Unit 2 Flashcards
1
Q
What is the nervous system?
A
Network of nerve cells that uses a rapid means of communication to adapt the body to external stimuli and coordinates internal processes.
2
Q
What are afferent neurons?
A
Neurons that send impulses from the receptor to the brain (At the brain).
3
Q
What are efferent neurons?
A
Neurons that send impulses from the the brain to the receptor (Exit the brain).
4
Q
What is the autonomic nervous system divided into?
A
Sympathetic and parasympathetic nervous system.
5
Q
What is the nervous system divided into?
A
Central nervous system and peripheral nervous system.
6
Q
What is the main function of the somatic nervous system?
A
Voluntary control of body movements via skeletal muscles.
7
Q
What is the main function of the autonomic nervous system?
A
Involuntary control of body movements via visceral organs.
8
Q
What is a neuron?
A
A functional communicating cell that transits nerve impulses.
9
Q
A typical neuron contains what three structures?
A
- Cell body
- Dendrites
- Axons
10
Q
What is myelin?
A
An insulating sheath that contains phospholipids which act as protection and insulation. Also conducts faster impulses along the axon.
11
Q
What are Nodes of Ranvier?
A
Part of the axon not covered by myelin.
12
Q
What is a synapse?
A
The gap between neurons which impulses pass by diffusion of a neurotransmitter.
13
Q
What is a sensory neuron?
A
Afferent neurons that send information into the CNS from the receptors.
14
Q
What is a motor neuron?
A
An efferent neuron that transmits information from the CNS to the effectors (muscles and/or glands).
15
Q
What are interneurons?
A
Neurons located within the CNS and are involved with integration.
16
Q
How is a membrane potential across the membrane produced?
A
A membrane potential occurs when there is an unequal distribution of ions occurs between the inside and outside of the cell, which also creates an unequal charge distribution.
17
Q
Extracellular fluid contains more ___ and ___.
A
Sodium and chloride. Outside cell more positive.
18
Q
Intracellular fluid contains more ___ and ___.
A
Potassium and negatively charged proteins. Inside cell more negative.
19
Q
How many more times permeable is the membrane to potassium?
A
The membrane is 40 times more permeable to potassium. Thus, potassium can move outward and sodium slightly inward. The outside becomes positive and inside becomes negative.
20
Q
What three forces are involved in maintaining the membrane potential?
A
- Chemical or concentration force
- Electrical force
- Na-K pump
21
Q
Explain the chemical or concentration force.
A
The chemical or concentration force is caused by the concentration gradient.
22
Q
Explain the electrical force.
A
The electrical force is the attraction and repulsion between charges.
23
Q
Explain the Na-K Pump.
A
Maintains the electrical and chemical gradients.
One way it does this:
Step 1. Sodium binds to receptor site on enzyme that’s in the membrane
Step 2. ATPase binds to enzyme and breaks off a phosphate which provides energy to change the shape of the pump
Step 3. Brings sodium inside of cell
Step 4: Potassium bonds to receptor site on enzyme
Step 5: Rechanges pump to original shape
Step 6: Potassium released outside of cell
24
Q
What is a nerve impulse?
A
Changes in membrane potentials that form electrical signals that travel down an axon.
25
What is depolarization?
Membrane potential becomes LESS NEGATIVE. Can be caused by an increase in sodium ion permeability (Na+ going into cell).
26
What is repolarization?
Membrane returns to resting state. Can be caused by an increase in potassium ion permeability (K+ going out of cell cell).
27
What is hyperpolarization?
When the membrane potential becomes more polarized or MORE NEGATIVE. Can be caused by an increase in chloride ion or potassium ion permeability (Cl- or K+ goes into cell).
28
What two types of electrical signals in the neuron are there?
1. Graded potential
2. Action potential
29
Where do graded potentials occur?
In the membranes of dendrites and cell body membranes.
30
Where do action potentials occur?
Start at the axon hillock, then axon, then axon terminals (knobs).
31
Describe the strength of graded potentials.
Strength of depolarization and hyperpolarization varies depending on the stimulus strength.
The stronger the stimulus, the stronger the depolarization and hyperpolarization.
32
What kind of transmission do graded potentials have?
Passive transmission. The signal or graded potential weakens with distance.
33
Describe the strength of action potentials.
All-or-nothing. Action potential is generated to its maximum strength or doesn't fire at all.
34
What kind of transmission do action potentials have?
Action transmission or propagation. Where the strength of the action potential at the end of the axon is the same strength as the beginning. It doesn't fade or weaken with distance.
35
Describe the refractory period of graded potentials.
There are no refractory periods.
36
Describe the refractory period of action potentials.
Refractory lasts about 10 milliseconds.
37
What is a refractory period?
A period of neuron insensitivity to another stimulation that prevents the creation of a second action potential.
38
What is an absolute refractory period?
No additional action potential can be generated.
39
What is a relative refractory period?
An additional action potential may be generated if the stimulus is increased.
40
What happens to the millivolts (mV) level for depolarization of action potential?
It goes from -70 mV to +30 mV.
Na+ ion gates open causing increased Na+ permeability 600x. This causes an influx of Na+ into the cell, making cell more positive.
41
What happens to the millivolts (mV) level for repolarization of action potential?
It goes from +30 mV to -70 mV.
Na+ ion gates close and K+ ion gates open to increase K+ permeability 10x. This causes an efflux of K+ into the cell, making cell more negative.
42
What happens to the millivolts (mV) level for hyperpolarization of action potential?
It becomes more negative than -70 mV.
43
Speed of action potential is influenced by two things:
1. Diameter of axon
2. Presence of myelinated axon
44
What is a neuromuscular junction?
Synaptic gap between muscles.
45
What is a neuroneural junction?
Synaptic gap between two neurons.
46
There are three types of neuroneural junctions:
1. Axodendritic (between axon and dendrite)
2. Axosomatic (between axon and cell body)
3. Axoaxonic (between axon and axon)
47
Two types of chemical synapses:
1. Neuromuscular junction
2. Neuroneural junction
48
Two ways presynaptic neurons affect likelihood of the postsynaptic neuron to fire:
1. Excitatory synapses: increases the likelihood of the postsynaptic neuron to fire
2. Inhibitory synapses: decreases the likelihood of the postsynaptic neuron to fire
49
Events at an excitatory synapse (7 steps):
Step 1: Action potential sweeps into axon terminals or knobs.
Step 2: This depolarization of the membrane opens Ca gates and an influx of Ca, from ECF, into presynaptic knob (voltage-activated).
Step 3: Ca causes vesicular migration to inner membrane of knob and exocytosis of the neurotransmitter.
Step 4: Neurotransmitter diffuses across synapse.
Step 5: Neurotransmitter attaches to the receptors on the postsynaptic membrane that causes permeability changes in the membrane and change in the postsynaptic membrane potential.
Step 6: Na+ ion (influx) and K+ ion (efflux) gates open that cause a small depolarization or excitatory postsynaptic potential (EPSP). Inside becomes more positive.
7. Removal of neurotransmitter.
50
Events at an inhibitory synapse (7 steps):
Step 1: Action potential sweeps into the axon terminals or knobs.
Step 2: This depolarization of the membrane opens Ca gates and an influx of Ca, from ECF, into the presynaptic knob.
Step 3: Ca causes vesicular migration to inner membrane of knob and exocytosis of the neurotransmitter.
Step 4: Neurotransmitter diffuses across synapse.
Step 5: Neurotransmitter attaches to the receptors on the postsynaptic membrane that causes permeability changes in the membrane and change in the postsynaptic membrane potential.
Step 6: Cl- ion (influx) and K+ ion gates open that cause a small hyperpolarization or inhibitory postsynaptic potential (IPSP). Outcome is to become more negative.
Step 7: Removal of neurotransmitter.
51
What is a summation?
The additive effect of many EPSP's until threshold is reached thus producing an action potential.
52
What is a temporal summation?
A type of summation that has multiple volleys of impulses along one knob.
53
What is spatial summation?
A type of summation where different knobs carry the impulses.
54
What is an inhibitory postsynaptic potential (IPSP)?
A small hyperpolarization.
A predominance of IPSP's causes inhibition of the neuron.
55
What is an excitatory postsynaptic potential (EPSP)?
A small depolarization.
A predominance of EPSP's causes postsynaptic neuron to fire.
56
How is acetylcholine synthesized or produced?
Choline Acetyltransferase (CAT) produced ACh
or
Acetyl COA + Choline → Acetylcholine (ACh) + COA
57
How is acetylcholine degraded or removed?
Degradation by enzyme acetylcholinesterase (ACHE).
Acetylcholine → Acetate + Choline
After degraded, Acetate + Choline are removed from the synapse.
58
What are two ACh receptors?
1. Nicotinic
2. Muscarinic
59
How are catecholamines (an amine) synthesized or produced?
L-Dopa → Dopamine → Norepinephrine
60
How are catecholamines (an amine) degraded or removed?
1. Broken down by monoamine oxidase (MAO) in the membrane of the axonal terminals.
2. Broken down by catechol-o-methyltransferase (COMT) on the postsynaptic membrane in the cytoplasm.
3. Absorbed (uptake) backed into the knobs.
61
Name four types of amino acid neurotransmitters:
1. Aspartate
2. Glutamate
3. Glycine
4. GABA
62
Name two types of neuro active peptides:
1. Endorphins
2. Vasopressin (ADH)
63
What are five modifications of neuronal activity by drugs:
1. Mimic the neurotransmitter (agonists)
2. Alters the release of the neurotransmitter
3. Influences the receptor site (antagonists)
4. Influences the removal of the neurotransmitter
5. Influences ion channels or gates
64
Examples of two drugs that mimic the neurotransmitter (agonists):
Nicotine and muscarine mimic acetylcholine.
65
Examples of four drugs that alter the release of the neurotransmitter:
Amphetamines increase the release of dopamine and norepinephrine in the brain.
Caffeine increases the release of ACh.
Botox and Botulism inihibits the release of ACh (less skeletal muscle activity).
66
Examples of drugs that influence receptor site (antagonists):
Curare and Botox block receptor sites for ACh (blocks muscle movement).
Atropine-belladonna block parasympathetic receptors (parasympathetic receptors block sphincter muscles which dilate pupils).
67
Examples of drugs that influence the removal of the neurotransmitter:
Cocaine reduces uptake of norepinephrine (you have more norepi, which constricts blood vessels).
Nerve gas or Organophosphates block acetylcholinesterase activity.
Amphetamines inhibit monoamine oxidase (MAO).
68
Examples of drugs that influence ion channels or gates:
Digitoxin (Foxglove plant) inhibits Na-K ATPase
Verapamil blocks calcium channels (lowers blood pressure).
Tetrodotoxin (puffer fish), Saxitoxin (dinoflagellates), and Apamin (honeybee) block ion channels.
69
What does the blood-brain barrier do?
Prevents the brain from potential injury from toxins.
70
What are the BBB’s capillary membranes permeable to?
Hydrophobic (lipophilic) molecules such as liquids, gases, and alcohol.
71
What are the BBB’s capillary membranes impermeable to?
Hydrophilic (lipophobic) molecules unless transport mechanisms are present such as glucose, amino acids, and ions.
72
What are ascending tracts or sensory pathways?
The pathway of sensory nerves that go from spinal cord to the brain.
73
What are descending tracts or motor pathways?
A nerve tract in the spinal cord that carries impulses away from the brain.
74
What is the brain?
The brain is the major processing center of the body.
75
What are the three main areas of the brain?
1. Brain stem
2. Cerebellum
3. Forebrain.
76
What are three parts of the brain stem?
1. Medulla oblongata
2. Pons
3. Midbrain
77
What does the medulla oblongata do?
Functions:
- Controls vital centers of respiration and cardiovascular functions.
- Controls non-vital areas of swallowing, coughing, and sneezing.
- Contains pyramids for the crossing over of fibers coming down from the brain.
78
What do the pons do?
Controls respiration.
79
What does the midbrain do?
Controls eye movements and auditory and visual reflexes.
80
What does the cerebellum do?
- Motor coordination and balance.
- Provides feedback to motor systems.
81
What is the major area of the forebrain?
The cerebral cortex (gray matter on the outer quarter inch of the brain).
82
What does the cerebral cortex do?
It is the most complex region of the brain that is involved in mind and intellect. The conscious area of the brain.
83
What is the left hemisphere of our brain specialized in?
The left side contains language centers (Wernicke’s & Broca’s area), verbal skills, and numerical skills. It also controls the right side of our body.
84
What is the right hemisphere of our brain specialized in?
The right side contains recognition of visual patterns, expression, and recognition of emotions or artistic abilities. It also controls the left side of our body.
85
What are the four lobes?
1. Parietal
2. Occipital
3. Temporal
4. Frontal lobe
86
What is the parietal lobe involved in?
Primary sensory (somatosensory) area receives input from receptors.
Sensory homunculus.
Vision (where does it fit in with memories and experiences).
87
What is the occipital lobe involved in?
Visual processing center.
Radiates anteriorly into temporal lobe and parietal lobe:
- Temporal portion: recognition of what is seen
- Parietal portion: where does it fit in with memories and experiences
88
What is the temporal lobe involved in?
Vision (recognition of what is seen), hearing, Wernicke’s area for language comprehension.
89
What is the frontal lobe involved in?
Primary motor area controls voluntary skeletal activity.
Motor homunculus.
90
What two structures does the basal nuclei and subcortical nuclei have?
Amygdala and hippocampus.
91
What are the basal nuclei and subcortical nuclei involved in?
Fine motor coordination.
92
What is Parkinson’s disease and what does it impair?
A disease where there is not enough dopamine. This interferes with fine motor coordination.
93
What is the thalamus involved in?
It is a sensory relay station to cortex, hypothalamus, etc.
94
What is the hypothalamus involved in?
This area controls body temperature, thirst, appetite, sexual activity, the pituitary gland, and the autonomic nerves.
95
What five structures does the limbic system have?
1. Hypothalamus
2. Thalamus
3. Fornix
4. Basal ganglia
5. Cingulate gyrus of the cortex
96
What does the limbic system do?
It controls emotions (pleasure and punishment centers) and emotional behavior (face recognition, natural smile, and artificial smile).
97
What processes are involved in face recognition?
Step 1: Visual input to cortex (lobes).
Step 2: Amygdala to limbic system for emotional input.
98
What processes are involved in natural smile?
Step 1: Visual cortex recognizes the face.
Step 2: Sent to limbic center.
Step 3: To basal ganglia.
Step 4: To muscles.
99
What processes are involved in artificial smile?
Step 1: Auditory input to higher brain centers (temporal lobe).
Step 2: Frontal lobe to muscles.
Step 3: Different responses.
100
What four structures does the RAS have?
1. Pons
2. Medulla
3. Thalamus
4. Hypothalamus.
101
What does the RAS do?
Influences the cortex and cerebellum. Involved in alertness.
102
What controls reflexes?
Either spinal cord or brain.
103
What is a reflex arc?
A neural pathway that controls an action reflex. Most sensory neurons do not pass directly into the brain, but synapse in the spinal cord
104
What is a stretch reflex?
A muscle contraction in response to stretching within the muscle.
Monosynaptic reflex.
Provides automatic regulation of skeletal muscle length.
105
What is a withdrawal reflex?
A spinal reflex intended to protect the body from damaging stimuli.
Polysynaptic.
Causes stimulation of sensory, association, and motor neurons.
Ipsilateral (one muscle flexes other underneath relaxes) AND contralateral (extend one knee and not the other).
106
Successful voluntary movement requires four aspects:
1. The idea or intention must be developed. Achieved by supplementary motor area and association area of the frontal lobe and the limbic system.
2. A program of motor commands must be formed for the contraction of the appropriate muscles. Controlled by the motor cortex and premotor cortex.
3. Execution of the motor pathways. Carried out by pyramidal tracts and motor neurons to the muscles.
4. Feedback into the movement program. Achieved by cerebellum, thalamus, basal nuclei, substantia nigra of midbrain, cortical areas and proprioceptors in the effectors.
107
What is Wernicke's area involved in?
Comprehension.
Sensory input form ears and eyes goes to Wernicke's area.
108
What is Broca's area involved in?
Language expression.
Speak and write words.
Syntax.
109
What is the neuronal basis of memory?
The development of synaptic circuits that are activated by an experience or thought.
110
What is immediate memory?
Ability to remember a small amount of information within fraction of seconds to seconds.
111
What is working memory?
Ability to remember a information within seconds to days.
It enables us to keep a thought in order to solve problems and in making plans.
112
Which part of the brain does working memory take place in?
Prefrontal cortex.
113
What receptors help to regulate working memory?
Dopamine receptors.
114
What is long-term memory?
Ability to remember a information within days to years.
Long-term memory requires the hippocampus to convert short term to long-term memory.
115
Where is long-term memory stored for future retrieval?
Associative cortex.
116
How is RAS involved in learning?
Attention and focus on area of sensory world.
117
How is the thalamus involved in learning?
Multiple senses for more memories.
More senses used makes learning easier.
118
How is the amygdala and limbic system involved in learning?
Emotional memory and consolidates learning.
119
How is the meso-limbic system involved in learning?
Learning should be pleasurable.
Drugs activiate learning; but also degenerates the pathway.
120
How is the hypothalamus involved in learning?
Stress reduced learning.
121
How does non-REM sleep help with memory?
Rebuilds memories and pathways.
122
How does REM sleep help with memory?
Consolidation of memories.
123
What three elements does the afferent (sensory) nervous system include?
1. Somatosensory system
2. Proprioception
3. Special sensory systems
124
Receptor or generator potentials = ___ (graded/action) potential.
Graded potential.
125
What are two ways for coding for stimulus strength?
1. Higher frequency of action potrntials (increased volley of impulses).
2. Recruitment of neighboring receptors.
126
Receptors can be classified according to their modality (type of stimulus or energy that activates them). The following four categories are:
1. Photoreceptors
2. Chemoreceptors
3. Thermoreceptors
4. Mechanoreceptors
127
What are photoreceptors?
Rod and cone cells in the eye that are sensitive to photons of light.
128
What are chemoreceptors?
Chemoreceptors are activated by chemicals found in odors, various foods, and within the body fluids.
Osmoreceptors are a specific type of chemoreceptor that receives changes in osmotic concentration.
129
What are thermoreceptors?
Thermoreceptors monitor temperature changes and include both cold and heat receptors within the skin.
130
What are mechanoreceptors?
Mechanoreceptors are activated mechanically by pressure, stretch, or distension. They are used throughout the body for perceiving stimuli ranging form touch, muscle tension, and hearing.
Types of mechanoreceptors:
- Baroreceptors for monitoring blood pressure
- Proprioceptors for tension
- Auditory receptors for sound
131
What are nociceptors?
Receptors that monitor pain from tissue damage.
They can be thermoreceptors or mechanoreceptors.
132
What four areas of the brain regulate the autonomic nervous system?
1. Hypothalamus
2. Pons
3. Medulla
4. Spinal cord.
133
What does the autonomic nervous system do?
Nerves innervate cardiac and smooth muscle and glands.
It's an involuntary system that can either excite OR inhibit the effector when stimulated.
Has pre-ganglionic, ganglionic, and post-ganglionic neurons.
Dual innervation (when sympathetic and parasympathetic nervous systems are stimulated, they do the opposite things. Ex: sympathetic increases heart rate and parasympathetic decreases heart rate... usually antagonistic actions)
134
What does the pre-ganglionic neuron do?
Releases neurotransmitter from central nervous system and travels to ganglion.
135
What does the ganglion do?
Neurotransmitter binds with receptors here.
136
What does the post-ganglionic neuron do?
Neurotransmitters travel from ganglion to effectors.
137
In the sympathetic nervous system: what _neurotransmitter_ does the PRE-ganglionic neuron release?
Acetylcholine.
138
In the parasympathetic nervous system: what neurotransmitter does the PRE-ganglionic neuron release?
Acetylcholine.
139
In the sympathetic nervous system: what are the _neuron and receptors_ for PRE-ganglionic fibers described as?
All preganglionic fibers are _cholinergic_.
140
In the parasympathetic nervous system: what are the _neurons and receptors_ for PRE-ganglionic fibers described as?
All preganglionic fibers are _cholinergic_.
141
In the sympathetic nervous system: what _neurotransmitter_ does the POST-ganglionic neuron release?
Norepinephrine.
142
In the parasympathetic nervous system: what _neurotransmitter_ does the POST-ganglionic neuron release?
Acetylcholine.
143
In the sympathetic nervous system: what are the specific _receptors_ for the POST-ganglionic synapse (from ganglion to post-ganglionic dendrites)?
Nicotinic cholinergic receptors.
144
In the parasympathetic nervous system: what are the specific _receptors_ for the POST-ganglionic synapse (from ganglion to post-ganglionic dendrites)?
Nicotinic cholinergic receptors.
145
In the sympathetic nervous system: what are the specific _receptors_ for the NEUROEFFECTOR synapse (from post-ganglion to effectors)?
Alpha and Beta receptors.
146
In the parasympathetic nervous system: what are the specific _receptors_ for the NEUROEFFECTOR synapse (from post-ganglion to effectors)?
Muscarinic cholinergic receptors.
147
In the sympathetic nervous system: what are the _neurons and receptors_ for POST-ganglionic fibers described as?
Adrenergic.
148
In the parasympathetic nervous system: what are the _neurons and receptors_ for POST-ganglionic fibers described as?
Cholinergic.
149
What is the general function of the sympathetic nervous system?
Fight or flight.
150
What is the general function of the parasympathetic nervous system?
Rest and digest.
151
What does the sympathetic nervous system do to the heart and what receptors are involved?
Speeds rate.
Increases force of contraction.
B1 receptors.
152
What does the parasympathetic nervous system do to the heart?
Slows rate.
153
What does the sympathetic nervous system do to the blood vessels and what receptors are involved?
Constriction/dilation.
Alpha & B2 receptors.
154
What does the parasympathetic nervous system do to the blood vessels?
Nothing...? No dual innervation.
155
What does the sympathetic nervous system do to the pupils and what receptors are involved?
Dilates.
Alpha receptors.
156
What does the parasympathetic nervous system do to the pupils?
Constricts.
157
What does the sympathetic nervous system do to the bronchioles and what receptors are involved?
Dilates.
B2 receptors.
158
What does the parasympathetic nervous system do to the bronchioles?
Constricts.
159
What does the sympathetic nervous system do to the digestive system and what receptors are involved?
Slows motility and inhibits secretions.
B2 receptors.
160
What does the parasympathetic nervous system do to the digestive system?
Increases motility and stimulates secretions.
161
What does the sympathetic nervous system do to the salivary glands and what receptors are involved?
Secretion of mucus.
Alpha receptors.
162
What does the parasympathetic nervous system do to the salivary glands?
Secretion of serous fluid.
163
What does the sympathetic nervous system do to the urinary bladder and what receptors are involved?
Relaxes.
B2 receptors.
164
What does the parasympathetic nervous system do to the urinary bladder?
Contracts.
165
What does the sympathetic nervous system do to the uterus and what receptors are involved?
Relaxes.
B2 receptors.
166
What does the parasympathetic nervous system do to the uterus?
Nothing...? No dual innervation.
167
What does the sympathetic nervous system do to the reproductive system and what receptors are involved?
Orgasm.
Alpha receptors.
168
What does the parasympathetic nervous system do to the reproductive system?
Erection.
169
What does the sympathetic nervous system do to the adrenal medulla?
Releases epinephrine and norepinephrine.
170
What does the parasympathetic nervous system do to the adrenal medulla?
Nothing...? No dual innervation.
171
What are the four receptor types of the sympathetic nervous system?
1. Nicotinic receptors
2. Alpha1 and Alpha2 receptors
3. Beta1 receptors
4. Beta2 receptors
172
Where are Alpha1 and Alpha2 receptors located and what do they do?
Smooth muscle and glands.
Receptors are excitatory when activated.
173
Where are Beta1 receptors located and what do they do?
Heart.
Receptors are excitatory and increase heart rate and the force of contraction.
174
Where are Beta2 receptors located and what do they do?
Smooth muscle.
Receptors are inhibitory and relax muscles.
175
What are the two receptor types of the parasympathetic nervous system?
1. Nicotinic receptors
2. Muscarinic receptors
176
Where are the muscarinic receptors located and what do they do?
Effectors (muscles/glands).
1. M1 = salivary glands and stomach
2. M2 = heart
3. M3 = smooth muscle contraction and vasodilation
177
What does the somatic nervous system do?
Neurons innervate skeletal muscles and it is ONLY excitatory when stimulated, NOT inhibitory (unlike autonomic).
Voluntary system except in spasms, shivering, and some breathing.
A single neuron goes from CNS to skeletal muscles. NO ganglions.
They secrete acetylcholine at neuromuscular junction onto muscle membrane. Cholinergic fibers with cholinergic (nicotinic) receptors on muscle membrane.
178
What is a motor unit?
The somatic nerve and its innervated muscle fibers.
One nerve may innervate as few as a dozen muscle fibers as in the hands with their fine movements or may innervate hundreds as in calf or back muscles.
179
"Indentations" of muscle membrane which contain acetylcholine receptors.
It's the "footprint" in the "mud."
180
What are four muscle properties?
1. Excitability
2. Contractability
3. Stretchability
4. Elasticity
181
What is a skeletal muscle or muscle bundle?
An organ composed of many cells called muscle fibers and are held together by connective tissue fascia (connective tissue has some elasticity to it).
182
What are the three structures of a muscle cell?
1. Sarcolemma (which contains transverse tubule)
2. Myofibrils (contains myofilaments)
3. Sarcoplasmic reticulum (which contains terminal cisternae)
183
What is the sarcolemma?
Muscle membrane.
184
What are transverse tubules?
Deep invaginations of sarcolemma where action potentials travel through and get deep into the muscle.
185
What are myofibrils?
Proteins that make up thin and thick filaments.
186
What is the sarcoplasmic reticulum?
Covers myofibrils. Stores and pumps calcium ions.
187
What is the terminal cisternae?
"Swellings" on sarcoplasmic reticulum. Stores Calcium.
188
What is a triad?
Two terminal cisternae and a t-tubule.
189
What are sarcomeres?
Functional units of muscle shortening or contraction.
190
What are Z lines?
Ends of sarcomere.
191
What protein do thick filaments contain?
Myosin.
192
What proteins do thin filaments contain?
Actin proteins w/ tropomyosin and troponin.
193
What two binding sites do myosin molecules have?
1. An ATP binding site which uses energy
2. An Actin binding site which attached to thin filaments
194
What binding site does actin have?
Myosin binding sites.
195
What binding site does troponin have?
Calcium binding sites.
196
What does tropomyosin and troponin do?
Regulate actin and myosin interaction. They inhibit interaction so no muscle contraction.
197
What are I bands?
The part of the sarcomere that ONLY contains THIN filaments.
198
What are A bands?
The part of the sarcomere with THICK filaments. Looks at length of THICK filament.
199
What is the H zone?
Part of sarcomere on center of A band where there is ONLY THICK filaments.
200
What is the sliding filament theory?
Sarcomere shortening causes muscle contraction.
201
What are the steps for the cross bridge cycle?
Step 1: Release. ATP attaches to myosin again for release of actin filament.
Step 2: Activation or the cocking of the myosin head. ATP binds w/ myosin and splits into ADP, thus producing a "high energy" myosin.
Step 3: Binding of myosin to actin.
Step 4: Sliding or power stroke. The myosin head pivots against actin shortening the sarcomere ADP is released.
Step 5: Repeat steps 1-4.
202
What are the steps for Excitation Contraction Coupling?
1. An AP on the somatic nerve arrives at neuromuscular junction.
2. Voltage-gated Ca channels open. Influx of Ca triggers exocytosis of ACH vesicles.
3. ACH diffuses across and binds to receptor sites on muscle motor end plate.
4. This opens both Na and K channels creating a large depolarization or end plate potential (EPP). The enzyme Cholinesterase found on motor end plate splits and deactivates ACH.
5. End plate potential migrates from motor end plate to "true sarcolemma" and triggers off an AP.
6. AP propagates down sarcolemma (actively) and into many t-tubules by the process of membrane transmission.
7. This depolarizes the terminal cisternae of the SR and causes them to increase their permeability (opens Ca gates) to their stored Ca ions.
8. Ca moves into sarcoplasm and binds with troponin causing the release of the regulatory inhibition of actin.
9. Thus the thick and thin filaments slide and sarcomeres shorten (Cross-Bridge Cycle).
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What are the steps for the Relaxation of Skeletal Muscle?
1. No AP on neuron, muscle sarcolemma or t-tubules.
2. ATP used to pump Ca ions back into terminal cisternae.
3. Ca unbinds w/ troponin and inhibits actin's interaction w/ myosin.
4. Thus no actin myosin interaction, the sarcomeres lengthen and the muscle relaxes.
204
What are three sources of ATP for muscle contraction?
1. Creatine phosphate
2. Aerobic respiration
3. Anaerobic respiration
205
What is creatine phosphate?
Immediate source for ATP.
Creatine phosphate + ADP ⇔ ATP + Creatine
Only needs 1 enzyme to activate creatine phosphate.
206
What is aerobic respiration?
Requires oxygen to create ATP.
Myoglobin: oxygen storage molecule
Cardiovascular: transports oxygem from hemoglobin to muscles
207
What causes oxygen debt?
Oxygen debt is due to the metabolism of lactic acid to glucose or to carbon dioxide that requires ATP or oxygen directly, the formation of creatine phosphate, and the replishment of myoglobin.
We have to breathe to pay off oxygen debt. That's why after intense cardio, you have to keep moving so cardiovascular system keeps going to remove lactic acid.
208
What is a muscle twitch?
The electrical events or AP, which lasts 2 milliseconds activates the mechanical event or muscle contraction, which lasts 50-250 millseconds.
209
What is a latent period?
Time from stimulus to beginning of contraction.
Cause: electrical event on membrane takes time and elasticity in muscle.
210
What is a contraction period?
Tension develops and the muscle shortens.
Cause: sliding filament theory
211
What is a relaxation period?
Tension fades and muscles become relaxed.
212
What is isotonic contraction?
The sarcomeres shorten and the muscle shortens, but the tension is the SAME.
(Think flexing your arm)
213
What is isometric contraction?
The sarcomeres shorten but the muscle cell DOESN'T shorten because of the series elastic component. It's the SAME length.
(Think pushing against wall)
214
What three factors that affect the force generated in a single fiber?
1. Frequency of stiulation (summation and tetanus)
2. Fiber length: optimum muscle length = more overlap = more cross-bridges
3. Fiber diameter: bigger diameter = more myofibrils = more thick/thin filaments to slide
215
What are two ways strength of force generated by whole muscles can be increased and/or sustained?
1. Recruitement of motor units: an increase in strength is determined by the number of motor units recruited, thus the number of muscle fibers recruited for contraction.
2. Asynchronous recruitement: delays muscle fatgue by rotating use of motor units so some can rest and recover.
216
What are two types of muscle fatigue?
1. Short-term maximal exertion fatigue is caused by a buildup of inorganic phosphate and a decrease in calcium release from the SR.
2. Extended sub-maximal fatigue is caused by glycogen and/or fatty acid depletion (calcium release).
217
What is hypertrophy?
Increase in muscle size.
218
What is atrophy?
Decrease in muscle size.
219
What are three types of fibers?
1. Slow oxidative
2. Fast oxidative
3. Fast glycolytic
220
What are three receptor types classified by stimulus location?
1. Exteroceptor
2. Interoceptor
3. Proprioceptor
221
What are exteroceptors?
Receptors that provide info about our external environment that include our receptors for light, sound, smell, taste, as well as the sensations from our skin.
222
What are interoceptors?
Receptors that receive stimuli from the internal visceral organs and include osmoreceptors and baroreceptors.
223
What are proprioceptors?
Receptors that inform the body about the amount of tension within tendons, ligaments and joints, and the state of muscle contraction. They're important in locomotion and maintaining body position.
224
What are two types of receptor or impulse firing patterns?
1. Tonic pattern
2. Phasic pattern
225
What are tonic receptors?
Receptors that fire continuously for the duration of the stimulus and include baroreceptors and nociceptors.
Think "buzzer."
226
What are phasic receptors?
Receptors that give a burst of activity at the onset of stimulation that fades as stimulation continues.
Think "doorbell."
227
What is sensory adaptation?
Sensory adaptation occurs quickly in phasic receptors and slowly or not at all in tonic receptors. This enables the brain to focus on changes in stimuli and to ignore continuous stimulation, thus allowing the brain to concentrate on other matters.
228
What is a large receptive field?
Fewer receptors within a particular region but has the disadvantage of having less discriminating ability or sensitivity to the location of the stimulus.
229
What is a small receptive field?
Has finer discrimination regarding stimulus input due to the greater density of receptors located in a given area of the body.
230
What is an ipsilateral reflex arc?
Receptors affecting effectors on the same side of the body.
231
What is a contralateral reflex arc?
Receptors affecting effectors on the opposite side of the body.
232
What is a bilateral reflex arc?
Receptors affecting effectors on both sides of the body.
233
What is a monosynaptic reflex arc?
Simplest reflex which consists of a single synapse, within the spinal cord, between a single sensory neuron and a single motor neuron.
234
What is a polysynaptic reflex arc?
Complex reflex which involve one or many interconnecting neurons (interneurons) within the CNS.
235
What specific area of the brain controls pupil diameter and blinking?
Superior colliculi of midbrain.
236
What cranial nerve innervates the iris muscles that change the diameter of the pupil?
Oculomotor nerve.
237
What causes dizziness?
Fluid movement within the semicircular canals of the inner ear are still moving. This gives us the sense that our body is still moving even though it's not.
238
How does the primary physiology of hearing work?
Sound waves enter external acoustic meatus of external ear.
Waves then vibrate tympanic membrane that in turn vibrates the three ear ossicles of the middle ear.
Ossicles amplify vibration or foce about fifteen times the pressure that is exerted on the tympanic membrane.
Stapes vibrates fluid within vestibular complex that vibrates fluid in cochlea of inner ear.
Fluid waves activate hair cells in the Organ of Corti of the inner ear.
Impulses generated by the hair cells are then sent to the brain by way of the vestibulocochlear nerve for analysis in temporal lobe of cerebrum.
239
What is nerve deafness?
Associated with problems with the cochlea, sensory neurons, or temporal lobe of brain.
