Exam 2 (A&P) Flashcards
1
Q
Osmotic equilibrium
A
The state where fluid concentrations are equal on the two sides of the cell membrane
2
Q
Chemical disequilibrium
A
Solutes are more concentrated in one of the two sides of a compartment
3
Q
Electrical disequilibrium
A
body as a whole is neutral, distribution of charges is unequal (across compartments like cell membrane and neurons)
4
Q
Intracellular fluid (within cell) concentrations
A
Na, Cl, and HCO3 are low
K and proteins are high
5
Q
Interstitial fluid concentrations
A
K and HCO3 are low
Na, Cl are high
6
Q
Plasma concentrations
A
Na, Cl, and proteins are high
K and HCO3 are low
7
Q
Intracellular Fluid
A
2/3 of total body water, water contained in all cells of body
8
Q
Extracellular Fluid
A
1/3 of total body water, water contained between cells is interstitial fluid and water portion of blood (plasma)
9
Q
What fluid content can the body regulate
A
ECF is regulated but NOT ICF
10
Q
Osmosis
A
The movement of water across a membrane due to a difference in solute concentration.
The movement stops when the 2 compartments are equal in concentration; water wants to move from low to high SOLUTE concentration
Movement occurs through aquaporins
11
Q
Osmotic pressure
A
Pressure that is needed to oppose the osmotic movement of water
12
Q
Molarity
A
Number of moles of ONE TYPE of dissolved solute per liter of solution (mol/L).
13
Q
Osmolarity
A
Number of osmotically active particles (all particles added together) per liter of solution (osmol/L or mOsM)
Osmolarity can be used to compare concentrations of two different solutions
14
Q
Isomotic
A
A comparison of osmolarity; 2 solutions contain the same number of solute particles per unit of volume
15
Q
Hyperosmotic
A
A comparison of osmolarity; a solution contains a higher number of solute particles per unit of volume
16
Q
Hyposmotic
A
A comparison of osmolarity; a solution contains a lower number of solute particles per unit of volume
17
Q
Tonicity
A
Physiological term to describe how a solution affects CELL volume.
Depends on osmolarity of solution and the nature/type of solutes in the solution; Compare non-penetrating solute concentrations between cell and the solution
18
Q
Hypotonic
A
If a cell placed in the solution gains water it will swell and the solution is hypotonic to the cell
(Solute concentration is greater in the cell)
19
Q
Hypertonic
A
If the cell loses water and shrinks the solution is hypertonic to the cell (solute concentration is less in the cell)
20
Q
isotonic
A
if the cell in the solution does not change size the solution is isotonic to the cell (equal concnetrations)
21
Q
How does tonicity differ from osmolarity
A
Osmolarity compares two SOLUTIONS. Tonicity allows us to predict how a solution affects CELLS. Osmolarity has units for # of particles per volume and tonicity has no units it is strictly comparative.
22
Q
Why do we care about water movement
A
Administration of drugs, dealing with dehydration and swelling.
23
Q
Penetrating solutes
A
Freely cross the membrane and enter/exit the cell
ex: urea and gases
24
Q
Non-penetrating solutes
A
Unable to cross the membrane freely and need a transport; only enter via specific transport. Most particles are non-penetrating
ex: ions, proteins, biomolecules
25
Biological transport
Transport of biological components require help to cross the cell membrane
26
Bulk flow
Most general form of transport; driven by pressure, temp, or chemical gradients. Move from high to low. May or may not cross cell membrane
ex: movement of blood via pressure gradient
gas movement between lungs and cells
27
Membrane permeability
Cell membranes are selectively permeable (the degree in which things can cross); permeability can be altered
Depends on: molecule's lipid solubility, molecule's size, lipid comp of membrane
28
Molecule properties that alter permeablity
size: the larger the molecule the less permeable
Lipid solubility: lipid and lipid-like substances are more permeable.
water and some gases move freely
29
Passive transport
Broad category of movement; uses potential energy stored in concentration gradients, does NOT need energy from outside source.
Uses kinetic energy of molecules bouncing off each other and potential E from CG
30
Active transport
Broad category of movement; REQUIRES input of energy from outside source (often from ATP or another molecule moving down its CG and bringing something with it)
31
Diffusion
Movement of molecules from an area of higher concentration to an area of lower concentration; does NOT require outside energy
Occurs in open or closed system, across a membrane or within.
Smaller diffuses faster
32
7 properties of diffusion
1. No energy needed
2. Molecules move from high to low concentration
3. Net movement occurs until equilibrium (if possible)
4. Rapid over short distance
5. Directly related to temp (high temp = high diffusion)
6. Inversely related to molecular weight/size (smaller diffuse faster)
7. Can take place in open or across separate compartments
33
Rate of diffusion is faster if...
Membrane's surface area is larger, membrane is thinner, the CG is larger, the membrane is more permeable to given molecule
34
simple diffusion
movement of a substance directly across the phospholipid bilayer. Rate depends on molecule dissolving in lipid layer (lipophobic vs lipiphilic, lipid content/charge) and the larger the surface area of membrane the faster things will move
35
Fick's law
Summarizes simple diffusion
Rate proportional to (SA)*(CG)*(Membrane permeability)
with membrane perm proportional to (lipid solubility/molecular size)
36
Protein-mediated transport
Proteins help move lipophobic/charged across membrane
Can be passive or active
37
Passive transport
No energy required
facilitated diffusion, ion channels, aquaporins
38
Active transport
Energy required, moves substances AGAINST their CG, maintains or creates disequilibrium
primary (direct) active transport
secondary (indirect) active transport
39
Structural proteins
Create cell junctions to hold tissue together, connect membrane to cytoskeleton, attach cells to ECM
40
Enzymes
Catalyze chemical reactions on or near cell membrane
41
Receptors
Chemical signaling, receptor-ligand binding triggers intracellular response
42
transport proteins
specialized proteins that allow substances to cross;
2 types: Channel and carrier
43
Channel proteins
Transport, create water filled passageways, link intracellular and extracellular fluid
Specificity is important; can be open or gated (chemical, voltage, or mechanical gate) which allows for control
ex: aquaporin
44
Carrier proteins
transport, only exposed to intracellular or extracellular fluid at one time.
Uniport, antiport, symport
specificity is important and direction of fluid it faces can change
Molecule binds, carrier changes shape, protein opens to other side fluid
45
Uniport carrier protein
transports only one kind of substrate
46
Symport carrier protein
Move two or more substrates in the same direction across the membrane
47
Antiport carrier protein
move substrates in opposite directions
48
Facilitated diffusion
Uses carriers to help molecules move down their CG;
no energy needed, dependent on CG, stops with equilibrium
ex: GLUT transporters
49
Why does glucose rarely reach equilibrium
When glucose enters the cell it goes to glycolysis and is used/changed into another molecule so the concentration rarely increases on inside of cell
50
Primary active transport
AKA ATPases, uses energy from hydrolyzing ATP to ADP (exergonic rxn) to move substances against their CG
ex: sodium potassium pump
51
Sodium-potassium pump (Know this brief diagram)
30% of cell's total energy, moves 3 Na+ molecules outside while moving 2 K+ molecules inside, maintains disequilibrium.
Na binds from ICF, protein closes and gets phosphorylated, protein change shape and open to ECF where sodium leaves, K+ binds now, loss of P will close protein and open it on other side, K+ moves into cell.
52
Secondary active transport
Use the concentration gradient of sodium (or another molecule) to move substances. The Kinetic energy of a substance moving down its gradient is used to push another molecule against its gradient
NO ATP USED, energy source is the other CG
Symport or antiport
Ex: Sodium-Glucose Transporters (SGLT)
53
Three properties of protein-mediated transport
Specificity, competition, saturation
54
Specificity
ability of transporter to move only one molecule or group of closely related molecules
ex: GLUT only moves 6 carbon sugars
55
Competition
similar molecules can compete for binding sites on transporters and slow down movement (i.e. competitive inhibitor- they can bind but can't activate)
56
Saturation
Rate of molecule crossing the cell membrane can be maxed out; too many molecules or too few transporters
57
Epithelial transport
Something that enters or leaves our body must cross an epithelial surface; substance crosses more than one membrane
58
Transport epithelium characteristics
Polarized and create one way movement
Apical membrane- faces the lumen/cavity
Basolateral membrane- faces the ECF/matrix
59
Absorption
substances move from lumen to ECF, taking something in, can be paracellular or transcellular
60
Secretion
substances move from ECF to lumen, exiting
61
Difference between secretion and excretion
secretion doesn't leave body but excretion is out of body
62
Paracellular vs. transcellular
Paracellular transport "sneaks" between two cells, controlled by tight junctions
Transcellular transport goes across the cell all the way from Lumen --> ECF or other way.
63
Membrane potential (Vm)
The inside of a cell is negatively charged (even though body is neutral, distribution of charge is uneven); cells use the change in MP to send a signal
Changing cells permeability to an ion will change the membrane potential
64
Electricity
atoms are neutral, removal of an electron creates a charged ion.
65
Principles of electricity
law of conservation of electrical charge (body is neutral)
opposite charges are attracted to each other
separating charges from one another requires energy
water is a good conductor of electrical charge and the lipid bilayer is a good insulator (doesn't allow signal to conduct easily across)
66
What creates membrane potential (the difference in charge)
Ion concentration gradients, controlled by ion channels (chemical disequilibrium and electrical gradient)
Selectively permeable cell membrane (controlling ion movement)
Na+, K+, Cl-
67
Electrical equilibrium
no membrane potential, = # of +/- charges on each side of membrane
68
Leak channels
disrupt the electrical and chemical gradients, allow ions to flow down concentration gradient (in or out of cell depending on gradient)
69
When leak channel first starts, what happens?
The ion moves down its CG and the electrical disequilibrium occurs
70
After the leak channel has been active, what happens?
The outside net charge (ex: +) is attracted to the inside net charge (ex: -) that got created by the ions leaving, so some of the ions are attracted back into the cell --> electrical equilibrium
Cell will never reach chemical equilibrium with leak channels because of the electrical disequilibrium that is initially created
71
Equilibrium potential
Movement of ions never stops but the net movement is equal
72
Common voltage inside a cell
-40 mV --> -90 mV with a common value of -70mV
73
Insulin secretion pathway between meals
1. Low glucose going through GLUT transport decreases metabolism which decreases ATP production.
2. Low ATP triggers opening of KATP channel and K+ leaves cell
3. Cells membrane potential (Vm) is low so Ca2+ channel stays gated
4. No insulin is secreted
74
Insulin secretion pathway after a meal
1. High glucose in blood goes through GLUT.
2. Metabolism increases, ATP production increases
3. ATP concentration closes KATP channel so K+ stops leaving cell Vm becomes higher.
4. Ca2+ channel opens due to the changing membrane potential. Ca is signal to release insulin
5. Insulin secreted via exocytosis
75
Three forms of signals
Electrical, chemical, and contact-dependent
76
Electrical signals
Change in membrane potential
77
Chemical signals
Molecules secreted by cells into ECF and have a target cell
78
Contact dependent signals
Cell-cell or cell-matrix junctions
Surface molecule of one cell binds to surface molecule of another cell, also between a cell and its matrix.
Loss of contact stops signal from being sent and can cause cell death
79
Communication in human body
Local: Gap junctions, contact-dependent signals, chemicals acting on nearby cells
Long Distance: Chemical and electrical signals that act on distant cells
80
Gap junction
Connects 2 side by side cells via a channel to transfer chemical or electrical signals, simplest form of communication, can be gated or open, large molecules like proteins can't pass through.
81
Local communication
Chemicals sent to OTHER nearby cell are paracrines
Chemicals released by a cell that act on the same cell are autocrines
Both auto and para crines diffuse through ECF
82
Long-distance communication
Endocrine system uses hormones released in blood that require a specific receptor
Nervous system uses signals along nerve cells (Neurohormones and neurocrines)
83
Neuorcrine
chemical signals through neurons, secreted across a small gap to target but is still long distance
84
Neurohormones
Hormone signals through neurons that are released into blood to reach target cells
85
Signal transduction
Converts extracellular signal to intracellular signal and response; cell can only respond to a particular chemical signal only if it has the appropriate receptor to bind it; Receptor proteins are vital, cascade and amplification of signal
86
All signal pathways share these feature
Signal molecule (ligand) [1st messenger, ligand-receptor binding activates receptor, receptor activates intracellular signal molecules [2nd messenger], signal molecules creates a response (modify or synthesize new proteins).
87
Extracellular Receptors
On cell membrane, interact with lipophobic signals, initiate faster response, classic "ligand-receptor", 4 major types
88
Intracellular Receptors
Interact with lipophilic signals, slower response because often for genetic response, cytosolic receptors in cytosol and nuclear receptors in/on nucleus
89
4 major types of extracellular receptors
Receptor (Ion) channel
G-protein coupled receptors
Integrin receptors
Receptor enzymes
90
Receptor (Ion) channel
Voltage and mechanical are not a receptor channel but are still gated, chemical gated is receptor.
General process: Signal binds, receptor opens, ions flow.
Some channels directly linked to G-proteins, some respond to intracellular second messengers
91
G-Protein coupled Receptor (Adenylyl Cyclase)
Signal molecules binds to GPCR which activates G-protein (a separate attached molecule), G protein turns on adenylyl cyclase, adenylyl cyclase converts ATP to cyclic AMP, cAMP activates protein kinase A, Protein kinase A phosphorylates other proteins, leading to cell response.
92
G-Protein coupled Receptor (Phospholipase C) PLC
Signal molecules binds to GPCR which activates G-protein, G protein activates PLC, PLC converts membrane phospholipids into DAG (which stays in membrane), and IP3 (which diffuses to cytoplasm) DAG activates PKC which phosphorylates proteins, IP3 causes Ca2+ to release causing a Ca2+ signal.
IP3, PKC, PLC are all secondary messengers.
93
Receptor enzymes
More direct signal pathway, one giant protein unit with a side on ECF and one on cytoplasmic side
Signal binds to surface receptor, protein in ICF is phosphorylated --> cell response
94
Types of cell response
Change in motor proteins, enzyme activity, membrane receptors/transporters, gene activity and protein synth
95
Novel signal molecuels
Ca2+: levels very low in cell, enters through gated channels, stored in ER and can be released from there causes exocytosis, movement, and alters protein activity
96
Properties of receptor-ligand binding
Specificity: receptor binds one specific ligand
Competition: ligands compete for receptor binding spot
Saturation: ligands saturate all receptors on cell surface
97
Agonists
Ligands that activate a receptor when they bind but are not the primary ligand
98
Antagonists
Ligands that bind to the receptor but don't cause activation
ex of competitive inhibitor
99
Determining cell response
Receptors determine cell's response NOT ligand
Ex: epinephrine can bind multiple receptors but cause opposite effects
100
Up-regulate
Increase the number of cell surface receptors, slower than down-regulate because we need to make receptors from scratch which takes time and energy
101
Down-regulate
Decrease number of cell receptors, fast process because endocytosis is fast
Ex: Drug-tolerance
102
Cell terminating signal
Receptors internalized/degraded, ligands degraded in ECF by enzymes, ligands removed by transport into nearby cells, ligands sequestered (time-out) to a part of the cell.
103
Homeostatic reflex control
Long distance communication, uses chemical and electrical signals, feedback through control
104
Canon's 4 postulates
1. nervous system has role in preserving function of internal environment
2. Some systems under tonic control
3. Some systems under antagonistic control
4. Same chemical signal can have different effects in different tissues
105
Tonic control
A system is always on but the signal quantity can be increased or decreased, one signal
ex: blood vessels
106
Antagonistic control
Anything not under tonic control, 2 signals one for on, one for off
Ex: autonomic nervous system
107
Long-distance pathways maintaining homeostasis
Involve one OR both endocrine (hormone) system and nervous system, forms a response loop
108
Steps of response loop
Stimulus (disturbance or change of setpoint)
Sensor/Receptor (monitors enviro)
Input signal (afferent signal initiates reflex)
Integrating Center (compares input with setpoint)
Output signal (efferent signal sent by IC)
Target (cell or tissue that response)
Response (brings variable back to normal)
109
Types of control systems
Simple and complex
Endocrine or neural
110
Simple endocrine and simple neural reflex
only ONE integrating center, involves neural OR hormonal signal but not both.
111
Compare and contrast simple neural and simple endocrine- Specificity
Neurons terminate on one or few cells... More specific
Endocrine release into blood... Less specific
112
Compare and contrast simple neural and simple endocrine-
Nature of Signal
Neurons send electrical signals and release chemicals, endocrine only release chemicals
Electrical vs. chemical
113
Compare and contrast simple neural and simple endocrine- Speed
Neural reflexes are much faster, endocrine are much slower
114
Compare and contrast simple neural and simple endocrine- Duration of action (effect)
Neural reflexes are quick/short they start and end quickly
hormones are longer lasting because released into bloodstream
115
Compare and contrast simple neural and simple endocrine- Coding of stimulus activity
Neurons' electrical signal is always same intensity
endocrine signal intensity depends on how much hormone gets released
116
Sodium-Glucose Transporter (SGLT)
Na+ binds to carrier from ECF, the binding of Na creates high affinity site for glucose, glucose binding changes carrier conformation so binding sits now face ICF, Na+ released into cytosol which changes GLu binding site and releases glucose too.
Na+ moving down its concentration gradient to power this, no ATP used. Glucose is moving AGAINST its CG.
117
GLUT Transport
Glucose moving down its CG. Allows glucose (lipophobic) molecule through the membrane
