C N S : B R A I N & S P I N A L C O R D ( A N D S O M E P N S )

Chapter 28: The Nervous System

The Nervous System

  Comprised of the Central Nervous System (CNS) and the Peripheral Nervous System (PNS)

  The PNS delivers information to the CNS and carries

messages from the CNS to other organs via NERVES

The Central Nervous System

 Central Nervous System: brain and spinal cord  Reflex: an automatic response to an event

 e.g. sensory neuron detects pain, send signal to spinal cord signal to interneurons signal to motor neurons

The Peripheral Nervous System

 Peripheral Nervous System: links central nervous system to organs via motor and sensory neurons.

 Motor Neurons:  Comprised of the Somatic (Skeletal) Nervous

System and the Autonomic Nervous System  Somatic (Skeletal) Nervous System: controls

voluntary movements of our skeletal muscles

The Peripheral Nervous System

 Autonomic Nervous System: controls many of the self-regulatory (involuntary) functions of the body (e.g. digestion, circulation)  Comprised of the Sympathetic and

Parasympathetic nervous systems  Sympathetic: prepares us for defensive actions

against threats (e.g. faster heart rate, increased breathing rate, inhibits digestion, dilates pupils to allow greater light sensitivity)

 Parasympathetic: counteracts effects of sympathetic nervous system, calms us down

The Central and Peripheral Nervous Systems

So Where is OUR Focus Today?

Structure of the Brain

 The human brain is comprised of “older” and “newer” parts.   “Older”: lower level

structures, responsible for basic survival mechanisms

  “Newer”: higher level structures, responsible for more advanced human faculties

The Brainstem

 Brainstem: the set of neural structures at the base of the brain, including the medulla, the reticular formation, and the pons   Facilitates communication between the brain and spinal

cord   Filters all the information going to and from the brain

The Brainstem

  Medulla: controls heartbeat, breathing, and swallowing

  Pons: bridge from brainstem to cerebellum; controls a variety of functions, including sleep and control of facial muscles

The Brainstem

  Thalamus: the brain’s sensory switchboard; receives signals from the sensory and motor systems, and relays them to the appropriate parts of the brain   Also receives signals from higher

brain structures, relays them to medulla and cerebellum

  Sorts information going to and from the cerebral cortex and enhances some signals

The Cerebellum

  “Little Brain” extending from rear of brainstem   Coordinates physical movement   Contributes to estimating time

and paying attention   Controls balance and coordinates

muscle movements  Cerebellum + other lower

level brain structures occur without conscious effort   Much of our brain’s activity

occurs outside of our awareness

The Limbic System

  Limbic System: doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres  Involved in the basics of emotion and motivation:

fighting, fleeing, feeding, and sex  Comprised primarily of the hypothalamus, the

hippocampus, and the amygdala

The Limbic System

The Limbic System

  Hypothalamus: brain structure that sits under the Thalamus and plays a central role in controlling:   Eating and drinking   Regulating the body’s

temperature, blood pressure, and heart rate

The Limbic System

  Hippocampus: brain structure that plays a key role in allowing new information to be stored in memory   Hippocampus does not contain memories itself, but does

trigger processes that store memories elsewhere in the brain

The Visible Brain

 Cerebral Cortex: the convoluted pinkish-gray surface of the brain, where most mental processes take place

 The brain is divided into two halves (cerebral hemispheres), separated by a deep fissure  Hemispheres control opposite side of body (e.g.

right-handers’ writing is controlled by the left hemisphere)

Brain Organization

Our Divided Brains

 Cerebral Hemispheres connected by the corpus callosum, a large band of neural fibers that transmits messages between hemispheres   Contains more than 200 million nerve fibers, can transfer

more than 1 billion bits of information per second

Structure of the Cortex

 Cerebral Cortex is divided into 4 lobes, or regions of the brain 1.  Temporal Lobe 2.  Occipital Lobe 3.  Frontal Lobe 4.  Parietal Lobe

  Each lobe is (roughly) responsible for different higher-level functions, but remember that they do not work merely in isolation.

Structure of the Cortex

 Temporal Lobe: The brain lobe under the temples, in front of the ears   Functions Include:

 Processing Sounds  Committing Information to Memory  Comprehending Language

Structure of the Cortex

 Occipital Lobe: Brain lobe at the back of the head  Responsible primarily for vision;

 Separate areas to specify visual properties such as:   Shape, Color, & Motion

Structure of the Cortex

  Frontal Lobe: The brain lobe located behind the forehead  The seat of planning, memory

search, motor control, reasoning, emotions, and many other functions

 In many ways, the frontal lobe is what makes us uniquely human.

Structure of the Cortex

 Parietal Lobe: Brain lobe at the top and center/rear of the head  Involved in:

 Registering Spatial Location  Attention  Motor Control