From Notes Flashcards
What is the primary composition of nervous tissue?
Neurons + Glial cells
What are the two main components of the nervous system?
Central nervous system + Peripheral nervous system
What structures comprise the central nervous system?
Brain + Spinal cord
What structures comprise the peripheral nervous system?
Cranial nerves, spinal nerves, ganglia
What are the two functional divisions of the nervous system?
Sensory nervous system + Motor nervous system
What are the components of the sensory nervous system?
Somatic sensory + Visceral sensory
What are the components of the motor nervous system?
Somatic motor + Autonomic motor
What are the three main functions of the nervous system?
Collect information, process and evaluate information, respond to information
What does the sensory nervous system do?
Receives sensory info from receptors and transmits to CNS
What type of sensory information does somatic sensory receive?
General somatic senses or 5 senses + special senses
What does visceral sensory transmit nerve impulses from?
Blood vessels + viscera to CNS
What does the motor nervous system transmit impulses to?
Effectors (muscles or glands)
What does somatic motor conduct?
Nerve impulses from CNS to skeletal muscles causing contraction
What does the autonomic motor regulate?
Smooth muscle, cardiac muscle, and glands
What are the key characteristics of neurons?
Excitable, conductive, secretory, long-lived, amitotic, highly metabolic
What are the main parts of a neuron?
Cell body, nucleus, axon, dendrites
What is the function of dendrites?
Receive information
What is the function of axons?
Transmit nerve impulses away from the cell body
What type of neurons do not have an axon?
Anaxonic neurons
Where do sensory neurons detect stimuli?
From receptors to CNS
Where do the cell bodies of most motor neurons lie?
In the spinal cord
What type of neurons are motor neurons classified as?
Multipolar
Where are interneurons located?
Within the CNS
What percentage of neurons are estimated to be interneurons?
99%
What are Glial Cells?
Smaller than neurons, capable of mitosis, do not transmit nerve impulses, assist neurons with their functions, protect and nourish neurons, provide organized supporting framework for nervous tissue, guide migrating neurons, play a role in memory through interactions with synapses.
How many types of glial cells are in the CNS?
4 types
What is the most abundant type of glial cell in the CNS?
Astrocytes
What do ependymal cells do?
Line internal cavities and produce cerebrospinal fluid
What is the function of oligodendrocytes?
Ensheath portions of axons and form myelin sheaths
From where are all three types of CNS glial cells derived?
Neural ectoderm
What are microglial cells derived from?
Stem cells in red bone marrow that become monocytes
What are the two types of glial cells in the PNS?
Satellite cells and neurolemmocytes (Schwann cells)
What is the role of satellite cells?
Surround neuronal cell bodies in ganglia, separate cell bodies from interstitial fluid, regulate exchange of nutrients and waste
What do neurolemmocytes (Schwann cells) do?
Wrap around PNS axons, insulating the axon and forming myelin sheaths
What forms the myelin sheath in the CNS?
Oligodendrocytes
What forms the myelin sheath in the PNS?
Neurolemmocytes (Schwann cells)
True or False: Glial cells transmit nerve impulses.
False
Fill in the blank: Glial cells provide organized supporting _______ for nervous tissue.
framework
What is the average brain volume?
1200 to 1500 cubic centimeters
What is the average weight of the brain?
1.35 to 1.4 kilograms
Does brain size determine intelligence?
No, the number of active synapses among neurons does.
What are the four major regions of the brain?
Cerebrum, diencephalon, brain stem, and cerebellum.
What are folds and depressions in the brain called?
Folds are called gyri and depressions are called sulci.
How many pairs of cranial nerves are there?
12 pairs of cranial nerves.
What are the three primary brain vesicles?
Prosencephalon, mesencephalon, and rhombencephalon.
What does the prosencephalon develop into?
Telencephalon (cerebrum) and diencephalon (thalamus, hypothalamus, epithalamus).
What is the mesencephalon renamed to?
Midbrain
What does the rhombencephalon develop into?
Metencephalon (pons and cerebellum) and myelencephalon (medulla oblongata).
What does gray matter contain?
Motor neuron and interneuron cell bodies, dendrites, terminal arborizations, and unmyelinated axons.
What is the outer layer of gray matter called?
Cortex
What does white matter contain?
Myelinated axons and lies deep to gray matter.
What are clusters of gray matter in white matter called?
Cerebral nuclei.
What provides rigid support for the brain?
Bony cranium.
What is the function of the meninges?
Protect, stabilize, and partition portions of the brain.
What is the function of cerebrospinal fluid (CSF)?
Cushioning.
What does the blood-brain barrier do?
Prevents harmful materials from leaving the blood.
What are the three layers of cranial meninges from deepest to superficial?
Pia mater, arachnoid mater, and dura mater.
What is the pia mater?
The innermost, thin layer of areolar connective tissue; highly vascularized and tightly adheres to the brain.
What is the arachnoid mater?
The middle layer, a delicate web of collagen and elastic fibers.
What is the subarachnoid space?
The space between the arachnoid and pia mater.
What is the subdural space?
The space between the arachnoid and dura mater.
What is the dura mater?
The dura mater is a dense irregular connective tissue and the strongest and outermost meninges.
How many layers does the dura mater have?
The dura mater has two layers: the meningeal layer and the periosteal layer.
What are cranial dural septa?
Cranial dural septa are double layers of dura mater.
Name the four cranial dura septa.
The four cranial dura septa are the falx cerebri, tentorium cerebelli, falx cerebelli, and diaphragma sellae.
What is the falx cerebri?
The falx cerebri is the largest of the four dural septa, a large, sickle-shaped vertical fold located in the midsagittal plane.
What does the tentorium cerebelli do?
The tentorium cerebelli is horizontally oriented and separates the occipital and temporal lobes of the cerebrum from the cerebellum.
What is the function of the tentorial notch?
The tentorial notch is a gap in the anterior surface of the tentorium cerebelli that allows for brainstem passage.
What is the falx cerebelli?
The falx cerebelli extends along the midsagittal plane inferior to the tentorium cerebelli and separates the left and right cerebellar hemispheres.
What does the diaphragma sellae do?
The diaphragma sellae is the smallest dural septa and forms a roof over the sella turcica of the sphenoid bone.
Where are the superior and inferior sagittal sinuses located?
The superior and inferior sagittal sinuses are located in the falx cerebri.
What is the transverse sinus?
The transverse sinus is located at the posterior border of the tentorium cerebelli.
Where is the straight sinus located?
The straight sinus is located in the midsagittal region of the tentorium cerebelli.
What is the confluence of sinuses?
The confluence of sinuses is where the superior sagittal sinus, falx cerebelli, and tentorium cerebelli meet, adjacent to the internal occipital protuberance.
What is the occipital sinus?
The occipital sinus is located within the posterior vertical border of the falx cerebelli.
What are ventricles in the brain?
Ventricles are cavities within the brain derived from the lumen of the embryonic neural tube.
How are the ventricles connected?
The ventricles are continuous with each other and the central canal of the spinal cord.
How many lateral ventricles are there?
There are two lateral ventricles in the cerebrum.
What is the septum pellucidum?
The septum pellucidum is the medial partition between the two lateral ventricles.
Where is the third ventricle located?
The third ventricle is located in the diencephalon and communicates with the lateral ventricles through the interventricular foramen.
What connects the third and fourth ventricles?
The cerebral aqueduct connects the third ventricle to the fourth ventricle.
Where is the fourth ventricle located?
The fourth ventricle is located between the pons/medulla and the cerebellum.
What is cerebrospinal fluid (CSF)?
CSF is a clear colorless liquid in the ventricles and subarachnoid spaces that bathes the exposed CNS and surrounds the brain and spinal cord.
What are the functions of cerebrospinal fluid (CSF)?
- Buoyancy: brain floats in CSF, supporting 95% of its weight.
- Protection: provides a liquid cushion and slows brain movement.
- Environmental stability: transports nutrients and chemicals and removes waste.
How is CSF formed?
CSF is formed by the choroid plexus, which consists of ependymal cells and capillaries within the pia mater.
What is the production rate of CSF?
The choroid plexus produces CSF at a rate of 500mL per day, with flow varying depending on time of day, respiration, posture, and ventilation.
What is the role of the blood-brain barrier (BBB)?
The BBB regulates what substances enter the interstitial fluid of the brain.
What structures are involved in the BBB?
Perivascular feet of astrocytes wrap around and envelope capillaries in the brain, and tight junctions between endothelial cells reduce capillary permeability.
What types of compounds can diffuse across the BBB?
Lipid-soluble compounds like nicotine, alcohol, and some anesthetics can diffuse across the BBB.
Where is the BBB reduced or missing?
The BBB is reduced or missing in the choroid plexus, hypothalamus, and pineal gland.
What is the cerebrum responsible for?
The cerebrum is the location of conscious thought processes and the origin of all complex intellectual functions.
What are the main structural features of the cerebrum?
The cerebrum consists of two large hemispheres on the superior aspect of the brain, formed from the telencephalon, with an outer layer of gray matter (cerebral cortex) and an inner layer of white matter.
How are the cerebral hemispheres separated?
The hemispheres are separated by a deep longitudinal fissure along the midsagittal plane, except at bundles of axons that form tracts for communication.
What is the largest tract in the cerebrum?
The largest tract is the corpus callosum.
How many distinct lobes does each hemisphere have?
Each hemisphere has 5 distinct lobes: 1) Frontal, 2) Parietal, 3) Temporal, 4) Occipital, 5) Insula (not visible).
What is the frontal lobe?
The anterior part of the cerebral hemisphere, ending at a deep groove called the central sulcus.
What is the precentral gyrus?
A mass of nervous tissue located anterior to the central sulcus.
What is the diencephalon?
A part of the prosencephalon located between the inferior regions of the cerebral hemispheres.
What structures make up the diencephalon?
The epithalamus, thalamus, and hypothalamus.
What is the function of the diencephalon?
It serves as relay and switching centers for some sensory and motor pathways and for control of visceral activities.
What is the epithalamus?
The partial posterior root of the diencephalon that covers the 3rd ventricle, housing the pineal gland and habenular nuclei.
What is the thalamus?
Paired oval masses of gray matter on each side of the 3rd ventricle, acting as the principal relay point for sensory information.
Where is the thalamus located?
In the superolateral walls of the 3rd ventricle, between the anterior commissure and pineal gland.
What connects the left and right thalamic bodies?
The interthalamic adhesion.
What is the function of the hypothalamus?
Master control of the autonomic nervous system and endocrine systems, regulation of body temperature, and control of emotional behavior, food/water intake, and sleep-wake cycles.
What connects the prosencephalon and cerebellum to the spinal cord?
The brainstem.
What are the three regions of the brainstem?
1) Midbrain 2) Pons 3) Medulla oblongata.
What is the midbrain responsible for?
Contains the cerebral aqueduct and cranial nerves (CN III and IV).
What is the function of the pons?
A bulging region that acts as a relay station and contains respiratory centers.
What is the medulla oblongata?
The inferior part of the brainstem that contains centers for vital functions.
What are cerebellar peduncles?
Three thick tracts that connect the cerebellum to the brainstem.
What do the superior cerebellar peduncles connect?
The cerebellum to the midbrain.
What do the middle cerebellar peduncles connect?
The pons to the cerebellum.
What do the inferior cerebellar peduncles connect?
The cerebellum to the medulla oblongata.
What is the spinal cord?
The spinal cord is a vital link between the brain and the rest of the body.
What are the two important functions of the spinal cord and attached nerves?
1) It serves as a pathway for sensory and motor impulses. 2) It is responsible for reflexes.
What is the size of the adult spinal cord?
The adult spinal cord is 3/4 inch in diameter and 16 to 18 inches long.
Where does the spinal cord extend from and to?
It extends inferiorly from the medulla oblongata through the foramen magnum and vertebral canal, ending at the inferior border of the L1 vertebra.
What are the five parts of the spinal cord from superior to inferior?
1) Cervical part 2) Thoracic part 3) Lumbar part 4) Sacral part 5) Coccygeal part.
How many pairs of spinal nerves are associated with the spinal cord?
The spinal cord is associated with 31 pairs of spinal nerves.
What are spinal nerves?
Spinal nerves are mixed nerves that contain both motor and sensory axons.
What protects and encapsulates the spinal cord?
The spinal cord is protected and encapsulated by spinal cord meninges, which are continuous with cranial meninges.
What are the structures/spaces encircling the spinal cord from outer to inner?
The structures are: vertebra, epidural space, dura mater, subdural space, arachnoid mater, subarachnoid space, and pia mater.
What are the two regions of the spinal cord?
The inner region is gray matter, and the outer region is white matter.
What does gray matter contain?
Gray matter contains dendrites, neuron cell bodies, glial cells, and unmyelinated axons.
What does white matter contain?
White matter contains myelinated axons.
What are the anterior horns of the spinal cord responsible for?
The anterior horns contain cell bodies of autonomic motor neurons.
What do the posterior horns of the spinal cord contain?
The posterior horns contain axons of sensory neurons and cell bodies of interneurons.
What is the structure of a neuron?
Each neuron has 1 axon and multiple dendrites.
How do autonomic neurons compare to somatic neurons?
Autonomic neurons are generally smaller than somatic neurons.
What is a synapse?
A synapse is the site of connection between neurons.
Do neurons undergo cell division?
Neurons do not undergo cell division.
What are glial cells?
Glial cells are repair cells that do undergo cell division.
What do oligodendrocytes produce?
Oligodendrocytes produce the myelin sheath in the autonomic nervous system.
What are neurolemmal or Schwann cells?
Neurolemmal or Schwann cells are involved in myelination in the peripheral nervous system.
Do microglial cells produce myelin?
Microglial cells do not produce myelin.
What do most brain capillaries do?
Most brain capillaries are continuous and do not leak.
What are the types of synaptic activities?
Synaptic activities can be electrical and chemical.
What is an example of electrical synaptic activity?
An example of electrical synaptic activity is cardiac activity.
What originates from the thalamus?
The thalamus originates from various sensory modalities.
What is the primary visual area of the brain?
The occipital lobe is responsible for primary visual processing.
What is the function of the temporal lobe?
The temporal lobe is involved in auditory and olfactory processing.
What is the role of the insula?
The insula is involved in gustation.
Where are speech centers located?
Speech centers are partly in the temporal lobe of the dominant hemisphere.
What is the dominant hemisphere responsible for?
The dominant hemisphere is the categorical hemisphere.
What is the non-dominant hemisphere responsible for?
The non-dominant hemisphere is the representational hemisphere.
Where are cranial nerves visible?
Cranial nerves are visible on the lateral olives.
Is the trigeminal nerve visible on the dorsal aspect of the cerebellum?
The trigeminal nerve is not visible on the dorsal aspect of the cerebellum.
Where is the cerebral aqueduct located?
The cerebral aqueduct is located within the midbrain.
What circulates around the brain?
Cerebrospinal fluid (CSF) circulates around the brain and in the subarachnoid space.
What is the subdural space?
The subdural space is a potential space.
How much cerebrospinal fluid is produced daily?
Approximately ¼ liter of CSF is produced daily.
What is the choroid plexus?
The choroid plexus consists of ependymal cells and capillaries.
What do the pyramids in the spinal cord become?
The pyramids go down the spinal cord and become tracts.
What type of neurons do pyramids have?
Pyramids have somatic motor neurons.
Which cranial nerves are associated with motor activity?
Cranial nerves associated with motor activity include CN III (oculomotor), CN IV (trochlear), CN IX (glossopharyngeal), CN X (vagus), and CN V (trigeminal).
What is the function of cranial nerve VII?
Cranial nerve VII (facial nerve) controls the facial muscles of expression.
What connects the two hemispheres of the brain?
The corpus callosum connects the two hemispheres of the brain.
What is the main function of the cerebellum?
The main function of the cerebellum is to coordinate movement.
What does the embryonic mesencephalon give rise to?
The embryonic mesencephalon gives rise to structures in the midbrain.
What do dural venous sinuses do?
Dural venous sinuses drain blood from veins to the internal jugular vein.
What are cerebral nuclei?
Cerebral nuclei consist of cell bodies that cannot be myelinated.
What is the hypothalamus connected to?
The hypothalamus is connected to the pituitary gland through the infundibulum.
What is located at the lower end of the spinal cord?
The lower end of the spinal cord is the connection of spinal cord roots with no spinal cord.
What is a dermatomal map?
A dermatomal map shows the areas of skin supplied by specific spinal nerves.
What is the lamina of vertebrae?
The lamina of vertebrae is located posterior to the spinal cord.
What is the Golgi tendon organ?
The Golgi tendon organ is a proprioceptive sensory receptor that senses tension in muscles.
What is the perineum?
The perineum starts from the pubic symphysis to the ischial tuberosities and the coccyx.
What is ovulation?
Ovulation is the release of an egg from the ovary.
What are other names for the uterine tube?
Other names for the uterine tube include fallopian tube and oviduct.
What is the primary function of the spermatic cord?
The primary function of the spermatic cord is to support the testes and facilitate the passage of blood vessels, nerves, and the vas deferens.
True or False: The spermatic cord is only found in males.
True
Fill in the blank: The spermatic cord contains the _______ which transports sperm from the testes to the ejaculatory duct.
vas deferens
Which structure within the spermatic cord is responsible for thermoregulation of the testes?
The pampiniform plexus
What are the two main blood vessels found in the spermatic cord?
The testicular artery and the cremasteric artery
Multiple Choice: Which of the following is NOT a component of the spermatic cord? A) Vas deferens B) Testicular artery C) Ureter D) Pampiniform plexus
C) Ureter
What nerve innervates the cremaster muscle found in the spermatic cord?
The genitofemoral nerve
Short Answer: Name a common clinical condition associated with the spermatic cord.
Spermatic cord torsion
True or False: The spermatic cord is located in the scrotum.
False
What is the significance of the cremaster reflex in relation to the spermatic cord?
The cremaster reflex helps in the elevation of the testes to regulate temperature and protect them.
