Physiology Midterm Flashcards
1
Q
What Nervous system are sensory receptors in? What do they respond to? What do they produce? Where does this product go?
A
PNS
Respons to stimuli
they produce graded potential that trigger AP along afferent nerve fibres.
Eventually the signal goes to the cortex
2
Q
How are sensory receptors classified?
A
Type of stimulus
location within body
complexity of the structure
3
Q
What are 5 types of stimulus?
A
Mechanoreceptors thermoreceptors photoreceptors chemoreceptors nociceptors
4
Q
What are the classifications of sensory recetora based on location?
A
exteroceptors
interoceptors
proprioceptors
5
Q
What are the classification based on complexity
A
simple and complex
6
Q
What are simple receptors involved in?
How can simple receptors be divided?
A
touch, pressure, vibration, temperature, pain, proprioception
Free (unencapsulated dendritic endings) & encapsulated dendritic endings
7
Q
What are examples of free dendritic endings?
A
Tactile (Merkel cells)
Hair follicle receptors
8
Q
What are 6 encapsulated dendritic endings?
A
Tactile (Meissner's corpuscle) lamellar (pacinian) corpuscle Bulbous (ruffini's endings) corpuscle Muscle spindles Golgi tendon organs joint receptors
9
Q
What are complex one?
A
sense organs for special senses (vision, smell, etc)
10
Q
What is the somatosensory system?
A
Part of the sensory system serving body walls and limbs. receives input from exteroceptors, interoceptors and proprioceptors.
11
Q
What are the 3 levels of organization within the sensory system?
A
Receptor level
Circuit Level
Perceptual Level
12
Q
What happens at the receptor level?
A
sensory receptors are specialized to respond to specific stimuli when in the receptive field. In response to stimuli a receptor potential is generated and then an AP.
Transduction, occurs which transforms a stimulus into an electrical response. The graded potential spreads to nodes of renvier (voltage gated channels) and AP is produced
13
Q
What is transduction?
A
Transduction is when a stimulus is transformed into an electrical response
14
Q
Which receptors adapt rapidly?
Slowly?
continuous?
A
Meissners/ Pacinicans
Merkel dics/ Ruffini’s endings
pain receptors and proprioceptors (non adapting)
15
Q
What do 1st, 2nd and 3rd oder neurons do?
A
1st: cell bodies=located in ganglia (dorsal or cranial) conduct impulses from sensory receptors to spinal cord/brain stem with 2nd order.
2nd: cell bodies reside in dorsal horn of s.c or medullar nuclei. Transmit to thalamus/cerebellum
3rd: located in thalamus conduct impusles to somatosensory cortex in cerebrum. No 3rd neurons in cerebellum
16
Q
What are the 3 ascending pathways? where found, termination and 1st synapse?
A
Spinothalamic: lateral and anterior spinothalamic tracts. Crosses over at the level of the spinal cord. Transmits pain, temperature, corse touch.
Dorsal Column Medial Lemniscal: formed by fasiculus cunatus and gracilis (dorsal white column) and medial lemniscal tracts. Synapses in medulla. Fine touch and conscious proprioception
Spinocerebellar tracts: anterior and posterior spinocerebllar tracts. Subconcious information to cerebellum. coordinates muscle activity
17
Q
What is the pons?
A
the bridge between cortex and cerebellum. Inferior to midbrain, and forms anterior wall of 4th ventricle. Axons carry info to and from cerebellum
18
Q
Where is the medulla ablongata?
What is it responsible for?
A
from pons to spinal cord. Has a role in the autonomic reflex centre for homeostasis. This includes the cardiovascular system, which controls cardiac and vasomotor centres It also includes the respiratory centre which controls the rate and depth of breathing. Some functions overlap with the hypothalamus which exerts control over most visceral functions by relaying instructions through medulla to effectors.
19
Q
What is the decussation of pyramids? Where is it located?
A
The medulla, and it is where the motor neurons cross over
20
Q
Where is the inferior olivary? what does it do?
A
It is located in the medulla and it relays proprioceptive information to the cerebellum
21
Q
Where is the cerebellum? what is it involved with?
A
located dorsal to the pons and medulla. It protrudes under the occipital lobes of the cerebral hemispheres.
It processes inputs from cerebral cortex, brain stem nuclei and sensory receptors. It is involved with timing and patterns of skeletal muscle contraction
22
Q
What are cerebellae peduncles?
A
3 paired fibre tracts that connect the cerebellum to the brain stem
23
Q
What are the 3 peduncles?
A
Superior: connects the cerebellum and midbrain. The fibers start in the deep cerebellar nuclei and project to the cerebral motor cortex through the thalamus
Middle: connects pons and cerebellum. It is a one way communication fromn the pons to cerebellar neurons. It informs the cerebellum of voluntary motor activities initiated by the motor cortex
Inferior: connects cerbellum and medulla. It contains afferent tracts. Carries sensory information to cerebellum from muscle proprioceptos and vestibular nuclei of the brain. It is involved in equilibrium and balance
24
Q
What happens in cerebral processing?
A
the cortex frontal motor association area indicates intent to initiate action and sends collateral to cerebellum to notify of intention.
-receives proprioceptive information and visual information and equilibrium pathways about body positioning. The cortex then receives information and determines the best way to coordinate force, direction and extent of muscle contraction. Through superior peduncles the cerebellum dispatches blueprints for coordination to the cortex. The output goes to brain stem nuclei which send to the motor neurons of the spinal cord.
25
What 4 structures protect the brain?
bones
meninges
cerebrospinal fluid
blood brain barrier
26
What do the meninges consist of and what do they do?
three connective tissue membranes that
- cover and protect the CNS
- Protect blood vessels and enclose venous sinuses
- Contain CSF
- Form partitions within the skull
27
What is dura mater?
a thick, tough layer that surround the brain. it has 2 layers, the periosteal and the meningeal. Spinal cord only has meningeal
Around the brain these layers are fused except where there is enclose of dural venous sinuses. (where drainage of CFS and blood occurs)
The dura septa anchors the brain in spots and separates different regions
28
What is arachnoid mater?
The loose covering separated by the dura by the subdura space.
29
What is the subarachnoid space? Where is it and what it used for?
The subarachnoid space is between the archnoid mater and the pia mater. It is filled with CSF and contains the largest blood vessels that are serving the brain. The arachnoid villi direct the CSF into the dural sinuses.
30
What is pia mater?
a thin delicate connective tissue and tiny blood vessels that cling tightly to the brain and follows the convolutions
31
What is CSF?
a liquid cushion that gives buoyancy to the delicate CNS tissue. Has protective, nutrient role. Similar to plasma with fewer proteins. Produced by choroid plexuses.
32
What are choroid plexuses?
clusters of permeable capillaries enclosed by ependymal cells. Forms CSF which then flows through ventricles. It transports CSF to sinuses and transport tubes and drains the blood out through the jugular vein,.
33
Explain process of CFS?
1. choroid plexus of each ventricle produced CSF
2. CSF flows through ventricles and into subarachnoid space via median/lateral apertures
3. CFS flows through subarachnoid space
4. CSF if absorbed into the dural venous sinuses via the arachnoid villi
34
What is the blood brain barrier?
A protective mechanism that helps maintain a stable environment for the brain
35
What is the blood brain barrier produced by?
1. continuous epithelium of capilary wall sealed by tight junctions
2. thick basil lamina that surrounds the external face of the capillary
3. bulbous feet of astrocytes
36
What is allowed to pass through the blood brain barrier?
glucose, essential amino acids, some electrolytes, fats, fatty acids, oxygen, carbon dioxide, and fat soluble molecules.
37
Where is the blood brain barrier permeable?
```
the hypothalamus (near the vomiting centre)
The capillaries are porous but ependymal cells are linked by tight junctions
```
38
Where is the spinal cord?
the foramen magnum to L1 or L2.
39
What is the end of the spinal cord?
The conus medullaris
40
What are 3 ways the spinal cord is important?
1. It is a 2 way conduction system
2. major reflex centre
3. Associated with 31 pairs of spinal nerves
41
What are cervical and lumbar enlargements used for?
Nerves to supply the upper and lower limbs
42
What 2 things hold the spinal cord in place?
1. Denticulate ligaments: shelves of pia mater along the length of the cord to the bony walls of the vertebral canal
2. filum terminale: fibrous extensions of pia mater inferiorly from the conus medullaris to the posterior surface of the coccyx
43
What is the Cauda Equina?
the lumbar and sacral spinal nerve roots that angel inferiorly for some distance before reaching the exit points
44
Explain about gray matter of the spinal cord?
It is located internal to white mater in the spinal cord. organized like butterfly wings and paired with ventral and dorsal horns connected by gray commisure. Ventral horns contain cell bodies.
45
Where is the dorsal root ganglion?
lateral to the spinal cord and contains cell bodies of sensory neurons.
46
What do axons do from the dorsal root ganglion?
1. Travel to higher spinal cord/brain centres
| 2. synapse with interneurons in the dorsal horns at the level they enter
47
What is a spinal nerve formed by?
The fusion or dorsal and ventral roots
48
What is white mater of the spinal cord?
myelenated and unmyelenated fibred used to communicate between different parts of the spinal cord and between the spinal cord and brain.
49
What are the three directions of white mater fibers in the spinal cord?
Ascending, descending and transverse
50
What are general properties of the spinal tracts?
1. most pathways cross over from one side of the CNS to another (decussate)
2. Most consist of a chain of 2 or three neurons
4. Most exhibit somatotopy: precise spatial relationships that reflects orderly mapping of the body
5. All pathways and tracts are paired. One on each side of the spinal cord or brain
51
What is a tract?
A connection of axons in the CNS
52
What is the general function of cerebral cortex? And what part of the brain is it in?
initiates motor function, localized and interprets sensory stimuli and is involved with intellectual and emotional processing. It is divided into motor, sensory and association areas.
It is in the cerebral hemisphere
53
What is the general function of white matter in the cerebral hemisphere?
Carries information between the cerebral areas and between the cortex and the lower CNS centres. It consists of myelenated Axons
54
What is the basil nuclei of the cerebral hemispheres?
It is involved with starting and stopping movements. It prevents unnecessary movements and consists of groups of cell bodies (nuclei) located at the base of the brain
55
What is the general function of the thalamus and where is it located?
It is involved with sorting and editing sensory informatiom that is going to the cerebral cortex. It is also important for connecting motor and sensory areas.
It is located in the Diencephalon
56
What is the general function of the Hypothalamus? Where is it loacted?
located in the diencephalon
Hypothalamus is the main control centre for the ANS. It also controls body temperature, food intake, thirst, water balance, biological drives and rhythms. It produces hormones and is part of the limbic system (emotional system)
57
What is the general function of the epithalamus and where is it located?
Location= diencephalon
| The epithalamus is involved with sleep wake cycles and the pineal gland produced the hormone melatonin
58
what is the general function of the midbrain and where is it located?
The midbrain is located in the brain stem. It is a conduction pathway from higher to lower centres. It is connected to craneal nerves
59
What is the general function of the pons and where is it located?
The pons is located in the brain stem
It is a bridge that is a conduction centre from higher to lower centres. It is connected to craneal nerves and control of vital functions such as respiration, blood pressure etc
60
What is reticular formation and where is it located?
A functional system located throughout the brainstem. It is involved with cerebral cortical alertness and filters repetitive stimuli. It is involved in some muscle contractions.
61
What is the general function and location of the cerebellum?
It coordinates muscle contractions and receives proprioceptive information as well as motor intentions. It integrates the sensory and motor information to create smooth movement.
62
What are tactile merkel discs cells?
Free endings are enlarged, disc shaped epidermal cells. They lie in the basil layer of the skin epidermis (light touch receptors)
63
What are hair follicle receptors?
Dendritic endings wrapped around hair follicles. They are free and are light touch receptors. Ex; they detect the bending of hair when a mosquito is nearby
64
What is a tactile (meissners) corpuscle?
encapsulated. Found in derman papillae and numerous in sensitive and hairless skin (ex fingertips, soles of feet) These receptors are used for discriminating touch
65
What are lamellar (pacinian) corpuscle?
(encapsulated) Located deep within the dermis and subcutaneous tissue. It is stimulated by deep pressure only when first applied. It is best for monitoring vibration
66
What is bulbous (ruffini's endings) corpuscle?
Located in the dermis, subcutaneous tissue and joint capsules, similar in appearance to Golgi Tendon organs. It responds to deep and continuous pressure in dense CT
67
What are golgi tendon organs?
Propcrioceptors located in the tendons close to muscle insertion. Stimulated when muscles contract and tendons stretches. The activation leads to muscle inhibition and relaxation.
68
What are joint receptors?
Proprioceptos that monitor stretch in articular capsules of synovial joints. They provide info on joint position and motion. They are made of 4 receptor types (Pacinian, rufini, free dendritic endings, GTO-like receptors)
69
What are the subdivisions of the brain?
Cerebral hemisphere
Diencephalon: Thalamus, hypothalmus, epithalmus
Brainstem: Midbrain, pons, medulla
Cerebellum
70
What are ventricles?
Represent space within the brain. They are continuous with one another and with the central cavity of the spinal cord. They are filled with CSF and lined with ependymal cells.
71
How are the 4 ventricles within the brain arranged?
1. Paired lateral ventricles (C shaped): located within the cerebral hemispheres
2. Each lateral ventricle communicates with narrow 3rd ventricle in he diecephalon via interventricular foramen (foramen of monro)
3. 3rd ventricle is continuous with the 4th ventricle (dorsal to pons) via cerebral aqueduct (cerebral aqueduct runs through the mid brain)
4. 4th ventricle is continuous with the central canal or the spinal cord
5. 3 aperatures in the 4th ventricle connectes the ventricles to the subarachnoid space (which surrounds the brain)
72
What is the spinal cord connected to? Where does it start and end? what is the cauda equina?
What are 3 reasons the spinal cord is important?
What is it held in place by?
Medulla, foramen magnus-L1/2 to conus medullaris. The cauda equina are the nerves endings that extend out and down resembling a horses tail.
- 2 way conduction system
- Major reflex centre
- Associated with 31 pairs of nerves
Held in place by:
- denticulate ligaments (pia matter shelves along length of cord)
- filum terminale (extensions of pia matter inferiorly from conus medullaris to surface of coccyx)
73
Where is the gray matter of the spinal cord?
how is it organized?
what is it paired with and connect by?
where are the cell bodies
Internal to the white matter.
like butterfly wings
paired with ventral/dorsal horns. connected by commisure.
Ventral horns contain cell bodies.
nerve cell bodies of ANS exit through ventral roots.
74
Where is the Dorsal Root Ganglion?
What do the axons do?
what is a spinal nerve formed by?
Lateral to the spinal cord and contains cell bodies of sensory neurons
The axons travel to higher spinal cord/brain centres. They also synapse withe interneurons in the dorsal horns at every level they enter.
Spinal nerves are formed by fusion of dorsal/ventral roots.
75
What is spinal cord white matter?
myelenated & unmyelanted fibres used to communicate between different parts of the SC and SC and brain. There are 3 directions of fibres:
ascending, descending and transverse.
76
What are 4 general properties of the SC?
Decussation
chain of 2-3 neurons
exhibits somatotopy
All pathways and tracts are paired on each side of SC
77
What do the cerebral hemisphres consist of?
What is the left hemisphere dominant for?
What is the outter hemisphere dominant for?
gyri, sucli, 5 lobes, 4 grooves, 3 regions
language, maths, logic
visual/spatial skills, intuition, emotion, appreciation or art or music, face recognition, creativity.
78
What are the 5 lobes of the cerebral hemisphere?
```
frontal
parietal
occipital
temporal
insular
```
79
What are the 4 grooves of the cerebral hemisphere?
longitdinal fissure
lateral sulcus
central sulcus
parieto-occipital sulcus
80
What are the regions of the cerebral hemisphere?
| Where are they located?
```
Cortex (superficial grey matter)
white matter (internal)
Basal nuclei (deep grey matter within white matter)
```
81
What are the 4 generalizations of the cerebral cortex?
2 functional areas (motor, sensory, association)
Lateralization
largely symmetrical but not 100% equal in sharing roles
No area of the cortex acts alone, all conscious behaviours involve the cortex.
82
What does the motor area do?
control voluntary movements including regions in the posterior part of frontal lobe
- primary motor cortex
- premotor cortex
- broca's area
- frontal eye field
83
What does the primary motor cortex do? and have?
| Why are smaller areas more dense with neurons?
precentral gyrus of frontal lobe, pyramid cells that allow control of skeletal muscles, the action projects to SC via pyramidal/corticospinal tracts.
Represents body spatially (map of body/somatotopy/homunculus)
For fine motor contorl
84
What does the pre-motor cortex do? where located?
anterior to precentral gyrus
| involved in planning movements, stores learned repetitious motor skills (typing)
85
What is brocas area?
Motor speech area, controlls muscles of larynx, pharynx, and mouth. usually in left hemisphere.
86
What does frontal eye field do?
controls voluntary movement of the eye
87
Where is primary sensory somatosensory coretx? what is it involved with?
post central gyrus of parietal lobe. Receives information from somatic sensory receptors found on the skin and proprioceptors found in joints and muscle.
Neruons involved with awareness of general senses and spatial discrimination and intensity of stimulus
88
Where is the somatosensory association cortex? what is it involved with?
posterior to primary somatosensory cortex but has many connections with it. It is involved in integration/analysis of somatic inputs such as temperature, pressure.
It interprets information with respect to size, texture, relationship of parts based on prior experience.
89
Where is the primary visual cortex? and association area?
PVC: posterior tip of occipital lobe, it is largest cortical sesnory
Association: surrounds PVC and interprets images based on prior experience.
90
where is the primary audio cortex?
| association area?
temporal lobe, sound impulses from receptors
| Association: area of interpretation based on memory (speech, words, music)
91
Where is the oflactory Cortex?
in the medial aspects of the temporal lobes (Uncus)
is involved with conscious awareness of different odurs. surrounds neural tissues and forms limbic systems such as emotions and memory.
92
What are the multimodal Association areas?
Pre-frontal cortex,
Posterior association areas
Limbic Association Areas
93
What happens in the pre frontal cortex?
involved with intellect and complex learning (cognition) as well as personality. It forms abstract ideas, judgement, reasoning, persistence, planning and thinking. Matures more slowly and is dependent on feedback from social environment
94
What happens in the posterior association area?
Helps with bringing different sensory inputs together to make a complete picture. It includes Wernickes area (written and spoken langauge)
95
What happens in the limbic association area?
Part of the limbic system that provides emotional significance to a scene and is involved with memory (hypocampus)
96
What is the gustatory Cortex?
Involved in taste sensation. It is located in the parietal lobe, deep to the temporal lobe
97
What is the vestibular cortex?
Involved in conscious awareness of balance. It is located in the posterior part of inusla which is deep to the temporal lobe
98
What is the white matter of the cortex?
myelinated axons that are bundles into tracts. It is responsible for communication between cerebral areas between the cortex and lower CNS centres. The axons are divided into 3 types
Commisural fibres
Association fibres
Projection fibres
99
What are the 3 groups axons are divided into in the white matter?
1. commissural fibres: connects corresponding areas between 2 hemispheres. The largest group of fibers is the corpus callosum
2. assosication fibres: connections within a hemisphere (connects the gyri and lobes)
3. Projection fibres: goes from cortex to rest of NS. They run vertically
100
What are the 3 parts of the basal nuclei?
1. caudate nucleus
2. putamen
3. Globus pallidus
101
What does the basal nuclei do?
Receives input from the entire cerebral cortex from subcortical nuclei. It sends information to the premotor and prefrontal cortexes to influence muscle movement as directed by the primary motor cortex. Has a role in starting, stopping, monitoring movements that are executed by the cortex. Inhibits against antagonistic/unecessary movement. Disorders lead to too much/little movement (huntingstons, parkinsons)
102
What does the diencephalon consist of?
| Where located?
Thalamus
Hypothalamus
Epithalamus
located centrally and surrounds 3rd ventricle
103
What is the thalamus?
masses of grey matter, 80% of diencephalon, consists of many different nuclei and afferent impules go to the thalamus. It is the post office of the brain. It sorts, edits, and groups impulses together to go to appropriate parts of the brain. it connects the basal nuclei and the cerebellum to the motor cortex areas.
104
What is the epithalamus?
Helps regulate the sleep wake cycle along with the hypothalamus. The pineal gland is part of the hypothalamus
105
What is the hypothalamus and where located?
It is located below the thalamus and is connected to the pituitary gland. It's nuclei maintain homeostasis. It is the main control centre for the NS and emotional centre of the brain. It connects with the nervous system with emotional behaviour
106
What are 7 roles of the hypothalamus?
1. Autonomic control centre: blood pressure, heart function, GI motility, respiration, eye pupil size.
2. Centre for emotional response/behaviour. Connects with corticol associations for perception of pleasure, rage, fear, biological drives,
3. body temperature regulation
4. regulation of food intake. Hunger/ satiety
5. Regulation of water balance/thirst release of direuretic stimulation of thirst
6. regulation of sleep wake cycles, biological clock responding to visual cues.
7. controls the endocrine system, releasing hormones that control pituotary function and nuclei that produce ADH & oxytocin
107
What is the midbrain?
contains 2 groups of cerebral peduncles that are part of corticospinal/ pyramidal tracts that go down to the spinal cord. It has hollow aqueducts that contain CFS that runs through the middle midbrain.
It contains substantia nigra, superior/inferior collliculli
108
What are substantia nigra,
| superior/inferior colliculi?
Substania nigra: produces dopamine and is connected with the basal nuclei
Superior colliculi: are groups of neurons that are involved with visual reflexes
Inferior Colliculi: are part of the auditory relay
109
What are neurotransmitters?
Used to communicate between two neurons or a neuron and an effector. Requires electrical events (graded and AP) they can be excitatory(depolarizing) or inhibitory (hyperpolarizing)
They are classified by structure and function
110
ACh is?
excitatory/inhibitory
111
What neuro transmitters are biogenic amines?
norephenphrine
dopamine
serotonin
Histamine
Which ones are both and which one only inhibitory?
Serotonin is inhibitory the rest are both
112
What NT's are amino acids?
GABA
Glutamate
GLycine
Glutamite is excitatory GABA & Glycine and inhibitory
113
Which NT's are purines?
```
ATP= both
Adenosine= inhibitory
```
114
What NT's are dissolved Gases?
NO
CO
both are excitatory
115
What are the two mechanisms of action when NT's bind to their receptors?
What do they mean?
Direct=binding leads to opening of channels through rapid action (ACh & Amino Acids)
Indirect = the binding of NT that leads to production of 2nd messengers which are longer lasting (biogenic amines and peptides).
They are channel linked for direct action and G-protein linked for indirect action
116
What is the process of Indirect G linked receptors?
1. NT and ligand (1st messenger) bind to activate the receptor
2. The receptor activates the G protein
3. The G protein activates the adenylate cyclase
4. The adenylate cyclase converts ATP to cAMP (2nd messenger)
5. The cAMP changes the membrane permeability to open/close channels or activate enzyme to destroy transmitter.
117
What are neuronal pools?
groups of neurons within the CNS
they are important for integration of information and most consist of thousands of neurons that can be excitatory or inhibitory
The incoming information travelling can be processed in a series of paralell pathways.
Serial processing and parallel processing
118
What is serial processing?
refers to a chain of neurons connected in a straight through matter to a specific destination, Ex; reflex arc
Parallel processing: information travelling along different pathways that run parallel to each other and will process information simultaneously. This information is integrated in different regions of the CNS and allows you to put parts together to understand a bigger picture. Ex; converging/diverging ciruits.
119
What are the functions of the meninges?
to cover/protect the CNS
Protect blood vessels and enclose venous sinuses
Contains CSF
forms partitions with the skull
120
What does the communication between neurons require?
Electrical(graded & AP) & chemical signals (neurotransmitters)
121
Where are signals received?
Dendrites and cell bodies
122
What is potential energy?
Energy associated with separate ions with opposite charges on either side of the plasma membrane
123
What is voltage?
Measures the potential energy between two points, occurring when ions flow across the membrane
124
Electrical Gradient
The difference of charges between the inside and outside of a neuron. Ions always flow to an area of opposite charge
125
Current
The flow of ions once the gate opens
126
Chemical/concentration gradient
The difference in concentration between ions between inside and outside of neuron. The ions flow high-low concentration
127
What are the types of channels?
non gated/leakage: always open
| Gated: a signal is required to open/close gates
128
What are the three types of gated channels?
Chemically: neurotransmitter/hormones
Voltage: change in membrane potential
Mechanical: physical deformation
129
What is resting membrane potential?
The measured Voltage. occurs around -70
When a neuron is not generating graded or action potentials. There is a separation of ions on either side of the plasma membrane.
130
What is voltage?
The electrical potential due to separation of positively charged ions
131
What are the AP produced by?
| what are the two phases?
axon hillock
local currents depolarizing to -55
Depolarization & repolarization
132
What are graded potentials?
short lived signals that weaken with distance. There are produced in dendrites and cell bodies and spread to axon hillock. Produced at receptive regions when NT binds to chemically gated channel
133
What is the absolute refractory period?
| Relative refractor period?
Period when neuron is producing AP and cannot produce another.
Period where strong signals can be produced.
134
What is saltatory conduction?
Skipping parts of membrane due to myelenation at nodes of Ranvier. Makes propogation faster.
135
What increases velocity of propogration?
myelin and diameter of axon
136
What are the 2 types of synapses?
chemical and electrical
137
What is a chemical synapse?
functions by releasing and binding of Nt's. Causes a change in membrane permeability by binding receptors leading to an opening/closing of channel.
138
What are the 3 parts of a chemical synapse?
What are the two mechanisms of communication?
1. axon terminal
2. receptor region
3. synaptic cleft
1. initiation
2. termination
139
What are the steps of initiation?
1. an AP arrived at the axon terminal
2. calcium gates open and calcium enters
3. Nt is released via excocytosis
4. NT diffuses across cleft and binds to postsynaptic membranes
5. ions open in post synaptic membrane
6. the binding of NT results in graded potential
7. Nt effects are terminated
140
What are 3 ways termination can occur?
1. degredation: by enzymes of the postsynaptic membrane. An example would be ACh.
2. Reuptake: By presynaptic terminal
3. Diffusion: neurotransmitter is taken away from the synaptic site
141
What are post synaptic potentials?
Graded potentials that are created by binding of Nt's. there are 2 EPSP's and IPSP's
142
What are EPSP's?
NT's binding to receptors causes opening of channel and depolarization. If strong enough will produce AP at Axon hillock
143
What are IPSP's?
binding of Nt's open channels cause cause hyperpolarization
144
What is summation?
A single EPSP cannot generate an action potential, they must add up to do so this can happen two ways.
Temporal: rapidly firing EPSP's that are close in time.
Spatial: one than 1 neuron fires from different locations.
145
What is a neural integrator?
Since both EPSP's and IPSP's are firing whichever is greatest will dominate. The axon hillock calculates this effect and determines what will happen
146
What is nervous tissue made of?
neuroglia and neurons
147
What are the 4 CNS neuroglia?
Astrocytes: stay shaped, abundant, anchor neurons to capillaries (blood brain barrier) role in nutrient exchange and controling neural environment
Microglia: protective cells, can remove debris and turn into macrophages
Ependmyal cells: ciliated cells line cavities of the brain and spinal cord. Fluid bathing and help circulate CSF
Oligodendroytes: provide myelin sheaths.
148
What are the 2 glial cells of the PNS?
Satellite; similar to astocytes
| Schwann cells: similar to oligodendrocytes
149
What does the nervous system do?
master controller and communicating system of the body. The cells communicate through electrical/chemical signals. Three functions are
sensory input, motor output and integration
150
What is somatic NS? & Autonomic?
voluntary, moves info from CNS to skeletal muscles
| Involuntary signals are sent from CNS to cardiac smooth muscles and glands
151
What are special features of neurons?
Extreme longevity
amitotic
high metabolic rate
152
What are the regions of a neuron?
| What is another name for cell body?
Cell body
One or more processes
Soma/perikaryon
153
What are collections of cell bodies in CNS and PNS called?
```
CNS= nucleus
PNS= ganglion
```
154
What is the most common type of processes in the body?
Least and where is it located?
Where are unipolar ones found?
multipolar (2nd/3rd order)
bipolar- special organs, retina etc
ganglia of PNS 1st order neurons
155
Where are the pyramid shaped cells that project to the spinal cord as the pyrimidal/corticspinal tracts?
The primary motor cortex
156
What are the 4 motor areas?
primary motor cortex
Pre motor corex
brocas area
frontal eye field
157
Where are the sensory areas located?
parietal, temporal, and occipital lobes
158
Where are the motor areas located?
the posterior part of the frontal lobe
159
What are the 9 sensory areas of the cerebral hemisphere?
```
Primary sensory somatosensory cortex
somatosensory association cortex
Primary visual cortex
Visual Association areas
Primary audio cortex
Auditory association area
oflactory cortex
```
160
What are 3 of the multimodal association areas
```
Any area corticol area that is not primary.
Example:
Pre frontal cortex
posterior association area
limbic association area
```
161
What does the reticular formation do?
| Where is it located?
The reticular formation is found in the brainstem, at the center of an area of the brainstem
Helps maintain consciousness and regulates arousal
162
what is the decussation of pyramids and where is it located?
The medulla and it is the area that neurons cross over to the otherside
