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General Biology 2 > Unit 5.1: Neural control of skeletal muscles > Flashcards

Unit 5.1: Neural control of skeletal muscles Flashcards

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1
Q

What is a voluntary control?

A

The primary motor cortex initiates movement by sending signal through spinal cord through motor neurons to skeletal muscle. It controls motor neurons on opposite side of body

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2
Q

What is an involuntary control?

A

They are reflexes : fast, predictable, automatic response to stimuli

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3
Q

Name the components of a reflex

A

a. receptor detects stimulus (at the beginning of the sensor neurons)
b. afferent sensory neuron (from receptor to CNS)
c. integrating center (brainstem or spinal cord)
d. efferent motor neuron
e. effector -> muscles -> contracts (effect)
- > glands -> secretes

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4
Q

what are somatic reflex

A

effectors are skeletal muscles - effect is muscle contraction
integrating center is spinal cord

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5
Q

what are withdrawal effect (flexor reflex)

A

uses more than 1 motor neuron to withdraw hand or foot

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6
Q

what are crosses extensor reflexes

A

occurs with withdrawal reflex involves contraction of muscles on opposite side of body

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7
Q

How are signals sent through a neuron

A

along the length of one neuron, uses electrochemical gradient (ions: elements with a charge).

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8
Q

What is the first step of impulse conduction

A

the resting neuron : resting membrane potential of -70 mV. positive outside, negative inside

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9
Q

what is the second step of impulse conduction

A

Na+ enter neuron through Na+ channels in neuron membranes triggered by: mechanoreceptors (physical disturbance like touch, pressure, movement), chemoreceptors (respond to specific chemicals/uses ligang-gated channels), photoreceptors (respond to light), electroreceptors (electric charge/voltage-gated channels), thermoreceptors (temperature change), pain receptor (nociceptors)

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10
Q

How is perceived an excess in stimulus?

A

Pain

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11
Q

What must happen to initiate a signal (impulse)

A

Membrane potential must reach -55 mV threshold.
No impulse if Na+ enters and potential does not reach threshold
If Na+ enters and potential exceed -55 mV, it will stimulate voltage gated Na+ channels to open

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12
Q

What is the third step of impulse conduction

A

Depolarization: volatage-gated Na+ channels open, Na+ rush into neuron, membrane potential increases dramatically, membrane potential reaches between 0 and + 30 mV. Na+ channels closes, membranes potential near +30 mV will stimulate K+ channels to open

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13
Q

What is the fourth step of impulse conduction

A

Repolarization: K+ flow out of the cell, at about -55 mV k+ channels start to close by hyperpolarization will occur (membrane potential less than -70 mV)

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14
Q

What is the fifth step of impulse conduction

A

restore ion concentration Na+ out K+ in

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15
Q

What are synapses

A

Junctions between neuron and target cell

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16
Q

What happens globally in a synaptic transmission

A

neuron releases neurotransmitters and theses chemicals bind to receptors in membrane of target cell

17
Q

What is the position of the receptors and what is his role

A

In membrane of post-synaptic cell

1) Bind and respond to specific neurotransmitter
2) sends signal if neurotransmitters present
3) many and ligand-gated ions channel

18
Q

What are the purpose of voltage-gated Ca++ channels

A

Open if impulse arrives at end bulb
allow calcium ion to enter
Ca++ initiates movement of vesicles

19
Q

Describe the steps of synaptic transmission

A

1) impulse arrives at synaptic end bulb
2) depolarization of pre-synaptic membrane
3) voltage-gated Ca++ channels open- Ca++ enters neuron end bulb
4) Synaptic vesicles move towards neuron cell membranes
5) Exocytosis of neurotransmitters- neurotransmitter release in synaptic cleft
6) neurotransmitters binds to receptor in target membrane, which allows ions to cross membrane

20
Q

What happens if : Na+ channels open?

A

Na+ enters –> impulse generated

21
Q

What happens if : K+ channels open?

A

K+ exits -> impulse suppressed

22
Q

What happens if : Cl- channels open?

A

Cl- enters -> impulse suppressed

23
Q

how does the synaptic transmission ends?

A

Termination. Must remove neurotransmitters to end contraction and be ready for the next transmission.

24
Q

What are the three common termination methods?

A

a. diffusion: neurotransmitter floats out of synaptic gap
b. degradation: neurotransmitter breakdown by specific enzyme and fragments reabsorbed
c. neurotransmitter re-uptake: neurotransmitter transported back intro pre-synaptic end bulb

25
Q

What are stretch reflex

A

receptors are muscle spindles- monitor changes in muscle length, help maintain body positions

26
Q

What are the three type of somatic reflexes

A

a. stretch reflex
b. withdrawal reflex
c. crossed extensor reflexes

27
Q

Is a muscle group considered a organ?

A

Yes.

28
Q

What does a muscle contain?

A

Blood vessels, 1 artery, at least 1 vein, nerves, adipose and connective tissue, bundles of muscle fibers.

29
Q

What is a fascicle?

A

bundles of muscle fibers

30
Q

Describe a cell (fiber) of the fascicle ?

A

Multinucleate, with glycosomes, myoglobin, many mitochondria, sarcoplasmic reticulum, surrounds myofibrils, stores Ca++

31
Q

What does a myfibrils contain?

A

Repeating units of sarcomeres (myofilaments proteins : actin (thin filaments) and myosin (think filaments)

32
Q

Name the five parts of a sarcomere?

A 
actin attached at one end to Z line
myosin (thick filament) = A band
I band - area with actin only
H zone - area with myosin only 
M-line area where myosin are connected together
33
Q

What is the first step in the physiology?

A

depolarization of sarcolemma: action potential initiated and travels into T-butules

34
Q

What happens after the depolatization in T-tubules

A

It stimulates sarcoplasmic reticulum to release Ca++

35
Q

What is the third step of physiology?

A

Ca++ binds to troponin (proteins on actin filament) Which make it moves thus opening myosin binding site on actin

36
Q

Describe the fourth step of physiology?

A

Movement of filaments (if there is a binding site available on actin)

a. activated myosin binds to actin release Pi
b. ADP released from myosin. Myosin head rotates actin filament movies = contraction
c. ATP binds to myosin detaches from actin
d. ATP hydrolyzed ADP + Pi –> activates myosin

37
Q

What is the last step of physiology?

A

Contraction ends when Ca++ ions are pumped back into sarcoplasmic reticulum

General Biology 2 (12 decks)

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