BIOL 1412 > TOPIC 2 - CELL PHYSIOLOGY > Flashcards

TOPIC 2 - CELL PHYSIOLOGY Flashcards

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1
Q

What is the phospholipid bilayer?

A
  • A continuous layer around the cell that is a barrier to water soluble substances (NOT to small molecules like O2 & CO2)
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2
Q

True or False:
The phospholipid bilayer is two layers of phospholipids with hydrophilic tails and hydrophobic heads.

A

FALSE
* The phospholipid bilayer is two layers of phospholipids with hydrophilic HEADS and hydrophobic TAILS

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3
Q

What membrane proteins can be found in the phospholipid bilayer? (6)

A
  • Transport proteins
  • Carrier proteins
  • Receptor proteins
  • Enzymes
  • Joining proteins
  • Identifying proteins
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4
Q

What are the 2 types of transport proteins?

A
  • Channels
  • Carrier proteins
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5
Q

Which membrane proteins form a pore in the membrane through which selected ions/molecules can move through freely?

A

Transport proteins - specifically Channels

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6
Q

What do Channels do? (Transport Protein)

A

Selectively permit channel-mediated Facilitated diffusion of specific ions

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7
Q

Channels can be…?

A
  • Gated: can open or close when signaled
  • Non-gated: always open (leakage channels)
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8
Q

What kind of membrane protein are carrier proteins and what do they do?

A
  • Transport protein
  • Bind to solute (ion/molecule) and help carry it across the membrane
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9
Q

What do carrier proteins allow for?

A
  • Carrier-mediated facilitated diffusion
    OR
  • Active transport
    E.g. glucose transporter
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10
Q

What is the function of receptor proteins?

A

Bind to specific extracellular molecules (=ligands) like hormones & neurotransmitters (nt)

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11
Q

Explain the 3 steps to how receptor proteins work in glucose uptake (by skeletal muscle (SkM) cells or adipose tissue (AT)).

A

1) Insulin binds to receptor on SkM or AT
2) Triggers movement of more glucose transporters to cell membrane
3) ^ glucose movement from flood into cells

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12
Q

Enzymes control….on outer or inner surfaces of the phospholipid bilayer.

A

Control Chemical reactions

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13
Q

What enzyme breaks down the most common neurotransmitter in the human body?

A

Acetylcholinesterase

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14
Q

What is the function of joining proteins?

A

To anchor cell membrane to cytoskeleton or an adjacent cell

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15
Q

What do junctional proteins between cells form?

A
  • Desmosomes
  • Tight junctions
  • Gap junctions
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16
Q

What do desmosomes do?

A

Hold cells together like rivets

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17
Q

What do tight junctions do?

A

Seal membranes of adjacent cells together to prevent leaking

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18
Q

What do gap junctions do?

A

Create channels between two adjacent cells

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19
Q

Joining (linker) proteins can sometimes be…..?

A

Extracellular fibers (usually glycoproteins)

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20
Q

What are identifying proteins also called?

A

Major Histocompatibility COmplex (MHC) proteins

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21
Q

Where can identifying proteins be found?

A

On surface of all cells except red blood cells

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22
Q

What are identifying proteins used for?

A

So cells/tissues can identify themselves as ‘self” and not foreign

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23
Q

What make up the membrane carbohydrates?

A

Glycoproteins & Glycolipids

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24
Q

True or False:
Membrane carbohydrates differ for every cell type to allow cells to recognize cell type (e.g. sperm recognizes egg). Also allows alike cells to cluster (muscle fibers, neurons)

A

TRUE

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25
What does homeostasis rely on to move solutes and/or solvents across the cell membrane?
The ability of cells to maintain the composition of the ICF and ECF fluids
26
What does salute mean?
A substance dissolved in a solution
27
What does solvent mean?
Substance solute is dissolved in (e.g. water, alcohol)
28
What are the 2 types of transport?
* Passive transport * Active transport
29
What makes passive transport passive?
No energy is required (no ATP)
30
True or False: Passive transport is movement from a low to high concentration (down the concentration gradient).
**FALSE** Passive transport is movement from a **HIGH** to **LOW** concentration
31
True or False: The greater the difference in concentration = the more molecules want to move
**TRUE**
32
What are the 5 types of passive transport?
1) Simple diffusion (solute movement) 2) Channel-mediated facilitated diffusion (solute movement) 3) Carrier-mediated facilitated diffusion (solute movement) 4) Osmosis (solvent movement) 5) Bulk flow
33
What is simple diffusion?
Solute diffuses directly through the cell membrane bilayer; small and lipid soluble molecules
34
What is channel-mediated facilitated diffusion?
_Ions_ diffuse through membrane via protein _channels_; The solute does not bind to the protein, but moves freely through the opening created by the channel
35
What is carrier-mediated facilitated diffusion?
* Large, charged or water soluble molecules * Diffuse across membrane using a specific _carrier protein_; must bind to protein to be transported
36
What is Osmosis?
Movement of H2O across a _semipermeable_ membrane due to difference (H2O moves down its concentration gradient) via pores (channels) or across the membrane bilayer
37
(Osmosis) High H2O = .....
Low solute (dilute solution)
38
(Osmosis) Low H2O = .....
High solute (concentrated solution)
39
What does solute depend on?
The # of ions or molecules not the type
40
What is osmotic pressure?
The pressure required to prevent the movement of water across a semipermeable membrane due to osmosis
41
What is osmotic pressure determined by?
The concentrated of solutes in a solution
42
Pure water has an osmotic pressure of ....?
0
43
True or False: The greater the solute concentration, the higher the _osmotic pressure_ will be.
**TRUE**
44
True or False: Water moves from areas of high osmotic pressure to ares of low osmotic pressure
**FALSE** * Water moves from areas of **LOW** osmotic pressure to areas of **HIGH** osmotic pressure
45
If there are 2 solutions, S1 & S2, and S1 is purely H2O and S2 is a high solute concentration solution, where will water move if both are connected via a semipermeable membrane?
From S1 -> S2 because S2 has a higher osmotic pressure
46
IF both S1 and S2 are purely H2O, is there a concentration gradient/osmotic pressure difference?
NO, the osmotic pressure of both solutions is 0
47
High osmotic pressure = .....
= High solute/low H2O
48
Low osmotic pressure = .....
= Low solute/High H2O
49
What is tonicity?
The response of a cell immersed in a solution
50
What does tonicity depend on?
* Solute concentration * Permeability of cell membrane to the solute
51
What are the 3 tonicity classifications?
1) Hypotonic 2) Hypertonic 3) Isotonic
52
What is a hypotnic solution? What happens?
* ECF has **lower** osmitic presser (**higher** concentration of water than ICF) * Cell swells and can burst/rupture (lysis)
53
What is it caled when a cell swells and bursts in a hypotonic solution? A red blood cell?
* **Lysis** * Hemo**lysis**
54
What is a hypertonic solution? What happens?
* ECF has a **higher** osmotic pressure (**Lower** concentration of water than ICF) * Cell shrinks (loses H2O)
55
What is an isotonic solution? What happens?
* ECF & ICF have = osmotic pressure * Cell neither shrinks nor swells
56
What tonicity do most cells in the human body have? What is the % concentration of saline?
* Isotonic * 0.9% saline solution (NaCl) (Normal)
57
What is the tonicity of a 10% sucrose solution? What will happen if it is injected into the bloodstream?
* Hypertonic * Will draw water into blood from tissues | Used to reduce brain edema (swelling)
58
What is the role of osmosis in regulation of solute concentration ?
Concentration of solutes in body fluids must be maintained within narrow limits or cells will die
59
What are the bodies major fluids?
* **ECF:** blood plasma, interstitial fluid (ISF) * **ICF:** Cystol
60
Give me a breakdown of fluid types in the body.
40% solids 60% fluids: * 2/3s ICF * 1/3s ECF: * * 80% ISF * * 20% plasma
61
If the body loses H2O (sweating), what happens to the concentration of blood?
It increases
62
If the concentration of blood increases due to a loss of H2O, what happens to its osmotic pressure?
It also increases
63
If the osmotic pressure of blood increases due to a loss of H2O (sweating), how does the body replenish H20?
Fluid moves from the tissues into the blood | (dehydration of tissues)
64
What is the response due to a dehydration of tissues?
* ↑ in thirst * ↓ Renal H20 loss, which leads to * ↓ urine production
65
What is bulk flow?
Movement of fluid (& solids) due to a **pressure gradient** (high -> low)
66
If diffusion moves solutes, and osmosis moves water, what does bulk flow move?
**BOTH**
67
What is hydrostatic pressure?
The pressure of a fluid **pressing** against a surface E.g.: * Cell membrane * Blood vessel wall ( + BP) * Capillary
68
What happens if blood has a higher pressure than ISF in a capillary?
Fluid flows **out** of the capillary (**Filtration**)
69
What happens if ISF has a higher pressure than blood?
Fluid flows from ISF **into** the capillary (**absorption**)
70
What do active processes of transport require to work?
**ATP** | Energy
71
Why do active process require ATP?
Because they move ions/molecules **against** their concentration gradient
72
What are the 2 types of active processes?
* Active transport * Vesicular transport
73
What is active transport?
Substances move against concentration gradient (low -> high)
74
Active transport is **ALWAYS**....?
Protein carrier mediated
75
What are the 2 types of active transport?
* Primary (1º) active transport transport * Secondary (2º) active transport
76
What is involved in primary (1º) active transport?
**Molecular pumps:** ATP breakdown is directly part of transport processes * Na+/K+ ATPase Pump - 3 Na+ out of cell and 2 K+ in per ATP ## Footnote One protein breaks fdown ATP **AND** transports the solute(s)
77
What is involved in secondary (2º) active transport?
Cotransport (use of ATP is **indirect**) * e.g. glucose absoprtion by enterocytes have 2 steps 1) A Na+ gradient is established by Na+/K+ ATPase (ATP used) 2) Glucose & Na+ both must bind to the carrier protein and are cotransported into cell -> Na+ down gradient drives glucose down gradient too ## Footnote One protein breaks down ATP and **another** transports
78
What is vesicualr transport?
Substance is surrounded by a membrane within the cell (vesicle)
79
What are the 2 types of vesicular transport?
* **Endocytosis:** movement into a cell * **Exocytosis:** movement out of a cell
80
What are the 2 types of endocytosis?
1) **Phagocytosis:** large items into cell (bacteria) (= cell "eating") 2) **Pinocytosis:** Fluids (+ disolved substances) (= Cell drinking)
81
What occurs during exocytosis?
Vesicles containing hormones, enzymes, neurotransmitters, etc, fuse with cell membrane releasing contents into ECF
82
What triggers vesicles in exocytosis to relase their contents into the ECF?
A rise in cytosolic Ca++
BIOL 1412
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