Lab Midterm Flashcards
Dendrites
recieve stimuli through ligand-gates or mechanically gated ion channels; in sensory neurons they produce generator or receptor potentials
Cell body
recieves stimuli and produces ESPs or ISPs through activation of ligand-gates ion channels
axon hillock
trigger zone in many neurons; controls initiation of electrical impulses based on input recieved and if input reaches threshold
axon collateral
propagates nerve impulses from initial segment (or from dendrites of sensory neurons) to axon terminals in self-regenerating manner, impulse amplitude does not change as it propagates along an axon.
axon terminal
inflow of Ca+ caused by depolarizing phase of nerve impulse, triggers exocytosis of neurotransmitter from synaptic vesicles
synaptic end bulb
enlarged endings of axon terminals; neurotransmitters are released from here via exocytosis
Schwann cells
form the myelin sheath around axons in the PNS just like oligodendrocytes in the CNS
Myelin sheath
multilayered lipid and protein covering around some axons that insulate them and increases the speed of nerve impulse conduction
Neurolemma
outer nucleated cytoplasmic layer of the schwann cell. Found only in the PNS
Myelin sheath gaps/ nodes of ranvier
gaps in the myelin sheath that appear at intervals along the axon
Gray matter: anterior horn
contain somatic motor neuron nuclei which are clusters of cell bodies of somatic motor neurons that provide nerve impulses for contraction of skeletal muscle
Gray matter: posterior horn
- contain axons of incoming sensory neurons as well as cell bodies and axons of interneurons.
- functions to receive incoming sensory information
White matter
contains major sensory and motor tracts which function as the “highways” along which sensory input travels to the brain and motor output travels from the brain to the skeletal muscle or glands (effectors)
Spinal nerves
paths of communication between the spinal cord and specific regions of the body
Central canal
at the center of the gray commisure; extends the entire length of the spinal cord and is filled with cerebrospinal fluid
Anterior nerve root
the anterior root and rootlets contain axons of motor neurons, which conduct nerve impulses from the CNS to effectors (muscles and glands)
Posterior nerve root
posterior root and rootlets only contain sensory axons which conduct nerve impulses from sensory receptors of the skin, mucles, and internal organs to the CNS
Ganglia
cell bodies of the sensory neurons are located in ganglion
- plays essential role in connecting parts of the peripheral and central nervous systems
Anterior median fissure
- Wide groove on the anterior side
- The spinal pia mater extends into the fissure to line the surfaces of the spinal cord
Posterior median sulcus
- A narrow furrow on the posterior side of the spinal cord
- Not as prominent as anterior median fissure
- divides the spinal cord into halves
Filum terminale
Arising from the conus medullaris is the filum terminale, an extension of the pia mater that extends inferiorly, fuses with the arachnoid mater and dura mater, and anchors the spinal cord the coccyx.
Reflex arc
the route and impulse takes to produce a reflex action
reflex action
the action the body takes when responding the stimulus to help the body maintain homeostasis
Receptor (in reflex)
Dendrites serve as sensory receptors. It responds to a specific stimulus. A change in the internal or external environment produces a graded potential. If the graded potential reaches threshold, it will trigger one or more nerve impulses in a sensory neuron.
Sensory neuron (in reflex)
the nerve impulses propagate from the sensory receptor along the axon of the sensory neuron to the axon terminals which are located in the gray matter of the spinal cord
Integrating center (in reflex)
consists of one or mote interneurons, which may relay impulses to other interneurons as well as to a motor neuron
Motor neuron (in reflex)
impulses triggered by the integrating center propagate out of the CNS along a motor neuron to the part of the body that will respond
Effector (in reflex)
The part of the body that responds to the motor nerve impulse, such as a muscle or gland. Its action is called a refelx
If the effector is skeletal muscle, then it is a [. ] reflex
somatic
if the effector is smooth muscle, cardiac muscle or a gland, it is a [. ] reflex
autonomic or visceral
What are the 4 somatic reflexes
- achilles
- patellar
- biceps
- triceps
What is a superficial/cutaneous reflex
plantar felxion
What are the 3 autonomic/visceral reflexes
- salivary
- pupillary
- diving
What are the 4 major sections in the adult brain
- cerebrum
- diencephalon
- cerebellum
- brainstem
The meninges of the brain
- are continuous with the spinal cord
- pia mater, arachnoid mater, dura mater
What is different about the dura mater in the brain
it has two layers that are fused together, except for where they enclose the venous sinuses:
- periosteal layer
- meningeal layer
What are the 3 extensions of the dura mater
- falx cerebri: separates the two hemispheres of the brain
- falx cerebelli
- tentorium cerebelli
Arachnoid mater in the brain
an avascular membrane that is involved in cerebrospinal fluid metabolism via the subarachnoid space
Pia mater in the brain
blood vessels that enter brain tissues pass along the surface of the brain, and as they penetrate inward they are sheathed by a loose fitting sleeve of pia mater
Arachnoid granulations (villi)
csf is gradually reabsorbed into the blood through arachnoid granulations, finger like extensions of the arachnoid mater that project into the dural venous sinuses
Subarachnoid space in the brain
csf continually circulates through cavities in the brain and spinal cord and around the brain and spinal cord in the subarachnoid space.
venous sinus
the dural venous sinuses drain into the internal jugular veins to return blood from the head to the heart
what is the cerebrum divided by
falx cerebri and the longitudinal fissure
where are the lateral ventricles enclosed
cerebrum
a prominent sulcus is called the…
central cerebral sulcus; which forms a landmark in the brain that separates the frontal and parietal lobes of the cerebrum
Frontal lobe description and function
important for voluntary movement, expressive language, and higher level executive functions such as creativity, reasoning and abstract thinking
Parietal lobe description and function
primarily responsible for receiving and processing sensory input such as touch, pressure, heat, cold and pain
Temporal lobe description and function
- sound and audio perception
- receives impulses for smell
- visual association
Occipital lobe description and function
receives visual information including color, form and motion
Lateral cerebral sulcus
separates the frontal lobe from the temporal lob.
- insula lies deep within the lateral cerebral sulcus
Insula
responsible for gustatory ad sensorimotor processing, risk-reward behaviour, autonomics, pain pathways and auditory and vestibular functions
it is because of the insula we are able to…
perceive pain and awareness about the body and self
Cerebral white matter
consists primarily of myelinated axons in 3 types of tracts:
- association tracts
- commisural tracts
- projection tracts
Cerebral cortex
specific types of sensory, motor and integrative signals are processed in certain regions of the cerebral cortex:
- primary sensory areas receives sensory information that has been relayed from peripheral sensory receptors through lower regions of the brain
What is the second largest part of the brain
cerebellum
What part of the brain contains nearly half of the neurons found in the brain
cerebellum
Function of the cerebellum
- plays a role in movement regulation and balance control
- coordinates gait, and maintains posture, controls muscle tone and voluntary muscle activity but is unable to initiate muscle contraction
the brainstem consists of…
the midbrain, pons and medulla oblongata
What does the brainstem do
transmit sensory and motor input from the spinal cord to the cerebral hemispheres to be processed
What is immediately superior to the spinal cord
the medulla oblongata
Most of the large motor tracts descending from the cerebrum cross over at the …
medulla so that skeletal muscle fibers on the right side of the body are controlled by the left side of the brain
Arbor vitae (cerebellum)
- deep to the gray matter are tracts if white matter called arbor vitae that resemble branches of a tree
- it brings sensory and motor information to and from the cerebellum
Pituitary gland
monitors and regulates bodily functions through the hormones it produces and releases
Infundibular stalk of pituitary gland
connects the pituitary gland to the hypothalamus
Midbrain (mesencephalon)
- extends from the pons to the diencephalon
- the aqueduct of midbrain passes through connecting the third ventricle
- like the medulla and pons, it contains both nuclei and tracts
Pons
- acts as a bridge connecting parts of the brain with others
- these connections are provided by bundles of axons; some axons of the pons connect to the right and left sides of the cerebellum
Medulla oblongata
its white matter contains all sensory (ascending) and motor (descending) tracts that extend between the spinal cord and other parts of the brainstem
The diencephalon is the central region of the brain that can only be seen
in saggital section as they are enclosed by the cerebrum, cerebellum and brainstem
The thalamus forms
lateral walls of the diencephalon and encloses the third ventricle
centrally located in the thalamus is the
interthalamic adhesion
the hypothalamus is the floor of the diencephalon and gives rise to
the infundibular stalk, a ventral down growth of tissue that attaches to the pituitary gland
The epithalamus is
the roof of the diencephalon, the tissue superior to the third ventricle
within the epithalamus is the
pineal gland, a small posterior projection of endocrine tissue
the pineal gland secretes…
melatonin
The cerebral hemispheres connected internally by a broad band of white matter containing axons is ….
Corpus callosum
The thalamus is mostly composed of
gray matter
Function of thalamus
- it is composed mostly of different nuclei that each serve a unique role ranging from relaying sensory and motor signals as well as regulation of consciousness and alertness
Function of hypothalamus
- controls many of the bodies activities and is one of the major regulators of homeostasis
- sensory impulses related to both somatic and visceral senses arrive at hypothalamus
- other receptors within the hypothalamus itself continually monitor osmotic pressure, blood glucose levels, certain hormone concentrations and the temperature of blood
The ventricles of the brain
cavities within the brain that are filled with cerebrospinal fluid
The 2 lateral ventricles that are enclosed in the cerebral hemispheres are separated by thin membranes called
the septum pellucidum
Where is the third ventricle found
in the thalamus
where is the fourth ventricle found
between the cerebellum and brainstem
Within each of the ventricles are networks of capillaries called
choroid plexuses that are lined by ependymal cells
What is the marking that allows csf to flow from the lateral ventricles to the third ventricle
interventricular foramina
where does csf flow after the third ventricle
into the aqueduct of the midbrain and into the fourth ventricle
from the fourth ventricle the csf goes to
the central canal of the spinal cord and the subarachnoid space
What are 3 functions of the spinal cord
- protect the brain and spinal cord from trauma by absorbing shock
- supplies nutrients to the nervous system tissue
- removes waste products via cerebral metabolism
Oxygen and glucose are brought into the brain via
interna carotid arteries
Why are the choroid plexuses important in the nervous system
form and circulate csf
- serves as a barrier in the brain separating the blood from csf, known as blood-csf barrier
What are two main functions of the cerebral arterial circle
- provides adequate blood supply to the brain; if one vessel gets blocked, blood has another way of reaching the brain
- multiple blood vessels helps to equalize the blood pressure in the brain
How does the cerebella function test demonstrate functions of the cerebellum
it tests gait and balance, and pronator drift; coordination, balance, smootheness of movement
optic chiasm
where the optic nerve decussates allowing the same visual field in both eyes
