Chapter 35: Nerves and the Nervous System

The two main divisions of the human nervous system

The Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

The three specific functions of the nervous system

Receiving sensory input, performing integration, and generating motor output.

Dendrites

Receives signals from sensory receptors or other neurons.

Nerve fiber

Any long axon of a neuron.

Motor neurons

Accept nerve impulses from the CNS and transmit them to muscles or glands.

Sensory neurons

Accept impulses from sensory receptors and transmit them to the CNS.

Interneurons

Convey nerve impulses between various parts of the CNS.

Glial cells

Support, protect, and nourish neurons.

Oligodendrocytes

Glial cells that form the myelin sheath in the CNS

Schwann cells

Glial cells that form the myelin sheath in the PNS

Meninges

The three protective membranes that wrap around the brain and spinal cord

Other parts of the CNS

Cerebrospinal fluid(subarachnoid space), ventricles, dura mater, arachnoid mater, subarachnoid space(CSF lives here), and the pia mater

Gray matter in the spinal cord

Consists of cell bodies and short unmyelinated fibers

White matter in the spinal cord

Consists of myelinated long fibers

Cerebrum

Largest portion of the brain in humans

Cerebellum

Receives sensory input from eyes, ears, joints, and muscles to coordinate balance and movement from the brain

Longitudinal fissure

Divides the cerebrum into cerebral hemispheres

What are the two main functions of the spinal cord?

It is a center for many reflex actions and is the main means of communication between the brain and spinal nerves

What structures compose the brain stem?

The midbrain, the pons, and the medulla oblongata

Cerebral cortex

A thin but highly convoluted outer layer of gray matter that covers the cerebral hemispheres

Diencephalon

Consists of the hypothalamus and thalamus

Hypothalamus

Controls the endocrine system via the pituitary gland and acts as the body's thermostat.

Thalamus

Acts as the gateway for sensory information traveling to and from the cerebral cortex.

Pineal gland

Secretes melatonin and contributes to dreams and R.E.M. during sleep

Dorsal parts of the CNS

Tend to be sensory in function

Ventral parts of the CNS

Tend to be motor in function

What is the primary difference between the somatic and autonomic nervous systems?

The somatic system controls skeletal muscles consciously, while the autonomic system controls smooth muscles, cardiac muscles, and glands involuntarily.

The two divisions of the autonomic nervous system

The sympathetic division and the parasympathetic division.

The primary function of the sympathetic division

Manages 'fight or flight' responses, such as accelerating the heartbeat and dilating bronchi.

The primary function of the parasympathetic division

Promotes internal responses associated with a relaxed state, such as digestion and slowing the heartbeat.

How many pairs of cranial nerves are there?

12

How many pairs of spinal nerves are there?

31