Chapter 15: Nervous System Flashcards
What are two major divisions of nervous system?
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
What is CNS?
Nervous system in brain and spinal cord
What is PNS?
Nerves that connect the brain and spinal cord with muscles, glands, and sense organs
What is the basic cell type for both CNS and PNS?
Neurons
What is somatic nervous system
Voluntary control of movements
What do afferent neurons do?
Afferent neurons bring signals from peripheral receptors to the CNS
What do efferent neurons do?
Efferent neurons bring signals from the CNS to the skeletal muscle fibres
What is autonomic nervous system?
Involuntary control of smooth and cardiac muscle and glands
What does autonomic nervous system work with?
It works with the endocrine system to maintain homeostasis
How many neurons does autonomic nervous system has?
Two neurons between the CNS and effector
What is the enteric nervous system?
Part of the autonomic nervous system that their neurons regulate the digestion
What does the Submocosal plexus do?
Submucosal plexus stimultaes secretions
What does the myenteric plexus do?
Myenteric plexus stimulates smooth muscle contractions
What is the plexus?
Plexus is the network of neurons and nerves that innervate a specific tissue, such as submucosal plexus in digestive system
What is the ganglion?
Group of cell bodies in a nerve, such as dorsal root ganglion bringing sensory information to the spinal cord
What are sensory receptors?
Sensory receptors detect specific sensory stimuli
What is the baroreceptor?
Receptor that detects stimulus of blood pressure
What is the proprioceptor?
Receptor that detects stimulus of body position
What is the nociceptor?
Receptor that detects stimulus of pain
Explain the sensory function
Sensory receptors detect internal and external stimuli and information is carried to the brain and spinal cord through cranial and spinal nerves
Explain the integrative function
Integrates sensory information by analyzing and storing some of it and by making decisions for appropriate responses
Explain the motor function
Elicitation of motor response in response to integrated sensory information activates effectors(muscle/glands)
What are two cells that nervous tissue contain?
Neuron and neurogila
What does neuron possess?
Electrical excitability
List 3 parts of nervous tissue
- Cell body 2. Dendrites 3. Axon
What does cell body contain?
Nucleus, cytoplasm, and typical organelles
What do dendrites do?
They receive or input parts of a neuron
What does axon do?
Conducting never impulses
List the parts of axon
- axon hillock 2. axon collaterals 3. axon terminals
What happens at axon hillock?
Nerve impulses begin at axon hillock
What happens at axon terminal?
Nerves terminate at axon terminal
What are synapses?
Microscopic space between the axon terminal and another neuron or cell
The point at which two neurons or a neuron and an effector cell communicate
What is a neuron?
A single cell in the nervous system
What is a nerve?
The nerve contains thousands of neurons that connect with specific tissue
What are glial cells?
cells that support the neurons in the CNS and PNS
List 3 types of neurons
- Multipolar
- Unipolar
- Bipolar
What are the multipolar neurons?
Motor neurons and interneurons
What is the unipolar neuron?
Sensory neurons
Where do bipolar neurons be found?
In the ear, retina, and olfactory area of brain
Explain astrocytes of glial cells-CNS
Astrocytes regulate extracellular fluid, Guide neuron growth during embryonic development, are Involved in the formation of the blood-brain barrier, store glycogen, and form scar tissue
Explain microglia of glial cells-CNS
Phagocytic immune cells
Migrate to infected areas Engulf pathogens and dead cells
Explain ependymal cells of glial cells-CNS
Ciliated and involved with the production of cerebrospinal fluid (CSF)
in brain ventricles
Explain Oligodendrocytes of glial cells-CNS
Make myelin, very fat content, protect and insulate axons
Explain glioma of glial cells-CNS
Brain tumors that are usually formed from glial cells
Explain satellite cells of glial cells-PNS
surround neuron bodies located in the PNS, similar to astrocytes in the CNS, and function to regulate extracellularfluid
Explain Schwann cells of glial cells-PNS
Surround and form myelin sheaths around the larger nerve fibres, Similar to oligodendrocytes in CNS
Explain Schwann cells of glial cells-PNS
Surround and form myelin sheaths around the larger nerve fibres, Similar to oligodendrocytes in CNS
What is the myelin sheath
Many-layered covering composed of lipid and protein
Protects axon, like insulation of an electrical wire
Increases the speed of nerve impulse conduction
And it is up to 100 layers of the myelin sheath
What are the nodes of Ranvier?
Gaps in the myelin sheath
What are clusters of neuronal cell bodies?
Ganglia(neural cell bodies in the PNS, nerves and spinal) and nucleus(neural cell bodies in the CNS)
What are bundles of axon?
Nerve and tract
What is white matter?
Primarily myelinated neurons
White colour imparted by myelin
What is gray matter?
Neuronal cell bodies
Dendrites
Unmyelinated axons
Axon terminals
Neuroglia
Grayish colour imparted bycellular organelles
What are ion concentration?
Different in the cytoplasm versus interstitial fluid
How is gradient of sodium and potassium ions maintained?
Gradient of sodium and potassium ions are maintained by the Na+/K+ pump
Is cytoplasm/inside of cell membrane positive or negative related to outside and what ions does cytoplasm have?
Cytoplasm is negative related to outside and cytoplasm has potassium ions
Is Interstitial fluid / Outside of cell membrane positive or negative related to inside and what ions does interstitial fluid have?
Interstitial fluid is positive related to inside and interstitial fluid has sodium and chloride ions
How much negative is inside of all cells
about -70mV
What does polarized mean for status of ions?
Polarized means negative inside compared to outside
What does depolarization mean for status of ions?
When Na+ (positive ions) move into the cell and becomes less negative, it is called depolarization
What do action potentials and graded potentials do?
Action potentials and graded potentials transmit electrical siganls by moving ions across the cell membrane which change their charge as well
Where do ions move cross?
Ions move cross the membrane using specific protein membrane channels
What channels do each ions use?
Each ions have their own specific channels, such as Na+ channel for Na+ ions
What causes the channels to open and let ions move in or out of the cell?
Voltage-gated and Chemically gated
What is voltage-gated?
opens when the membrane charge changes
What is Chemically gated (ligand-gated)?
opens because of the binding of a chemical or ligand, such as a neurotransmiKer or hormone
How is the speed of action potentials?
Action potentials are generally very rapid as brief as 1-4 milliseconds
What is excitability?
Ability to generate action potentials possessed by neurons, muscle cells, and some other types of cell
What kind of reponse is action potential?
Action potential is the all or none response as it is a large change in membrane potential
What is the charge of Resting membrane potential?
About -70 mV
What is the charge of Threshold level?
About -50mV, triggered by stimulus
What is the charge of Depolarization?
About +30mV, Na+ enter the cell
What is the charge of Repolarization?
About -70mv, K+ leaves the cell
What is the charge of hyperpolarization?
About -80mV, extra k+ leaves the cell
When does depolarization stop charging?
When it hits +30mV, it triggers inactivation of Na+ entering the cell
What happens when it’s at +30mV charge?
It stimulates k+ channel to open, k+ leaves the cell
What is refractory period?
The time sodium inactivation gate closes and that prevents further depolarization of the membrane
What happens during hyperpolarization phase?
Another action potential can occur, Only if stimulus is strong enough to reach threshold
What is the result of action potential?
Charge changes causing neurotransmitters to be released from axon terminal
What do neurotransmitters do after the action potentials occur?
The neurotransmitters signal molecules and stimulate the neurons and another muscle cell
What is the synapse?
Space between pre-synaptic neuron (axon terminal) and Post-synaptic neuron (dendrite)/Muscle cell (motor end plate)
Where are neurotransmitters?
Produced / stored in vesicles at axon terminal
When do voltage-gated calcium channels open?
When action potential reaches axon terminal
What happens when calcium from calcium channels enter the cell?
Calcium causes vesicles to bind to axon terminal membrane and release neurotransmitters = exocytosis
What does a synapse include?
Presynaptic neuron, Synaptic cleft, and Postsynaptic neuron
What is presynaptic neuron?
The neuron sending the signal
What is Synaptic cleft?
Tiny space between neurons
What is Postsynaptic neuron?
The neuron receiving the signal
What are graded potential?
Changes in membrane potenUal confined to a small region of the plasma membrane—usually dendrites
What are various names given to the graded potential?
receptor potential, synaptic potential, and pacemaker potential
What are two kinds of graded potential?
EPSP(excitatory post-synaptic potential) and IPSP(inhibitory post-synaptic potential)
What is Tempolar summation?
More action potentials in same location in same time period
What is spatial summation?
More action potentials affecting multiple areas of the post-synaptic neuron at the same time
What is saltatory conduction?
Action potentials that occur in myelinated neurons
Which part of axon has ion channels?
Nodes of ranvier
What do nodes of ranvier do in the conduction?
They speed up the conduction down the axon
What are the functions of spinal cord?
- Carry sensory(to brain) and motor(to nerves) information
- Spinal reflexes, get sensory from the spinal nervers and give motor to the spinal nerves
Where are spinal cord located?
From foramen magnum to vertebrae L1 and L2
Which parts is spinal cord protected from?
Spinal cord is protected by vertebrae, adipose tissue, spinal meninges, and cerebrospinal fluid
What is dura mater of spinal meninges?
Outer meninges that is tough and single layered membrane deep to the epidural space
What is Arachnoid mater?
Middle layer of the meninges, Collagen and elastic fibers resembles a spider’s web
What is Subarachnoid space?
A space between the arachnoid mater and pia mater, Filled with cerebrospinal
fluid
What is pia mater?
Delicate, transparent inner layer, Adheres to the surface of the spinal cord
Where is spinal cord located?
Spinal cord is within vertebrae column and is central butterfly-shaped area of grey matter
What does grey matter have?
Composed of interneurons
Cell bodies and dendrites of efferent neurons
Entering axons of afferent neurons
Glial cells
What are two regions of grey matter?
- Toward back of body = Dorsal horns (Posterior)
- Toward front = ventral horns (Anterior)
What is white matter that is surrounding grey matter?
Groups of myelinated axons
Where do spinal cord extend from and where it ends?
Extends from Medulla oblongata (brainstem) to the upper border of L2 (the conus medullaris).
What is Cauda Equina?
Collection of spinal nerves that angle down the vertebral canal below L2
Which part of neurons innervate upper limb?
Cervical
Which part of neurons innervate lower limb?
Lumbar
How many pairs of cervical spinal nerves?
8 (first from the skull and 7 cervical vertebrae)
How many pairs of thoracic spinal nerves?
12
How many pairs of lumbar spinal nerves?
5
How many pairs of sacral spinal nerves?
5
How many pairs of coccygel nerves?
1
How are spinal nerves placed?
Spinal nerves branch-off the spinal cord, leaving the vertebral column through the
intervertebral foramina
How are spinal nerves arranged?
Spinal nerves are arranged like muscles as neurons grouped together in fascicles and collection of fascicles is a nerve
What do individual axons, fascicles and whole nerve have in common?
They all have protective connective tissue coverings
What are 3 parts of coverings for spinal nerves?
Endoneurium, Perineurium, and Epineurium
What is endoneurium?
covering surrounds axons of individual neurons
What is perineurium?
covering surrounds bundles of neurons, called fascicles
What is epineurium
Covering over the entire nerve
What is plexus and what are the plexus of spinal nerves?
Plexus is a network of spinal nerves and plexus of spinal nerves are cervical plexus, branchial plexus, lumbar plexus, and sacral plexus
What does cervical plexus innervate?
Innervates skin and muscles of head, neck, and upper shoulders, and diaphragm (C1-C5)
What does branchial plexus innervate?
Innervates upper limbs, neck and shoulder muscles (C5-T1)
What does lumbar plexus innervate?
Innervates abdominal wall, genitals, parts of lower limbs (L1-L4)
What does sacral plexus innervate?
Innervates bufocks, perineum, lower limbs (L4-S4)
What is reflex?
a rapid and involuntary response to a stimulus
What is Monosynaptic reflex?
Reflex that involves only one synapse between the sensory neuron to the motor neuron in the spinal cord, such as knee-jerk response
List the process of monosynaptic
- Sensory receptor
- Sensory neuron
- Integrating center
- Motor neuron
- Effector
What is polysynaptic and the example of polysynaptic?
Polysynaptic involves more than one synapse (two effectors) and the example of that is withdrawal reflex (touching something hot)
What is the reciprocal innervation of polysynaptic?
When one muscle is stimultaed, antagonistic muscle is inhibited
What is brain composed of?
About 3 lbs of tissue
What are brain and spinal cord protected by?
Meninges and cerebrospinal fluid (CSF)
What are 3 layers of meninges for brain?
Dura mater, Arachnoid mater, and Pia mater
List the functions of meninges
Cover and protect the CNS
Protect blood vessels and enclose the venous sinuses
Contain cerebrospinal fluid
Form partitions in the skull
What is meningitis?
Inflammation of the meninges, Serious threat to the brain – bacterial or viral meningitis can spread to the CNS
What is Encephalitis?
Inflammation of the brain itself
What does brain blood supply do?
Brain blood supply bring oxygen and glucose that brain needs
What are Capillaries?
Capillaries are composed of high density endothelial cells that are restricting the substances of blood stream into the fluid
What do Astrocytes surrounding blood brain barrier do?
Astrocytes surrounds the endothelial cells that are essential to the blood brain barrier
What does blood brain barrier do?
BBB protects the brain from harmful substances and pathogens
What is a cerobrospinal fluid?
Cerobrospinal fluid is a clear, colorless liquid that carries oxygen, glucose, and other chemicals to neurons and neuroglia and removes their toxic substances
What is cerobrospinal fluid produced by?
Produced by ependymal cells that are found in the choroid plexuses of each ventricle of brain
Where do cerobrospinal fluid circulate?
it circulates through the subarachnoid space (around brain and spinal cord)
Where do cerobrospinal fluid become reabsorbed?
CSF is reabsorbed by arachnoid villi (between dural sinus and subarachnoid space
What is the total volume of CSF?
About 125-150 mL
How much CSF does choroid plexus produce and how many times are they recycled a day?
About 400-500 and 3 times a day
What do ventricles produce?
CSF
How many ventricles are interconnected?
4
Where do CSF flow in which ventricle?
CSF flows in 4th ventricle into central canal of spinal cord and the subarachnoid
space around the surface of the brain and spinal cord
What are 4 regions of brain?
Diencephalon, Brainstem, Cerebellum, Cerebral cortex
What is the diecephalon?
The thalamus: a collection of several large nuclei
What does the diecephalon do?
Diecephalon serves as synaptic relay stations and important integrating centres for most inputs to the cortex and plays a key role general arousal
Thalamus also involved in focusing atention
What is the hypothalamus of diecephalon?
it is below thalamus and contains different cell groups and pathways and forms master command centre for neural & endocrine coordination
What behaviours relate to the hypothalamus?
Preservation of the individual (eating and drinking) and species (reproduction)
What is Pituitary gland?
Gland below hypothalamus connected by a stalk, important endocrine structure regulated by hypothalamus
What is Pineal gland?
Gland that has a role in regulating biological rhythms and secretes melatonin in low light that helps to promote sleep
It involves dreaming as well
What is brainstem composed of?
Brainstem is composed of the midbrain, pons, and medulla oblongata
What pass through brainstem?
All neurons that pass through the spinal cord
What is reticular activating system?
Core of the brainstem, neurons that regulate consciousness and sleepwake cycles
What does midbrain of brainstem have?
Midbrain contains the substantia nigra which has cells releasing dopamine
Where does dopamine act on?
Dopamine acts on the basal nuclei (in cerebrum) to regulate muscle movements
How is Parkinson’s disease caused?
Parkinson’s disease caused by the loss of neurons in the substantia nigra
What does pons of brainstem do?
Pons plays a role in relaying information between the cerebrum and the cerebellum
Coordinates muscle movements and control regulation of breathing
What is medulla oblongata of brainstem?
Main respiratory control centre and regulator of heart contractions
Centre for many reflexs such as coughing and sneezing
Where is cerebellum located?
Base of brain
What does cerebellum do?
Controlling and learning muscle movements, fine motor control such as writing with a pen, and coordinating muscle groups when moveing with the body
What is cerebrum?
The subcortical regions lie underneath the cerebral cortex
What does cerebrum contain?
Basal nuclei (muscle movements), amygdala (emotion), nucleus accumbens (reward), caudate nucleus (Learning), and corpus callosum (connects right and left side of brain)
What is limbic system?
Limbic system is a group of structures that are involved in emotions
What is olfactory bulb?
Olfactory bulb is part of limbic system that involve in sense of smell
What is hippocampus?
Location of long term memory
What is frontal lobe of cerebrum?
Frontal lobe contains motor cortex and premotor cortex
Frontal lobe involves planning & initiating muscle movements and higher thinking functions, goal sending, reasoning, decision making, and regulating the limbic system
What is Broca’s area of cerebrum?
Broca’s area is part of the frontal lobe that controls muscles involved in speaking
What is parietal lobe of cerebrum?
Parietal lobe contains sensory cortex and associated areas that interpret sensory information
What does right side of parietal lobe involve?
spatial relationships and interpreting images
What does left side of parietal lobe involve?
recognizing numbers and letters and patterns
What does temporal lobe of cerebrum have?
auditory cortex and associated areas that interpret sound
What is Wernicke’s area?
Part of the temporal lobe that is involved in comprehension of language
What does occipital of cerebrum have?
visual cortex and associated areas that interpret visual stimuli
What is function of nerve I Olfactory?
Olfactory epithelium
What is function of nerve II Optic
Retina of eye
What is function of nerve III Oculomotor
Intrinsic muscles of the eye
What is function of nerve IV Trochlear
Muscles of the eye
What is function of nerve V Trigeminal
Sensory: head & face
Motor: chewing
What is function of nerve VI Abducens
Eye
What is function of nerve VII Facial
Sensory: taste
Motor: facial expression
What is function of nerve VIII Vestibulocochlear
Hearing
Motion and balance
What is function of nerve IX Glossopharyngeal
Muscle: Pharyngeal muscles
What is function of nerve X Vagus
Thoracic and abdominopelvic cavity
What is function of nerve XI Accessory
Neck
What is function of nerve XII Hypoglossal
Tongue muscles
What are 2 efferent divisions?
- Somatic nervous system and
- Autonomic nervous system
What is enteric nervous system of autonomic nervous system?
Enteric nervous system is in the gastrointestinal tract and includes sensory neurons and interneurons
What are divisions of autonomic nervous system?
Sympathetic and parasympathetic division
Where are sympathetic fibres?
from the thoracic (chest) and lumbar regions of the spinal cord
Where are parasympathetic division?
from the brainstem and the sacral portion of the spinal cord
What is sympathetic division also called?
thoracolumbar division, Short preganglionic and long postganglionic axons
What are major neurotransmitters of sympathetic division?
Acetylcholine (ACh) at the preganglionic synapse
& Usually norepinephrine (NE) and epinephrine (Epi) at the postganglionic synapse
What response system is sympathetic division?
The “flight or fight” response system
What is parasympathetic division also called?
craniosacral division, Long preganglionic and short postganglionic axons
What are major neurotransmitters of parasympathetic division?
ACh at both pre- and postganglionic synapses
What response system is parasympathetic division?
The “rest and digest” system
What does one set of postgaglionic neurons in the sympathetic division provide?
They form the adrenal medulla not axons
Upon what kind of activation do cells of adrenal medulla release mixture (NE 20% and Epi 80%) into the blood?
Upon activation by preganglionic sympathetic axons
What are the mixture (NE 20% and Epi 80%) called?
They are called hormones which transported via blood to effector cells that have receptors sensitive to them
Which autonomic system do heart, many glands, and smooth muscles are innervated by?
Innervated by both sympathetic and parasympathetic fibres = dual innervation
What is the relationship between sympathetic division and parasympathetic division in terms of how are they affected by one and other?
Whatever effect one division has on the effector cells, the other division usually has the opposite effect
Two divisions are usually activated reciprocally
