Bio- Organisation Of Nervous System 2

Front 1

CNS divisions

Back 1

brain and spinal cord

Front 2

PNS divisions

Back 2

motor neurones, sensory neurones,, somatic nervous system, autonomic nervous system, sympathetic division parasympathetic division

Front 3

autonomic vs somatic nervous systems

Back 3

somatic- Consists of spinal and cranial nerves connected to skeletal muscles and skin receptors. These enable us to feel changes we can control
Autonomic

Consists of cranial nerves connected to non-skeletal muscles and glands. These nerves control functions that control breathing heartbeat and organ functions: things we cannot control

Front 4

how does the ANS operate

Back 4

via reflex arcs

Front 5

what is white matter made of

Back 5

axons with myelin sheaths

Front 6

gray matter is made out of

Back 6

axons without mylein sheaths

Front 7

brain reflex centre

Back 7

medulla oblangata

Front 8

somatic nervous system

Back 8

has pre and post ganlion neurones
ganglions release acetyle choline or adrenaline to inhibit or excite responses

Front 9

what are the 2 types of autonomic ganglia

Back 9

sympathetic trunk ganglia and ganglia prevertebral ganglia

Front 10

how many preganglionic cell bodies are there in the nuclei of cranial nerves

Back 10

4

Front 11

to maintain homeostasis the nervous system must be....

Back 11

capable of detecting change or stimuli

Front 12

what carries out specialised cells carry out detection

Back 12

sensory neurones called receptors

Front 13

in most effector organs what is the response cased by ?

Back 13

neurotransmitter

Front 14

congenital analgesia

Back 14

Children with this condition often suffer oral cavity damage or fractures to bones. Unnoticed infections and corneal damage are also seen.
Because the child cannot feel pain, they may not respond to problems, thus being at a higher risk of more severe diseases
There are some cases where the condition is caused by increased production of endorphins, in which case naloxone may be used as treatment. This treatment does not always work.
In some cases, this disorder can be in the voltage gated-sodium channel. Patients with such mutations are congenitally insensitive to pain and lack other neuropathies.

Front 15

what is sensation

Back 15

– conscious or subconscious detection of external or internal stimuli

Front 16

what part of the brain is reposnible for conscious thought

Back 16

cerebral cortex
lower brain stem

Front 17

what is perception

Back 17

– conscious awareness and interpretation of sensations

Front 18

what area is responsible for perception

Back 18

cerebral cortex

Front 19

how many sensory neurons carry information for to a modality

Back 19

1

Front 20

how many sensory receptors respond to one kind of stimulus e.g hearing

Back 20

1

Front 21

somatic senses

Back 21

– tactile (touch, pressure, vibration)
– thermal (warm and cold)
– pain
– proprioception (moving, nonmoving, limb
position)

Front 22

visceral

Back 22

– conditions within internal organs by ANS

Front 23

Sense Organs

Back 23

-Sense organs enable awareness of conditions or events in the internal or external environment
-The stimuli or the sensations are detected by special sensory cells called receptors, generating impulses.
-Sensory neurons relay this information about the stimulus to the CNS = interpretation, integration & perception
-Motor neurons relay the CNS command to relevant effector organs where a response occurs.

Front 24

process of sensation

Back 24

1. Stimulation of sensory receptor (specialised cell or dendrites of sensory neurone) selectivity
• must occur within receptive field

2. Transduction of stimulus
• transduce = convert energy in a stimulus to a graded potential

3. Generation of impulses
• when graded potential reaches threshold
• triggers action potential/s toward CNS

4. Integration of sensory input
• occurs in cerebral cortex

Front 25

sensory receptors classification

Back 25

1.The first order sensory neurons are in the dorsal root ganglia or the sensory ganglia of cranial nerves.
2. The second order sensory neurons are in the dorsal gray column or various sensory nuclei of the brainstem.
3. The third order sensory neurons are in the thalamic nuclei.

EXAMPLE:

Typically, the perception of pain travels through three orders of neurons. The first-order neurons carry signals from the periphery to the spinal cord; the second-order neurons relay this information from the spinal cord to the thalamus; and the third-order neurons transmit the information from the thalamus to the primary sensory cortex, where the information is processed, resulting in the "feeling" of pain.
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.

Front 26

microscopic structure of nerve

Back 26

1.free nerve endings of first order sensory neurones (e.g. Pain & temperature)
2.encapsulated nerve endings of first order sensory neurones (Pacinian corpuscles for touch)
3.Separate cells that synapse with first order sensory neurones (hair cells, gustatory receptor cells, photoreceptors)

Front 27

what graded potentials do sensory receptors produce

Back 27

generated potentials
receptor

Front 28

what is a generator potential

Back 28

A generator potential is a graded response to a stimulus and if it becomes large enough it produces an action potential. These generator potentials "add" together which is called summation and allows an action potential to fire.

Front 29

what is an action potential

Back 29

An action potential is not graded and is all or nothing. Also an action potential travels along a nerve fibre where as a generator potential does not it is localised change is the concentration of charges

Front 30

what are exteroreceptors

Back 30

sensory receptor located near or at body surface. provide info about external environment e.g 5 senses and pain, pressure

Front 31

interoreceptors

Back 31

sensory receptors in blood vessels and visceral organs, nervous system. they provide info on internal environment

Front 32

what are proprioreceptors

Back 32

they are sensory receptors in the muscles tendons joints and inner ear and they provide info on body position and motion joints and balance

Front 33

what is the function of mechanoreceptors

Back 33

they detect deformation of adjacent cells and provide sensations for touch pressure hearing, bp, stretching

Front 34

thermoreceptors

Back 34

change in temp

Front 35

nocireceptors

Back 35

respond to stimuli resulting from physical or chemical damage to tissue

Front 36

photoreceptors

Back 36

detect light that strikes retina

Front 37

chemoreceptors

Back 37

detects chemicals in mouth taste, smell and body fluids

Front 38

osmoreceptors

Back 38

sense osmotic pressure of body fluids

Front 39

Adaptation in Sensory Receptors

Back 39

Generator or receptor potential decreases in amplitude during a maintained constant stimulus
frequency of nerve impulses in first-order neuron decreases
perception of sensation may fade or disappear even though stimulus persists
receptors vary in how quickly they adapt

Front 40

what are rapidly adapting receptors

Back 40

phasic e.g touch

Front 41

slowly adapting receptors

Back 41

tonic- temperatures

Front 42

what is somatic sensation

Back 42

Stimulation of sensory receptors in skin or subcutaneous layer, mucous membranes, tendons, muscles

Front 43

somatic sensation

Back 43

Front 44

phantom limb

Back 44

After amputation may still experience itching, pressure or pain
Severed endings of sensory axons are still present
If activated the cerebral cortex interprets the sensation as coming from sensory receptors in the phantom limb
Area of cerebral cortex undergoes extensive functional reorganisation to respond to stimuli from other body parts
Gives rise to false sensory perception

Front 45

Somatic sensory pathways

Back 45

Relay information from the somatic sensory receptors to the primary somatosensory area in the cerebral cortex
The pathways are made of thousands of sets of 3 neurones
First order neurones: conduct impulses from the somatic receptors into the brain (via cranial or spinal nerves)
Second order neurones: conduct impulses from the brain stem & spinal cord to the thalamus. Axons decussate here
Third order neurones: conduct impulses from the thalamus to the primary somatosensory area of the cortex

Front 46

what are regions in the CNS where neurones synapse are called

Back 46

relay station

Front 47

where do neurones of many sensory pathways synapse ?

Back 47

in the thalamus, spinal cord & brain stem (they are all relay stations)

Front 48

Somatic sensory impulses ascend the cerebral cortex via 3 pathways which are ?

Back 48

-Posterior column-medial lemniscus pathway
-Anterolateral (spinothalamic) pathway
-Trigeminothalamic pathway

Front 49

Posterior column-medial lemniscus pathway

Back 49

is the sensory pathway responsible for transmitting fine touch, vibration and conscious proprioceptive information from the body to the cerebral cortex;[1] as well as tactile pressure, barognosis, graphesthesia, stereognosis, recognition of texture, kinesthesia and two-point discrimination.[2]

The name comes from the two structures that the sensation travels up: the posterior (or dorsal) columns of the spinal cord, and the medial lemniscus in the brainstem.

Front 50

posterior column pathway

Back 50

1st order neurones extend from sensory receptors into spinal cord & ascend to the medulla oblongata
Cell bodies are in the posterior (dorsal) root ganglia
Their axons form the posterior column
Synapse with 2nd order neurone in medulla
Axons cross to opposite side & enter medial lemniscus

Front 51

spinothalamic tract

Back 51

The spinothalamic tract is a sensory pathway originating in the spinal cord.
t transmits information to the thalamus about pain, temperature, itch and crude touch.
The pathway decussates at the level of the spinal cord, rather than in the brainstem like the posterior column-medial lemniscus pathway and corticospinal tract.

Front 52

posterior column pathway

Back 52

Front 53

anterolateral pathway

Back 53

Front 54

Wallenberg syndrome

Back 54

Lateral medullary syndrome (also called Wallenberg syndrome) is a disease in which the patient has a constellation of neurologic symptoms
characterised by sensory deficits affecting the trunk (torso) and extremities on the opposite side of the infarction and sensory deficits affecting the face and cranial nerves on the same side with the infarct.
Specifically, there is a loss of pain and temperature sensation on the contralateral (opposite) side of the body and ipsilateral (same) side of the face.

Front 55

syphilis

Back 55

Caused by Treponema pallidum.
If left untreated progresses to tertiary stage: debilitating neurological problems
Degeneration of posterior portions of spinal column
Somatic sensations are lost, the persons gait becomes jerky as impulses fail to reach the cerebellum

Front 56

Olfactory receptors

Back 56

Recognise about 10 000 different odours
Nose contains 10 million to 100 million receptors for the sense of smell in the olfactory epithelium
olfactory epithelium consists of olfactory receptors, supporting cells and basal cells

Front 57

Olfactory epithelium

Back 57

Supporting cells: columnar epithelial of mucous membrane lining the nose
Physical support, nourishment, electrical insulation, detoxification
Basal cells: stem cells. Olfactory receptors live for 1 month (they are neurones, which tend not to be replaced)

Front 58

Odour thresholds and adaptations

Back 58

low threshold
Eg methyly mercaptan 1/25billionth of a mg/ml
Adaptation (decreasing sensitivity) occurs rapidly- about 50% in the first second

Front 59

asomnia

Back 59

inability to detect odors

Front 60

hyposmia

Back 60

- Decreased ability to detect odours

Front 61

parosmia

Back 61

Altered perception of smell in the presence of an odour, usually unpleasant

Front 62

phantosmia

Back 62

perception of smell without ordour present

Front 63

Agnosia

Back 63

Inability to classify or contrast odours, although able to detect odours