7 The Nervous System (Finals) Flashcards
What are the basic functions of the nervous system? (3)
- Sensation
- Integration
- Reaction
The nervous system monitors changes/events occurring in and outside the body. Such changes are known as __ and the cells that monitor them are __.
- stimuli
- receptors
The parallel processing and interpretation of sensory information to determine the appropriate response
Integration
- Motor output.
- The activation of muscles or glands (typically via the release of neurotransmitters)
Reaction
What is the main similarity between the nervous and endocrine systems?
They both monitor stimuli and react to maintain homeostasis.
1) Which system is known for rapid, fast-acting responses?
2) What system acts slower using hormones via the bloodstream and has longer-lasting actions?
1) Nervous System
2) Endocrine System
What are the two initial divisions of the nervous system? (2)
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)
What does the Central Nervous System (CNS) consist of?
- brain
- spinal cord
Initial division of the nervous system: Integration and control, processing information, initiating responses, and mental activity
Central Nervous System (CNS)
Initial division of the nervous system: To carry information to and from the brain and spinal cord
Peripheral Nervous System (PNS)
What does the Peripheral Nervous System (PNS) include? (4)
- Sensory receptors
- nerves
- ganglia
- plexuses
- A division that conducts action potentials from the periphery to the CNS
- Conducts impulses from receptors to the CNS and informs the CNS of the body’s state
Sensory division
- A division that conducts action potentials from the CNS to the periphery
- Conducts impulses from the CNS to effectors (muscles and glands)
Motor division
What are the three types of neurons that connect the CNS to the body? (3)
- Sensory (Afferent)
- Motor (Efferent)
- Interneurons
Which type of neuron conducts signals from sensory receptors to the CNS?
Sensory (Afferent) neurons
Which type of neuron conducts signals from the CNS to muscles and glands?
Motor (Efferent) neurons
What type of neuron connects different regions within the CNS?
Interneurons
What are the two (2) subdivisions of motor (efferent) division?
- Somatic Nervous System
- Autonomic Nervous System
What division of the motor system controls voluntary actions and innervates skeletal muscles?
Somatic Nervous System
What division of the motor system controls involuntary actions like heartbeat and digestion?
Autonomic Nervous System
What are the two subdivisions of the Autonomic Nervous System? (2)
- Sympathetic Nervous System
- Parasympathetic Nervous System
Which nervous system division is responsible for the “Fight-or-Flight” response?
Sympathetic Nervous System
Which nervous system division is responsible for the “Rest and Digest” response?
Parasympathetic Nervous System
What are the two (2) subdivisions of the sensory (afferent) division?
- Somatic sensory
- Visceral Sensory
A subdivision of sensory (afferent) division that provides sensory information about touch, pain, pressure, vibration, temperature, and proprioception in the skin, body wall, and limbs. Also, hearing, equilibrium, vision, and smell.
somatic sensory
A subdivision of sensory (afferent) division that provides sensory information about stretch, pain, temperature, chemical changes, and irritation in the viscera; nausea and hunger. Also, taste.
visceral sensory
What effect does the sympathetic nervous system have on heart rate and blood pressure?
increases it
What effect does the parasympathetic nervous system have on heart rate and blood pressure?
lowers it
Which neurons control involuntary muscle movements and regulate internal organs?
Visceral motor neurons
What are the special visceral motor neurons that innervate pharyngeal arch muscles called?
Branchial Motor Neurons (Special Visceral Motor Neurons)
What are the two main cell types in nervous tissue? (2)
- Neurons (nerve cells)
- Neuroglia (glial cells)
Cells in the nervous tissue that receive stimuli and transmits action potentials
Neurons (nerve cells)
Cells in the nervous tissue that support and protect neurons
Neuroglia (glial cells)
How much more numerous are neuroglia compared to neurons?
They outnumber neurons by about 10 to 1
What part of the neuron is responsible for receiving inputs?
Dendrites
What part of the neuron is responsible for sending outputs?
Axons
Name the four types of neuroglia found in the CNS. (4)
- Astrocytes
- Oligodendrocytes
- Ependymal Cells
- Microglia
Which CNS glial cell helps form the blood-brain barrier?
Astrocytes
Cells that produce the myelin sheath for electrical insulation in the CNS
oligodendrocytes
Which CNS glial cell lines brain ventricles and the spinal cord’s central canal?
Ependymal Cells
Which CNS glial cell acts as specialized macrophages?
Microglia
What are the two types of glial cells found in the PNS? (2)
- Satellite Cells
- Schwann Cells
Glial cells in PNS that form myelin sheaths around larger nerve fibers and aid in neuronal regeneration
Schwann cells
Which PNS glial cell surrounds clusters of neuronal cell bodies?
Satellite Cells
Where is the concentration of K+ higher, inside or outside the neuron?
Inside the neuron
Where is the concentration of Na+ higher, inside or outside the neuron?
Outside the neuron
What maintains the concentration gradients of Na+ and K+ across the cell membrane?
Na+/K+ pumps
What is the typical resting membrane potential of a neuron?
-65 to -85 mV
What causes changes in a neuron’s membrane potential? (2)
- Changes in membrane permeability
- flow of ions
What type of ion channel is always open?
Non-gated ion channels (leak channels)
What type of ion channel opens only in response to a stimulus?
Gated ion channels
Name the three types of gated ion channels. (3)
- Voltage-gated
- ligand-gated
- stress-gated channels
Where do graded potentials typically occur in a neuron? (2)
- dendrites
- cell body
How far do graded potentials travel?
Only a short distance (a few millimeters)
Where does an action potential begin in a neuron?
axon hillock
What type of ion channels open during an action potential?
Voltage-gated Na+ and K+ channels
An action potential occurs at full strength if threshold is reached, or not at all if threshold is not reached.
“all-or-none” principle
What triggers an action potential?
Membrane depolarization to the threshold potential
How is the strength of an action potential signal maintained over long distances?
self-propagating and does not lose strength.
What is myelin primarily composed of?
lipids
Known as a lipid insulator and membranes of certain glial cells
myelin
Gaps in the myelin sheath containing many Na+ channels
Nodes of Ranvier
What is the name for the type of conduction in myelinated axons where signals “jump” from one node to the next?
Saltatory conduction
By how much does saltatory conduction increase action potential (AP) conduction speed?
50-100 times
Which organisms have more myelinated axons, vertebrates or invertebrates?
Vertebrates
What type of ion channels are found in high numbers in the terminal bouton of a chemical synapse?
Voltage-gated Ca2+ channels
What happens when an action potential reaches the terminal bouton of a neuron?
Ca2+ channels open, allowing Ca2+ to rush in and trigger exocytosis of synaptic vesicles.
What occurs after neurotransmitters are released into the synaptic cleft?
They diffuse across the cleft and bind to receptors on the subsynaptic membrane.
What is the effect of prolonged exposure to high levels of a neurotransmitter on receptor proteins?
The nerve cell may reduce the number of receptor proteins in the membrane.
It prolongs the transmission of signals across synapses by keeping neurotransmitters in the synapse for extended periods. (Name the drug and what do you call this drug)
- cocaine
- neuromodulator
Which neurotransmitter is associated with the pleasure messages affected by cocaine?
Dopamine
What is a potential cellular response to prolonged exposure to cocaine?
The cell may lower the number of dopamine receptor proteins on its surface.
Explain cocaine at synapses
- In synapses, cocaine acts by blocking the reuptake of certain neurotransmitters, mainly dopamine, serotonin, and norepinephrine, by binding to their respective transporter proteins.
- Normally, these neurotransmitters are released into the synaptic cleft, activate receptors on the postsynaptic neuron, and are then reabsorbed by the presynaptic neuron for recycling.
- By inhibiting reuptake, cocaine prolongs the presence of these neurotransmitters in the synaptic cleft, intensifying their effects and leading to increased stimulation of the postsynaptic neuron.
What type of matter in the CNS consists of bundles of myelinated axons?
White Matter
What type of matter in the CNS consists of masses of cell bodies and dendrites covered with synapses?
Gray Matter
In the spinal cord, the location of white matter is __, the gray matter is __
- at the surface
- inside
- conducts sensory information from the peripheral nervous system (both somatic and autonomic) to the brain
- conducts motor information from the brain
Spinal cord
What are the four (4) brain to effectors?
- skeletal muscles
- cardiac muscles
- smooth muscles
- glands
Somatic reflexes of clinical importance (6)
- Knee jerk reflex
- Ankle (Achilles) reflex
- Babinski reflex
- Plantar reflex
- Corneal reflex
- Abdominal Reflex
Extension of the lower leg in response to tapping the patellar tendon.
knee jerk reflex
What does a hypoactive knee jerk reflex indicate? (4)
- Peripheral nerve damage
- chronic diabetes
- neurosyphilis
- coma
Extension of the foot in response to tapping the Achilles tendon.
ankle jerk (Achilles) reflex
What does an absent ankle jerk reflex suggest? (2)
peripheral neuropathy due to diabetes mellitus and hypothyroidism
- Extension of the great toe in response to stimulation of the sole of the foot.
- normal in infants up to 1/2 years old
Babinski reflex
What does a positive Babinski reflex in adults indicate? (1 main, 3 diseases/conditions)
Damage to the corticospinal tract, seen in conditions like
- spinal cord injury
- brain tumors
- cerebral palsy
Plantar flexion of all toes and slight turning in of the foot in response to stimulation of the sole.
plantar reflex
What condition does the Babinski sign in adults indicate? (1 main, 2 diseases/conditions)
Upper motor neuron lesions, such as in
- stroke
- multiple sclerosis (MS).
A protective reflex causing the eye to blink in response to corneal stimulation.
corneal reflex
What does an absent corneal reflex indicate? (2)
damage to the trigeminal nerve or facial nerve due to cranial disease or brain disorders.
Drawing in of the abdominal wall in response to stroking the abdomen.
abdominal reflex
What does an absent abdominal reflex suggest? (2 main, 2 diseases/conditions)
corticospinal tract damage or issues with abdominal muscle nerves
- stroke
- multiple sclerosis (MS).
- Membranes that cover the brain and spinal cord, providing support by suspending, compartmentalizing, and coating these structures.
- They cannot be transplanted and are essential for brain support and protection.
meninges
The outermost, tough, durable layer of the meninges attached to the skull, also known as “Tough Mother.”
dura mater
The middle, web-like layer of the meninges, with a subarachnoid space containing cerebrospinal fluid (CSF).
arachnoid
The innermost, delicate layer of the meninges that adheres directly to the brain’s surface, also known as “Gentle Mother.”
pia mater
What is the region between the arachnoid and pia mater filled with?
Cerebrospinal fluid (CSF)
Where is cerebrospinal fluid (CSF) produced?
In the lateral ventricles by the choroid plexus.
What structure absorbs cerebrospinal fluid (CSF)?
arachnoid villi
It is the site of CSF production.
choroid plexus
They act as specialized “absorbing” filters for cerebrospinal fluid.
arachnoid villi
Supports the brain by holding cerebrospinal fluid (CSF) and supporting the meninges.
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