The Nervous System
Lucas Greb, Anuja Mehta, Will Cooper, Shreya Krishnan, Jeet Kothari
Function of the Nervous System
The nervous system consists of the brain, spinal cord, and nerves (neurons).
It is responsible for connecting all the body parts and allowing for communication.
Pathway of a Nerve Signal
Neurons
Neurons are the basis of the nervous system
When linked together, they become capable of performing complex processes such
as thought and understanding
For the nervous system to be functioning, neurons need to be functioning
Neurons
Structures:
Axon: long-stem that extends to dendrite of another neuron
Axon hillock: where the axon meets the cell body
Dendrite: receiving node of the neuron
Cell body/soma: neurons need to live too
Synapse: where the axon meets the dendrite
Synaptic Cleft: the gap between
Glia: non-neuronal cells that help the neurons maintain homeostasis
Neurons
Neurons
Neural Communication:
Synaptic cleft is where all the action takes place
Movement of ions cause the neuron to fire
Positive ions increase the chance of firing and
negative ions decrease the chance of firing
Agonists vs Antagonists
Agonists act positively
Antagonists act negatively
Neurotransmitters
Neurotransmitters deliver the signal
Specific neurotransmitters deliver different
signals such as dopamine for excitement
and melatonin for drowsiness
Reuptake takes the neurotransmitter
back
The neurotransmitters are reabsorbed into
the neuron after they are fired and deliver
the signal.
Divisions of the Nervous System
Central Nervous System (CNS)
The main “trunk” of the nervous system
Composed of the brain and the spinal cord
Transmits signals to the rest of the body
decides how the body will react to stimuli
Protected by the cranium (brain) and by
the vertebrae of the spinal column
(spinal
Peripheral Nervous System (PNS)
Nerves that carry information in and out
of the central nervous system
Sends messages to the CNS (sensory neurons)
Acts based on the feedback from the CNS
(motor neurons)
Connects the CNS to the rest of the body
Not protected by bones
Somatic Nervous System
Controls the body’s skeletal muscles
Controls voluntary movement
Walking
Waving
Autonomic Nervous System
Controls the glands, organs, and other muscles
In charge of involuntary actions
Breathing
Blood circulation (heart)
Releasing hormones
Divided into the
Sympathetic Nervous System
Sympathetic Nervous System
Arouses the body
Provides energy in stressful situations
Fight
Flight
Fear
Intercourse
Parasympathetic Nervous System
Calms the body
Conserves its energy in non-stressful situations
Rest
Digest
Structures of the Brain
Brain Stem
Medulla: the base of the brainstem that controls heartbeat and breathing.
Reticular Formation- the nerve network that plays an important in controlling arousal
Thalamus- the brain’s sensory switchboard, located on top of the brainstem. It directs
messages to the sensory areas in the cortex and transmits replies to cerebellum and
medulla.
Cerebellum
The cerebellum is attached to the rear of the brainstem. It helps coordinate voluntary
movements and balance.
Limbic System
The Limbic System is a doughnut- shaped system at the border of the brainstem and
cerebrum, associated with emotions like fear and aggression. It includes the
hippocampus, amygdala, and hypothalamus
Amygdala
The Amygdala consists of two neural clusters linked to the emotions of fear and anger.
Hypothalamus
Lies below the thalamus
Directs maintenance activities: drinking, body temperature, control of emotions
Governs endocrine system
Cerebral Cortex
Covers the cerebral hemisphere (the outer layer)
Made up of interconnected neural cells
Ultimate control and info processing center
Outer, dark purple layer is the cerebral cortex
Hemispheres of the Brain
Left Hemisphere:
Right Hemisphere:
Processes reading, math, science, etc.
Recognition
Comprehension skills
Processes patterns
Analytic thought and logic
Responsible for nonverbal thinking
Detailed
Thoughts
Sequential
Feelings
Daydreams
Corpus Callosum
These are neural fibers that connect the two hemispheres of the brain and allow for
communication
When cut, functions of the hemispheres are impaired
Lobes of the Brain
Frontal: speaking and muscle movements, as well as making plans and judgements,
short term memory
Occipital: includes visual and perception areas
Parietal: receives sensory input for touch and body position
Temporal: includes auditory areas, long term memory,
Lobes of the Brain
Diseases of the Brain
Diseases
Multiple sclerosis - myelin sheath around some axons in the CNS becomes damaged,
causing conduction to slow or even stop, with symptoms such as visual disturbances,
muscle weakness, trouble with coordination and balance, and thinking/memory
problems
Alzheimer’s disease - type of dementia that causes problems with memory, thinking, and
behavior based on the extent of the disease (mild, moderate, severe)
Parkinson’s disease - progressive disease characterized by loss of neurons in particular
locations, resulting in imbalance, rigidity, and slowed movement
Diseases
Epilepsy - recurrent seizures as a result of any trauma to brain causing brain to be
excitable or irritable; seizures depend on part of the brain that is affected
Stroke - blood clot travels to the brain causing flow to either slow or stop completely with
symptoms such as numbness on one side of the body, trouble speaking, trouble seeing
in both eyes, or loss of balance
Meningitis - infection of membranes covering brain and spinal cord, centered in the
cerebrospinal fluid that surrounds the nervous system with symptoms such as
fever/chills, nausea/vomiting, severe headache, sensitivity to light, and mental status
changes
Diseases
Diseases
Quiz
1. What are the two divisions of the autonomic nervous system and what are their
functions?
2. What is the function of the cerebellum?
3. What is the function of a nerve?
4. What does the somatic nervous system do?
5. What are the three components of the brain stem?
6. What neurologic disease is characterized by loss of neurons, resulting in issues in
movement?
7. What is the function of the corpus callosum?
8. What are neurotransmitters?