BIOS 3450 Ch. 5 Central Nervous System

What are the two major divisions of the nervous system?

Central nervous system (CNS) and peripheral nervous system (PNS).

What structures make up the central nervous system?

The brain and spinal cord.

What does the afferent division of the PNS do?

It carries incoming messages to the CNS.

What does the efferent division of the PNS do?

It carries outgoing messages from the CNS to effector organs such as muscles and glands.

What does the somatic nervous system control?

Motor neurons.

What does the autonomic nervous system control?

Smooth muscle, cardiac muscle, and glands.

What is the sympathetic nervous system associated with?

"Fight or flight."

What is the parasympathetic nervous system associated with?

"Rest and digest."

What are some functions affected by the autonomic nervous system?

Heart rate, blood pressure, pupils, digestion, and bladder function.

What is the enteric nervous system?

A separate portion of the autonomic nervous system consisting of a neural network associated with the digestive tract.

What does the enteric nervous system regulate?

Peristalsis, secretion of enzymes/hormones/mucus, blood flow, and other digestive functions.

How does the enteric nervous system communicate with the CNS?

Through hormones, the vagus nerve, nutrients, and other signals.

What are the three functional classes of neurons?

Afferent neurons, efferent neurons, and interneurons.

What does an afferent neuron do?

It carries sensory input toward the CNS.

Where does an efferent neuron originate?

In the CNS.

What does an efferent neuron do?

It delivers commands to muscles and glands.

Where are interneurons located?

Entirely within the CNS.

What is the primary role of interneurons?

They integrate afferent information with efferent responses and process information throughout the CNS.

What are glial cells?

Cells that support neuron structure and metabolism.

What do astrocytes do?

They provide structural support, help form the blood-brain barrier, help store and transfer nutrients, and affect neuronal excitability.

Which glial cells form myelin in the CNS?

Oligodendrocytes.

What is the primary role of microglia?

They provide immune defense in the CNS and respond to damage and inflammation.

What do ependymal cells do?

They line the ventricles, help form CSF, and use cilia to move CSF through the ventricles.

What percentage of CNS cells are described as glial cells in the lecture?

About 50%; the lecture notes that the textbook says 90%.

What structures protect the brain?

The cranium, meninges, cerebrospinal fluid (CSF), and blood-brain barrier (BBB).

What are the three layers of the meninges?

Dura mater, arachnoid mater, and pia mater.

Where is cerebrospinal fluid found?

In the subarachnoid space and ventricles.

What is the main function of CSF?

It cushions and bathes the brain.

Where is CSF formed?

By ependymal cells in the choroid plexus along the ventricle walls.

What is the pathway of CSF flow?

CSF is formed in the choroid plexus, circulates through the ventricles, exits the fourth ventricle, flows through the subarachnoid space, and is reabsorbed across arachnoid villi into the dural sinus.

What is the blood-brain barrier?

A highly regulated system that controls substances entering the brain from the blood.

Is the BBB a continuous physical barrier surrounding the brain?

No. It is an integrated part of the brain's vasculature.

What cells are important components of the neurovascular unit?

Endothelial cells, astrocytes, and pericytes.

How do substances cross the BBB according to the lecture?

They must pass through endothelial cells rather than between them.

What is the neurovascular unit?

An integrated system involving neural, glial, and vascular components.

What are the major regions of the brain listed in the study guide?

Brain stem, cerebellum, and forebrain regions including the diencephalon and cerebrum.

Approximately how many neurons does the brain have?

About 86 billion neurons.

What is gray matter composed of?

Neuron cell bodies, dendrites, and glial cells.

What is white matter composed of?

Bundles of myelinated axons.

What is the function of white matter?

It transmits signals between different parts of the brain and body.

What are the four paired lobes of the cerebral cortex?

Frontal, parietal, temporal, and occipital lobes.

What is the primary function of the frontal lobe?

Motor control, speaking, thought, planning, emotion, problem solving, and executive function.

Where is the primary motor cortex located?

In the precentral gyrus of the frontal lobe.

What does the primary motor cortex control?

Voluntary motor control.

What is the premotor cortex involved in?

Movement planning and motor control.

What is the prefrontal cortex involved in?

Higher-order thinking, executive function, planning, problem solving, and related functions.

What does contralateral organization mean?

The cortex primarily controls or processes information from the opposite side of the body.

What is the primary function of the parietal lobe?

Processing sensory information, including somesthetic information and proprioception.

Where is the somatosensory cortex located?

In the postcentral gyrus of the parietal lobe.

What does the somatosensory cortex process?

Somatic sensory information and proprioception.

What does the posterior parietal cortex do?

It integrates complex sensory information.

What is the primary function of the temporal lobe?

Auditory processing, language processing, memory formation/retrieval, visual perception, and emotional processing.

What is Wernicke's area associated with?

Speech/language processing.

What is Broca's area associated with?

Planning sound patterns to coordinate with the primary motor cortex.

What is the primary function of the occipital lobe?

Receiving, processing, and interpreting visual information.

What is the primary visual cortex responsible for?

Processing visual input.

What does the visual association cortex do?

It helps interpret visual information.

What does the parietal-temporal-occipital association cortex do?

It integrates somatic, auditory, and visual information.

What is a gyrus?

A hill or ridge of the cerebral cortex.

What is a sulcus?

A valley or groove of the cerebral cortex.

What are the major functions of the basal nuclei?

Motor control, motor learning, habits, reward, and inhibition of unwanted movement.

How do the basal nuclei influence movement?

Dopaminergic neurons regulate direct excitatory and indirect inhibitory motor pathways.

What happens to dopamine in Parkinson's disease according to the lecture?

Degeneration of cells in the substantia nigra reduces dopamine.

What is the function of the thalamus?

It relays sensory signals to the cortex and motor signals from the cerebellum and basal nuclei to the motor cortex.

How does the thalamus contribute to consciousness?

It helps regulate consciousness, sleep, and awareness by filtering incoming sensory stimuli.

What is the main function of the hypothalamus?

Homeostatic regulation.

How does the hypothalamus connect different body systems?

It links the autonomic nervous system and endocrine system.

What functions does the hypothalamus help control?

Body temperature, hunger, thirst, urine output, pituitary hormone output, autonomic coordination, and emotional/behavioral patterns.

What brain structure is important for short-term memory?

The hippocampus and surrounding medial temporal lobe.

What is the role of the hippocampus in memory?

It helps potentiate short-term memory into long-term memory in the cortex.

Is the hippocampus the storage site for long-term memories?

No. The study guide states that it is not a site of long-term memory storage.

What is long-term potentiation?

A process that strengthens preexisting synaptic connections and helps form long-term memories.

Where is long-term memory primarily stored?

In the cerebral cortex across various lobes.

What is declarative memory?

Memory for facts and events, primarily associated with temporal and frontal regions.

What is non-declarative memory?

Memory for skills and habits, associated with the cerebellum and basal ganglia.

What is working memory?

Active manipulation and "rehearsed" echo of incoming information.

Which brain region is associated with working memory?

The prefrontal cortex.

What structure has close ties to the hippocampus and emotional memory?

The amygdala.

What is the main function of the cerebellum?

Coordination of balance and movement.

What does the vestibulocerebellum control?

Balance and eye movement.

What does the spinocerebellum do?

It integrates and coordinates movement.

What does the cerebrocerebellum do?

It helps plan and initiate movement.

What is the role of the primary motor cortex in movement?

It issues the initial command and final descending signal.

What is the role of the basal nuclei in movement?

They act as an "editor" by inhibiting unwanted movement.

What is the role of the cerebellum in movement?

It acts as an "adjuster" by correcting movement errors in real time for balance and coordination.

What is the role of the thalamus in movement?

It relays processed information to the cortex.

What structures make up the brain stem?

The midbrain, pons, and medulla.

What are some essential functions regulated by the brain stem?

Breathing, heart rate, blood pressure, and digestion.

What is the pons associated with?

The origin of 10 of the 12 cranial nerves and regulation of essential autonomic functions.

What are some functions of the midbrain?

Eye movement, motor control, auditory/visual processing, startle response, and relaying information between the cerebrum and cerebellum.

What does the reticular formation do?

It integrates sensory input and contributes to respiratory and cardiovascular centers.

What protects the spinal cord?

The vertebral canal.

Where do paired spinal nerves emerge?

At each vertebra.

Where do afferent neurons enter the spinal cord?

Through the dorsal root.

Where are the cell bodies of afferent neurons located?

In the dorsal root ganglion.

Where do efferent neurons exit the spinal cord?

Through the ventral root.

Where are the cell bodies of efferent neurons located?

In the ventral horn of the spinal gray matter.

What is a ganglion?

A cluster of cell bodies located outside the CNS.

What is a nerve?

A bundle of axons that can contain many independent afferent and efferent axons.