PSIO 201 test #4 Flashcards
1
Q
- Nucleus (nuclei)
- Ganglion (ganglia)
- Tract
- Nerve
A
- Nucleus is a cluster of neuronal cell bodies in the CNS
- Ganglion is a cluster of neuronal cell bodies in the PNS
- Tract is a bundle of axons in the CNS
- Nerve is a bundle of axons in the PNS
2
Q
Hypothalamus
A
- Located inferior to the thalamus
- contains 12 nuclei in 4 major regions
- controls and integrates the ANS and pituitary gland-> controls homeostasis
- the link between nervous system and endocrine system
3
Q
Hypothalamus Functions
A
- regulates body temp, eating and drinking behavior, other bio drives
- main control center for visceral functions
- receives info from cerebrum and from brain stem and spinal cord
- regulates emotions- pain, pleasure, aggression
- regulates diurnal rhythms with help from pineal gland (melatonin)
4
Q
Epithalamus
A
- Located superior and posterior to the thalamus
- pineal gland (melatonin)- contributes to setting the bio clock
- habenular nuclei- emotional responses to odors
5
Q
Cerebellum
A
- Receives input from proprioceptors in muscles and tendons about movement; sends signals to motor cortex to improve and coordinate movements
- receives input from visual and equilibrium receptors and sends input to motor cortex to aid in regulating posture and balance.
6
Q
Pons
A
- Bridge between medulla oblongata, cerebellum and higher brain centers in the cerebral cortex
- pontine nuclei- gray matter centers connecting the cerebral cortex and cerebellum-> coordinate voluntary motor output
- Contains Apneustic Area (controls depth of breath) and Pneumotaxic area (controls rate of breathing)
7
Q
Medulla Oblongata
A
- connects brain to spinal cord
- involves tracts that ascend (sensory) to or descend (motor) from the brain; axons cross over from one side to the other of the brain stem
- contains the cardiovascular center- control heart rate, force, and BP
- control respiratory rhythm
- controls swallowing, coughing, sneezing, vomiting
8
Q
Midbrain (mesencephalon)
A
- located between pons and the diencephalon
- contains superior colliculi (reflex to visual stimuli)
- contains inferior colliculi (reflex to auditory stimuli)
9
Q
Midbrain
A
- contains nuclei called substantia nigra (releases dopamine)
- red nucleus helps voluntary movement of the limbs
10
Q
Limbic System
A
- encircles upper part of the brain stem and the corpus callosum
- functional system compose of parts of cerebral cortex, diencephalon, and midbrain
- called the emotional brain
11
Q
Spinal Meninges
A
Dura Mater is not attached to bony vertebral column- creates epidural space (anesthesia) where CSF flows
12
Q
Internal anatomy of spinal cord (gray matter)
A
- posterior horns: cell bodies of somatic and visceral sensory neurons
- gray commisure: connects posterior horns
- anterior horns: cell bodies of somatic motor neurons
- lateral horns: cell bodies of visceral motor neurons; found only in thoracic lumbar and sacral regions of spinal cord
- posterior columns: sensory tracts (ascending)
- lateral columns: motor and sensory tracts
- anterior columns: motor tracts (descending)
- anterior white commisure: connects white matter on the left and right side of SC
13
Q
Input and Output to spinal cord
A
- dorsal root of spinal nerve: carries sensory info
- dorsal root ganglion: cluster of sensory cell bodies outside the CNS
- ventral root: carries motor info from the anterior portion of the cord
- spinal nerves: joining of dorsal and ventral roots; only 2 cm long; mixed nerves. 31 pairs of spinal nerves exit sc
14
Q
Components of Reflex Arc
A
- sensory receptor
- sensory neuron
- integrating center (may or may not include an interneuron)
- motor neuron
- effector
15
Q
classification of relfexes
A
- monosyaptic vs polysynaptic
- somatic vs visceral
- cranial vs spinal
- ipsilateral vs contralateral
16
Q
Pathways of four reflex arcs
A
1) stretch reflex
2) tendon reflex
3) flexor reflex
4) crossed extensor reflex
- > all are somatic and spinal
17
Q
stretch reflex
A
- to prevent injury from over-stretching a muscle
- contracts muscle that was streched
- stretch sensed by muscle spindle
- monosyn, ipsilateral, spinal, somatic reflex
18
Q
tendon relfex
A
- prevent damage from too much tension in a muscle
- inhibits the muscle that is contracting
- tension sensed by golgi tendon organ
- polysyn, ipsi, spinal, somatic reflex
19
Q
Flexor reflex
A
- protectt body part from further injury
- flexes affected limb
- pain sensed by nociceptors
- polysyn, ipsi, spinal, somatic relfex
20
Q
crossed extensor reflex
A
- purpose to stabilize body position after painful stimulus causes flexion of opposite limb
- usually paired with flexor reflex
- extends opposite limb
- pain sensed by nociceptors
- ploysyn, contralateram spina, somatic
21
Q
The Autonomic Nervous System
A
- operates without conscious control
- operates via reflex arcs
- controlled by centers in the hypothalamus and brain stem
- output is two efferent neurons exit CNS
- first efferent neuron (preganglionic neuron) exits spinal cord and synapses with another efferent neuron in a ganglion (postganglionic neuron)
22
Q
Sympathetic Division of ANS
A
Fight or Flight
Goal to increase mental awareness, increase energy availability (break down fuels), redistributions of blood flow, decrease urinary and digestive functions, increase heart rate and BP, dilation of pupils, increase sweat glands, increase diameter of bronchioles
23
Q
Parasympathetic Division ANS
A
Rest and Digest
- 80% of PSNS information carried by Vagus (X)
- preganglionic neurons found in ganglia at pons or medulla (ciliary, pterygopalatine, submandibular, otic)
- info carried by cranial nerves III, VII, IX, X
- SLUD (salivation, lacrimation, urination, defecation)
24
Q
Location of Sympathetic Ganglia
A
- Sympathetic trunk (chain) ganglia- paired ganglia near spinal cord, postganglionic neuron innervates visceral organs in thoracic cavity
- prevertabral (collateral) ganglia - unpaired ganglia anterior to vertebral bodies whose postganglionic neurons innervate abdominopelvic organs
- Adrenal Medulla- acts as modified sympathetic ganglion, postganglionic neurons are short and release norepinephrine and epinephrine (80%) into the blood stream
25
Neurotransmitters of sympathetic division of ANS
- preganglionic neurons release ACh
| - postganglionic neurons release NE except at sweat glands (ACh)
26
Norepinephrine (NE)
- Neurotransmitter when released from sympathetic nerve endings directly a target tissues (short lived effects)
- hormone when released from adrenal gland into blood stream (longer lasting effects)
* Epinephrine is always a hormone
27
Sympathetic Division repeptors
- Cholinergic receptors-> bind ACh (Muscarinic receptors and Nicotinic receptors)
- Adrenergic receptors->bind NE and Epinephrine (alpha (bladder and arterioles) and beta (heart, bronchioles, liver) adrenergic receptors)
28
Cholinergic receptors
respond to Acetylcholine
1. Nicotinic receptors- found in symNS and PsymNS cell bodies and dendrites of postganglionic neurons (within ganglion)- can only generate excitatory post-synaptic potentials
2 Muscarinic receptors - found in target tissues- can generate excitatory post-synaptic potentials and inhibitory post-synaptic potentials
29
Syncope
Syncope=fainting=vasovagal reaction
- transient loss of consciousness due to insufficient cerebral perfusion from hypotension because of failure of ANS to maintain blood pressure
- can be avoided by laying down supinely and elevating feet
30
Resting membrane potential
-chemical force (K+ gradient) pushes K+ out
-electrical force (negative inside) pulls K+ in
two forces equal at rest
31
Resting membrane potential
- K+ leak channels present in ALL cells
- Na,K-ATPase developps and maintaisn steady-state ion gradients for all cells
- pumping creates ionic gradient for K+, K+ leaks out (down its concentration gradient) and the inside of the cell becomes more negaive, and two forces develop
- typical potential difference is -50 to -100 mV
32
Regulated ion channels
1. chemically (ligand)-gated channels- open when signal molecule binds to channel protein (e.g., ACh)
2. Mechanically-gated channels- open when membrane gets stretched
3. voltage-gated channels- open when the membrane potential gets less negaive (depolarized)
* there are other ways to regulate channels
33
Neuronal Action Potential
A. Neurons are excitable cells- channge mebrane potential to generate electrical signal
B. principla mechanism- voltage-gated Na+ channel
34
Events of generating Action Potential
1. local change in membrane potential (depolarizing or hyperpolarizing), action potential begins w/ local depolarization
2. depolarization to a threshold value induces a population of voltage-gated Na-channels within local region of membrane to open (positive feedback cycle)
3. critical point: shortly after Na-channels open-> they spontaneously close ('inactivation' which helps with repolarization)
4. depolarization also opens (more slowly) a second population of voltage-gated K+ channels (helps with repolarization)
35
Importance of Refractory Periods
1. establish maximum rate of Action Potentials
| 2. Influence the characteristics of AP propagation- forward propagation from axon hillock to axon terminal
36
Graded potentials
Arise mainly in dendrites and cell body
37
Propagation of the Action Potential
1. Entry of Na+ produces 'local current' (spreads laterally to depolarize adjacent areas of membrane)- if adjacent membrane area is depolarized to threshold it starts a new cycle of action potential
2. entry of Na+ in the new region of membrane produces a local curret that spreads to adjacent areas
38
Velocity of Propagation
Two factors:
1. Size (diameter of axon)- bigger is faster
2. Myelination- faster with myelination
39
Demyelination
Multiple Sclerosis (central NS)
Guillan-Barre (peripheral NS)
- disruption of myelin sheath slows or blocks conduction
40
Synaptic Transmission
```
electrical signal (Action potential) from one excitable cell to another through a graded potential in the synapse. Can by EPSP or IPSP
-signals from many pre-synaptic neurons add up at trigger zone
```
41
Gustation
TASTE
42
Sensory Transduction
1. Stimulus arrives at receptor and alters membrane potential of receptor ('graded potential', depolarizing or hyperpolarizing)
2. Receptor potential influences rate of AP production in a sensory neuron
3. APs travel to CNS along afferent pathway
4. CNS interprets/processes these incoming signals
43
Olfaction
- G protein-coupled olfactory receptor activated by oderant
- G protein uses ATP to create cAMP, which opens Na+ channel
- the Na+ depolarizes cell and causes action potential
44
Tongue parts
Vallate papilla- has many taste buds
| Filiform papilla- gives roughness to tongue
45
Accomodation
change the lens shape by lessening tension on lens created by ciliary muscle which makes the lens more round, which bends the light more
46
Presbyopia
after aging, lens loses elasticity. Lens doesn't round and cannot focus on nearby objects
47
Rods
~125 million in periphery of retina
- very sensitive to light
- permit sensation of movement
- large receptor field
- made of 1000 discs, each disc containing rhodopsin (opsin and retinal), the light receptor
48
Cones
~6 million center of retina
- macula lutea has no rods, all cones
- fovea-> smallest receptive field
- less sensitive to light
- can discriminate between different wavelengths
- COLOR VISION
49
Rod Phototransduction
1. light photon activates rhodopsin
2. this activates an enzyme that breaks down cyclic GMP (cGMP)
3. cGMP-gated Na+ channels close
4. The rod hyperpolarizes
5. glutamate release is reduced
50
External Ear
- auricle
- external auditory canal
- eardrum (tympanic membrane)
51
Middle Ear
- Auditory ossicles (malleus, incus, and stapes on oval window)
- auditory tube
52
Internal ear
- Semicircular ducts (equilibrium and balance)-> has crista which is bundle of hair cells and Ampulla which hold fluid that moves crista cell
- Saccule and Utricle (gravity and acceleration)
- Cochlea (hearing)
53
Hearing: structural issues
1. sound wave arrives at tympanic membrane
2. vibration moves auditory ossicles
3. stapes depresses oval window, generates pressure wave in cochlear ducts
4. pressure wave distorts basilar membrane (different regions by different wavelengths)
5. Vibration of basilar membrane excites overlying hair cells- produces receptor potentials
54
Stereocilia
Hair Cells- common receptor for hearing and balance/equilibrium
-mechanically-gated channels in stereocilia membrane open-> cations (K+) enter (depolarization) -> receptor potential
55
Summary of auditory transduction
1. vibration of basilar membrane at different places depending on pitch
2. movement of stereocilia on hair cells
3. opening of mechanically gated channels
4. movement of K+ into hair cells causes depolarization
5. Depolarization causes opening of Ca2+ channels at base of hair cell
6. Ca2+ triggers exocytosis of neurotransmitter and depolarization of underlying sensory neurons in VIII nerve
56
Thalamus
- relay station for sensory and motor info
- crude interpretation of touch, temp, pain, pressure
- forms walls of 3rd ventricle
- organized into 7 groups of nuclei
