary: neural tissue and secretes 2 neurohormones (vasopressin and oxytocin)
  • see google doc
55
Q

Describe the anterior pituitary and the secretion of hormones from it

A
  • Anterior pituitary: endocrine tissue and secretes six true hormones
  • Release of hormones is controlled by neurohormones from the hypothalamus, the region of the brain just above
  • Portal circulatory system: specialized modification where two sets of capillaries are connected in series by a set of small veins
  • see google doc
56
Q

Vasopressin

A

antidiuretic hormone or ADH

BPK 205 (2 decks)

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