Exam 2 Flashcards
(212 cards)
1
Q
What does axon myelination consist of?
A
Myelin “coat”
2
Q
What is the myelin sheath?
A
Intermittent lipid coverings down the axon
3
Q
What type of cells is the myelin sheath formed by?
A
Non-neuron support (Glial) cells
- Schwann cells –> PNS
- Oligodendrocytes –> CNS
4
Q
What are Nodes of Ranvier?
A
Bare axon surface
5
Q
Where are Nodes of Ranvier?
A
Between myelin sheaths
~ 1 mm apart
6
Q
What does axon myelination = ?
A
Speed, speed, speed
6
Q
What does axon myelination = ?
A
Speed, speed, speed
7
Q
What is saltatory conduction?
A
- Action potential “skips” over myelinated areas of axon membrane
- Increases action potential propagation speed
8
Q
Synapse
A
Association between axon terminal and target cell
9
Q
What are the 3 types of target cells?
A
Another neuron, muscle cell, secretory cell
10
Q
Synaptic Cleft
A
Space between synaptic knob and target cell
11
Q
What is the synaptic knob?
A
Bell-shaped ending of axon
12
Q
What does the synaptic knob contain?
A
Synaptic vesicles that hold packaged neurotransmitters
13
Q
What does the AP open?
A
Ca 2+ channels
14
Q
What does the action potential opening the Ca 2+ channels do?
A
Causes exocytosis of neurotransmitters
15
Q
What happens when the nuerotransmitters are released?
A
They cross the cleft, bind to receptors on target
16
Q
Steps once action potential is released
A
- Action potential reaches terminal
- Voltage-gated Ca 2+ channels open
- Calcium enters axon terminal
- Nuerotransmitter is released and diffuses into the cleft
- Nuerotransmitter binds to postsynaptic receptors
- Nuerotransmitters are remobrf from synaptic cleft
17
Q
Excitatory Post-Synaptic Potentials (EPSPs)
A
Nuerotransmitter-receptor Ligands open gated channels
- Mostly Na+ channels
- Each brings target closer to “threshold” (-55 mV)
18
Q
Inhibitory Post-Synaptic Potentials (IPSPs)
A
Neurotransmitter-Receptor Ligans increase membrane permeability
- K+
- Cl-
Hyper polarizes membrane (Higher Resting Potential)
–> Further away from “threshold” (-55 mV)
19
Q
Grand Post-Synapic Potential (GPSP)
A
The “sum” of concurrent EPSPs and IPSPs
20
Q
Temporal Summation
A
- From one upstream neuron
- Rapid enough to “build up”
21
Q
Spatial Summation
A
“Build up” from multiple upstream neurons
22
Q
What do neuropeptides act on?
A
Act on the target cell
- near, but not within the synapse
23
Q
What do neuropeptides do?
A
Alter (^ / v ) responsiveness to neurotransmitter
24
What is pre-synaptic inhibition / potentiation?
- Regulation of the pre-synaptic nueron
- By 3rd party neuron
- Influences amount of neurotransmitter released
25
What is the central nervous system made of?
Brain and spinal cord
26
What does the brain do?
- Regulation of body
- Higher thought/memory
- Lower "thought" (reactions, emotions, etc)
27
What does the spinal cord do?
- Passageway between the brain and body
- Coordination of some basic reflexes
- Source of motor neurons
- Destination of sensory nerves
28
What is the cerebrum?
- Outermost neural tissue
- Highest complexity
- Highest thought
29
What is the cerebrum composed of?
- Cerebral cortex
- Hippocampus
- Olfactory bulb
- Basal nuclei
30
What is gray matter made of?
- Cell bodies/dendrites
- Vasculature
31
What is white matter made of?
- Bundles of myelinated axon fibers
- "Tracts" for neural pathways
32
Right hemisphere
- Spatial relationships
- Music, art
- Creativity
33
Left Hemisphere
- Language
- Fine motor control
- Logic
34
Where is the occipital lobe? What does it do?
- Back of the cerebral cortex
- Visual processing cortex
35
Where is the temporal lobe? What does it do?
- Sides of the cerebral cortex
- Hearing
36
Where are the parietal lobes? What does it do?
- Top of the cerebral cortex
- Touch, pressure. heat/cold, pain, body position
37
Where is the frontal cortex?
in the front of the cerebral cortex
38
Primary motor cortex
Voluntary motor control
39
Supplementary motor cortex
Stores motor programs
- "memorized" specific movements
40
Premotor cortex
- Works in conjunction with posterior parietal cortex
- Integration of motor programs with incoming sensory information
41
Limbic association cortex
- Motivation
- Emotion
- Memory
42
Hippocampus
Coverts short-term memory to long term
43
Olfactory bulb
Smell
44
Basal nuclei
- Inhibits unnecessary muscle tone
- Helps maintain posture
45
Thalamus
- "Relay station"
- Coordinates sensory input from output
- Filters out "useless noise"
46
Hypothalamus
Regulation of homeostasis
- Body temp
- Thirst / urine output
- Food intake / appetite
Controls anterior pituitary hormone secretion
Coordinates autonomic NS
Emotional & behavioral patterns
47
Cerebellum
Orb shaped structure located in the back of the brain
48
Vistibulocerebellum
- adjacent to brain stem
- maintains balance
- controls eye movement
49
Spinocerebellum
- located at midline
- coordinates w/ cc motor cortex
- predicts body position
~ makes adjustment
50
Cerebrocerebellum
- majority of cerebellum
- "lower" voluntary action
- some "procedural" memories
51
What is the brainstem made of (3 components) andwhat level of function does it have?
Medulla, pons, midbrain
- lowest / least conmplex function
~ sleep/awake, alertness, basic touch/pressure
~ systems activity
52
Medulla
- swallowing/salvation
- vomiting (chemoreceptor trigger zone)
- respiration
- blood pressure
- heart rate
53
Pons
- Changes in respiratory rate, blood pressure
- Analgesic system, sleep
54
Midbrain
motivation
55
What is the spinal cord continuous with?
the brainstem
56
What is the spinal cord made of?
White & gray matter
Meninges
Cerebrospinal fluid
57
Lateral grat matter horns
cell bodies of autonomic (involuntary) efferent neurons
58
Ventral / anterior gray matter horns
Cell bodies of somatic (voluntary) efferent neurons
59
Dorsal/posterior gray matter horns
- cell bodies of interneurons
- receive signal from afferent / sensory neurons
60
Withdrawl (spinal reflex)
withdrawing body part from the pain source
61
Stretch (spinal reflex)
contracting SKM to counteract stretch
62
Crossed extensor (spinal reflex)
shifts load from injured limb to another
63
Peripheral nervous system
Nerves carrying info between CNS and body
64
Sensory neurons - afferent division
- detect specific conditions in body tissues
- alerts central nervous system
65
Motor neurons - efferent
- Begins in CNS
- Terminate on target tissues
66
Somatic division
voluntary
67
Autonomic division
involuntary
68
Order of spinal nerves (top --\> bottom)
cervical \> thoracic \> lumbar \> sacral \> coccygeal
69
Receptor / dendrite
- receptor near dendrite tips
- receptor part of dendrite tips
- affect axon hillock potential
70
Axon
- connects to dendrites
- carries signal to CNS (via action potential)
71
Cell body
- axon "offshoot"
- Skeps depolarization during action potential
- groups located in same place
~ dorsal root ganglia
72
What do sensory neuron receptors respond to?
changes in SPECIFIC sources of energy
73
Photoreceptors
light
74
mechanoreceptors
stretch/bending
75
thermoreceptors
heat/cold
76
osmoreceptors
ECF molarity
77
Chemoreceptors
detect certain chemicals
- taste/smell , O2/CO2 in blood, nutrients in GI tract
78
Nociceptors
pain
79
What is intensity of sensation determined by?
action potential amount
80
Frequency code =
frequency of action potentials
81
Population code =
number of simultaneous action potentials
82
Receptor adaptation
Become less/non-responsive to stimuli
- often due to "over-stimulation"
83
Tonic receptors
- NO adaptation / gradual adaptation
- Example: muscle stretch receptors
84
Phasic receptors
Rapidly adapt
- "off response"
- cease firing when stimuli strength becomes constant
- example: odor, touch, temperature
85
Efferent division (PNS)
Autonomic nervous system
- involuntary
86
Sympathetic
- fight or flight
87
Parasympathetic
- rest and digest
- feed and breed
88
Somatic nervous system
- Voluntary
- Innervates skeletal muscle
89
Sympathetic fibers
Short preganglionic neurons
- originate in middle spinal cord
- neurotransmitter = acetylcholine (Ach)
90
Long postganglionic neurons
From ganglion to target
- allow coverage in greater area
- neurotransmitter = norepinephrine (NE)
91
Sympathetic tone
^ HR
constricts blood vessels to GI tract and skin
dilates blood vessels to heart & skeletal muscle
dilates lung bronchioles / stops mucus
slows activity of gall bladder, bladder, and GI tract
^ sweat & saliva
^ adrenaline/NE, v digestive hormones
Increased brain alertness
92
sympathetic immediate needs
Life or death
Fight or flight
Short term, high-input task
93
Parasympathetic tone
Slower HR
No effects on blood vessels
Constricts bronchioles/increases mucous production in lungs
Increases activity of GI tract and digestive organs
Gallbladder and bladder emptying
Stimulation/potentiation of many digestive enzymes and hormones
Readjusts pupil "near" vision
94
Longer-term parasympathetic needs
Food digestion/ nutrient level
Fertility/ reproduction
Recuperation
"Resetting" from major sympathetic event
95
Properties of muscle
Excitability
Contractility
Stretchability
Elasticity
96
Excitability
Change in function in response to stimulation
97
Contractility
Intentionally shorten length
98
Stretchability
can be lengthened w/out damage
99
Elasticity
Recoil from stretch to "resting" length
100
Skeletal muscle hyperplasia
Tissue growth via new cell formation
SKM hyperplasia is completed early
- before birth for most mammals
- early neonatal for some litter bearers
101
Skeletal muscle hypertrophy
Tissue growth via existing cell growth
Hypertrophy is postnatal mechanism for SKM growth
102
What do hyperplasia and hypertrophy both require?
Myoblasts
103
What are myoblasts?
Skeletal muscle stem cells
104
What 2 functions must myoblasts perform?
1. Differentiate into specific cell type(s)
2. Self-renew
105
Pre-natal hyperplasia
1. myoblasts proliferate
2a. Most myoblasts differentiate into myocytes
2b. Some are "moth-balled" into satellite cells
3. Differentiated myocytes fuse to form myotubes
4. Myotubes mature to form functional muscle fibers
106
Post-natal hypertrophy
1. *Quiescent satellite cells are activated* into myoblasts
2. Myoblasts proliferate
3a. Most myoblasts differentiate into myocytes
4. Differentiated myocytes fuse *w/ existing fibers*
107
Myofibril
Make up majority of the fiber
Functional unit of myofibers
Contain dark and light straining bands
108
Sarcomere
Repetitive contractile unit of myofibril
Z-line to z-line
109
Thick filaments
**_Myosin_** polymer chains
* run length of A-band
* H-zone = strictly thick filament
* Anchored by m-line
110
Thin filaments
**_Actin_** polymer chains
* make up I band (hang over into A-band a little bit)
* Anchored by stabilizing proteins at the z-line
111
What binds to thin filament?
myosin head
112
myosin neck purpose
hinge
113
Myosin tail
filament core
114
Titin
anchor protein
115
Actin
myosin attachment site
116
Tropomyosin
covers/exposes actin binding site
117
actinin
anchor protein
118
Sliding filament theory
Acting & myosin interdigitate at sarcomeres
* Myosin head (thick fil.) binds actin (thin fil.)
* Myosin undergoes conformational change
* Physically fulls think fil. toward center of thick ful.
* Power stroke
* Ca mediated
119
How do sarcomeres shorten?
Simultaneously (decreased overall fiber length)
120
Sliding filament theory steps
1. Binding of myosin to actin
2. Power stroke
3. Rigor (myosin in low-energy form
4. Unbinding of myosin and actin
5. Cocking of the myosin head
121
What is muscle contraction facilitated by?
Calcium
Upstream neuron → action potential
122
How does calcium get into the muscle?
Travels down the t tubule
123
Where is the AP carried to?
The sarcoplasmic reticulum
→ major Ca dumping from blind pouches
123
Where is the AP carried to?
The sarcoplasmic reticulum
→ major Ca dumping from blind pouches
124
Skeletal muscle contraction mechanism
1. Ca influx → outside cell & SR
2. Ca binds to troponin
* Conformational change moves tropomyosin
* Uncovers actin's myosin binding site.
3. Myosin binds to actin
* ADP+Po keeps myosin head in “cocked” position
* Binding to actin: pi dissassociates
* Power stroke ensues (myosin neck hinges)
4. Myosin and actin disengage
* Myosin binds another ATP, causing disengagement
* ATP → ADP+Pi recocked myosin head
* Ready to repeat
125
What keeps the thin filaments from sliding back once myosin disengages?
Staggered action
126
Relaxation
1. Calcium re-sequestered → Ca-ATPase pump: pumps back into SR out of cell
2. Troponin reverts to original conformation
3. Myosin remains in cocked position (no binding site0
127
Glycolysis
2 ATP / glucose
Short term energy needs
No oxygen needed (anaerobic)
128
Oxidative phosphorylation
36 ATP per glucose
Long term-energy needs
Requires oxygen (aerobic)
* stores O2 in muscle cell
* Increases O2 extraction from blood
129
Energy sources
1. ATP - very little “extra”
2. Creatine phosphate
* “Holds” PO4 for ADP
* Phosphocreatine + ADP = ATP
* No oxygen needed
130
Fatigue
Acute Muscle fatigue
* ATP and/or CP depletion
131
Neuromuscular fatigue (chronic)
Lag in Ach production/ release
132
Type I fibers
red, slow oxidative
* slower, less powerful contraction
* Maintained longer
* High oxidative phosphorylation
133
Type IIa fibers
red, fast oxidative-glycolytic
* Medium-powered contraction
* Intermediate oxid. phos. vs. anaerobic glycolysis
134
Type IIx fibers
White, fast glycolytic
* Fast, powerful contraction
* Easy to fatigue
* High anaerobic glycolysis
135
What are cardiac muscle cells?
Cardiomyocytes
136
How do cardiac muscle cells compare to SKM?
Smaller & shorter than myocytes
Mono or binucliated
137
How to t tubules in cardiac muscle compare to SKM?
Shorter, broader
138
Intercalated discs
(cardiac muscle)
Specialized cellular junctions
139
Cardiac muscle - involuntary contraction
Autorhythmic pacemaker cells
Spread through gap junctions
140
Smooth muscle
single cells
* more thick filaments, myosin heads than SKM
* More myosin binding sites on actin
* No troponin
* Intermediate filaments → connect thin/thick networks, adds elasticity
141
Smooth muscle contraction steps
1. Ca enters the cell
2. Ca activates **_calmodulim_**
3. Calmodulin activates **_myosin light chain kinase_**
4. MyLHK phosphorylates MyLCs
5. Phospho-MyLCs allow myosin to uncurl
6. Uncurled myosin binds to actin
142
Endocrine system
Hormones → chemical messengers transported in circulation
143
Endocrine glands
* produce and secrete hormones
* Responsive to stimulus and/or inhibition
144
Hormone receptors
* Expressed by target cells only
* Allow tissue-specific responses to hormones
145
Hydrophilic
Amine hormones
* Amino derived
* Adrenaline, thyroid hormone
146
Peptide hormones
Short peptide chains
Oxytocin
147
Protein hormones
Large globular proteins
Insulin, growth hormone
148
Lipophilic
Steroid hormones
* cholesterol-derived
* Testosterone, estrogen, cortisol
Eicosanoid hormones
* Fatty acid-derived
* Prostaglandins, thromboxanes, lipoxins, leukotrienes
149
Hormone signaling
Circulate in blood
* Lipophilic hormones → transported by carrier proteins
* Hydrophilic hormones → dissolved in plasma (or carrier protein)
150
Cellular Signaling
Hydrophilic → membrane receptors / 2nd messenger systems
Lipophilic hormones → nuclear receptors/hormone response elements (HREs) on DNA , membrane receptors also
151
Hypothalamus
Brain center for homeostasis
* Makes hormones that regulate other hormones
* Makes hormones secreted by posterior pituitary
* oxytocin - uterine contracts, maternal behavior
* Vasopressin (ADH) - water balance
151
Hypothalamus
Brain center for homeostasis
* Makes hormones that regulate other hormones
* Makes hormones secreted by posterior pituitary
* oxytocin - uterine contracts, maternal behavior
* Vasopressin (ADH) - water balance
152
Anterior pituitary (epithelial)
“tropic hormones”
* Somatotrope - GH
* Thyrotrope - TSH
* Corticotrope - ACTH
* Gonadotrope - FSH / LH
* Lactotrope - prolactin
153
Target glands
Produce hormones with specific actions
* regulation of activities requiring DURATION rather than SPEED
* Associated with a single (or few) specific activities or functions
154
Examples of target glands
Thyroid/ parathyroid glands
Adrenal glands
Gonads (testes/ ovary)
Mammary glands
Liver, muscle, fat
155
Where is the thyroid located?
Around the trachea, below larynx
156
What is thyroid made of?
Follicles - clusters of secretory epith. cells
157
What does the thyroid use?
accounts for 99% of iodine usage
158
What is the thyroid stimulated by?
TSH from ant. pit.
159
What is thyroid product?
T3 and T4 (thyroxine)
160
What does the thyroid control?
Biol. effect: basal metabolism, body heat
161
Where is the adrenal gland?
Marble sized glands (2) sitting atop of each kidney
162
Adrenal gland medulla
Modified nerve endings
* secretes norepinephrine & epinephrin (adrenaline) into blood
* Acute stress responses, fight or flight
163
What is the adrenal cortex stimulated by?
ACTH from anterior pituitary
164
What are the adrenal cortex products?
1. Cortisol
2. Aldosterone
165
Adrenal gland biol. effect
1. changes metabolism in response to stress “anti-stress / anti-inflammation”
2. regulates mineral balance
166
What are the 2 types of gonads?
Ovaries in female, testes in males
167
What do gonads produce?
Haploid germ cells for reproduction
168
What are gonads stimulated by?
Gonadotropins from ant. pit.
* Follicle-stimulating hormone (FSH)
* Luteinizing hormone (LH)
169
Gonads products
Testosterone, estrogen, progesterone
170
Gonads biol. effect
Spermatogenesis, folliculogenesis, uterine quiescence, secondary sex (gender) characteristics
171
Liver, muscle, fat
Not traditional endocrine glands, but secrete hormones
172
What are muscle, liver, fat stimulated by?
Growth hormone
Other growth promoters/ inhibitors
173
Liver product
Insulin-like growth factors (IGFs)
174
Muscle product
IGFs, myostatin, etc
175
Fat product
leptin
176
Liver, muscle, fat biol. effect
IGFs promote tissue growth, cell proliferation
Myostatin inhibits growth
Leptin inhibits hunger
177
Pineal gland
Melatonin → regulates circadian rhythm
178
Thyroid
Calcitonin → stimulates production of bone
179
Parathyroid
Parathyroid hormone
→ stimulates breakdown of bone when blood Ca is low
→ stimulates activation of vitamin D by kidney
180
Liver
Angiotensin
→ stimulates vasoconstriction
→ stimulates release of aldosterone from adrenal cortex
181
Duodenum
Secretin & cholecystokinin
Stimulates
* biocarb & bile from liver
* Digestive enzymes from pancreas
* Gastric emptying
182
Stomach
Ghrelin, neuropeptide Y (NPY)
→ stimulate hunger
183
Kidney
Renin → activates angiotensin I
Erythropoietin → stimulates the production of RBCs
Somatostatin → Inhibits release of insulin, digestive enzymes from pancreas
184
Pancreas
Insulin → uptake & metabolism of glucose, especially by muscle + uptake & storage of FFA by fat cells
Glucagon → inhibition of glucose uptake + stimulates glucogenesis by liver
185
Where are non-coding RNA's produced
via transcritption
186
What is special about non-coding RNAs
Don't code for proteins … but affect those that do
187
What do non-coding RNAs regulate?
mRNA lifespan and mRNA translation rates
188
RNA slicing steps
1. Base sequence creates double strand with hairpin loop
2. Enzymatic processing
3. RISC binds mRNA w/ compl. sequence
4. Disables target mRNA
* Destroys it via cleavage
* Prevents ribosomal attachment
189
How much of mRNA's are regulated by microRNA's?
~ 60%
190
What is major structure in testes?
Seminiferous tubules
191
What happens in the testes?
* Site of spermatogenesis
192
What are Sertoli cells?
Tight-junctioned cells
* harbor developing sperm
193
Testes interstitial tissue
* Surround tubules
* Contain Leydig cells → produce testosterone
194
Epididymis
Common collection area for tubules
195
Spermatocytogenesis
Mitotic cellular reproduction
* multiple rounds
* Few spermatogonia become many
* Stop after G2 (2 x 2n)
196
Meiosis
One (2 x 2n) → Four (1 x 1n) spermatocytes
197
Meiosis 1
Crossing over occurs btwn chromosome pairs
1 cell w/ 2 pairs → 2 cells w/ 1 chromosome
4 immature spermatids
198
Spermiogenesis
Morphological transformation (differentiation)
Immature spermatid → mature spermatozoa
199
Ovary Medulla
Inner
Dense connective tissue
→ blood supply, nerves, lymphatic
200
Ovary cortex
Outer
Follicle (cell aggregate)
* 1 oocyte (femal gamete)
201
Granulosa cells
Produce estrogen
Interact w/ oocyte
202
Theca cells
Support granulosa
203
Stroma
Soft connective tissue
Supports follicles
204
Follicular phase
Primordial \> primary \> secondary \> early antral \> large antral
205
Ovulation
release of a mature egg from the female ovary
206
Luteal phase
**luteinizing hormone and follicle-stimulating hormone levels decrease**. The ruptured follicle closes after releasing the egg and forms a corpus luteum, which produces progesterone. During most of this phase, the estrogen level is high.
207
Oogenesis steps
Meiosis 1
Meiosis 2
208
Meiosis I
Begins prenatally
* crossing over
Arrested before splitting
Resumes after puberty
* 2 x 2n nucleus → 2 x 1n nucleus + 2 x 1n polar body
209
Meiosis 2
Just after ovulation
* 2 x 1n nucleus → 1 x 1n nucleus + 1 x 1n polar body
