Exam 3 Short Answer Questions (Nervous System) Flashcards
What is a neurological reflex? Why are reflexes important?
A neurological reflex is a quick, unconscious, automatic response to a stimulus to protect or maintain homeostasis.
Reflexes are important because they minimize any damage to the body from potentially harmful conditions, such as touching something hot.
What structures are involved in a reflex arc?
The reflex arc is a neural pathway involved in the production of a reflex.
Structures include:
- receptor
- sensory neuron
- integrating center (brain or spinal cord)
- motor neuron
- effector
Draw a simple diagram of a typical stretch reflex and a withdrawal reflex and explain these reflexes.
- Stretch Reflex
1) Stretching of muscle tendon stimulates muscle spindles.
2) Activation of motor neuron produces reflex muscle contraction. - Withdrawal Reflex
1) Arrival of stimulus & activation of receptor
2) Activation of a sensory neuron
3) Information processing in the CNS
4) Activation of a motor neuron
5) Response by peripheral effector
Describe in detail the process of Action potential conduction.
1) A graded depolarization brings an area of excitable membrane to threshold (-60mV)
2) Voltage-gated sodium channels open & sodium ions move into the cell. The membrane potential rises to +30mV
3) Sodium channels close, voltage-gated potassium channels open & potassium ions move out of the cell. Re-polarization begins.
4) Potassium channels close & both sodium and potassium channels return to their normal states.
What are the functions of Cerebrospinal fluid (CSF)?
Cerebrospinal fluid (CSF) functions in:
- protection of central nervous system (CNS)
- support
- nutrient supply
- waste removal
Where is CSF produced? What structures create it, and by what process is it created?
Cerebrospinal fluid is produced within ventricles of the brain. It is a clear colorless fluid formed by filtration of blood plasma by choroid plexuses.
Describe the pathway of CSF circulation within and around the CNS.
Cerebrospinal fluid circulates through ventricles, into central canal of spinal cord, around the brain and spinal cord in sub arachnoid space.
How and where is CSF reabsorbed?
Cerebrospinal fluid is reabsorbed through arachnoid granulations into dura sinuses and then into bloodstream.
What type of information (in general) is carried along the ascending tracts/pathways?
Ascending tracts carry sensory information up the spinal cord to areas of the brain.
What type of information (in general) is carried along the descending tracts?
Descending tracts carry motor information from the brain down to specific levels of the spinal cord.
