The Nervous System

The role of the NS is to send signals throughout the role of the body to maintain homeostasis, control movement, and thoughts

The Four Main Functions of the Nervous System:

1. Reception of General Sensory Information (relates to touch senses)

2. Receiving and Perceiving Special Sensations (all other than touch(taste, smell, vision, and sounds))

3. Integration of Sensory Information from other parts of the body (the brain and spinal cord) and processing them

4. Response Generation your response by speaking

Major 2 Categories of Functions of the NS:

1. Somatic Functions- people can control voluntarily like picking up a pencil

2. Autonomic/Automatic functions- people CANNOT control involuntarily like your heart beating

Divisions of the NS:

• Central Nervous System (CNS)- made up of only the brain and spinal cord

• Peripheral Nervous System (PNS)- made up of nerves that connect to the CNS and the rest of the body

Three General Functions of the NS:

1. Sensory Input- info gathered through various sensory systems such as vision, hearing, touch, taste, and smell (5 senses).

2. Integration- the process that interprets the sensory input to make a decision

3. Motor Output- the response affected by the effector organs which are muscles and glands

Pathway of Nerve Impulse:

sensory receptor; sensory neuron; interneuron

; another interneuron; motor neuron;effector

Explanations of the Nerve Impulse Pathway:

• Sensory Receptor- monitors changes both inside and outside the body

• Sensory Neuron- the nerve cells that are activated by sensory input/ the environment

• Interneuron-neuron that transmits impulses between other neurons, especially as a part of a reflex arc

• Reflex Arc- neural pathway that controls reflexes

• Motor Neuron- cells in the brain and spinal cord that allows us to move and speak by sending commands from the brain to muscles.

• Effector- a cell that reacts in response to stimuli

Central NS:

Brain meniges: the covering of the brain and spinal cord

Functions:

1. Protect the brain and spinal cord

2. Produce cerebrospinal fluid from the outside in: Dura mater; Arachnoid mater; Pia mater

• Dura Mater: the tough outer layer of tissue that covers and protects the brain and spinal cord and is closest to the skull.

• Arachnoid Mater: a thin, transparent membrane surrounding the spinal cord like a loosely fitting sac.

• Pia Mater: delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord.

Peripheral NS:

Somatic- overseas voluntary movements

Autonomic- controls involuntary movements

1. Maintaining Homeostasis- stable internal environment

2. Two Divisions:

   Parasympathetic Division-operates under normal conditions

   Sympathetic Division- operates under stressful or fearful conditions

The Four Main Divisions of the Brain:

• Cerebrum- largest portion; higher mental functions; logic

• Diencephalon- processes sensory input

• Cerebellum- coordinates muscle activity; balance

• Brain Stem- regulates actions of internal organ; internal; stability

Cerebrum:

• Corpus Callosum- connects the two hemispheres

• Gyri are the high parts while sulci are the groves (increases the surface area)

• Ventricles- cavities in the cerebrum and are filled with cerebrospinal fluid

• Cerebral Cortex- outer layer of the cerebrum made of gray matter (under that is white matter)

• Thalamus- directs sensory info to the correct place

• Hypothalamus- maintains homeostasis

• Limbic System- controls emotional experiences

• Pituitary Gland- the master gland of the body; produces hormones

Four Lobes:

1. Frontal

2. Parital

3. Temporal

4. Occipital

Higher Brain Functions

• Senson oracles- interprets sensory input (senstations)

• Association- area-analyze and interpret

• Motor Area- speech and vision

Brain Stem

• Midbrain (superior)- connects the brain and spinal cord

• Pons- controls rate and depth of breathing

• Medulla Oblongata- contains centers

  1. Cardiac Center- controls heart rate

  2. Respiratory Center- rate and depth of breathing

  3. Vasomotor Center- controls blood pressure

Cerebellum

• Located between the cerebrum and brainstem

• Integrates sensory info about body position

• Coordinates skeletal muscle activity and maintains posture

Responsibilities of the Right Side of the Brain

• Right Frontal Lobe- decision making, logic, understanding, arts

• Right Premotor Area- planning movement

• Right Motor Cortex- moves the left side of the body

• Right Sensory Cortex- feeling in the left side of the body

• Right Parietal Lobe- understanding dimensions

• Right Occipital Lobe- controls the left eye

• Right Temporal Lobe- smell, hearing, rhythm of speech, and interpreting facial expressions

Responsibilities of the Left Side of the Brain

• Left Frontal Lobe- sequencing, analyzing, and math logic

• Broca’s Area- forming sentences/speaking

• Left Premotor Area- planning movements

• Left Motor Cortex- moving the right side of the body

• Left Sensory Cortex- feeling in the right side of the body

• Left Parietal Lobe- understanding dimension

• Left Occipital Lobe- controls the right eye

• Left Temporal Lobe- hearing, speech, smell

• Wernicke’s Area- understanding sentences