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PHGY216 > Module 2 > Flashcards

Module 2 Flashcards

CNS

1
Q

How do the CNS and PNS work together

A
  • Afferent division of PNS carried sensory infor from the pheriphery o the CNS where it is processes
  • The CNS sends instructions from the efferent division
  • the efferent division is then broken down into somatic and autonomic system
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2
Q

How is the nervous system divided

A

Divided between the CNS, brain and spinal cord, and the PNS, the rest of the body, somatic and autonomic system

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3
Q

What are the 3 types of neuronal cells

A

AFFERENT NEURONS
* lie within the PNS
* Send information to the CNS
* Pheripheral ending as a sensory receptor
* in response to the proper triggering event it generates action potential down the afferent fiber to the nerv cell body
* Cell body does not have dendries as it is connected to the sensor

INTRANEURONS
* 99% of all neurons in the body
* These are only in the CNS
* The connector neurons that lie between the dufferent types of neurons create circuits for integrating responses
* Part of learning, decision making, Their role is not fully understood

EFFERENT NEURONS
* cell body Lie within the CNS where they recieve converging presynpaic inputs
* Initiate action potentials, it travels down the efferent fiber to the effector organ
* Mainly outside the CNS - the response organs are

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4
Q

Non neuronal cells of the nervous system what are they

A

GILAL CELLS
* Use the chemical signals to communicate with otehr gilal cells and neurons
* form the CT of the brain
* Do not use action potenbtials
* They maintain homeostatic control the ECE around the neurons
* Most numerous cell in the body
* 50% of total brain volume

OLIGODENDROCYTES
* Cells that produce myelination for the CNS

EPENDYMAL CELLS
* Line the different lobes and ventricles of the brain
* They are cillated
* produce CSF
* Keep fluid flowing through the central canal

ASTROCYTE
* Form the primary CT that house proper spatial relationships between neurons
* repair brain and spinal cord injuries
* halt neurotransmitter activity
* enhance synpase formation and modify synaptic trabsmission
* Take up excess K to maintain ECE for neurons
* They raise the k levels in ECE, either increase membrane potential pr bring it closer to threshold

MIRCROGILIA
several dendrite like branches
support neuron and otehr gilal cells
Secrete nerve growth factor

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5
Q

What is activated microgillia

A
  • When they sense any damage, they migrate towards the area and perform phagocytosis
  • Due to the blood brain barrier they cannot be replaced outside of the CNS
  • In the activated form they can divide
  • They can also release cytotoxic chemicals
  • Many diseases are related to this hypersecretion, stroke, dimentia, microgillia can actually destroy neurons
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6
Q

How the CNS protect itself

A
  • Bone - Physical damage
  • Protective membranes - there are 3 of them
  • Cerebrospinal fluid
  • Blood brain barrier
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7
Q

Explain how the bone protects the CNS

A
  • Skull and vertebrae
  • skull completely surrounds the brain
  • Vertebrae surrounds the spinal cord
  • Hard physical barriers against damage
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8
Q

Explain the 3 protective membranes in the CNS

A

DURA MATER
* The outermost membrane
* tough double membrane that lines the bone
* some sections it created fluid filled spaces called dural sinuese
* Venous vlood and CSF can drain into these spaces

ARACHNOID MATTER
* Middle membrane
* far more delicate than the dura matter
* highly vascularized in the dural sinuses, create projections called arachnoid granuluations, They have Villi
* Transfer CSF between the spaces

PIA MATER
Innermost membrane
tightly adheres to the surface of brain and spinal cord
dips deeper into the brain
brings blood supply to ependymal cells linning the ventricles

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9
Q

What is cerebrospinal fluid and what does it do

A
  • Shock absorber
  • Similar to brain tissue itself
  • In the subarachnoid space - between pia matter and arachnoid matter
  • essential for transfer of materials between the blood and nural tissues
  • The brains ECF that supplies neurons and gilal cells are not in direct contact with the CSF or blood stream. However, they are able to alter its composition.
  • CSF has stronger influence than the blood

Choroid plexus create the CSF
* Highly vascularized masses of piam atter that dip into pockets of ependyma cells and create the CSF
* This can be found in each of the 4 ventricles
* CSF is 125-150ml that is replaced 3x a day

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10
Q

What is the blood brain barrier

A
  • Exchange of materials between capillaries and intersititial spaces
  • does not occur in the brain
  • endotheulial cells of brain capillaires are joined by tight junctions to prevent materials from passing through
  • exchange of materials between blood and brain is highly regulated
  • Must pass through endothelial cells and is therefore highly regulated
  • Sudden changes in blood plasma composition will not influence composition of the brains intersitial fluid and affect neuronal functions
  • Circumventricular organs lack blood brain barrier such as endocrine glands
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11
Q

What is the spinal cord

A
  • Long tube of neurons and support cells
  • extends from brainstem through a hole in the skull to the lumbar region
  • Highway of blow of information between the brain and body
  • Independently control reflexes
  • Encapsulated control reflexes
  • Adaddional physical protections by the vertebra
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12
Q

Descrube the cross section of the spinal cord

A
  • Butterfly pattern all along
  • Made of gray and white matter

GRAY MATTER
* Nerv cell bodies
* SHort intraneurons
* gilal cells
* contains a canal fileld with CSF
* Each part of gray matter is divided into regions called horns
* / - dorsal horn, cell bodies of intraneyrons on which afferent neurons terminate
* | - lateral horn, cell bodies of autonomic efferent nerve fibers
* \ - Ventral horn, cell bodies of somatic efferent neurons

WHITE MATTER
* Bunds of nerve fibers or axons
* Each bundle is connected to a specific region of the brain to transmit information from the brain to pheriphery
* The ascending tracts or afferent neurons are named for their point of origin and termination

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13
Q

Overview Afferent and efferent connections

A
  • Efferent cell bodies are in the ventral horns
  • Lateral horn contains cell bodies for autonomic efferent fibers
  • Afferent nevres are located outside of the spinal cord in a region called the dorsal root ganglia
  • Dorsal root ganglia connected to the spinal cord in 2 ways. The dorsal root with the afferent nevres and the ventral root containing the efferent output
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14
Q

Briefly descirbe the structure of a nerve

A
  • Bundle of peripheral afferent and efferent axons covered in CT that are following the same pathways
  • Axons share common pathways and do not communicate with each other from the myelination
  • Nerves do not contain the cell bodies of the neurons. They are found in the ganglia or the CNS
  • A single nerve contains several nerve fasicles which are bundles of myelinated or unmyelinated axonal connected tissues
  • as well as blood vessels
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15
Q

What is the structure of the spinal cord

A
  • Spinal nerves project from the between the vertebrae. These are named according to the regions they innervate
  • 1-7 = cervical
  • 1-12 = thoracic
  • 1-5 = lumbar
  • 1-5 = sacral
  • 1 - end = coocygeal nerve
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16
Q

Functions of the spinal cord

A
  • Connections between the brain and the rest of the body
  • Conduit for transmitting unformation between the brain and periphery
  • Integrate afferent inouts and efferent outputs which bypass the brain itself
  • These are called spinal reflexes. Can be simple or acquired
  • SImple - born with such as pulling away from soemthing hot
  • Acquired - swimming or riding a bike
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17
Q

Describe the proccesses in the reflex arc

A
  • > Neuron pathway for reflexes
  • Knwon as the reflex arc
  • Made of 5 components
  • Receptor in the skin - receptor sense physical or chemical change in the environment and produces an action potential
  • afferent neuron - action potential is transmitted from the receptor to the integrating center
  • Interneuron - Integrating center generally within the CNS - simple reflex arc are genrally integrated in the spinal cord or brainstem. Acquired reflexes are processed in higher brain centers. Once the signal is processes. A response is initiated
  • Efferent neurons - Response transmitted from the CNS
  • Effector - muscle - Target of the efferent pathwau and is a muscle or gland. Required to carry the desired response
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18
Q

What is the pathway of the withdrawl reflex

A
  • Touching a hot stove activates thermal pain receptor in finger
  • Action potentials generated by afferent neurons propagate impulses to the spinal cord
  • Afferent fibers in the spinal cord stim excitatory intraneurson to act on motor neurons to act on bicep muscle
  • Inhibitory intraneurons act on the neurons f the triceps
  • Interneurons that ascend to the brain
  • once efferent pathway stimulated contraction of the bicep muscles. Another efferent pathway leads to relaxation of the tricept muscles
  • Effectos are stimed and allow the withdrawal of the hand
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19
Q

Give a basic overview of the brain stem

A
  • Consists of the muedulla oblongata (lowest part), pons (bridge), and midbrain - top part
  • vitaline between spine and higher brain functions
  • all comms pass through this
  • Some nerves do pass through the brainstem
  • But most and synapsese within the brainstem for further processing
20
Q

What are the functions of the Brainstem

A

HOUSING CRANIAL NERVES
* most cranial nerves start at the brainstem
* Supply sensory and motor fibers in the head and neck
* Control hearing, eye movement, facial sensation, taste, and movement of face, neck, shoulder, and tongue muscles

VEGETATIVE FUNCTIONS
* Cardiovascular
* respiratory
* digestive
* Detects Co2 and O2 levels in the blood and determines what changes are needed
* Low O2 stims greater Respiratory function

POSTURE REFLEX
* ability to maintain the body upright
* Provide stable background
* Bus moves forward, we move word to counteract the force
* maintenance of good postire and normal allignment

RETICULAR ACTIVATING SYSTEM
* formation is the network of interconnted neurons which run throughout thje brain stem and up into the hypothalamus
* Monitors sensory inputs
* Acts as a filter for sensor input that is consciously percieved
* ORiginate from the reticular formation which pass this elected information to the cortex
* Fibers decending from the cortex can also activate the RAS

EEP
* Nruons in brain produce neurotransmitters that act on various parts of the brain that control whether we are asleep or awake
* Balance between These sleep promoting beurtransmitters determmines whether an individual is experiencing wakefullness or is sleeping
* GABA is the major inhibitory neurtransmitter in the bodty and is therefore heavily present during eep

21
Q

What are the roles of the hypothalamus

A
  • Production and secretion of pituitary hormones
  • Sleep-wake cycle
  • Autonomic nervou system coordinating center
  • Controls uterine contractions and milk ejection
  • Controls fluid intakes
  • Influences urine output and thirst
  • Involved in emotion and behaviour
  • COntrols body temperature
22
Q

What does the thalamus do

A
  • Deep within the brain
  • Inetrgating center for sensory input
  • Conducts preliminary processing in that it can remove lesser signals and ensure stronger more important impulses are sent to the appropriate cortical areas
  • The thalamus can also amplify or increase the importance for signals of specific interest
23
Q

What does the Hypothalamus do

A
  • Integrates sensory information
  • This is the center for homeostatic function
  • Serves as a link between the autonomic nervous system and the endocrine system
24
Q

What is the structure of the cerebral cortex

A
  • COmposed of gray matter
  • Divided into left and right hemispheres that are connected to the corpus callosum
  • Consists of 6 well defined layesrs
  • each composed of different cell types
  • Though consired independnt the layers are highly connected to form cortical microciruits
25
Q
A
26
Q

What are the lobes of the cerebral cortex

A

Frontal lobe - Locate at the front of the head and is responsible for voluntary motor activity, speech, and thought

Parietal lobe - Located between the frontal and occpital lobe
* Primary responsible for reciving and processing sensory inputs

Occipitial lobe - Located just above the cerebellum
* back of the head
* does initial processing for vision

Temporal lobe - Located on the side of the head and is involved in vision and hearing

27
Q

What happens in the parietal lobe

A
  • Somatosenation
  • Receives info on physcial sensation
  • Pheripheral nervous system transmits
  • Somaesthetic sensation to the somatosensory cortex
  • Located at the most anterior region of the parietal lobes
  • Initial input as well as proicocetive input
  • Goes to higher sensory areas for further processing
  • Analysis and interpretory of sensory input

Somatosensory cortex
* Recieves somatosynthetic and proiceptive inputs frpm specific areas of the body
* Not every part of the body is equally represented in the somatosensory cortex. Look at the figure.

28
Q

what does the frontal lobe do

A
  • Contains primary motor cortex which is located beside the somatosensory cortex of the pareital lobes
  • Seperated by the central culcus
  • This area contains large pyrimidal neurons that send axons down the spinal cord and synpases with the alpha motor
  • The primary motor cortex works in conjunction with premotor cortex
  • Located a fewmm anterior to the primary motor cortex
  • Not ever Motor neuron is equally represented like the somatosensory cortex. The premotor cortex and primary motor cortex are not the only parts involved in motor control
29
Q

What does the Cerebellum do

A
  • Integrates motor and sensory control
  • Does play a role in voluntary initiation of movement
  • contains the most neurons in the brain
30
Q

The cerebellum is divided into 3 parts, Vestibulocerebellum, spinocerebellum, cerebrocerebellum. What do they do

A

VESTIBULOCEREBELLUM
* Small green section in the middle of the structure
* Important for balance and spatial orientation and controls eye movemnt

SPINOCEREBULLUM
* Regulates voluntary movements
* Reaching for an object - the spinocerebellum is constantly recieving vision inputs as well as spatial location of your arm and hand to allow complex movements to be smooth and precise

CEREBROCEREBELLUM
* Recieves all of its inputs from the cerebral cortex
* involved in planning of voluntary movements as well as the evaluation of sensory information

31
Q

What is the basal ganglia

A
  • Consists of several masses of gray and white matter
  • Associated with a variety of functions including
  • Motor control
  • cognition
  • emotions
  • learning

Divided into 4 sections
Caudate nucleus - located near the middle of the brain near the corpus callosum
Putamen - some orange shit next to the hypothalamus
Globus pallidus - another blob of orange shit
Claustrum - a longer string of the orange shit in the samilar location

  • It is highly connected to all brain regions
  • Thalamus involved in positively reinfocing voluntary movbemnts initiated by the cortex
  • Can exert inhibitory effects on the thalamus
  • Influence brainstem to inhibit motor activity
32
Q

WHat are the functions of the basal ganglia

A
  • Inhibit muscle tone throughout the body - regulated by excitatory and inhibitory inputs. Adjusting one or the otehr allows for precise movements
  • Permits purposeful motor activity while supressing unwanted movements
  • Helping monitor and coordinate sustained contractions such as those related to posture
33
Q

WHat is the limbic system

A
  • Not a specific structure but many interconnected regions
  • Includes lobes of the cerebral cortex, basal ganglia, thalamus and the hypothalamus
  • Involved in emotions
  • behaviour and motivation and learning
34
Q

How does the limbic system have to do with emotions

A
  • Various feelings and moods
  • Includes behaviopural patterns
  • Emotional responses vary greatly between individuals
  • One person can be terrifed of snaked and one person mioght not be
  • So complex not well understood
    *
35
Q

How does the limbic system have to do with behaviour

A
  • Includes sexual behavior
  • Two major structures involved with this
  • Hypothalamus
  • Plays a role becasue it governs involuntary internal responses in preparation for the appropriate action
  • When angry, hypothalamus can increase heart rate and repsiratory rate and increase blood pressure
  • Shunt blood to skeletal muscle in preparation to fight

Cortex
* Neural mechanism for regulating skeletal muscle responses
* Higher cortical areas can also modify or reinforce supress behaviopural responses to permit more refined responses based on analysis of the current situation

36
Q

How does the limbic system have to do with motivation

A
  • This is the behvaiour towards specific goals
  • Some behaviours are homeostatic in nature. If you are thristy the kidneys are signalled to conserve water and initiate the thirs response. Up to the CNS - you if you want to do that or not
  • Brain reward circuit
  • Behaviours that are proven gratfifying with result in repeat actions
  • Actions that yield the opposite effect will initiate the opposite response
  • SOme individuals are motivated by punishment centers if it will lead to a long term reward
37
Q

Give the brief overview on learning

A
  • Acquisition of reinfocing knowledge or skills
  • Major influence on learning is punishment and reinfocement. Both rewards can be positive or negative
  • Experiemntatoon showed that when an animal was rewarded for its behaviour it was likely to do it again
38
Q

Posiitve and negative reinforcement

A
  • Punishment - Decreasing behaviour
  • Reinforcement - Increasing behaviour
  • Positive punishment - adding something to decrease behaviour
  • Negative punishment - subtracting something to decreases behaviour
  • Positive reinforcement - adding something to increase behaviour
  • Negative reinforcement - removing something to increase behaviour
39
Q

What is memory

A
  • Storage of acquired knowledge
  • Forms the basis that elts individuals change behaviour
  • Neural changes occur during learning that are stored in memory traces
  • They can be complex and are reinforced through learning such as memorization
  • A memory trace is not a single neuron but a pattern of signals trabsmitted across a vast synapse memory
40
Q

How does the acquistion of memory work

A
  • newly acquired memory is stored in the short term memory
  • This has limited capacity
  • Has 2 fates - forgotten, or transffered to long term storage throigh prac and rehearsal
  • The more likely info is recycled into short term memory the more likely it is to be transfferd to long term memory which has large capacity
41
Q

what is short term memory

A
  • Remain availble from 30 seconds to several days
  • Majority of short term memories will be forgotten and will be effetcively pushed out of the brain to make way for new facts and short term memories
42
Q

what is long term memory

A
  • Events or experiences or facts that were learned weeks or months or years ago
  • Recall of knowledge happens at different rates
  • Memories involving information or skill used frequently such as writing are never forgotten and always accessible
  • less frequently accessed memories are long term and slower to recall
43
Q

How are memory traces stored

A
  • No one memory storage center
  • Neurons involved in memory traces are widespread
  • Spread across the following 3 regions
    HIPPOCAMPUS
  • Vital in short term memory
  • Important for consolidation and initial storage of long term memories
  • hippocampus seems to play a role in declartive memories
  • “what memores” of specific people, palces and facts

CEREBELLUM
* Plays a role in “how to” procedural memories
* Involving motor skills gained through repetitive training. These memories can be recalled without conscious effort

PRE-FRONTAL CORTEX
* Compex reasoning skills
* associated with working memory
* responsible for execution of cuntions involving integration for planning, juggling priorites, problem solving and organizing activities

44
Q

How do we learn from aplysia

A
  • These snails have small amount of brain
  • They are simple.
  • There are 2 forms of memories.
  • habituation
  • sensitization
45
Q

What is habituation

A
  • Decreased responsiveness to an indifferent stimulus that does not punish nor reward
  • Alpysia can withdraw their gill. If you touch it and does nothing eventually they will stop reacting because the stimulus is nor harmful
46
Q

What is Sensitization

A
  • Increased responsiveness to mild stimuli that occur following as strong or noxious stimulus
  • The syphon is struch hard, s subsequent gentle touch will withdrawl the gill.

PHGY216 (6 decks)

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