Lecture 13 The Nervous System Lecture 13 1. Introduction 2. Functions of the Nervous System 3. Neurons 4. CNS Brain and Spinal Cord 5. Peripheral Nervous System 6. Nervous System Health Concerns 1
The Nervous System Control center for all body activities Communicating Coordinating Controlling Regulating Responds and adapts to changes that occur both inside and outside the body (Ex: pain, temperature, pregnancy) Homeostasis Maintenance of a relatively constant internal state under a much wider range of environmental conditions. 2
Functions of the Nervous System Functions of the Nervous System Sensory - gathers info about changes occurring within and around the body; 3
Functions of the Nervous System Integrative - information is brought together, interpreted, to create sensations, create thoughts, add to memory, make decisions, etc. Functions of the Nervous System Motor - sending of signals to muscles and/or glands to elicit a response 4
Functions of the Nervous System Bottom Line = Maintenance of Homeostasis Neurons 5
Building Block of the NS: Neurons - microscopic nerve cells that make up the brain, spinal cord, and nerves - 30,000 neurons can fit on a pinhead Neurons 6
Neuron Cell Body with nucleus Dendrites - fibers that receive messages from other neurons Axons - fibers that send messages to other neurons Neuron Action Potential electrical signal 7
Signal Propagation in Neurons Saltatory (jumping) Conduction Speed- 100 meters/second! Neuron Neurons do NOT touch each other; there is a gap between them called a synapse Messages are sent across the synapses by special chemicals called neurotransmitters 8
Neuron - Synapse Multiple Sclerosis 9
Communication Between Neurons The use of neurotransmitters causes an electrical current There is enough electrical current in the brain to power a flashlight Divisions of the Nervous System 10
Main Divisions of the Nervous System Central Nervous System (CNS) Brain Spinal cord Main Divisions of the Nervous System Peripheral Nervous System (PNS) Nerves and Ganglia (bundles of nerve cells) located outside of the brain and spinal cord 11
Two Major Divisions of the Nervous System CNS - The Brain 12
The Brain weighs 1300-1400 g made up of about 100 billion neurons the most complex living structure on the universe Society for Neuroscience makes us who we are Cerebrum -The largest division of the brain. It is divided into two hemispheres, each of which is divided into four lobes. Cerebrum Cerebrum 13
Anatomy of the Brain Cerebrum - Responsible for: - Thought - Language - Senses - Memory - Voluntary movement Brain Surface Features Gyri Elevated ridges winding around the brain. 14
Brain Surface Features Sulci Small grooves dividing the gyri Brain Surface Features Fissures Deep grooves, generally dividing large regions/lobes of the brain 15
Gyri (ridge) Sulci (groove) Fissure (deep groove) Cortical Homunculus Wilder Penfield 16
Anatomy of the Brain Cerebellum : at base of brain Does not initiate movement, but is.. Responsible for: - Muscle coordination - Balance - Posture Anatomy of the Brain Brain Stem : connects brain to spinal cord Responsible for: - Breathing - Swallowing - Heartbeat - Blood pressure 17
Spinal Cord - Column of nerves from brain to tailbone protected by vertebral column CNS Spinal Cord Responsible for: - Conducting impulses between the brain and the rest of the body CNS Spinal Cord Cervical region Thoracic region Lumbar region Sacral region Coccygeal region 18
Peripheral Nervous System (PNS) The part of the nervous system comprising the nerves and ganglia outside of the brain and spinal cord. The main function of the PNS: connects the central nervous system (CNS) to the limbs and organs Serves as a communication relay going back and forth between the brain and the extremities Peripheral Nervous System (PNS) Nerves - visible bundles of axons and dendrites that extend from the brain and spinal cord to all other parts of the body 19
Types of Nerves Sensory nerves - carry messages from body to brain (pain, pressure, temperature) Motor nerves carry messages from brain to body to respond Reflex Action If you were cooking and you accidentally touched a hot pot on your stove, you would involuntarily (and nearly instantaneously) snatch your hand away from the pot. This response is called a reflex action'. 20
Reflex Arc Nervous System Health Concerns 21
Nervous System Health Concerns Nervous System Health Concerns Concussion A temporary disturbance of the brain s ability to function due to a hard blow to the head Chronic Traumatic Encephalopathy (CTE) is a progressive degenerative disease of the brain found in athletes (and others) with a history of repetitive brain trauma. 22
Nervous System Health Concerns Paralysis A loss of sensation and movement of part of the body due to an injury of the spinal cord or brain Parkinson s Disease The brain does not produce enough of the neurotransmitter that transmits messages from the brain to the muscles Symptoms: tremors, rigid muscles, shuffling walk, and loss of facial expression 23
Alzheimer s Disease A gradual shrinking of the neurons in the cerebrum and a build up of tangles and plaques that disrupt nerve function. Symptoms: memory loss, emotional disturbances, inability to function on own, death? 24