1. The Nervous System

2. Division of the Human Nervous System
Nervous System (NS)
Peripheral NS
Central NS
Autonomic NS
Somatic NS
Brain
Spinal cord
sympathetic
parasympathetic
forebrain
midbrain
hindbrain
Cerebrum
Hippocampus
Amygdala
Thalamus
Hypothalamus
Cerebellum Pons Medulla

3. The Nervous System
The human nervous system is divided into three sub-systems:
The Central Nervous System (CNS): the brain and the spinal cord
The Peripheral Nervous System (PNS): nerves that bring information to and from the CNS
The Autonomic Nervous System: controls organs and functions independently from the CNS

5. The Central Nervous System
The central nervous system includes the Brain and the spinal cord
The average adult human brain weighs 1.3 to 1.4 kg (approximately 3 pounds). The brain contains about 100 billion nerve cells (neurons) and trillions of "support cells" called glia (glial cells).
The spinal cord is about 43 cm long in adult women and 45 cm long in adult men and weighs about grams. The vertebral column, the collection of bones (back bone) that houses the spinal cord, is about 70 cm long. Therefore, the spinal cord is much shorter than the vertebral column

6. The Central Nervous System

7. The Brain The Cerebrum The Cerebellum The Brain Stem
Located inside of the cranium
Divided into three parts:
The Cerebrum
The Cerebellum
The Brain Stem
See this website:

9. The Brain

10. The Cerebrum The largest part of the brain
The cerebrum is composed of grey matter (in the cortex and the limbic system) and white matter (the rest of the cerebrum)

11. The Cerebrum
The cerebral cortex, the outer part, is divided into four lobes: frontal, parietal, occipital and temporal
Each lobe has its own particular responsibilities:
Frontal: movement, thinking, problem-solving
Parietal: touch, pain and pressure information
Occipital: visual information
Temporal: auditory information

14. The Cerebrum The Cerebrum is divided into two Hemispheres.
The left hemisphere controls the right side of the body.
The right hemisphere controls the left side of the body.

15. Left Hemisphere vs Right Hemisphere

16. The Cerebral Cortex
The thickness of the cerebral cortex varies from 2 to 6 mm. The right and left sides of the cerebral cortex are connected by a thick band of nerve fibers called the “corpus callosum”
In higher mammals such as humans, the cerebral cortex looks like it has many bumps and grooves. A bump or bulge on the cortex is called a gyrus (the plural of the word gyrus is "gyri") and a groove is called a sulcus (the plural of the word sulcus is "sulci"). Lower mammals, such as rats and mice, have very few gyri and sulci.

17. Functions of the Cerebral Cortex:
Thought
Voluntary movement
Language
Reasoning
Perception.

18. Lymbic System
The inner part of the cerebrum known as the limbic system, controls learning, emotion and memory (long-term and short-term memory)

19. Functions of the Lymbic system
The Hypothalamus
1. Controlling Body Temperature
2. Emotions
3. Hunger
4. Thirst
5. Circadian Rhythms
The Thalamus
1. Sensory processing
2. Movement
Amygdala and Hippocampus
Emotions
Learning
Memory

20. Functions Continued Frontal Lobe Olfactory Lobe Planning Organizing
Problem solving
Memory
Impulse control
Decision making
Selective attention
Controlling behaviour and emotions
Olfactory Lobe
Relays Sensory Signals to the Olfactory Tract
Sense of Smell

21. The Cerebellum The rear part of the brain Is responsible for: Posture
Coordination of movement
Balance
The rear part of the brain

22. The Brain Stem
The bottom of the brain between the thalamus and spinal cord
Connects the brain to the spinal cord.
This is where you will find most of the cranial nerves.
Is responsible for:
Sleep, waking & dreaming
Heart rate, respiration & blood pressure
Coughing & sneezing

23. The Brain Stem

24. Functions of the Brain Stem
Medulla Oblongata - The medulla oblongata functions primarily as a relay station for the crossing of motor tracts between the spinal cord and the brain. It also contains the respiratory, vasomotor and cardiac centers, as well as many mechanisms for controlling reflex activities such as coughing, gagging, swallowing and vomiting.
Pons - The pons is a bridge-like structure which links different parts of the brain and serves as a relay station from the medulla to the higher cortical structures of the brain. It contains the respiratory center.

25. Cerebrum Cerebellum Brain Stem Part Description Role
Largest part of the brain.
Divided into left and right hemispheres.
Outer layer called the cerebral cortex.
Divided into various lobes.
Complex analysis of stimuli from the PNS.
Controls intelligence, emotions and physiological functions.
Controls voluntary movements.
Cerebellum
Located underneath the cerebrum.
Controls balance and coordination.
Brain Stem
Located between the cerebrum and the cerebellum. Connected to both.
Connects the brain to the spinal cord.
Processes internal stimuli.
Controls involuntary movements of the body.

26. The Spinal Cord
A cord between 40 and 50 cm long found inside the vertebral column
Made of grey matter (inside) and white matter (outside)
Is responsible for:
Transmitting nerve impulses
Reflexes

27. The Spinal Cord

28. What is a stroke?

29. The Peripheral nervous system includes all nerve fibers that run in and out of the brain and spinal cord.
Somatic Nerves - These are “Voluntary fibers” .
These are part of the Somatic nervous system.
1. Sensory fibers - bring impulses to the CNS
2. Motor fibers - bring impulses away from the CNS to the
voluntary skeletal muscles
B. Autonomic nerves - These are “Involuntary Fibers”
These are part of the Autonomic Nervous system
1. Sympathetic nerves
2. Parasympathetic nerves
Both of these fibers may activate or deactivate certain body functions during times of stress or stimulus.

30. The Peripheral Nervous System
Made up of nerves
12 pairs of cranial nerves
31 pairs of spinal nerves
Types of nerves:
Sensory nerves – carry info from the sensory organs towards the CNS
Motor nerves – carry info from the CNS to muscles and organs

31. The Function of Somatic Nerves
1. Sensory Neurons

32. 2. Motor Neurons

33. Reflexes vs Reactions
Reflexes are automatic, involuntary responses. They are usually controlled by the spinal cord
Reactions involve the brain. The cerebrum interprets sensory information and decides how to respond

35. Autonomic Nervous System
The Autonomic Nervous System is a part of the Peripheral Nervous System.
It is made up of nerve Fibers that control involuntary body action. It acts as a control system to maintain homeostasis in the body.
There are two types of Fibers that connect to different regions of the spinal cord
a) The Sympathetic fibers -thoracic and lumbar
b) The Parasympathetic fibers- cervical and sacral

36. What the sympathetic fibers do to a certain part of the body the parasympathetic fibers will have the opposite effect. Here are some examples:
Sympathetic
Parasympathetic
Accelerates heartbeat
Slows heartbeat
Dilates pupil
Constricts pupil
Inhibits flow of saliva
Stimulates flow of saliva
Inhibits peristalsis
Stimulates peristalsis

38. What is the nervous system made of?
Neurons
All of the organs and nerves of the nervous system are made of neurons
Neurons are special cells that can send, receive and transmit electrical messages called nerve impulses
Each neuron is made of:
Dendrites
An Axon
A Cell Body

39. Neurons
Neurons are connected to each other by small gaps or spaces called SYNAPSES
Nerve impulses are carried across the synapses by chemicals called NEUROTRANSMITTERS

41. The dendrites and axons of sensory neurons and motor neurons that lie outside of the central nervous system in the peripheral nervous system may be myelinated.
Myelin sheaths (neuron wraps) are formed by Schwann Cells. Schwann cells form multiple layers of membrane around the neuron and insulate it. In between the areas if myelin sheath, Nodes of Ranvier or bare patches exist.
The nerve impulse or action potential (more on this later) will jump form node to node greatly increasing the speed of nerve transmission.
This node to node transmission, called saltatory conduction, can produce transmission speeds of up to 200 meters per second and explains the speed at which we can react to potentially harmful stimuli.

42. Information from one neuron flows to another neuron across a synapse
Information from one neuron flows to another neuron across a synapse. The synapse contains a small gap separating neurons. The synapse consists of:
1. Presynaptic ending that contains neurotransmitters, mitochondria and other cell organelles
2. Postsynaptic ending that contains receptor sites for neurotransmitters
3. Synaptic cleft or space between the presynaptic and postsynaptic endings.

43. Myelinated nerves can conduct impulses at up to 720 km/hr