NP Midterm Flashcards
1
Q
List some physiological needs of the cells discussed in class:
A
Energy source, O2, environmental temperature, osmotic pressure, ion concentrations, removal of toxic compounds, defines against foreign organisms.
2
Q
The internal environment of the cells where cellular activities occur is called?
A
Intracellular Fluid = cytoplasm
3
Q
Plasma + interstitial fluid = _____________
A
Extra Cellular Fluid
4
Q
T or F
Many homeostatic mechanisms are aimed at maintaining the content of the ECF
A
True
5
Q
Name the parts of the Homeostatic System?
A
Sensors
Integrating Center
Effectors
6
Q
What is the set point?
A
Ideal level of a variable to be maintained
7
Q
Can homeostatic systems be entered contained within a single cell?
A
Yes
8
Q
Sensors can be?
A
Sensory cells of the nervous system
Endocrine Cells or any cell in the body.
9
Q
An effective negative feedback system does what?
A
Shuts itself off before the effectors push the body to far in the other direction
10
Q
When the body is too hot, the temperature regulating centre in the Hypothalamus will activate an efferent pathway to activate sweat glands, increases heat loss and inhibits skeletal muscles from shivering. In this example the hypothalamus, the skeletal muscles, and the sweat glands represent what part of a feedback system?
A
Hypothalamus = integrating centre
Sweat Glands = effectors
Skeletal muscles = effectors.
11
Q
Describe a Closed Loop Regulatory System
A
A self regulating system contained within the body that manages to maintain the variable within a normal range.
12
Q
In a closed loop system the factors that cause change come from where?
A
Cells in the body
13
Q
What is the Settling Point?
A
The ideal set point of the moment. The ideal set point for some variables change with physiological circumstances.
14
Q
Give examples of the set point changing with physiological circumstances:
A
Body temp changes during the course of the day and with infection
Body weight set point changes with age and activity level
Blood pressure set points change with posture, body size, activity
15
Q
What does a change in the set point allow our body to do?
A
Adapt to new environments and new body states (puberty, starvation, growth)
16
Q
What is a major difference between homeostatic and homeodynamic systems?
A
Homeodynamic can change the set point. Homeostasis has a very strict set point range ex) pH of the body
17
Q
A change in one direction that leads to a further change in the same direction is an example of what type of feedback?
A
Positive
18
Q
The bad side of positive feedback is called?
A
Vicious Cycle
19
Q
How does a feed forward system work?
A
Within the CNS there are control centres that send out signals to direct actions in advance of feedback information. These are often seen in response to external stimuli
20
Q
Are the external stimuli in the feed forward system considered to be open or closed loop input?
A
Open - bc we have no control over them.
21
Q
From where to where in the body do primary messenger molecules convey information and please give examples of primary messengers.
A
From one cell to another
Neurotransmitters, cytokines…
22
Q
When do we need second messengers?
A
If the messenger is not lipid soluble.
23
Q
Paracrine communication occurs between?
A
Cells within the same organ.
24
Q
T or F
Paracrine is considered to have extrinsic or local factors
A
False!
Intrinsic and local
25
What type of communication occurs or acts on the same cell type that produced it? Give an example.
Autocrine
| Follicular cells producing 10x more estrogen during first 12 days.
26
A gap junction is an example of what type of cell to cell communication?
Juxtacrine
27
When molecules produced by one system that control other systems this is an example of what type of communication?
Extrinsic
28
Hormones are an example of this type of communication? Why?
Endocrine - they are molecules that are secreted into the blood and reach target cells via the circulatory system.
29
Can hormones have a paracrine effect within the organs that produce them?
Yes!
30
What is the mechanism of action of a hormone?
It will influence all of a cell's functions by altering enzyme activities and gene expression.
31
Where are neurotransmitters released?
By neurons directly onto target cells at synapses
32
How do neurotransmitters affect cells?
They cause a change in membrane potentials by either opening or closing ion channels.
33
Neurotransmitters can either be __________ like Na+ or __________ like K+
Excitatory
| Inhibitory
34
Neuromodulators may reach the neurons in what two possible ways?
Through the circulatory system or be delivered directly onto the target cell.
35
How do neuromodulators work?
They alter a cell's response to Neurotransmitters but do not change the membrane potential themselves.
36
What type of cells can produce neuromodulators?
Immune cells, endocrine cells, and glial cells. Neurotransmitters can produce them as well.
37
What are neuropeptides?
A short sequence of aa made by the nervous system that may act as neurotransmitters, modulator, growth factor or hormone.
38
The immune system will directly deliver these molecules onto target cells via the circulatory system?
Cytokines
39
T or F
| Transmitters, modulators and hormones can also be cytokines
True
40
Give some examples of molecules that fit into several categories of hormone, neurotransmitters, and neuromodulators, and cytokines
Norepinephrine
Dopamine
Serotonin
41
________ is a cytokine that has a neuromodulatory effect on emotions
Interferon
42
Describe the mechanism of action of all primary messenger molecules
Act by binding to a protein receptor
Initiate a change in the receptor structure
Chemical reactions within the cell
Physiological changes in the cell's activity
43
Give an example of an ion channel that is also the receptor
Nicotinic Acetyl Choline
44
Does the Nicotinic Acetyl Choline ion channel use secondary messengers?
No
45
What type of receptors use regulatory proteins -> G Proteins
Muscarinic Receptors
46
Intracellular signaling molecules that convey information from the cell membrane to the inside of the cell are known as?
Secondary messenger molecules
47
List the different type of 2dary messenger complexes:
```
Cyclic AMP
Cyclic GMP
Diacyl Glycerol
Inositol Triphosphate
Ca++/Calmodulin
Prostoglandins
Leukotrienes
```
48
The binding of the primary messenger to a receptor on the outside of the cell acts through what regulatory protein located in the cell membrane?
G Proteins
49
The 2dary messengers will activate what kind of enzymes? What do these enzymes do?
Protein Kinases that phosphorylate proteins, or elevate intracellular Ca++ levels or cause other changes in cell function.
50
What does phosphoylation of proteins cause?
Changes the shape and activity of the protein (opens or closes channels, activates or inhibits enzymes, activating or inhibit gene expression.
51
Increased intracellular Ca++ can bind to a variety of proteins and causes changes in: (3)
The cytoskeleton structure
Actin-Myosin interactions -> cell contraction
Enzyme activity -> changes in cellular function
52
The more receptors/cell - the more or less the primary messenger is needed to get a response?
Less
53
What will cause a cell to be more sensitive to a messenger?
The more receptors a cell has for the primary messenger.
54
Give an example of up regulation in the body in regards to muscle neuron innervation
If a muscles loses its motor neuron innervation there will be an increase in the number of Acetylcholine receptors on the muscle. More sensitivity!
55
What occurs more quickly: up or down regulation?
Down regulation
56
What does the body do to the receptors in down regulation?
The receptor may either be destroyed or recycled back to the membrane
57
A mechanism of addiction is an example of up or down regulation in the body?
Down - the more cocaine a person uses, the more receptors for Cocaine are lost -> need more of the drug to get the same effect on the cells.
58
HANDOUT 2
HANDOUT 2
59
The Extracellular fluid is made up of: (2)
Plasma and Interstitial Fluid
60
Is the Cytoplasm Intracellular or Extracellular fluid?
Intracellular
61
What part of the cell has largely negatively charged proteins? What ions are more abundant here?
Inside
| K+ , PO4-
62
Outside of the cell we find more of these ions (3)
Sodium Na+
Chlorine Cl-
Calcium Ca++
63
Cytoplasmic levels of what ion activate muscle contraction?
Ca++
64
What is meant by "electrochemical gradients"
When the membrane becomes permeable to specific ions they will move according to their electrochemical gradients
65
What is Kinetic energy?
Energy in use for work ( movement of objects through space and or given off as heat)
66
What controls movement of molecules across the cell membrane?
Simple Diffusion *Osmosis
Facilitated Diffusion
Active Transport
Endocytosis and Exocytosis
67
Of all the control mechanisms for movement of molecules across cell membranes give an example of carrier mediated .
Facilitated Diffusion
| Active Transport
68
This type of diffusion depends on random motion of molecules.
Simple
69
Is Simple Diffusion passive or active?
Passive
70
Name the Laws of Diffusion
```
Concentration Gradient
Surface Area
Distance
Temperature
Size and Shape of Molecules
Electromotive Forces
```
71
What happens to diffusion when you increase strength?
Increase rofd
72
What other LOD will increase the rofd?
Increased surface area!
73
How does temperature effect diffusion?
Increase temperature = increased rate of random movement = increased diffusion
74
If we increase mass or volume what happens to the rofd?
Decreased
75
Of the Laws of Diffusion this one is said to be 2 dimensional
Surface Area
76
What Law of Diffusion is 1 dimensional?
Distance
77
Aka for Electromotive Force EMF
Electrical potential energy across the cell membrane
| aka "Membrane Potential"
78
Define the K+ Equilibrium Potential
The electrical potential across the membrane that exactly balances the concentration gradient force.
79
What type of substances can cross the cell membrane?
Fats, Cholesterols, Steroid Hormones, Alcohol, Gasses: No2, O2, N2, CO2
80
T or F
| The more lipid soluble the quicker it moves through a cell membrane
True
81
Give examples of some polarized molecules that cannot cross the phospholipid membrane
Glucose
| Amino Acids
82
Name the three possible membrane channel states: (3)
Closed - but openable
Open
Inactivated - closed and cannot be reopened in this state.
83
What does the open or closed state of membrane channels depend on?
1. Ungated Channels aka leaky channels - always open
2. Voltage Gated - channel depends on the electrical charge across the membrane
3. Ligand Gated Channels aka Chemically gated.
84
In the resting state the channels are ________.
Closed
85
What chemical messenger controls many of the Ligand Gated Channels?
Neurotransmitters
86
Describe how polar and non polar molecules cross the cell membrane.
Polar needs: 1. ion specific protein channels and their electrochemical gradient allows their simple diffusion.
2. Carrier proteins
3. Endocytosis or exocytosis
Nonpolar: Simple Diffusion
87
How does water move in the body?
Down its concentration gradient from a region of high water concentration to low water.
88
A solution with high water concentration & has little solute would have high or low osmotic pressure?
Low osmotic pressure
89
What would make for high osmotic pressure?
A solution with high solute concentration and has little water
90
In terms of osmotic pressure, how will water move?
Water will move to the region with the highest osmotic pressure.
91
Solute particles that cannot cross the cell membrane are said to be:
Osmotically Active Particles
92
What do Osmotically active particles do to water?
Exert osmotic force on water ex) they draw water to them as a sponge soaks up water.
93
How is osmotic pressure calculated?
The number of dissolved particles/amount of solvent
94
T or F
| The lower the osmotic pressure the less water is in the solution
False - Higher osmotic pressure = less water
95
What is the pure water osmotic pressure?
Zero
96
What type of particles will contribute 2 osmotically active particles?
NaCl -> Na to Cl
97
How is Osmolarity calculated?
Osmoles/litre of solution
98
How is an osmolar solution made?
By weighing the solute and then adding just enough solvent to bring the solution to a final volume of 1 litre.
99
How is an Osmolal solution made?
Weighing both the solute and the solvent - solvents change density with changes in temp, but weigh of a specific number of molecules doesn't change.
100
The composition of an Osmolal or Osmolar is more exact?
Osmolal
101
Cells have an internal osmotic pressure of?
300 mOsmoles
102
What is tonicity?
The ability of a solution to move water across the cell membrane or solution.
103
A solution that is hypertonic to a cell will do what?
Pull water out of a cell. Cell shrinks as water leaves.
104
When a solution is hypotonic to a cell where does water move?
Pulls water into a cell.
105
A solution that causes no net water movement is said to be?
Isotonic
106
What can cause a cell to burst?
If enough water moves into the cell and causes swelling which disrupts the structure and interrelationships of the cell's organelles.
107
T or F
| A solution's Osmotic pressure is the same as tonicity
False
108
What is solvent drag?
When particles that are permeable to the cell membrane move down their concentration gradients into the cell and drag water with them.
109
What is meant by a Transport Maximum with Facilited Diffusion and Carrier Proteins?
That the carrier proteins are saturated.
110
Does Facilitated Diffusion require energy?
No
111
With facilitated diffusion how does the molecule to be transported get into the cell?
The molecule will bind to a part of the carrier protein on the outside of the cell -> carrier protein changes shape such that the molecule is now on the inside of the cell and the molecule than is released from the carrier protein.
112
This type of transport requires energy
Active
113
When is Active Transport used?
To transport molecules against their concentration gradient
114
Primary Active Transport works for these ions: (5)
Na, K, Ca, H, Cl
115
Give an example of a Counter-transport system
Na/K pump
116
How many binding sites for Na and K are there on the cell?
3 binding sites for Na on the inside of the cell
| 2 binding sites for K on the outside of the cell
117
This enzyme helps with the phosphorylation of the carrier protein in the sodium potassium pump
ATPase
118
When the sodium potassium pump is pumping more positive charges out of the cell this is called?
Hyperpolarizes the cell membrane making it more negative on the inside.
119
What is Secondary Active Transport?
When energy is used to create a concentration gradient for one molecule by a primary active pump, the concentration gradient for that molecule is then used to transport another molecule against its concentration gradient.
120
Give an example of a Secondary Active Transport system
Na+ and glucose. Sodium moves down its concentration gradient from outside the cell to inside.
121
What makes a Secondary Active Transport system "secondary"
The need for 2 separate carrier proteins.
122
This is the theoretical electrical force needed across the membrane to balance the forces acting upon the gradient: concentration and EMF
Nernst Equation
123
What is the equilibrium potential for Na+?
+65 mV
124
How did the Goldman-Hodgkin-Katz equation expand on the Nernst equation?
It took into consideration the reality that the membrane potential is determined by several ions and membrane permeability to each ion.
125
Where do action potentials happen?
Axons
126
What happens when you increase the frequency of the AP on the axon?
Increases the strength of the message you are trying to get through.
127
If a message is really important where will it synapse?
Closer to the cell body
128
Where do local graded potentials occur? Why
On the dendrites and cell bodies due to Ligand gated ion channels.
129
T or F
| Graded potential are proportional to the size and strength of the stimulus.
True
130
Post synaptic potentials can be either ________ or ________
Excitatory or Inhibitory
131
When Na+ or Ca++ enter the cell and the membrane becomes closer to threshold potential (less negative) this represents what type of post synaptic potential?
Excitatory
132
Give an example of an Inhibitory Post Synaptic Potential
Open K+ channels -> K+ moves out
OR
Open Cl- channels -> Cl- moves in
*Membrane potential is more negative and further from threshold.
133
What is the equilibrium potential for K=?
-90 mV
134
This type of 1ary messenger molecule will activate their receptors which brings about change in metabolic processes in neurons, often via G protein coupled to a second-messenger system.
Neuromodulators
135
What has faster communication neurotransmitters or neuromodulators?
Neurostransmitters
136
Neuromodulators tend to be associated with slower body events such as:
Learning
Development
Motivational States
137
Exocytosis is usually linked to up or down regulation?
Up
138
What ca secondary messenger systems do to the postsynaptic cell?
1. Can open specific ion channels
| 2. cAMP or cGMP activation, enzyme activation, gene expression activation.
139
When the postsynaptic receptor is inhibitory what will happen?
It will open CL- and/or K+ channels to make the inside of the cell more negative.
140
What is an action potential?
A rapid change in the membrane potential that spreads in nerve fibres by voltage-gated ion channels.
141
What ion fluxes into the cell during Depolarization?
Na+
142
This ion rushes into the cell during Repolarization
K+
143
What does hyperpolarizaton prevent?
The neuron from receiving another stimulus during this time or from the signal coming backward.
144
Why is the resting membrane potential at -90mV if the equilibrium potential for K+ is -94mV?
The membrane has K+/Na+ leak channels (100x more permeable to K+ than Na+ and free movement of K+ brings the EMF close to K+ equilibrium potential. Opposed by Na+ entry (-86) and restored in part by Na+/K+ pump.
145
What determines the resting potential of a cell?
The balance of the permeabilities of ions
146
Where do Action Potentials occur on the cell?
Axon
147
What will tell the strength of the message you are trying to get through with an Action Potential?
The frequency of the Action Potential
148
What is non decremental conduction?
"All or None" magnitude propagated along an axon membrane without a change in magnitude.
149
What causes decremental conduction of membrane potentials on the dendrites?
Diminishing EPSP with distance from the opened channels due to the small amount of cytoplasm in the dendrites - high resistance to flow and leak of K= ions out of the cell membrane.
150
Where does non decremental conduction take place?
Soma - due to the large amount of cytoplasm and surface area of the soma, any membrane potential that occurs anywhere on the soma will be fully spread over the entire membrane.
151
Summing the effects of synapses over space is called?
Spatial Summation
152
What is temporal summation?
When several action potentials on the presynaptic cell release neurotransmitters one after another, their effects on the post synaptic cell add.
153
Threshold Potential is reached where?
On the hillock of the axon where the highest density of voltage gated Na+ channels exists.
154
Why don't action potentials occur on the soma or dendrites?
Because they do not have enough voltage gated Na+ channels .
155
How do graded potentials on the soma maintain the EPSP's and IPSP's?
Neurotransmitters will open channels for a long time (100's of msec) and generate multiple action potentials.
156
Describe the resting stage of an AP
both Na+ and K+ voltage channels are closed.
157
Na+ ion channels are inactivated when the membrane potential reaches?
+ 30 mV
158
What is the overall effect of the Na+/K+ pump?
To make the inside of the cell more negative than it would otherwise be.
159
In what scenario would no action potential occur?
If the stimulus fails to open enough Na+ channels.
160
What will determine the magnitude of an action potential?
The concentration gradient and EMF for Na+ which will drive Na+ into the cell until the channels become inactivated at about +30mV
161
What is the time frame of the Absolute Refractory Period?
Technically begins as soon as the threshold potential is reached and lasts until the voltage gated Na+ channels shift from being inactivated to being closed but openable.
162
When will the Na+ channels shift back into closed but openable?
When the membrane potential is restored to resting potential.
163
Define Threshold stimulus
A stimulus with just enough strength to change the membrane from resting potential to threshold stimulus.
