Chapter 8 Nervous System (Hard) Flashcards
3 major functions of the nervous system
1- Monitor the body’s internal and external environments
2- integrate sensory information
3- Coordinate voluntary and involuntary responses of many other organ systems
Central Nervous System (CNS)
The brain and spinal cord
- this is where 90% of the neurons are
Peripheral Nervous system (PNS)
Every other nerve in the body that is not in CNS
Name two subcategories of the PNS system
Afferent division
Efferent division
Afferent division
the part of the PNS that bring sensory information from the receptions to the CNS. From nerves/senses to brain
Efferent division
The part of the PNS that carries commands from the CNS to muscles and glands. It leads to an effect or a response to happen.
From the brain to cause a reaction.
Autonomic nervous system (ANS)
is automatic, you don’t have to think about it. The parts of the CNS and PNS that deal with subconscious (involuntary) signals–this is what regulates smooth muscle, cardiac muscle, and glandular secretions.
Two subcategories of the ANS and what they do
Sympathetic division: Fight or flight
Parasympathetic: rest and digest
Somatic nervous system
the parts of the CNS and PNS that control skeletal muscle
Name three types of neurons
Sensory neurons
motor neurons
interneruons
Sensory neurons
neurons of the AFFERENT division of the PNS. Send sensory information to the CNS
Motor neurons
EFFERENT neurons that send instructions from the CNS to other organs or organ systems
Interneurons
Always in the CNS. Make extra connections. These connect other neurons together, distributing sensory information and coordinating motor activity, These perform complex functions such as memory
Multipolar neuron
- dendrites funnel signals to the cell body, which signals are then sent down a long axon to the synaptic terminals.
- Most CNS neurons and all motor neurons (to skeletal muscle) are multipolar.
- can be super long
- MOST COMMON
Unipolar neuron
- The cell body is off to the side, there is a straight shot from the dendrites to the axon and then to the synapses.
- most sensory neurons of the PNS are unipolar.
- can be as long as multipolar neurons
Bipolar neuron
- one dendrite and one axon, with the cell body between them.
- these are rare and usually found in special sense organs
Receptors
- Sensory structures that detect changes in the internal or external environment.
- These start AFFERENT pathways
Effectors
- Target organs whose activities change in response to neural commands.
- these are the destinations of EFFERENT pathways
Somatic sensory receptors
monitor the OUTSIDE world and our position in it.
Visceral sensory receptors
monitor INTERNAL conditions and the status of other organs
Somatic efferent neurons
Type
Cell body location
Distribution of impulses
- Type: Multipolar
- Location: Cranial nerve motor nuclei, spinal cord, anterior gray matter
- Distribution: motor neuron to skeletal muscle
Visceral Efferent Neurons
Type
Cell body location
distribution of impulses
- Type: Multipolar
- Location: Motor nuclei of cranial nerves 3,7,9,10, Spinal cord: lateral gray column in sacral region, Autonomic Ganglia
- Distribution: Motor to smooth muscle, cardiac muscle, and glandular epithelium
Somatic Afferent Neuron
Type
Cell body location
distribution of impulses
- Type: pseudounipolar
- Location: Retinal and sensory ganglia of cranial and spinal nerves
- Distribution: Sensory form retinal (vision), internal ear (audition and balance), skin, skeletal muscle bonds and joints
Visceral Afferent Neuron
Type
Cell body location
distribution of impulses
- Type Pseudounipolar
- Location: Nasal mucosa and sensory ganglia of cranial and spinal nerves
- Distribution: Sensory from nasal mucosa (smell), oral mucosa (taste), and deep body organs
3 functions of glial cells
- Support cells for neurons
- make up about half of the volume of the nervous system
- found in both PNS and CNS, but CNS has a greater variety
Glial cells in the CNS (4)
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
Astrocytes
- Largest and most numerous
- Maintain the blood brain barrier (cell membrane)
- have feet that surround capillaries and secrete chemicals so fluid can’t get through (hormones, amino acids)
- create a framework for CNS
- Do repairs on damage neural tissues.
- Can look like stars
oligodendrocytes
- Small and have fewer processes than astrocytes
- wraps (secretes) myelin sheath around axons and make an electrical insulation
- helps electrical signals move faster because they skip over the sheath cover parts
- myelinated axons are white matter
Microglia
- Smallest and least numerous
- White blood cells
- These are specialized phagocytic leukocytes that are the defense system and clean up crew for the CNS
Ependymal cells
- Cuboidal epithelial cells
- line the cavities in the CNS filled with cerebrospinal fluid
- found in the central canal of the spinal cord and the ventricles of the brain.
- NO basement membrane
Glial cells in the PNS (2)
Satellite cells
Schwann cells
Satellite cells
- the PNS equivalent of astrocytes.
- Surround and support neuron cell bodies
Schwann cells
- Rough equivalent of the oligodendrocyte
- Cover every axon outside the CNS
- it BECOMES not secretes myelin to cover axons
- can wrap around a lot of axons, but they need to be arranged in such a way that the cell body can wrap around all of them.
Depolarization
Moving the voltage of the membrane potential toward 0 mV
Hyperpolarization
Moving the coltage of the membrane potential even more negative than -70 mV. Get more polarized than before
Graded potential
changing the membrane potential locally in response to a stimulus. all cells can do this. Does not spread
Action potential
Changing the membrane potential in a cell that’s excitable (not all cells can do this) to make a propagating change in membrane potential. In nerves, these are called nerve impulses
Steps to transmission fo a nerve impulse
step 1: signal is generated and goes to the axon hillock
step 2: membrane of the hillock depolarizes to the threshold, allowing action to occur
Step 3: Na+ channels open Na goes INTO the cell and depolarizes the membrane until it hits the threshold (+30 mV)
Step 4: Na channels close
Step 5: K Channels open and K moves OUT of the cell and repolarizes or hyperpolarizes the cell (-90 mV)
Step 6: K channels close
Step 7: Na/K ion pumps exchange ions to reset membrane (refractory period)
Name 3 cells that nerves talk to
- Other Neurons
- Muscle cells
- Glandular cells
Synapse
The terminal end of the neuron is a set of synapses, were the nerve transfers information to the next cell or set of cells
Synaptic process
- Step 1: action potential arrives and depolarizes the axon terminal
- Step 2: the axon terminal releases the neurotransmitter into the synaptic cleft
- Step 3: the neurotransmitter binds to receptors and depolarizes the postsynaptic membrane
- (if the signaling causes threshold depolarization then the action potential continues on the new neuron)
- Step 4: the neurotransmitter is removed by an enzyme
Name to neurotransmitters
Acetylcholine (Ach)
Norepinephrine
Reflex
A rapid, automatic response to a specific stimulus.
- Designed to be homeostatic adjustment
Types of reflexes (2)
Monosynaptic reflex
polysynaptic reflex
Monosynaptic reflex
- only ONE synapse between signal and response
- The AFFERENT neuron synapse directly on the EFFERENT neuron (synapse in the spinal cord)
Ex: Stretching muscles, doctor knee reflex
Polysynaptic reflex
Have more that one synapse between the start of the afferent signal and the end of the efferent signal.
- Takes longer but does more stuff
Ex: withdraw you arm/ body when you touch a hot surface
Meninges
CNS organ covering/ membrane
there are three of them
the 3 layers of the meninges
Dura mater
Arachnoid mater
Pia Mater
Meninges: Dura Mater
- Most external
- tough and fibrous
has two layers of fibrous tissue
- outer layer: fused to skull but NOT to vertebrae
- inner layer: space between it and the outer layer filled with blood vessels and tissue fluids. Makes Dural folds that act like a seat belt for the brain
Meninges: arachnoid mater
- Middle layer
- made of simple squamous epithelial tissue
- has a subarachnoid space filled with cerebrospinal fluid and a network of collagen and elastic fibers that look like a spider web
Meninges: Pia Mater
- Deepest layer
- firmly bound to the neural tissue underneath
- highly vascular
- brings the blood vessels close to the brain so the brain can get easy access to the nutrients it desperately needs
- contains capillaries
Cerebral hemispheres function
ORIGINATE
- Conscious thoughts
- sensations
- intellectual functions
- memory storage and processing
- complex movements
Frontal lobe function
- Executive function
- attention
- memory
- speech/language (side of non-dominant hand)
- mood
- personality
- self-awareness
- social and moral reasoning
Parietal lobe function
- sensation and perception
- integrating sensory input
- perceive what is on the outside
Occipital lobe function
vision processing center
temporal lobe function
- auditory processing center
- olfactory (smell) cortex
insular lobe function
- limbic system
major parts of the cerebrum
Diencephalon
- Thalamus - Hypothalamus - Epithalamiums
Thalamus function
Relay and processing centers for sensory information
Hypothalamus function
Contains centers involved with
- emotions
- autonomic function
- hormone production
- connected to the pituitary gland
Means below the thalamus
Pituitary gland
- the master gland
- connects to the nervous and endocrine system
Epithalamus function
Contains the pineal gland
Parts of the diencephalon
thalamus
hypothalamus
epithalamus
Cerebellum functions
- Adjusts voluntary and involuntary motor activities on the basis of sensory information and stored memories of previous movements
- responsible for proprioception (knowing where your body is in space)
- Coordinates balance and the movement of limbs and trunk
Parts of the Brainstem
Midbrain
pons
medulla oblongata
Midbrain function
- process visual and auditory info
- generate involuntary motor responses
- essential for maintaining consciousness
Pons function
- connects cerebellum to brain stem
- contains lots of relays and tracts
- has areas involved in somatic and visceral motor control
Medulla oblongata function
- relays sensory info to thalamus and other brainstem centers
- contains the major centers that regulate autonomic functions (e.g. heart rate, blood pressure, respiration, digestive activities)
- connects brain to spinal cord
Cerebrospinal fluid function
transports dissolved gases, nutrients, chemical messengers, and waste products, like blood and lymph.
- also acts as a shock absorber
Brain Nucleus
Cluster of neruons in the CNS.
They usually have roughly similar connections and functions.
Gyrus
Fold or ridge in the brain
top of the mountain
sulcus
- Groove between gyri
- The valley
Tract
bundle of neurons forming a neural pathway that connects relatively distant areas of the brain
Limbic system definition
Functional (not anatomic) grouping of different nuclei, gyri, and tracts along the border between the cerebral hemispheres and diencephalon.
- makes you want to perform complex tasks
Limbic system function
- Establish emotional states
- Link the conscious with the subconscious, intellectual functions of the cerebral cortex with the unconscious and autonomic function of the brainstem
- aid long-term memory storage and retrieval
- makes you want to perform complex tasks
Parts of the limbic system (4)
Amygdala
hippocampus
fornix
hypothalamus
Amygdala
Multiple nuclei that link the limbic system, cerebrum, and various sensory systems
- play a role in regulating heart rate, responding to fear and anxiety, controlling fight or flight response, and linking emotions with specific memories
Hippocampus
important in learning and storing long-term memory
- If i saw a hippo on campus I would remember it
Fornix
Track of white matter that connects hippocampus and hypothalamus
Hypothalamus
has centers that control
- emotional states such as rage, fear, and sexual arousal
- reflex movements that can be consciously controlled (e.g. chewing, licking, swallowing)
PNS functions
- Links the CNS to the rest of the body and its internal and external environments
- carries all sensory info to the CNS
- Carries all motor commands from the CNS to the rest of the body
Name CN nerves in order 1-12
Remember: Ooh, Ooh, Ooh, To Touch And Feel Very Good Velvet. Ah Heaven!
I= Olfactory bulb II= Optic III= Oculomotor IV= Trochlear V= Trigeminal VI= Abducens VII= Facial VIII= Vestibulocochlear IX= Glossopharyngeal X= Vagus XI= Accessory XII= Hypoglossal
List type of CNs in order
Remember: Some Say Marry Money Buy My Brother Says Big Brains Matter More I= Special sensory II= Special sensory III= Motor IV= Motor V= Both VI= Motor VII= Both VIII= Special sensory IX=Both X= Both XI= Motor XII= Motor
CN 1
Name: Olfactory bulb
Type: Special sensory
Function: Transmits the sense of smell from the nasal cavity
CN 2
Name: Optic nerve
Type: Special sensory
Function: Transmits visual signals from the retina of the eye to the brain
CN 3
Name: oculomotor
Type: motor
Function: which collectively perform most eye movements.
- Inferior rectus, superior rectus, medial rectus, inferior oblique, and intrinsic muscles of the eye
CN 4
Name: Trochlear
Type: Motor
Function: superior oblique muscle of the eye which depresses, rotates laterally, and intorts the eyeball.
CN 5
Name: Trigeminal
Type: both
Sensory functions: sensation from the face
Motor: chewing muscles
CN 6
Name: Abducens
Type: motor
Function: Lateral rectus muscle of the eye which abducts the eye
CN 7
Name: Facial
Type: Both
Sensory function: taste on the anterior 2/3 of the tongue
Motor function: Face muscles, lacrimal (tear) gland, and salivary glands
CN 8
Name: Vestibulocochlear
Type: Special sensory
Function:
Cochlea= receptors for hearing,
Vestibule= receptors for motion and balance
CN 9
Name: Glossopharyngeal
Type: Both
Sensory Function: 1/3 of tongue taste, pharynx and part of the palate. Receptors for blood pressure, pH, oxygen, and CO2
sensation at the back of your mouth and nose
Motor function: Pharyngeal muscles, parotid salivary glands,
CN 10
Name: Vagus
Type: Both
Sensory function: : pharynx, auricle and external acoustic meatus (part of external ear), diaphragm, visceral organs in thoracic and abdominopelvic cavities
Motor Functions: palatal and pharyngeal muscles, visceral organs in thoracic an abdominopelvic cavities. controls muscles for voice and resonance and the soft palate.
CN 11
Name: Accessory
Type: Motor
Function: moves sternocleidomastoid and trapezius muscles. Also helps vagus with voluntary muscles of palate, pharynx and larynx
CN 12
Name: Hypoglossal
Type: Motor
Function: Tongue muscles
