Notes 1-5 Flashcards
(119 cards)
1
Q
Homeostasis
A
Maintaining a relatively constant internal environment within the body
2
Q
What are your cells surrounded by
A
A small amount of extra cellular fluid
3
Q
The two general mechanisms involved in homeostatic regulation
A
1)auto regulation
2extrinsic regulation
4
Q
What does movement across membranes rely on
A
Gradients
5
Q
How to maintain homeostasis
A
- There is a receptor that monitors the changing level of the variable(temperature,blood pressure,and CO2 levels)
- The receptor then sends info (about the level of the variable which may be above or below the set point) to the control center.
- The control center then sends info to an effector which can change the level of the variable, bringing the level back to the normal range.
6
Q
negative feedback
A
maintains homeostasis by resisting change (brings levels towards the set point)
7
Q
Cell Membrane
A
Practice drawing
8
Q
positive feedback
A
Increases the deviation from the set point
9
Q
active processes
A
1) Receptor mediated Endocytosis
2) pinocytosis
3) phagocytosis
4) active transport
5) contransport(symport)
6) Countertransport (antiport)
7) exocytosis
10
Q
passive processes
A
1) Simple Diffusion through pho’pholipid Billayers or leak channels
2) Osmosis
3) Facilitated Diffusion
11
Q
Why is fluidity important for membranes?
A
Fluidity in the membrane allows for some things to cross in the membrane easily
12
Q
What kind of molecule can cross the membrane
A
Small
Uncharged
And hydrophobic
13
Q
What kind of molecules can’t cross the membrane
A
Large
Charged
And hydrophillic
14
Q
Biology
A
The study of life of living things
15
Q
Anatomy
A
Study of structure
16
Q
Physiology
A
Study of function
17
Q
What does the phospholipid bilayer hold together
A
Proteins,cholesterol,carbohydrates and its very fluid.
18
Q
What is the bilayer made of
A
A double sheet of phospholipid molecules.
They are not anchored together
Contains hydrophobic and hydrophilic ends that regulate what can enter and exit the cell
19
Q
Gradient
A
The physical difference of a substance between 2 adjoining regions(higher in one area and lower in another)
Ex: temp gradients,pressure gradients,electrical gradients and concentration gradients
20
Q
Diffusion
A
The net movement of molecules or other particles down a concentration gradient
Moves from area of high concentration gradient to area of low concentration gradient
21
Q
What does it mean to have a greater concentration gradient
A
Faster rate of diffusion then goes to equilibrium
22
Q
Passive Transport (Diffusion)
A
Down a concentration gradient, no energy required
23
Q
Active transport
A
against the concentration gradient, energy is required
Ex:sodium and potassium pumps
24
Q
How does simple diffusion work
A
There’s 2 ways
1)small lipid soluble particles can pass through the phospholipid bilayer(in gaps between the phospholipids) ex O2 and CO2
2)small water soluble particles can diffuse through channel proteins ex Na+ and K+
No energy required
25
What does rate depend on
Solubility and concentration gradient
26
How does facilitated diffusion work?
No energy required
Uses carrier proteins to transport large or water soluble molecules
Ex Amino Acids
27
What is Osmosis?
The diffusion of water down its concentration gradient
| Moves to area with less available water
28
What do dissolved substances in a solution do
Lower the concentration of water
29
isotonic solution
Equal concentration of solute in the 2 environments being compared
Ex:no osmotic flow occurs in red blood cells in a isotonic solution
30
hypotonic solution
Lower solute concentration in solution compared to inside cell (therefore water moves in and expands the cell)
Ex: a red blood cell would swell up in a hypotonic solution
31
hypertonic solution
Higher solute concentration in solution compared to inside cell (water moves out and cell gets smaller)
Ex:red blood cell shrivels up in a hypertonic solution
32
Secondary active transport (2 kinds)
Establishes and uses a concentration gradient as a source of energy for active transport
Required ATP
1)cotransport (symport) : both go in the same direction
2)countertransport (antiport): one goes in, the other goes out
Ex: sodium-glucose transporter to get glucose into the cell(atp is not directly used)
33
What is endocytosis and how does it work
Endocytosis is the vesicular(uses a vesicles)transport where things are pulled into the cell
Used to pull large particles into the cell
Requires energy
34
What are the 2 types of Endocytosis
1) Phagocytosis = (cell eating) solid particles are engulfed seen in cells of our immune systems like debris or bacteria
2) Pinocytosis = (cell drinking) taking in liquid and engulfing dissolved particles
35
Exocytosis
Requires energy
When the vesicles fuses to the plasma membrane releasing its contents and then becomes a part of the plasma membrane.
Ex for fluid and cellular wastes
36
Multipolar neuron
Multiple processes attached to the cell body
37
Bipolar
2 processes attached to the cell body
Ones carrying info towards cell body(dendrite)and ones carrying info away(axon)
Not too common in some sensory pathways.
38
Unipolar
1 process attached to cell body
39
Anaxonic
Neutrons that have lots of processes attached to the body but no identifiable axon
40
Why are neuroglia cells important
They’re are numerous and important and without them the neutrons wouldn’t be able to function
41
What is a neuron
A cell
42
What is a nerve
An organ because it’s got lots of different cells and tissues
43
Functions of the nervous system
1) Generate rapid responses to changes in your environment by: gathering sensory input to monitor the changes occurring in/outside the body.
2) Integration:process and interpret sensory input, cause a response if appropriate to remain homeostasis.
44
Know how to draw a typical multipolar neuron
Practice drawing
45
Different environments around membrane in a neuron
Above membrane:
- ECF
- More Na+
- Less K+
- Less proteins
Below membrane:
- ICF
- Less Na+
- More K+
- More proteins
46
What does the sodium and potassium pump do
Maintains concentration gradients to have : more Na+ outside of the cell than inside
and more K+inside the cell than outside
47
How do sodium potassium pumps work
Using ATP the sodium- potassium pump, pumps sodium ions out of the cell and potassium ions in
At the same time we have leak channels that let potassium ions and sodium ions to diffuse through.
So the leak channels let them diffuse out and then you use ATP to pull it back in.
48
What is the charge difference called
The membrane potential (potential difference)
49
What is resting membrane potential
The potential differences across the cell membrane in an “unstimulated” cell at rest
50
Na+ and K+ movement across and unstimulated
| membrane
-Na+ will tend to diffuse OUT of the cell down its concentration gradient
-K+ will tend to diffuse IN to the cell
-both moving down their concentration gradients through leak channels that are always open
-the membrane is more permeable to K+ than Na+ so more K+ moves out and not so much Na+ moves in
-the Na+ K+ exchange pumps also transport Na+ from in to out and K+ from out to in
-at equilibrium the net effect of all this is :
resting membrane potential of -70mv(more neg. inside cell than outside)
51
How can the ICF and ECF change?
| And why does this matter?
1)gated channels could open or close,altering which particles (usually ions) can cross the membrane
It matters because it can affect the charge on either side of the membrane
Example: if gated Na+ channels open, then Na+ can easily diffuse across the membrane (from the ECF to the ICF) making the ICF more positively charged
52
Types of gated ion channels
Chemically-gated channel (ligand-gated)
Voltage-gated channel
Other types such as: pressure or temperature
53
Chemically-gated channel (ligand-gated)
Molecule (ligand) binds to receptor, changing the structure of that membrane protein, opening the channel
54
Voltage-gated channel
Change in charge across the membrane causes the channel to open/close
55
Can the resting membrane potential (-70mv) change or no?
Yes it can change if ions cross the membrane (making it more neg. or more pos.)
56
Depolarization
a decrease in charge difference of across the membrane
| (becomes more positive)
57
Repolarization
A return to resting potential
58
Hyperpolarization
membrane potential becomes more negative! (a bigger difference between the charge inside and outside the membrane)
59
Graded potential (local potential)
A change in membrane potential at one place on the membrane
Called a graded potential because it can be small-large
And it will also spread out from where it starts
60
What can cause a graded potential
Opening or closing any gated channels because when you open or close a gated channel you’re changing what ions are getting through the membrane.
And since ions have charges you’re gonna change the charge across a membrane.
61
What happens to the graded potential at “the trigger zone” If it reaches threshold?
An action potential will occur
62
Where can the graded potential occur
Anywhere on the cell body , it starts in one spot,spreads away from that spot.
63
How do you get to a graded potential
1) membrane becomes exposed to a chemical that opens up the ion channels and allows for + charged ion to enter cell
2) due to concentration gradient and electrical gradient the positive charge moves to the right therefore flow of charge is current
64
How does the action potential occur
If the amount of depolarization adds up that if at the threshold an action potential(all or none response) will occur.
A rapid depolarization followed by a repolarization and hyperpolarization
Happens at 1 spot of the cell membrane in one direction
65
Know how to describe what happens during a action potential when sodium and potassium leak channels close
Draw
66
Can you move backwards on the membrane
No because once you hit a threshold you reach the absolute refractory period in which the voltage gated sodium channels are already open and can’t open even more also the membrane can’t respond to any further stimuli so it moves onto to the relative refractory period
67
What’s the relative refractory period
Where it’s not likely for an action potential to occur. But can
68
Passing along the electrical signal across the cell membrane(from one end to another end of the cell )during action potential is called
An action potential propagation
69
Continuous propagation
Passing the electrical signal all the way down the surface of the membrane from one end to another
70
Can you speed up an action potential propagation yes or no?
Yes if :
AP can travel more quickly along a myelinated axon (because AP only needs to occur at the Nodes of Ranvier, not the whole length of the axon.)
Also, a larger diameter axon will transmit the AP faster (due to greater surface area/less resistance)
71
What is Saltatory Propagation
There’s enough charge that the local current carries the wave of depolarization past the spot of insulation and to the next node of ranvier and generates an action potential their.
72
How do signals from one cell get to the next
Crossing a synapse
73
What’s a synapse
A junction between 2 cells made of:
-presynaptic cell
-synaptic cleft
-postsynaptic cell
There’s 2 main types (electrical and chemical)
May pass or block a signal to your postsynaptic cell
74
What’s an electrical synapse
gap junctions are ways of connecting one cell to the neighbouring cells with little protein tubes/tunnels called connexons.These allow the things going on in one cell to pass through to the tunnels and happen in the other cell as well.
Ex:if we have an action potential in a presynaptic neuron the local current can go right through connexons and be picked up in postsynaptic neuron.
75
Chemical synapses
Very common throughout nervous system
Where an action potential at the end of presynaptic cell triggers the release of chemicals that cross the synaptic cell and bind to the receptors on the postsynaptic membrane.
This may open or close ion channels making an AP more or less likely.
76
Cholinergic synapse
1) action potential arriving at very end of axon
2) causes voltage gated calcium channels to open
3) influx of calcium triggers exocytosis which release the neurotransmitter(acetylcholine)
4) acetylcholine crosses synaptic cleft and binds to receptors on the post synaptic cell
5) the receptors are chemically gated sodium channels that open to allow sodium to enter postsynaptic cell.
6) sodium ions move across membrane changing membrane potential,if add ups to threshold you’ll get AP which then will continue along potsynaptic cell
At the end of a chemical synapse we want to get rid of the neurotransmitter so that we don’t keep effecting the post synaptic cell beyond the time that we want.
Ex: for acetylcholine there’s an enzyme : acetylcholinesterase (an enzyme) splits ACh into acetate and choline. Choline gets recycled within
presynaptic neuron.
77
why is it necessary to remove the neurotransmitter from the synaptic cleft?
That communication is important because it tells the postsynaptic cell that the presynaptic cell is delivering a signal. But you don’t want to keep delivering a signal when a signal is gone. You only want it to respond to the signal when the signal is there.
It needs to enough but not too much
78
Postsynaptic potentials (2 kinds)
1) Excitatory postsynaptic potential (EPSP)
| 2) Inhibitory postsynaptic potential (IPSP)
79
Excitatory postsynaptic potential (EPSP)
If the membrane potential becomes closer to threshold and depolarizers a little bit
Influx of positive charge
Might produce a AP
Ex:open Na+ gates to let more Na+ enter the cell
80
Inhibitory postsynaptic potential (IPSP)
If the membrane potential gets further away from threshold and hyperpolarizes we called that inhibitory
Harder to reach AP now
Influx of new. charge
Ex:open Cl- gates to let more Cl- enter the cell
Or
Ex: more outflow of pos charge by open K+ gates to allow more K+ to exit the cell
81
Temporal Summation
```
One synapse is active repeatedly
Adding up multiple stimuli over time
If there is enough stimulation,
threshold can be reached and an AP is generated
in the post-synaptic cell
```
82
Spatial summation:
Two different synapses are active simultaneously
If there is enough stimulation,
threshold can be reached and an AP is generated
in the post-synaptic cell
83
Regulatory Neurons (Presynaptic Inhibition and Facilitation)
facilitate or inhibit the activities of the presynaptic
neuron
Doesn’t contact the postsynaptic neuron
Make it more or less likely for the presynaptic neuron to release its neurotransmitter..
84
Sensory receptors
Cells that respond to specific stimuli, and send
| information about that stimulus toward the CNS
85
Chemoreceptors
Respond to chemicals in solution
| Ex: respond to taste(sour,sugar)and smell(mucus)
86
Thermoreceptors
Sensitive to temperature changes
| Ex: respond to warm or cold internal and external temperatures
87
Nociceptors
Respond to painful stimuli (potential or actual harm) due to tissue damage from trauma, ischemia, or heat/chemicals
Ex: respond to damaged cells (pain) also respond to hot or cold
88
Mechanoreceptors
Sensitive to mechanical force
| Ex: respond to touch,stretch,vibration
89
Photoreceptors
Respond to light energy
90
How do sensory receptors get stimulated?
1st ) Energy from the stimulus (mechanical, heat,
light, etc.) changes a receptor protein(usually a membrane protein on sensory receptor cell)
2) Changing the receptor protein changes some
property of the membrane (“receptor potential”)
It might open or close an ion channel… altering the
membrane potential… making an action potential more or less likely…!
Leads to sensory transduction
91
What do sensory receptors do
Convert the energy from the stimulus into an electrical signal.
In your sensory receptors: a signal from outside of
the cell is transduced so that it can be transmitted throughout the body (as electrical signals)
92
Sensory transduction
The conversion of stimulus energy into a receptor
potential (which could become an action
potential…)
Transducers convert energy from one form to another
93
Receptor cells: Two main mechanisms of action
● Direct effect on membrane potential
● Indirect effect on membrane potential
94
Direct effect on membrane potential
The stimulus directly causes the opening or closure of ion channels which changes the membrane potential (making an action potential
more or less likely to occur, or affecting the release of
neurotransmitter…)
Ex:Gustation (taste)
95
Indirect effect on membrane potential
The stimulus binds to a receptor protein, then activates a SECOND MESSENGER (inside of the receptor cell). This triggers a cascade of events that change membrane potential (making an action potential more or less likely to occur, or affecting the release of. neurotransmitter…)
Ex:olfaction (smell)
96
Steps for sensory receptors
1)sensory receptors becomes stimulated by the stimulus
2)either in that cell or the neuron next to it an action potential has been generated then propagated to the CNS
3)once in the CNS you can send that info to become an
-involuntary immediate response
Or
-voluntary response(this requires the info needing to reach the cerebral cortex,which hardly happens)
97
Adaptation
Reducing the amount of sensory input
● Decreased sensitivity to a continued stimulus ● Adaptation can be central (within the CNS) or
peripheral (at the sensory receptor itself)
● Receptors can be tonic or phasic
98
Tonic receptors
Always sends information about the stimulus
| Ex:”still normal”if somethings changes it send more signals at once to let brain now
99
Phasic receptors
Send info only when things are changing
Ex:at normal level they’re not sending info because things are constant then all of a sudden there’s an increase in activity and phasic receptors detect that change.if you maintain that elevated level they stop sending the signal because things stop changing.
100
Olfaction
Sense of smell
1)Receptors are chemoreceptors(respond to chemicals in solution in this case mucus)
2)Mucus acts as a solvent to dissolve airborne
odorants
3)Odorant binds to specific receptor, triggering a
series of events inside the receptor cell that
leads to the opening of Na+ channels
-Indirect effect on membrane potential
-Receptor cell is a bipolar neuron
101
Gustation
Sense of taste
1)Tastants dissolve in saliva in the mouth, enter
the taste pore, and cause depolarization of the
taste cells
-Chemoreceptors
-Different mechanisms for different “tastes”
-Some types of taste stimuli have direct effects, others have indirect effects
102
What are the two main photoreceptors in your retina
1) Rods: for vision in low light; peripheral
| 2) Cones: colour vision, visual acuity (must be in bright light); central give us detail.
103
Rod cells
Tell us if they’re in the light or not
If in the dark: sodium is released causing membrane potential to decrease
If in the light:the chemical rhodopsin changes shape no longer allowing sodium in. Therefore there’s a decrease in membrane potential
104
Cone sensitivity to colour the three kinds
Red sensitive cones
Green sensitive cones
Blue sensitive cones
Each type of cone cells sensitive to different wavelengths.
105
Hearing
Receptors are hair cells in the organ of Corti (which is in the cochlea, in the inner ear)
- Stereocilia on each hair cell are attached to each other by tip links
- Move these stereocilia, and the K+ channels are opened…
106
How do we perceive different pitches? (high/low)
Pitch is related to the frequency of the sound waves
-Waves of different frequencies cause vibrations of
different parts of the basilar membrane
-Different cells are stimulated, which we interpret as different pitch
107
Equilibrium receptor cells
Move based on your bodies position of movement
-the receptors in a gelatinous material,when the fluid is moving it creates a lag that distorts the stereocilia which we then interpret as changes or movement.
Also moved based on your bodies position in gravity
108
How can you reduce the amount of pain you feel
We can reduce the amount of communication and signal that goes up to the cerebral cortex
Ex: distraction,breathing practice , or putting pressure on the spot that hurts.
109
Do thing appear brighter in our peripheral vision
Yes, because rods work in low light conditions
110
Path of blood flow through heart
1) Inferior vena cava and superior vena cava deliver blood from body to right atrium
2) to right ventricle, then out to lungs via pulmonary arteries
3) pul. veins to left atrium then left ventricle
4) to left ventricle then to the body through the aorta
111
What is diastole
Diastole = relaxation/ filling
112
What is Systole
Systole = contraction
113
Actions potential in cardiac muscle
Depolarization:
● Voltage-gated Na+ channels open
● Voltage-gated Ca2+ channels start to open
● (Voltage-gated K+ channels are closed) • Early repolarization and Plateau:
● Voltage-gated Na+ channels close
● Voltage-gated Ca2+ channels are open (Ca2+ moves in)
while some voltage-gated K+ channels are also open (K+ moves out…)
• Final repolarization:
● Voltage-gated Ca2+ channels close
● Lots of voltage-gated K+ channels open
114
What is autoryhmicity
(When cells set their own rhythm and can cause an action potential all on their own)
Meaning they don’t have a stable resting potential and will drift toward threshold (depolarize)
Why?
Because their is sodium influx all the time, they don’t have a balance point so the sodium coming in is always depolarizing the cell.
115
SA node
In wall of right atrium
● 80-100 action potentials / min (with no other input)
Above is their natural rythm
116
AV node
Between atria and ventricles
| ● 40-60 action potentials / min(with no other input)
117
Is the AV node or the SA node the pace maker
The SA node is the pacemaker because of rate. SA nodes can send signals with action potentials faster and the AV nodes follow that rythm
118
What does parasympathetic do to the heart
Makes your heart beat slower
119
What does sympathetic do to the heart
Makes your heart beat faster
