The NERVOUS SYSTEM Flashcards
master all mntanami
what makes up the CNS
The spinal cord and the brain
what makes up the peripheral nervous system
nerves
what are neurons and how do they function
cells responsible for nervous system signaling
they are specialized for communication.
what are dendrites
be able to identify these Mnumzana
cytoplasmic extensions of the body
they receive information from other neurons and receptors
define an axon and its function
tube of the cell membrane
enclosed with the myelin sheath
it transmits Action Potential away from the cell body
what is the function of Schwann cells
to create fatty myelin sheath in PNS
produce myelin
what are oligodendrocytes
myelinating cells in the CNS
demyelination definition
loss of myelin sheath in the axons
caused by neurodegenerative autoimmune diseases
diseases caused by demyelination of the axons
multiple sclerosis
Guillain Barre Syndrome
Acute encephalomyelitis
what is multiple sclerosis
an autoimmune disease that involves the loss of oligodendrocytes
the immune system attacks the nervous system leading to demyelination
disrupts the CNS from communicating
how is Ms diagnosed?
based on signs and symptoms
supporting imaging and laboratory testing
(neuroimaging is used– which is the analysis of the cerebrospinal fluid and action potentials)
during MS diagnosis using neuroimaging, what is the cerebrospinal fluid tested for
the cerebrospinal fluid is tested for Oligoclonal bands of IgG on electrophoresis( which are inflammation markers found in 75% to 85% of people with MS)
what are the 3 stages of information processing?
- Input( sensory input) gathering of information
- Integration- processing of information
- Motor output- response to the information transmitted
what are the 2 cells that make up the nervous system
neurons(20% of the nervous system)
A-N-D
glia cells
what are the 3 types of neurons
- sensory( afferent) neurons
- Interneurons- connect neurons to specific regions of the CNS
- motor ( efferent) neurons
What are the 4 types of Glia cells
- Microglia
- Astrocytes
- Oligodendrocytes and Schwann cells
- Ependymal cells
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HE MUST REMEMBER TO REMAIN DISCIPLINED AND BE CONSI
BE ABLE TO IDENTIFY ALL GLIA CELLS IN A DIAGRAM
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what are glia cells?
glia means glue, and hence these cells can be understood to support the structure of the nervous system
maintain homeostasis
do not generate impulses
neurons initiate action potentials
what is ACTION POTENTIAL?
transient (only lasting for a short time) alteration of the transmembrane voltage across an excitable membrane in an excitable cell
Generated by the activity of voltage-gated ion channels embedded in the membrane.
definition of the resting/membrane potential
the difference in charge between the cell’s membrane and extracellular fluid when the cell is not electrically charged.
it results from ionic gradients
what is the function of the sodium/potassium pump
prevents leaking of ions and also prevents the cell gradients from running down.
the resting potential of neurons is -70mV. the pump maintains this PUMP.
what happens if the resting potential of -70mV changes?
a neuron is triggered to fire and send electrical impulses.
there are two types of ion channels. What are these?
active channels
passive channels
what are graded potentials?
short-lived depolarizations or hyperpolarizations of the membrane
can only act as signals over short distances
what is the difference between action potentials and graded potentials?
basically,
the sum of graded potentials that are enough to reach the triggering threshold is called ACTION POTENTIALS
it is only an action potential if it is greater than the threshold potential
explain what happens during hyperpolarization
membrane potential becomes negative(the cytoplasm/ inside of the membrane) becomes negative
K+ open and increase permeability to K+
hyperpolarization occurs after depolarization. as K+ ions exit, the inside of the cell because less and less positive…the graph goes down.
potential approaches -92mV
explain what happens during depolarization
membrane potential becomes more positive as the opening of Na+ channels increases the permeability of Na+
potential approaches E(Na)= +62mV
the change in the postsynaptic potential can be inhibitory or excitatory
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WHAT ARE THE METHODS BY WHICH IONS ENTER AND EXIT CELLS»>?
- Diffusion
- Ion channels
` passive
` voltage gated-> open in response to voltageLigand-gated--> open in response to chemicalsStretch-gated—> mechanically transformed - Ion pumps–which expand energy. eg. the sodium/ potassium pump.
what is the role of voltage-gated ion channels in the Action Potential?
regulate the action potential by controlling what exits and enters the cell (Na+ or K+)
Allow Na+ to enter the cell during depolarization
Allow K+ to exit the cell during repolarization and hyperpolarization.
how does the depolarization ( action potential) spread/ travel down the axons?
the influx of positive charges attracts negative charges inside the CELL, and repulses POSITIVE charges.
Because the Na+ channels have closed and the K+ continues to exit the cell, the membrane cannot depolarize again.
The action potential continues to travel down the AXON.
what is saltatory conduction?
The action potential travels down the axon by jumping from Node to Node.
saltatory conduction increases the speed of nerve impulse transmission
unmyelinated= 2,3 m/s Myelinated= 110m/s
what advantage does saltatory conduction prove in nerve impulse transmission?
saves neuron energy, as it Prevents slow inward leak of Na+ and outward leak of K+ because maintaining membrane potential requires ENERGY>
briefly explain how neurotransmitters are released?
Neurotransmitters are stored in synaptic vesicles at the ends of axons
AP reaches synaptic terminal it depolarises the terminal pre-synaptic membrane opening voltage-gated Ca2+ channels. Ca2+ then enters.
Calcium triggers exocytosis of neurotransmitters (held in membrane bound vesicles) into the synapse
Neurotransmitter diffuses across synaptic cleft – effect either direct or indirect
Many receptors for neurotransmitters are ligand-gated channels
what happens to neurotransmitters after they are released from the presynaptic neuron.
- taken back presynaptic neurons and be repackaged into membrane-bound vesicles
- Destroyed by enzymes in the cleft
- diffuse away from the synaptic cleft and into circulation where they are later destroyed.
- Glia cells take up neurotransmitters and use them as a source of energy.
what does the response of postsynaptic cell to neurotransmitter depend on?
- Type of neurotransmitter
- The concentration of the neurotransmitter
- Types of receptors and chemically sensitive ion channels in the postsynaptic membrane.
there are 8 examples that you need to know
what is adrenaline responsible for
flight or fight response
what is noradrenaline(norepinephrine) responsible for?
concentration transmitter
has excitatory or inhibitory effects in CNS and autonomic division of PNS
IN sympathetic nervous system, it increases heart rate, metabolizes fat, and increases muscle readiness
What is dopamine
Pleasure neurotransmitter
feeling of pleasure
affects mood, sleep, appetite, and sexuality
can be both inhibitory or excitatory
found inside the brain, plays a role in motor control, motivation, arousal, reinforcement and reward
motivation, reward and addiction.
Serotonin?
Mood neurotransmitter–
major targets for antidepressant drugs( many are Selective Serotonin Reuptake Inhibitor(SSRIs) increase concentration of serotonin in the synaptic cleft.
eg. Prozac (fluoxetine), Zoloft, Fontex- Enhance effect of serotonin by inhibiting its uptake after release.
what is GABA
calming neurotransmitter
Acetylcholine?
Learning neurotransmitter
most common- muscle simulation, memory and learning
excitatory or inhibitory in CNS depending on the type of receptor.
shortage of ACh leads to alzheimer’s disease, mental imparement
Glutamate?
Memory neurotransmitter
Endorphins?
Euphoria(a feeling or state of intense excitement and happiness) neurotransmitter
what is Botulinum toxin or Botox?
Neuroprotein produced by the bacterium Clostridium botulinum
prevents the vesicle where ACh is stored from binding to the membrane where the neurotransmitter can be released
prevents muscle contraction for 3-4 months.
What are biogenic amines?
derived from amino acids
1.catecholamines- produced by amino acid- tyrosine
they include Epinephrine (adrenaline) , norepinephrine and dopamine.
2. Indolamines- derived from amino acid tryptophan
include serotonin
what is Attention Deficit Hyperactivity Disorder
………..
DOPAMINE DISORDERS
- Parkison’s disease
- Schizophrenia
- Amphetamines and cocaine
- LSD and Mescaline ( psychoactive drugs)
what is Parkinson’s disease????????
Associated with reduced levels of dopamine neurons in the brain.
what is Schizophrenia?
Associated with abnormal levels of dopamine
What effect do amphetamines and cocaine have on dopamine levels??
Increase dopamine levels, and hence excessive stimulation of the postsynaptic neurons.
What are the effects of LSD and Mescaline?
Produce hallucinatory effects by binding to brain receptors for serotonin and dopamine.
What is the Vertebrate CNS derived from?
Dorsal embryonic nerve cord
What is the brain 🧠 made of?
Include the %
Water 💦 (78%)
Fat.(10%)
Protein(8%)
The front section of the brain shows Gray and White matter
Define these 2 terms.
Gray matter– Neuron cell bodies
White matter– Bundled Axons
In the spinal cord, the white matter in on the outside, which shows its role in linking CNS to PNS.
In the brain, white matter plays a role in signalling between neurons for learning, emotions, senses etc.
The brain 🧠 has 3 layers of protection
What are these layers?
- Bone-Skull
- 3 LAYERS OF CONNECTIVE TISSUE(Meninges)
- Cerebrospinal Fluid(CSF)–Liquor cerebrospinalis.
What are the 3 layers of connective tissue(meninges) that protect the brain (among other 2 brain protections)???
Dura Mata (Outer)
Arachnoid (Middle)
Pia mater (Inner)
Where is the cerebrospinal fluid(CFS) located?
It is located between Arachnoid and Pia mater.
How does the Cerebrospinal fluid protein the brain?
It has Cushioning effect(physical barrier) Chemical barrier (isolates from infection)
What are the 3 major anatomical and function divisions of the brain?
- FOREBRAIN
- MIDBRAIN
- HINDBRAIN
What is the Forebrain responsible for?
Determine complex behaviour and conscious thought.
Receives and integrates sensory input from External environment
What is the function of the Midbrain?
Relays visual and auditory inputs
Monitors the unconscious movement of the muscles
What is the Function of the HINDBRAIN?
Responsible for basic, automatic and vital tasks
Connected to the spinal cord
The Forebrain has 4 functional lobes
Name these functional lobes and state their functions
- Frontal lobe
Initial yes motor activity
Responsible for speech and conscious thought. - Parietal lobe
Receives and interprets sensory information (from skin) - Occipital lobe
Processes visual information - Temporal lobe
Interprets auditory information.
Comprehends spoken and written language.
Perceptual judgement.
What is the left hemisphere of the brain 🧠🧠🧠 responsible for (IN GENERAL)?,
Languages, mathematics, logical operations, sequences of information.
Right hemisphere of the brain 🧠🧠🧠
Pattern and face recognition, spatial relations, non-verbal thinking, emotional processes.
What is the function of the PNS?
Transmits information to and from the CNS
Regulated vertebrates movement and internal environment
Sensory neurons– from stimulus to the CNS receptors of the stimuli
Motor neurons–from CNS to the Muscles and Glands (CALLED EFFECTORS)
There are 2 types of efferent neurons
Name these
1.Autonomic nervous system
Sympathetic division
Parasympathetic division
Enteric division
2.Motor system
Functional components of the somatic or Motor divisions.
Describe the functions of the somatic/motor division and autonomic division.
Somatic/Motor—-√• Carries signals to and from skeletal muscles, mainly in response to external stimuli
Autonomic•√•√ Regulates internal environment by controlling smooth and cardiac muscle, and organs of digestive, cardiovascular, excretory and endocrine systems.
$tate the Functions of the motor or somatic division of the PNS.
Conscious and involuntary control
Skeletal muscle actually controlled by reflexes mediated by Spinal cord and/or brainstem
What are the 4 special senses?
Taste
Smell
Hearing
Sight
Sensory receptors may be grouped to form sensory organs
What are sensory receptors?
Specialised cells or neuron ending that converts stimuli into electrical signals
The AP stimulates by light striking eye is the same as AP triggered by air vibrating in the ear.
What is sensation?
Activation potentials that reach the brain 🧠🧠🧠 via sensory neurones, aware of stimulus.
What is perception?
This is where the brain 🧠🧠🧠 interprets, giving understanding of what the sensation means.
There are 6 types of sensations
Name these.
Visual(eyes) Auditory(ears) Olfactory (smell) Gustatory(👅 tongue) Somatosensory --cutaneous(skin) and proprioception (vestibular and kinesthetic) Osmoreception(thirst)
What are the functions of sensory receptors?
- Sensory transduction– change stimulus into electrical energy, change in membrane potential is known as Receptor potential, graded potentials.
- Amplification– enhancement of signal
- Transmission–Synapses
- Integration—Processing begins as soon as information is received,
What are the 2 types of sensory receptors?
- Somatic sensations
2. Special senses
What are somatic sensations ?
Originate from more than one location in body (temp, touch, vibration, pressure, pain, awareness of body movements)
What are special senses?
Receptors that are restricted in particular areas in the body (taste, smell, hearing balance, Vision)
Highly specialised information about the external world.
What are mechanoreceptors?
Receptors that sense physical deformation–pressure, touch, stretch, motion, sound
There are 4 types of mechanoreceptors
Name these and their functions..
- Tactile receptors
- Proprioceptors
- Statocysts(in vertebrates)
- Hair cells
What are tactile receptors?
°•located in the skin.
°•may simply be nerve endings or may form specialised receptors.
Name the types of tactile receptors
Be able to identify these in a diagram
Meissner corpuscle
Merkel discs
Un-encapusulated dendritic endings
Pacinian corpuscle
Ruffino corpuscle
What are proprioceptors (function) and where are they located?
Provide the information needed to distinguish different types of movement, by transducing changes in muscle shape and length
Located in muscles tendons and joints
Allow animal to perceive positions of body parts and overall position of the body.
They have little sensory adaptation–continuosly supply information.
There are three main types of proprioceptors
Name them.
- Muscle spindles
- Golgi tendon organs
- Joint receptors.
muscle spindles
Function
Location
Detect muscle movement
Located parallel to muscle fibres
Respond to stretch (tap patellar tendon)
GOLGI TENDON ORGANS
function
Location
Monitor skeletal muscle tension
Stretch when muscle contracts
Located in dendrites around collagen in muscle-tendon junction..
Joint receptors function
Monitors pressure, tension. And movement in JOINTS.
What are statocysts (in invertebrates)band their function
Respond to gravity–ALLOW INVERTEBRATES TO MAINTAIN ORIENTATION WITH RESPECT TO GRAVITY.
What are Hair cells and what are their function?s
These are sensory receptors responsible for functions of AUDITORY AND VESTIBULAR APPARATUS.
What are chemoreceptors?
What are they responsible for?
These are sensory receptors that TRANSDUCE CHEMICAL COMPOUNDS INTO NEURAL IMPULSES.
Responsible for:::
Gustation( taste–chemicals dissolved in water) - occurs in Tatar buds
Olfaction–(smell–gaseous chemicals in air)–Occur in olfactory epithelium.
Function of elctromagnetic receptors?
Transduce various forms of electromagnetic energy e.g. Light, Electricity and magnetism.
Well developed in fish and sharks and some mammals.
What are thermoreceptors?
Detect temperature 🌡️🌡️🌡️ in internal and external environments.
Humans: located in skin and anterior hypothalamus
IR receptors in many 🐍 snakes.
What do snakes use to detect prey?
Use infrared radiation
Capsaicin is an active ingredient in spicy food. What receptor does it bind to?
Binds to a special class of Vanilloid receptor inside our mouth called VR1 receptors.
After capsaicin binds to these receptors, the sensory neuron is depolarized, and it sends along a signal indicating the presence of spicy stimuli.
What are pain receptors (Nociceptors)
These are un-encapusulated endings near skin surface
Respond to excessive pressure, heat, light or chemicals. Density highest in Skin.
There’s Fast and slow pain that can be detected by Nociceptors
Differentiate between these 2
Fast pain(sharp or acute pain)—Physical pressure, heat, near surface of body, strong withdrawal response.
Slow pain–Muscles or internal organs, chemically sensitive pain receptors, chemicals from damaged tissue(Histamine)
I know all this can get Overwhelming
You will ask yourself if this is the correct way of studying
No matter what
There’s a person who’ll figure it out
Who’s that person?
NKANYISO NELSON ZULU
ME MYSELF AND I
What are chemoreceptors responsible for in the Special senses?
- Taste
2. Smell
Let’s dig a little bit deeper. Acquiring knowledge may be painful, but acquired knowledge is Golden, and Feels Good.
Anyway
What is taste
What makes up taste buds
Mammalian tongue
Chemical signal converted to action potential
The tongue is rough-Papillae, taste buds at surface of folds
There are 10 000 taste buds-mostly on 👅 tongue
Taste buds=25 taste cells and 25 supporting cells.
Taste hairs at tips||~ contain chemoreceptors
Tastants bind to chemoreceptors
Chemical molecules in food bind to receptors leading to K+ closing–Depolarization
Are taste cells Neurons?
A BIG NO
Taste cell+Sensory neuron are required to convert chemical stimulus to nerve impulse
4 taste qualities respond to specific receptors
What are these taste qualities and what do they respond to
Sweet(sugar)
Sour(Hydrogen H+ ion)
Salty(Na)
Bitter(toxic plant chemicals)
Fun facts
Flavours are recognised mainly through the sense of smell
Taste cells and smell cells are the only sensory cells that are regularly replaced throughout a person’s life span.
Taste cells usually last a out 10 days
What are odours detected by?
Olfactory receptor cells–Upper part of nasal passages.
SMELL
what is the modified dendritic ending?
Branches to several olfactory hairs that extend into mucous covering of nasal passages.
Receptors for smell located on TRUE SENSORY NEURONS
What is Olfaction?
When does it Occur?
Chemoreception that forms the sense of smell.
Has many purposes such as the detection of hazards, pheromones and food.
Occurs when odorants bind to specific sites on olfactory receptors located in the nasal cavity.
How does olfaction occur?
Glomeruli aggregate signals from the olfactory receptors and transmit them to the olfactory bulb, where the sensory input will start to interact with parts of the brain 🧠🧠🧠 responsible for smell detection, memory and emotion.
Smell
There are chemoreceptors for 1000’s odorant chemicals.
….
What detects odours?
Olfactory receptor Cells
The upper part of nasal cavity.
How are Gaseous and airborne odorants smelled?
Enter nasal passages and dissolve in mucous
Bind to chemoreceptors on Olfactory hairs to generate impulse.
Olfactory receptor Cells synapse with olfactory neurones in nearby olfactory bulb in brain.
What are mechanoreceptors?
For special senses
Include::::::::
Hearing
Balance
Hearing
What is the unit of sound
Sound is measured in decibels (dB)
0 dB is barely audible– it is the threshold of human hearing
Hearing
How do we hear sounds?
The ear 👂 transduced sound waves into nerve impulses that brain 🧠 perceive as Sound.
There are hair cells that detect motion.
The TONE is determined by frequency(Hz)
What is the range of tone/frequency can humans hear?
20-20 000 Hz
SOUND
What determines Tone/Pitch?
FREQUENCY
What determines Volume or loudness of sound?
AMPLITUDE OF SOUND WAVES.
What is responsible for transducing sound waves into Neural signals(electrical impulses)?
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AUDITORY APPARATUS.
KNOW THE LABELS
The ear has 3 main Parts, namely the outer ear, the middle ear and the inner ear.
Explain the functions of each part of the ear..
- Outer 👂 Ear
•Pinna and Auditory Canal
•Sound channeled to tympanic membrane(also called the Eardrum) - Middle 👂 Ear
•Air filled chamber in temporal bone of Skull, bridges by 3 small bones.
•Amplify sound
• Kept at atmospheric pressure by auditory tube. - Inner 👂 Ear
èFluid filled
èIt sorts and coverts sound
√®Cochlea (sound converted) & Vestibular apparatus (✓ vestibule & 3 semicircular canals; balance)
Hearing
What is the function of the Basilar Membrane?
…
What’s is the function of the organ of Corti ?🤸🤸🤸🤸🤸
Everything’s easy, as long as you put your whole mind into it. Love you Brother.
Sup ports 15 00l hair cells
The hair-like projection is embedded in TECTORIAL MEMBRANE.
THE organ of Corti converts pressure waves 🌊 to impulses.
Vibration of basilar Membrane causes hairs to bend. Movement of hair cells Opens ion channels and neurotransmitters to auditory nerve.
MECHANORECEPTORS
BALANCE
What are the 3 semicircular canals responsible for?
Vestibule?
3 semicircular cans–Rotational movement
Vestibule–static position and Linear Acceleration.
•••√✓ Input from joint receptors, muse spindles & tendon receptors(also vision)+ Sense organ in the 👂 Ear=Integration of multiple sensory inputs.
I KNOW IT ALL SEEMS TOO MUCH
BUT WE WILL MANAGE
And then God said,”It is done”
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The vestibular system is the sensory apparatus of the inner ear that helps the body maintain its postural equilibrium
What are the 3 primary purposes of vestibular apparatus?
- They play a dominant role in the subjective sensation of motion and spatial orientation of the Head.
- Adjusts muscular activity and body position to maintain posture.
- Stabilizes in space the fixation point of the Eyes when the head moves, providing a stable image upon the Retina.
Sensing Rotational Movement
What are the semicircular canals?
… complete
Sensing Head position and acceleration
…complete this🥵
Photoreceptors(•Special senses)
Vision
What is the function
¶ Light(Electromagnetic Radiation| 300 000m/s)
¶ Transduce light into Neural Impulses
¶ Retina of EYE- Collects Light.
¶✓ Photoreceptors- Receive and Process Visual Information.
The Retina is mostly studied in the CNS.
The Retina has 4 layers
What are these layers?
Also name their functions.
- Pigmented cells&Choroid–Absorb light not captured by photoreceptor cells
- Rods&Cones- Photoreceptor cells, synapse with…
- Bipolar cells– Neuronal that synapse with layers of rods and cones, synapse with…
- Ganglion Cells– Also neuronal, long axons become optic nerves– integrate information
What are Photoreceptors-?🤸🤸🤸
Please 🥺🙏 know the diagram associated with it.
These are divisible into Rods and Cones i.e. Rhodopsin(rods) and photopsins (cones)
(NB) Light passes through several layers of connecting neuronal before reaching the rods and cones.
Light is converted to Action Potentials.
