Introduction to the Nervous System Flashcards
Learning Objectives
Review the function and general organization of the central and peripheral nervous systems
Summarize the differences between gray and white matter with regard to location, composition, and nomenclature.
Contrast the general features of the sympathetic and parasympathetic nervous systems.
Briefly describe the meningeal layers of the brain and spinal cord.
Identify the major areas of the ventricular system.
Identify the different lobes and divisions of the brain and their associated functions.
Describe the features of a transverse section of spinal cord.
Briefly describe the basic anatomy of a typical spinal nerve.
What does the Central nervous system consist of?
Consists of the spinal cord, brain stem, cerebellum and cerebrum
What does Peripheral nervous system consist of?
Cranial and spinal nerves consisting of ganglia
What does the encephalon (brain) consist of?
Consists of brain stem, cerebellum and cerebrum
What are three parts of the brain stem from superiorly to inferiorly?
Midbrain, medulla and pons
Know where the CNS is and where the parts are anatomically
Use Flash cards to self test
What is a neuron
An excitable nerve which transmits information as electric signals or action potentials
What does a neuron consist of?
A neuron consists of a cell body (soma) and neurite. A neurite can either be an axon or dendrite
What is an axon
An axon is a single long dendrite covered with myelin or Schwann sheath
What is a dendrite?
They are short, multiple, thin neurites.
What are glial cells?
Glial cells maintain homeostasis, form myelin, and provide support and protection for neurons in the central and peripheral nervous systems
Name the glial cells in the PNS and their functions
Satellite cells: cells that cover the surface of nerve cell bodies in sensory, sympathetic and parasympathetic ganglia
Schwann cells: Myelin production
Name the glial cells in the CNS and their functions
Oligodendrocytes: Myelin production
Astrocytes: Blood brain barrier
Microglia: Remove unwanted material
Ependymal cells: CSF production
What does Myelin do?
Myelin makes electrical conduction faster and with less energy required
What cell makes unmyelinated axons?
Oligodendrocytes
Explain how neurons communicate
Neurons communicate through vesicles holding neurotransmitters in an axon going to the synapse and jumping across to the receptor of a dendrite
What is a ganglion?
The ganglion is a group of nerve cell bodies where usually the synapse takes place
What is gray matter?
Cell bodies of neurons and unmyelinated neurites
What is white matter?
Usually myelinated axons
Where do you find gray matter?
Grey matter is found on the surface of the brain and cerebellum and in the middle of the spinal cord
Where do you find white matter?
On the brain it is deep from the grey matter and is found on the surface of the spinal cord
What is afferent division?
Sensory neurons which conveys info from receptors in peripheral tissues and organs to the CNS
What is efferent division?
Comprises motor neurons which transmits signals from CNS to the effector cells (skeletal and smooth muscles, organs and glands)
Describe the basic task of the nervous system
A sensory input which is conveyed by afferent neurons goes to CNS. CNS decides to act on it by sending an impulse to the efferent neurons to the effector cells
What is the somatic nervous system?
A type of efferent division. Innervation of skeletal muscles which are voluntary movement.
What is the autonomic nervous system?
A type of efferent division. Innervation of smooth, cardiac muscles and glands which are involuntary movement
What is the sympathetic system ?
A type of autonomic nervous system. Fight or flight
What is the parasympathetic system?
A type of autonomic nervous system Rest and digest.
Where can the sympathetic system be found?
Found at the lateral horn of T1-L2 spinal cord segments
Where can the parasympathetic system be found?
Found at brain stem and S2-4 spinal cord segments
What is the function of meninges?
Protect the CNS
What are the layers of meninges from innermost to outermost?
Pia, arachnoid and dura
Describe the Dura
The most superficial and toughest layer
Has 2 layers, inner meningeal and outer periosteal layer. In between is the dural septa which secures the brain to the skull, dampen movement of the brain in the cranial cavity and divide the cranial cavity into freely communicating compartments
Describe the Arachnoid:
Web like structure near the dura
Describe the pia
Deepest structure in contact with the CNS tissue and enters every sulci. Highly vascular
Name the cerebral ventricles and locate them on flash cards
Lateral ventricle, 3rd and 4th centricle and central canal
What is CSF and where does it get absorbed?
A clear, cell free fluid produced in the choroid plexus in the lateral and 3rd ventricles
It gets absorbed by arachnoid granulations into dural venous sinuses
What does CSF do?
CSF acts as a cushion or buffer for the brain, providing basic mechanical and immunological protection to the brain inside the skull.
What are Gyri and Sulci?
Gyri are outside grooves of the brain and the sulci are the deep foldings of the brain
Describe the cerebrum in terms of layers.
Cerebral cortex, gray matter most superficial
Cerebral white matter
More gray matter most deep called nuclei
Know the lobes of the brain and sulci and where they are using cue cards
Check cue cards
What are the functions of the cerebrum?
Motor: Frontal lobe
Sensory:parietal lobe
Vision: occipital lobe
Auditory lobe: temporal lobe
Difference between right and left hemisphere of brain
Left: Language and math skills
Right: visual spatial and creativity skills
What does the diencephalon consist of?
Thalmus and Hypothalamus
What does the thalmus do?
Major relay station for sense
What does the hypothalamus do?
Autonomy control (para and symathetic), endocrine control, body temp, eating and sexual behavior
Midbrain functions
Visual and auditory reflex sense, motor skills
Pons functions
Conduction area between forebrain and cerebellum.
Respiration, hearing and balance
Medulla functions
Crossing of of hemisphere axons
Vital centers regulating respiration, blood pressure, heart rate
Non vital centers regulating coughing, sneezing, swallowing and vomiting
Explain the structure of the cerebellum
Convoluted with gray matter, white matter and nuclei.
Connect to the brain stem by superior, middle and inferior peducles
Function of cerebellum
Coordinated of motor activity, and memory of motor activity. (riding a bike)
Explain the structure of the spinal cord
A two way impulse conduction and reflex center which resides in the vetebral canal. Extends from the skull base but does not extend the length of the vertebral column
Types of spinal segments
Cervical: 8 Thoracic: 12 Lumbar: 5 Sacral: 5 Coccygeal:1
Types of spinal segments
Cervical: 8 Thoracic: 12 Lumbar: 5 Sacral: 5 Coccygeal: 1
How does the spinal nerve work?
Answer in lecture slides
