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Mam Physiology > Slide set 4 > Flashcards

Slide set 4 Flashcards

1
Q

Function of Nervous system

A

along with the endocrine system, is to control and communicate

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2
Q

Components of nervous sytem

A

the brain, the spinal cord, and peripheral nerves

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3
Q

why nervous system is organized

A

to detect changes in internal and external environments, evaluate the information, and initiate appropriate response

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4
Q

Nervous system is subdivided into

A

Central nervous system (CNS)

Peripheral nervous system (PNS)

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5
Q

Characteristics of CNS

A

Structural and functional center of entire nervous system
•brain and the spinal cord
•Integrates sensory information, evaluates it, and initiates an outgoing response

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6
Q

Characteristics of PNS

A

Nerves that lie in “outer regions” of nervous system
•Cranial nerves—originate from brain
•Spinal nerves—originate from spinal cord

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7
Q

CNS is divided into

A

Somatic vs autonomic

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8
Q

Somatic nervous system include

A

Somatic motor division—carries information to the somatic effectors (skeletal muscles)
2.Somatic sensory division—carries feedback information to somatic integration centers in the CNS fromPNS

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9
Q

Two divisions in Autonomic nervous system (ANS)

A

without voluntary control
•Afferent division (incoming) messages from the visceral receptors
•Efferent division (outgoing)of ANS—carries information to the visceral effectors (smooth and cardiac muscles and glands)

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10
Q

Efferent pathway of ANS is divided into

A

Sympathetic division—prepares the body to deal with immediate threats to the internal environment; produces “fight-or-flight” response
•2. Parasympathetic division—coordinates the body’s normal resting activities; sometimes called the “rest-and-repair” division

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11
Q

What controls heart beat in emergency situation

A

Sympathetic branch of the ANS

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12
Q

How Sympathetic branch of the ANS stimulates heart to beat faster

A

Stimulates SA (sinoatrial) node by releasing norepinephrine which acts by accelerating inactivation of K+ channels-less able to leave the cell
–Cell becomes less negative
–Swifter drift to AP
–Heart beats more forcefully and squeezes out more blood.

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13
Q

Parasympathetic control over stomach

A
  1. The distension of the stomach caused by the presence of food triggers parasympathetic reflexes
  2. increase secretion of gastric juice.
  3. In response to presence of amino acids Parasympathetic innervation causes Gastrin (digestive hormone) secreted by mucosa in presence of food causes increased secretion of gastric juice.
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14
Q

Two major types of cells, that compose the nervous system

A

Neurons and Glial cells

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15
Q

Neurons and glial cells are

A

Neurons:are excitable cells that conduct impulses (functional cells)and are required for all nervous system activities
•Glial cells: do not conduct information,but support the functions of the neurons

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16
Q

Difference between axon and dendrites

A

Dendrites receive incoming signals; axons carry outgoing information

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17
Q

Cytoskeleton inside neurons are responsible for

A

Microtubules and microfilaments, as well as neurofibrils(bundles of neurofilaments=intermediate filaments, supporting framework)
–Allow the rapid transport of small organelles
–Vesicles (some containing neurotransmitters ex acetycholine,Ach), mitochondria

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18
Q

Where neurotransmitters are produced and where is their action

A

Produced in the body of the neuron, where all organelles are, but then shipped to axon where they are going to be released

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19
Q

5 types of glial cells in CNS

A 
Astrocytes
Microglia
Ependymal cells
Oligodendrocytes
Schwann cells
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20
Q

Physical appearance of astrocytes

A

Star-shaped, largest, and most numerous type of glial

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21
Q

Function of astrocytes

A

Cell extensions connect to both neurons and capillaries
–Astrocytes transfer nutrients from the blood to the neurons
–Form tight sheathsaround brain capillaries, which, with tight junctions between capillary endothelial cells, constitute the blood-brain barrier

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22
Q

What is the blood-brain barrier

A

The blood-brain barrier (BBB) is the specialized system of capillary endothelial cells that protects the brain from harmful substances in the blood stream, while also allowing for supplying the brain with the required nutrients for proper function

Made up from the foot processes of astrocytes and the wall of the blood capillary.

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23
Q

How BBB protect the brain

A

Unlike peripheral capillaries that allow relatively free exchange of substance across / between cells, the BBB strictly limits transport into the brain through both physical (tight junctions) and metabolic (enzymes) barriers.

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24
Q

How specific transport is achieved in BBB

A

1.The BBB capillaries are specialized as they are held together by tight junctions
–this acts as a barrier against molecules
2. Second specialization involves the feet of the astrocytes

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25
What molecules can and cannot penetrate BBB
Lipid soluble, glucose,ethanol caffeine Water soluble cannot( like Na and K)
26
Consequences of excess iodine
When you have excess of iodine, it causes decrease in secretion of T3 and T4 , because it inhibits enzymes involved in the cycle In response to excess iodine, sodium-iodine symporter becomes less active-> less iodine in the thyroid follicle->normal T3 and T4
27
Insulin like growth factor is stimulated by
GH
28
IGF effect of glucose, lipid and protein metabolism
3. Increases blood glucose levels (Decreases glucose uptake by cells) • Less use of glucose as an energy source 2. Decreases lipogenesis (Enhances lipolysis) • Use of fatty acids for ATP production 1. Increases amino acid uptake into cells, accelerate protein synthesis • Decreased protein breakdown
29
Insulin effect on glucose,lipids and protein metabolism
``` 1. decreases blood glucose • Increased conversion of glucose into glycogen • Decreased glycogenolysis and gluconeogenesis ``` 2. Increases lipogenesis 3. Increases amino acid uptake into cells, accelerate protein synthesis • Decreased protein breakdown
30
Grave's disease vs hashimoto's
``` Grave's disease- hyperthyroidism Autoimmune: Autoantibodies bind to the TSH receptors on thyroid gland leading to excessive stimulation ``` Hashimoto's disease- hyperthyroidism. Autoimmune: Autoantibodies destroy thyroid gland
31
What is used to deliver drugs through BBB
Liposome-A, spherical vesicle with a membrane composed of a phospholipid bilayer
32
Microglia are a type of
macrophages (WBC) in the brain
33
What do they usually look like and what happens when inflamed
–Small, usually stationary, cells –Exception is in inflamed brain tissue, where they enlarge, move, and carry on phagocytosis to remove micoroganismsand cellular debris
34
Function of ependymal cells and where they are found
Resemble epithelial cells and form thin sheets that line fluid-filled cavities (cerbral-spinal fluid) in the CNS –Some produce fluid; others aid in circulation of fluid (reason for cilia) -Barriers between compartments, because they line interspine canal -Source of neural stem cells
35
Function of oligodendrocytes and where they are found
–Smaller than astrocytes with fewer processes | –Hold nerve fibers togetherand produce the myelin sheath in CNS
36
Interneurons are found
Between sensory and motor neuron
37
Astrocyte function: summary
- Substrates forATP production - Blood-brain barrier - Neurotrophic factors - K+, water,neurotransmitters - Source of neural stem cells - Barriers between compartments
38
Multiple sclerosis is a disorder of
Oligodendrocytes
39
Multiple sclerosis is characterized by
myelin loss and destruction Failure in nerve conduction •Communication interrupted
40
Treatment to Multiple sclerosis
immune modulating, inflammation reducing
41
Schwann cells are found in ___ and it is a functional equivalent of ___
only in PNS (functional equivalent of the oligodendrocyte
42
Schwann cells function
Support nerve fibers and in some cases form myelin sheaths
43
Gaps in myelin sheaths are called
nodes of Ranvier
44
Another type of Schwann cells and their function
Satellite cells type of Schwann cells that cover and support neuron cell bodies in the PNS –Do not form Myelin sheath
45
Difference between white fibers and grey fibers
E-Some Schwann cells serve only a supporting role and do not form the myelin sheath. Here we have a Schwann cell supporting a bundle of nerve fibers in the PNS. =Grey fibers F-Here we have the forming of the myelin sheath which is formed by another type of Schwann cell wrapping around the nerve fiber that ultimately forms a many layers of plasma membrane made up of myelin (phospholipid)= White fibers
46
Schwann cells can myelate ___ cell, when oligodendocytes ___ cell
1 cell | Multiple
47
How schwann cells myelate axon
By wrapping around the nucleus multiple times and the nucleus of schwann cells is pushed to the periphery
48
Functional regions of the neuron
Zones: - Input - Summation - Conduction - Output
49
What is an input zone of the neuron
receiving information at dendrites and cell body
50
What is a summation zone of the neuron
axon hillock-serves as the site where the nerve impulses combine and may trigger an action potential to be conducted along the axon
51
What is a conduction zone of the neuron
axon-has many voltage gated channels Na+and K+
52
What is an output zone of the neuron
synaptic knobs of axon. Contains many Ca2+channels. Nerve impulse triggers the release of neurotransmitters.
53
Functional classification of neurons
Afferent(incoming-sensory) neurons—conduct impulses to spinal cord or brain –Efferent (motor) neurons—conduct impulses away fromspinal cord or brain toward muscles or glandular tissue –Interneurons-lie only within the central nervous system(brain and spinal cord). Conduct impulses from sensory neurons (afferent) to motor neurons.
54
What is a reflex arc
A signal conduction route to and from the CNS, with the electrical signal beginning in receptors and ending in effectors.
55
What is the most common reflex arc
Three-neuron arc—most common; consists of afferent neurons, interneurons, and efferent neurons . –1. Sensory receptor send message to CNS –2. Reaches interneuron –3. Interneurons elicits outgoing (efferent) response from motor neuron.
56
Where we can find nerves and where tracts
Nerves—within the PNS, bundles of peripheral nerve fibers (bundles of axons) held together by several layers of connective tissue •Tracts—within the CNS, bundles of nerve fibers are called tracts rather than nerves
57
axons are bundled together in the nerve to form fascicles and they are surrounded by
Epineurium perineurium Endoneurium
58
Can nerve fibers repair?
Neurons have limited capacity to repair themselves-PNS little or none in CNS •Nerve fibers can be repaired if the damage is not extensive, the cell body and neurilemma (Schwann cell cytoplasm surrounding the nerve fiber) are intact, and scarring has not occurred But usually no
59
The largest nerve in the body
Sciatic nerve
60
Neurons exhibit both ___
Conductivity and excitability
61
Nerve impulses are ___
electrical signaling
62
What is resting membrane potential
When a neuron is not conducting electrical signals it is said to have a resting membrane potential –The mechanisms that promote this RMP is a slight ionic imbalance across the plasma membrane which is typically –70 mV –The slight excess of positive ions on a membrane’s outer surface is produced by ion transport mechanismsand the membrane’s permeability characteristics
63
Why intracellular space is said to be negative to the outter space
Because of a lot of protein anions
64
``` Where you can find these ions K Na Cl Ca A- (protein anions) ```
Inside: K,little Ca inside ER,A-, little Na and Cl Outside:Cl,Na,little K, Ca
65
How RMP is achieved
Membrane more permeable to K+ to let out than to Na+ to let in. Everything is moving down the concentration gradient - A small amount of Na+ leaks into the cell. - Na+ pumped out by the Na+/K+ pump . - The pump contributes to the membrane potential by 3 Na+ out for every 2 K+ pumped in. 3 vs 2 + charges-> more negative inside comparing to outside There are no channels for the exit of anionic proteinswhich dominate the intracellular fluid. They are trapped inside. •Like wise the chloride ionswhich dominate the extracellular anions are trapped on the outside of the cellas they are repelled by the protein anions inside the cell
66
Deporalization, repolarization, hyperpolarization terminology
Membrane potential becomes less negative=depolarization •Return to RMP =repolarization •hyperpolarization=RMP moves even further away from -70
67
3 types of gated channels
Mechanically gated -sensory neurons, physical trigger –Chemical gated -most neurons, respond to ligands –Voltage gated -changes in cell membrane potential
68
What is action potential
Is a change in RMP
69
Simple version of action potential
An adequate stimulus triggers stimulus-gated Na+channels to open, allowing Na+to diffuse rapidly into the cell, producing a local depolarization->excitation As more Na+ rushes into the cell the membrane moves rapidly towards 0mV and then continues in a positive direction towards +30mV. –The action potential is an all-or-none response: if local depolarization fails to reach -59 mV the voltage gated Na+ channels do not open and the membrane returns to resting potential –Voltage-gated Na+channels stay open for only about 1 millisecond before they automatically close-therefore the same magnitude of action potential is always reached.
70
Inhibition of the neuron happens when ____
a stimulus triggers the opening of additional K+ channels (occurs at chemical synapses), increasing the membrane potential by allowing more K+ to diffuse out of the cell. –The excess of K+ outside the cellresults in (hyperpolarization) due to an increase in the membrane potential (below -70mV)
71
What is the depolarization threshold
-59mv, if it reaches-> then it will cause the next one to open as well ( it is achieved in summation zone)
72
Repolarization is
After the action potential peaks, the membrane begins to move back toward the resting membrane potential –This is achieved by opening of K+channels, allowing outward diffusion of K+;this process is known as repolarization –Brief period of hyperpolarization, because K+ channels remain open as the membrane is returning to the RMP.
73
There are 2 types of the gates on electrical signal transduction
Activating and inactivating
74
What is an absolute refractory period
brief period (lasting approximately half a millisecond) during which a local area of a neuron’s membrane resists restimulationand will not respond to any stimulus, no matter how strong
75
What is relative refractory period
time during which the membrane is repolarized and is restoring the resting membrane potential; the few milliseconds after the absolute refractory period; membrane will respond only to a very strong stimulus
76
at what membrane potential Na channels close
+30 mv
77
How propagation of the signal happen along the axon
Unidirectional movement, because the preceding part of the axon is on refractory period, like dominos effect In myelinated fibers the insulating properties of the thick myelin sheath resist ion movement and the local flow of current, so it will just propagate the signal very quickly In mylinated fibers action potentials in the membrane only occur at the nodes of Ranvier; this type of impulse conduction is called saltatory conduction–where impulse regeneration leaps from node to node
78
What is saltatory conduction
where impulse regeneration leaps from node to node (nodes of ranvier)
79
What happens with signal transduction in demyelinating diseases
The signal leaks out of the axon, slows the signal and interrupting it-> altered motor movements
80
Action potential is what kind of loop
positive feedback
81
Where the neuron receives all the signal and decides to fire or not
Axon hillack
82
A neuron can terminate on one of three structures
Muscle, gland or neuron
83
Most common type of synapse
Chemical synapsesoccur where presynaptic cells release chemical transmitters (neurotransmitters) across a tiny gap to the postsynaptic cell
84
What is synaptic knob
tinybulge at the end of a terminal branch of a presynaptic neuron’s axon that contains vesicles housing neurotransmitters
85
Three arrangements of synapses
Axodendritic- axon is sending signals to a dendrite Axosomatic Axoaxonic- may regulate action potential of postsynaptic axon
86
Mechanism of neurotransmitter releasae
1. Action potential depolarizes the axon terminal 2. The depolarization opens voltage-gated Ca channels and Ca enters the cell 3. Ca entry triggers exocytosis of synaptic vesicle contents 4. Neurotransmitter diffuses across the synaptic cleft and binds with receptors on the post synaptic cell 5. Binding intitiates a response in the postsynaptic cell
87
What happens after neurotransmitters bind to postsyneptic neuron
Opening of ion channelsproduces a postsynaptic potential, either an excitatory postsynaptic potential (EPSP-Na->depolarization) or an inhibitory postsynaptic potential (IPSP, Cl in or K+ out->hyperpolarization) –Transmitters are inactivated or removed from the cleft
88
defects/imbalance in neurotransmitters leads to
diseases, Alzheimers, depression, anxiety, Schizophrenia, Parkinson’s etc.
89
2 classification of neurotransmitters
1) Function | 2) Chemical structure
90
Function classification
two major functional classifications are excitatoryneurotransmitters and inhibitoryneurotransmitters; can also be classified according to whether receptor directly opens a channelor instead uses a second messenger mechanism involving G proteins and intracellular signal
91
What kind of neurotransmitter is acetylcholine
acetycholine is excitatory at muscle cells (nicotinic receptors), directly linked to ion channel •Ach is inhibitory at cardiac muscle (parasympathetic input from cardiac inhibitory center of brain stem), slows heart rate acts by Muscarinic receptors (letting Potassium channels to open)
92
Four main chemical classes of neurotransmitters according to structure
1. acetycholine •2. Amines •3 aminoacids-glycine •4. other small molecules
93
Example of acetylcholine group and what they do
junctions with motor effectors (muscles and glands)-salivary and sweat-autonomics system fight and lfightresponse. PNS and CNS (excitatory in brain)
94
Example of amines and what they do
monaminessuch as serotonin-CNS,inhbitory, moods and emotion.
95
Example of AAs as neurotransmitter
glycine-spinal cord, most common inhibitory neurotransimitter
96
Example of other small molecules neurotransmitters
nitric oxide which may be a signal from post to pre-synaptic neuron,
97
Example of indirect stimulation of a post-synaptic receptor
norepinephrine (involved in emotional responses in CNS and ANS) binds a G-protein linked receptor which triggers activation of adenylate cyclase which in turn catalyzes ATP to cAMP. cAMPis a second messenger that triggers a protein kinase signaling cascade and the opening of channels
98
How neurotransmittor action is terminated
The neurotransmitter’s action is quickly terminated by either neurotransmitter molecules being transported back into the synaptic knob (reuptake) and/or metabolized into inactive compounds by enzymes (in postsynaptic) and/or diffused and taken up by nearby glial cell or they can diffuse out of the synaptic cleft ( to the blood vessel)
99
Acetylcholine is made up from
Choline and acetyl CoA
100
In the synaptic cleft acetylcholine is rapidly broken down by ____ and then ___
acetylcholinesterase | Then choline is transported back into the axon terminal and is used to make more ACh
101
Describe anatomy of the neuromuscular junction
On the postsynaptic membrane there is a motor end plate where are nicotinic Acetylcholine receptors.

Mam Physiology (16 decks)

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