1
Q
Homeostasis
A
Ability of cell or organism to maintain its internal environment regardless of the influences of the external environment
2
Q
Set point
A
- Range or point at which a variable physiological point tends to stabilize
- Optimal conditions
3
Q
Homeostatic control system
A
- Must be in place to maintain a set point
- Includes 3 components: sensor, integrator, effector
4
Q
Sensor
A
Responsible for detecting an environmental variable
5
Q
Integrator
A
Compares variable being detected to its set point
6
Q
Effector
A
Responsible for initiating the changes to restore the variable back to its set point
7
Q
Intrinsic control
A
- Sensor, integrator and effector are all located within a tissue
- Tissue can regulate its own internal environment
8
Q
Extrinsic control
A
- Regulatory mechanisms are outside the tissue or organ
- More common than intrinsic control
9
Q
Negative feedback
A
- A process where the body reverses a change to stay near a set point
- Ex: how glucose is regulated in the body
10
Q
Positive feedback
A
- A process where the body amplifies a change instead of reversing it
- Ex: Childbirth
11
Q
3 primary functions of plasma membrane
A
- Ensure cell’s survival
- Maintain homeostasis
- Function with surrounding cells
12
Q
Phospholipid makeup
A
- 1 hydrophilic head
- A negatively charged phosphate group
- 2 hydrophobic tails
13
Q
Cholesterol
A
- Keeps membrane fluid
- Prevents fatty acid chains from packing too closely together
14
Q
Membrane proteins function (4)
A
- Maintain cell structure
- Regulate cell function
- Allow transport across cell membrane
- facilitate signalling
15
Q
Ion channels
A
Permit entry or exist of ions
16
Q
Carbohydrate chain functions (3)
A
- Stabilize membrane structure
- Act as cell surface receptors
- Help transportation across cell membrane
17
Q
Cystic fibrosis
A
- Caused by defect in a chloride ion channel involved in fluid and mucous in the lungs
- Patients experience a buildup of fluid making breathing difficult
18
Q
Alzheimer’s disease
A
- Results in oxidative stress (ROS)
- Alters and degrades the phospholipids in brain cells
- Causes memory loss and reduced cognitive function
19
Q
Extracellular matrix
A
- A network of proteins in a gel-like fluid that surrounds and supports cells
- Allows diffusion of nutrients and removal of waste from cells
20
Q
Collagen
A
Forms cable-like fibres and gives ECM its strength
21
Q
Elastin
A
Allows tissues to stretch and then recoil
22
Q
Fibronectin
A
Promotes cell adhesion
23
Q
Cell Adhesion Molecules (CAMs)
A
- Transmembrane proteins
- Helps cells stick to each other and to their surroundings
24
Q
Desmosomes
A
Used to anchor together two adjacent cells
25
Makeup of desmosomes
Dense intracellular plaques that are connected by glycoprotein filaments
26
Tight junctions
- Creates tight seal between cells, preventing movement of molecules
- primarily found in epithelial tissues
27
Kiss site
Spot where tight junction proteins from two neighbouring cells touch and seal together
28
Gap junctions
- Channels connecting adjacent cells for direct communication
- Allow passage of small, water-soluble molecules and ions between cells
- Common in cardiac and smooth muscle cells
29
Connexon
Assembly of six connexin proteins form half of a gap junction pore
30
Plasma membrane permeability
- Semi-permeable
- Some substances can pass freely while others cannot
31
Factors which determine membrane permeability
1. Size
2. Solubility
32
Size - Membrane permeability
- Small ions cross membranes through ion channels
- Larger molecules (e.g. glucose) need transport proteins
33
Solubility - Membrane permeability
- Depends on lipophilicity
- Nonpolar/uncharged (O₂, CO₂, fatty acids) = lipophilic → cross easily
- Polar/charged (Na⁺, Ca²⁺, glucose) = lipophobic → need help crossing
34
Diffusion
- Movement from high to low concentration
- Stops at dynamic equilibrium (no net movement)
35
Diffusion & Membrane Permeability
- If membrane is permeable → solute diffuses down gradient until equilibrium
- If impermeable → no diffusion, gradient stays
36
Aquaporins
Channels that allow water molecules to freely pass
37
Osmosis
- Diffusion of water from an area of high concentration to low concentration
- Down its concentration gradient
38
Osmosis & Non-Penetrating Solute
- Solute can’t cross → only water moves by osmosis
- Water moves to dilute solute side until concentrations balance
- Unequal volumes → cells may shrink or swell depending on water movement
39
Osmosis & Penetrating Solute
- If solute can cross (penetrating), solute diffuses and water moves by osmosis
- Result → both solute and water evenly distributed
40
Osmotic pressure
- Force driving water down its concentration gradient
- Bigger gradient → stronger osmotic pressure
41
Hydrostatic Pressure
- Force from water volume
- More volume → greater hydrostatic pressure
- At steady state: not equal solute concentration, but equal pressures
42
Facilitated diffusion
- Does not require energy
- Uses a carrier protein to assist in the transport of a substance
43
Active transport
- Uses carrier proteins to move substances against gradient, area of low concentration to high concentration
- Requires ATP because it opposes diffusion
44
Na+/K+ ATPase Pump
- Example of active diffusion
- pumps 3 Na+ out of the cell
- Pumps 2 K+ inside the cell
45
3 characteristics of carrier mediated transport
1. Specificity
2. Saturation
3. Competition
46
Specificity - Carrier mediated transport
- Each carrier protein is specialized to recognize and transport a specific substance
- Structurally related substances can share the same transporter
47
Saturation - Carrier mediated transport
- Carrier proteins are limited → transport maximum exists
- Once Tm is reached, transport cannot increase further
48
Competition - Carrier mediated transport
- Different substances can share the same carrier protein
- When competing, none reach full transport maximum (Tm)
49
Vesicular Transport
- Moves large molecules/ions using membrane-enclosed vesicles
- Requires energy, form of active transport
50
Endocytosis
Vesicular transport that moves substances from outside a cell into it
51
Pinocytosis
- Cell membrane engulfs a small droplet of extracellular fluid
- Non-selective, vesicle will contain whatever substances were close at the time
52
Receptor-Mediated Endocytosis
Similar to pinocytosis but vesicle forms when a substance binds to specific receptor on cell surface
53
Phagocytosis
- Internalization of large multi molecular particles
- Only occurs in a few cells, i.e white blood cells
54
Exocytosis
- Reverse of endocytosis
- Vesicle fuses with plasma membrane and releases contents outside cell
- Often used by materials produced from Golgi and ER
55
Exocytosis Purpose 1
- Releases large polar molecules that can’t cross the membrane
- Often triggered by a signal
56
Exocytosis Purpose 2
- Adds proteins to the plasma membrane
- Vesicle membrane fuses, proteins become part of the cell membrane
PHGY 215
flashcards
Decks in class (28)
# Cards
-
Module 1: Section 1 + 256
-
Module 1: Section 316
-
Module 1: Section 413
-
Module 1: Section 531
-
Module 2: Section 120
-
Module 2: Section 216
-
Module 2: Section 332
-
Module 2: Section 451
-
Module 2: Section 511
-
Module 4: Section 127
-
Module 4: Section 235
-
Module 4: Section 333
-
Module 4: Section 426
-
Module 4: Section 59
-
Module 4: Section 628
-
Module 5: Section 115
-
Module 5: Section 234
-
Module 5: Section 352
-
Module 5: Section 47
-
Module 5: Section 533
-
Module 5: Section 67
-
Module 6: Section 121
-
Module 6: Section 223
-
Module 6: Section 344
-
Module 6: Section 428
-
Module 6: Section 512
-
Module 6: Section 613
-
Module 6: Section 743
