1. The Nervous System

2. Functions of the Nervous System
Respond to internal and external stimuli
Transmit nerve impulses to and away from CNS
Interpret nerve impulses at the cerebral cortex
Assimilate experiences in memory and learning
Initiate glandular secretions and muscle contraction
Program instinctual behavior

3. Organs and Divisions of the Nervous System
Central nervous system (CNS)— brain and spinal cord
Peripheral nervous system (PNS)—all nerves
Autonomic nervous system (ANS) – sympathetic and parasympathetic

4. Cells of the Nervous System
Neurons
Consist of three parts
Cell body of neuron—main part
Dendrites—branching projections that conduct impulses to cell body of neuron
Axon—elongated projection that conducts impulses away from cell body of neuron

5. Cells of the Nervous System
Neurons
Neurons classified according to function or direction of impulse
Sensory neurons: conduct impulses to the spinal cord and brain; also called afferent neurons
Motor neurons: conduct impulses away from brain and spinal cord to muscles and glands; also called efferent neurons
Interneurons: conduct impulses from sensory neurons to motor neurons; also called central or connecting neurons

6. Nerves Nerve—bundle of peripheral axons Tract—bundle of central axons
White matter—brain or cord tissue composed primarily of myelinated axons (tracts)
Gray matter—brain or cord tissue composed primarily of cell bodies and unmyelinated fibers

7. Nerves Nerve coverings—fibrous connective tissue
Endoneurium—surrounds individual fibers within a nerve
Perineurium—surrounds a group (fascicle) of nerve fibers
Epineurium—surrounds the entire nerve

8. Reflex Arcs
Nerve impulses are conducted from receptors to effectors over neuron pathways or reflex arcs
Conduction by a reflex arc results in a reflex (i.e., contraction by a muscle or secretion by a gland)
The simplest reflex arcs are two-neuron arcs— consisting of sensory neurons synapsing in the spinal cord with motor neurons; three-neuron arcs consist of sensory neurons synapsing in the spinal cord with interneurons that synapse with motor neurons

9. Reflex Arcs https://www.youtube.com/watch?v=wLrhYzdbbpE

11. Nerve Impulses
Self-propagating wave of electrical disturbance that travels along the surface of a neuron membrane; sometimes called action potentials

12. Nerve Impulses Mechanism
At rest, the neuron’s membrane is slightly positive on the outside—polarized—from a slight excess of Na+ on the outside
A stimulus triggers the opening of Na+ channels in the plasma membrane of the neuron
Inward movement of Na+ depolarizes the membrane by making the inside more positive than the outside at the stimulated point; this depolarization is a nerve impulse (action potential)
The stimulated section of membrane immediately repolarizes, but by that time the depolarization has already triggered the next section of membrane to depolarize, thus propagating a wave of electrical disturbances (depolarizations) all the way down the membrane

14. The Synapse
Place where impulses are transmitted from one neuron to another (the postsynaptic neuron)
Synapse made of three structures—synaptic knob, synaptic cleft, and plasma membrane
Neurotransmitters bind to specific receptor molecules in the membrane of a postsynaptic neuron, opening ion channels and thereby stimulating impulse conduction by the membrane
- easier video
Bozman science

16. Neurotransmitters Actions Disorder Involving It Acetylcholine Dopamine
-Triggers muscle contraction and stimulates the excretion of certain hormones
-In CNS: involved in wakefulness, attentiveness, anger, aggression, etc.
Alzheimer’s disease (lack of acetylcholine in certain areas of the brain)
Dopamine
-Controls movement and posture, modulates mood, and plays a central role in positive reinforcement and dependency
Parkinson’s disease (loss of dopamine in certain areas of the brain)
GABA (gamma-aminobutyric acid)
-Contributes to motor control, vision, and many other cortical functions; regulates anxiety
Drugs that increase GABA in the brain are used to treat epilepsy and Huntington’s disease
Glutamate
-Learning and memory
Thought to be associated with Alzheimer’s disease, whose first symptoms include memory malfunctions
Norepinephrine
-Attentiveness, emotions, sleeping, dreaming, and learning; also released as a hormone into the blood, where it causes blood vessels to contract and heart rate to increase
Mood disorders like manic depression
Serotonin
-Regulating body temperature, sleep, mood, appetite, and pain
Depression, impulsive behavior, and aggressiveness

17. Central Nervous System (CNS)
Brain
Divisions
Brainstem
Cerebellum
Cerebrum
Spinal Cord

18. Brain - Brainstem
Consists of three parts, named in ascending order: medulla oblongata, pons, and midbrain
Structure—white matter with bits of gray matter scattered through it
Functions
All three parts of brainstem are two-way conduction paths
Sensory tracts in the brainstem conduct impulses to the higher parts of the brain
Motor tracts conduct from the higher parts of the brain to the spinal cord
Many important reflex centers lie in the brainstem

19. Brain - Brainstem Medulla oblongata Pons Midbrain
Connects brain to spinal cord
Regulates breathing, heart and blood vessel function, digestion, sneezing, and swallowing
Pons
Helps relay messages from the cortex and the cerebellum
Midbrain
Associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation

20. Brain - Cerebellum Second largest part of the human brain
Helps control muscle contractions to produce coordinated movements so that we can maintain balance, move smoothly, and sustain normal postures
Recent evidence shows the coordinating effects of the cerebellum may be more extensive, also assisting the cerebrum and other regions of the brain

21. Brain - Cerebrum Largest part of the human brain
Outer layer of gray matter is the cerebral cortex; made up of lobes; composed mainly of dendrites and cell bodies of neurons
Interior of the cerebrum composed mainly of white matter (i.e., nerve fibers arranged in bundles called tracts)
Functions of the cerebrum—mental processes of all types, including sensations, consciousness, memory, and voluntary control of movements

22. Brain – Lobes of the Cerebrum
Frontal Lobe
Personality, behavior, emotions
Judgment, planning, problem solving
Speech: speaking and writing (Broca’s area)
Body movement (motor strip)
Intelligence, concentration, self awareness
Occipital Lobe
Interprets vision (color, light, movement)
Parietal Lobe
Interprets language, words
Sense of touch, pain, temperature (sensory strip)
Interprets signals from vision, hearing, motor, sensory and memory
Spatial and visual perception
Temporal Lobe
Understanding language (Wernicke’s area)
Memory
Hearing
Sequencing and organization

23. Deep Structures of the Brain
Hypothalamus gland: hunger, thirst, sleep, and sexual response, regulates body temperature, blood pressure, emotions, and secretion of hormones
Pituitary gland: known as the “master gland,” it controls other endocrine glands in the body; produces many hormones
Pineal gland: regulates the body’s internal clock and circadian rhythms by secreting melatonin
Thalamus: serves as a relay station for almost all information that comes and goes to the cortex
Limbic system (includes hypothalamus, amygdala, and hippocampus)
Amygdala: emotional reactions
Hippocampus: memory
Corpus callosum: allows for communication between hemispheres

24. Brain Myths: Fact or Fiction?
You only use 10% of your brain.
A person can be either left-brained or right-brained.
Each person’s brain has a set learning style.
Some people are able to multitask very well.

25. Testing your memory I will recite a list of 10 words
Do not record them in any way
Try to remember as many of them as you can (in order if possible)
You will then be able to write them down to see what you were able to remember

26. Sunflower ball
Red money
Chair rain
Woman
Globe
Comb
theater

27. Spinal Cord
Columns of white matter, composed of bundles of myelinated nerve fibers, form the outer portion of the H-shaped core of the spinal cord; bundles of axons called tracts
Interior composed of gray matter made up mainly of neuron dendrites and cell bodies
Spinal cord tracts provide two-way conduction paths— ascending and descending
Spinal cord functions as the primary center for all spinal cord reflexes; sensory tracts conduct impulses to the brain, and motor tracts conduct impulses from the brain

28. Coverings and fluid spaces of the brain and spinal cord
Cranial bones (skull) and vertebrae
Cerebral and spinal meninges
Fluid spaces
Subarachnoid spaces of meninges
Central canal inside cord
Ventricles in brain
Fluid
Cerebrospinal fluid – cushions and provides immune protection

29. Peripheral Nervous System (PNS)
Cranial nerves
12 pairs—attached to undersurface of the brain
Connect brain with the neck and structures in the thorax and abdomen
Spinal nerves
31 pairs—contain dendrites of sensory neurons and axons of motor neurons
Conduct impulses necessary for sensations and voluntary movements
After exiting the vertebral column, they split, combine, and split again forming a plexus (there are 4)
Cervical plexus
Brachial plexus
Lumbar plexus
Sacral plexus

30. Autonomic Nervous System
Responsible for controlling unconscious bodily functions (heartbeat, breathing, digestion)
Composed of two divisions: the sympathetic system and the parasympathetic system

31. Autonomic Nervous System
Sympathetic nervous system
Serves as the emergency or stress system, controlling visceral effectors during strenuous exercise and when strong emotions (anger, fear, hate, or anxiety) are elicited
Group of changes induced by sympathetic control is called the fight-or-flight response
Parasympathetic nervous system
Dominates control of many visceral effectors under normal, everyday conditions