The Nervous system

Functions of the Nervous System 1. Sensory input – gathering information To monitor changes occurring inside and outside the body Changes = stimuli 2. Integration To process and interpret sensory input and decide if action is needed

Functions of the Nervous System 3. Motor output A response to integrated stimuli The response activates muscles or glands

Structural Classification of the Nervous System Central nervous system (CNS) Brain Spinal cord Peripheral nervous system (PNS) Nerves outside the brain and spinal cord Spinal nerves Cranial nerves

Central Nervous System

Peripheral Nervous System

Functional Classification of the Peripheral Nervous System Motor & Sensory Divisions Motor division Two subdivisions Somatic nervous system = voluntary Autonomic nervous system = involuntary Figure 7.1

Organization of the Nervous System Figure 7.2

Sympathetic and parasympathetic divisions typically function in opposition to each other

Nervous Tissue: Neurons (Nerve Cell)

Neuron Anatomy Electrical to Chemical Signal Figure 7.4a

Nervous Tissue: Support Cells Schwann cells Form myelin sheath that protects signal Figure 7.3e

Neuron Anatomy Extensions outside the cell body Dendrites – conduct impulses toward the cell body Axons – conduct impulses away from the cell body Figure 7.4a

Signal Pathway: Sensory to Interneuron (spinal cord) to Brain to Motor Neuron

Functional Classification of Neurons Sensory (afferent) neurons Carry impulses from the sensory receptors Cutaneous (Skin) sense organs, for example Motor (efferent) neurons Carry impulses from the central nervous system to the muscles, for example

Functional Classification of Neurons Interneurons (association neurons) Found in neural pathways in the central nervous system Connect sensory and motor neurons

Neuron Classification Figure 7.6

Axons and Nerve Impulses Axons end in axonal terminals Axonal terminals contain vesicles with neurotransmitters Axonal terminals are separated from the next neuron by a gap Synapse – junction/space between nerves

How Neurons Communicate at Synapses Figure 7.10

Parts & Functions of the Human Brain Check out 3-D Brain Anatomy for more parts & more functions! Main Menu

3 Major Parts of The Brain

Frontal Lobe Found under your forehead. Center of reasoning, planning, some parts of speech, movement (motor cortex), emotions, and problem solving. Return to brain parts

Phineas Gage https://www.youtube.com/watch?v=MvpIRN9D4D4

Parietal Lobe Found on the top of your head. Receives sensory input from the skin. (touch, pressure, temperature, & pain)

Temporal Lobe Found on the sides of your head above your ears. Functions include speech perception, hearing, some types of memory (Broca’s Area) http://video.nationalgeographic.com/video/brain-tumor-sci Return to brain parts

Occipital Lobe Found at the back of your head. Receives input from the eyes Often referred to as the visual cortex Return to brain parts

Cerebellum Found at the at the back of your head under the cerebrum. Means “little brain” Responsible for movement, balance, posture. Often takes over learned activities- Like riding a bike!

Brainstem Most basic part of your brain. Controls functions essential to life (breathing, digesting, eliminating waste, sleeping, maintaining body temperature…) Maintains life without “thinking” Return to brain parts

Three parts of Brain Stem: 1. medulla oblonga: innate relfexes, eg. vomiting, coughing, sneezing, heart rate, breathing rate, blood pressure 2. pons: reflexes 3. mid brain: visual

Corpus Callosum This is located centrally between the left and right hemispheres of your brain. It is a bundle of fibers that connects the left and right hemispheres. It is believed this area is involved in creativity and problem solving. Click here to find out more about split brains!

Hypothalamus The hormones produced by this area of the brain govern body temperature, thirst, hunger, sleep, circadian rhythm, moods, and the release of other hormones in the body.