The Nervous The Nervous System System

and the Brainand the Brain

Information in this presentation is taken from UCCP contentInformation in this presentation is taken from UCCP content

The Nervous SystemThe Nervous System

Our nervous system has three primary Our nervous system has three primary functions:functions:

1. to gather and process information1. to gather and process information

2. produce responses to stimuli2. produce responses to stimuli

3. coordinate the working of different 3. coordinate the working of different cellscells

It is divided into two parts: central It is divided into two parts: central nervous system (brain and spinal cord) nervous system (brain and spinal cord) and the peripheral nervous system.and the peripheral nervous system.

Peripheral Nervous Peripheral Nervous SystemSystem

The peripheral nervous system consists of neurons that The peripheral nervous system consists of neurons that transmit messages to and from the central nervous transmit messages to and from the central nervous system. system.

There are two types of neurons in this system: sensory There are two types of neurons in this system: sensory neurons and motor neurons. neurons and motor neurons.

SensorySensory, or , or afferentafferent, , neuronsneurons receive the information receive the information from muscles and glands and transmit the message to from muscles and glands and transmit the message to the brain and spinal cord. the brain and spinal cord.

MotorMotor, or , or efferentefferent, , neurons neurons receive messages from the receive messages from the brain and spinal cord and transmit the information to brain and spinal cord and transmit the information to muscles and glands. muscles and glands.

An easy way to remember what afferent and efferent An easy way to remember what afferent and efferent neurons do is to remember the mnemonic, SAME. neurons do is to remember the mnemonic, SAME. Sensory neurons (S) are Afferent neurons (A); Motor Sensory neurons (S) are Afferent neurons (A); Motor neurons are Efferent neurons (E).neurons are Efferent neurons (E).

Peripheral Nervous Peripheral Nervous SystemSystem

There are two divisions of the peripheral nervous There are two divisions of the peripheral nervous system: the somatic nervous system and the system: the somatic nervous system and the autonomic nervous system. autonomic nervous system.

The The somatic nervous systemsomatic nervous system connects the CNS to connects the CNS to sensory receptors and muscles. Neurons in the sensory receptors and muscles. Neurons in the somatic nervous system transmit messages about somatic nervous system transmit messages about sights, sounds, smell, temperature, and body position sights, sounds, smell, temperature, and body position to the CNS. It also transmits information from the to the CNS. It also transmits information from the brain to produce purposeful motor movements. brain to produce purposeful motor movements.

The The autonomic nervous systemautonomic nervous system is “automatic”. It is “automatic”. It controls and regulates the glands and muscle of controls and regulates the glands and muscle of internal organs. For example, it controls activities internal organs. For example, it controls activities such as heart rate, respiration (breathing), digestion, such as heart rate, respiration (breathing), digestion, and pupil dilation. These activities occur and pupil dilation. These activities occur automatically.automatically.

Autonomic Nervous Autonomic Nervous SystemSystem

There are two branches of the autonomic nervous There are two branches of the autonomic nervous system: sympathetic and parasympathetic. system: sympathetic and parasympathetic.

The The sympathetic nervous systemsympathetic nervous system is most active during is most active during processes that involve spending the body’s energy processes that involve spending the body’s energy from stored reserves. It prepares the body to respond from stored reserves. It prepares the body to respond in times of danger or high emotion. Basically, it is in times of danger or high emotion. Basically, it is arousing the body to take action. (example: if you see arousing the body to take action. (example: if you see a mean dog running towards you, your body will a mean dog running towards you, your body will prepare you to expend your energy and RUN!)prepare you to expend your energy and RUN!)

The The parasympathetic nervous systemparasympathetic nervous system is most active is most active during processes that replenish reserves of energy. It during processes that replenish reserves of energy. It quiets the body and lowers its level of arousal. It is quiets the body and lowers its level of arousal. It is most active after high emotional states. It works to most active after high emotional states. It works to keep your heart rate and breathing at moderate levels. keep your heart rate and breathing at moderate levels.

The Nervous SystemThe Nervous System

The somatic and autonomic nervous systems work The somatic and autonomic nervous systems work together to coordinate the inner world of the together to coordinate the inner world of the body with what is going on in the outside world. body with what is going on in the outside world. For example, if a large dog growls and lunges at For example, if a large dog growls and lunges at you, your autonomic nervous system you, your autonomic nervous system (sympathetic) increases your blood pressure and (sympathetic) increases your blood pressure and heart rate and prepares you to react. At the heart rate and prepares you to react. At the same time, the somatic nervous system is same time, the somatic nervous system is sending messages to your leg muscles allowing sending messages to your leg muscles allowing you to run. you to run.

Sometimes people’s sympathetic nervous system Sometimes people’s sympathetic nervous system overreacts. In the absence of external threats, overreacts. In the absence of external threats, their bodies still respond as if they were faced their bodies still respond as if they were faced with danger, such as in anxiety or panic attacks. with danger, such as in anxiety or panic attacks.

The Central Nervous The Central Nervous SystemSystem

The central nervous system consists of The central nervous system consists of the brain and spinal cord.the brain and spinal cord.

Its primary functions are to:Its primary functions are to:

1) receive, process, interpret and 1) receive, process, interpret and store sensory input andstore sensory input and

2) initiate motor outputs2) initiate motor outputs

The Central Nervous The Central Nervous SystemSystem

The spinal cord is like an information highway. The spinal cord is like an information highway. It is a column of nerves that transmits It is a column of nerves that transmits messages (1) from sensory receptors to the messages (1) from sensory receptors to the brain and (2) from the brain to muscles and brain and (2) from the brain to muscles and glands. The most basic pattern of neural glands. The most basic pattern of neural responses, however, does not even include the responses, however, does not even include the brain. brain.

Spinal reflexes are unlearned, automatic Spinal reflexes are unlearned, automatic responses to stimuli that typically include only responses to stimuli that typically include only two neurons, a sensory neuron and a motor two neurons, a sensory neuron and a motor neuron. Sometimes interneurons will transmit neuron. Sometimes interneurons will transmit the neural impulse from the sensory neuron the neural impulse from the sensory neuron through the spinal cord to the motor neuron. through the spinal cord to the motor neuron.

The Central Nervous The Central Nervous SystemSystem

The pain reflex illustrates this neural pathway. Imagine if The pain reflex illustrates this neural pathway. Imagine if your right hand touches the burner on the stove. The your right hand touches the burner on the stove. The sensory neurons in your hand detects the pain and sensory neurons in your hand detects the pain and instantly fires off a message to your spinal cord. When instantly fires off a message to your spinal cord. When the message reaches your spinal cord it connects with the message reaches your spinal cord it connects with an interneuron that in turn activates a motor neuron. an interneuron that in turn activates a motor neuron. The motor neuron sends a message to cells in your arm The motor neuron sends a message to cells in your arm muscles that are capable of muscle movement. Muscle muscles that are capable of muscle movement. Muscle cells in your right arm contract, causing you to lift your cells in your right arm contract, causing you to lift your right hand off the stove. If this happened, would it right hand off the stove. If this happened, would it require any brain activity or thinking on your part?require any brain activity or thinking on your part?

However, the spinal cord will also send a message to the However, the spinal cord will also send a message to the brain notifying it about what you have done. After you brain notifying it about what you have done. After you withdraw your hand, you will most likely feel the pain withdraw your hand, you will most likely feel the pain and shout, “Ouch!”and shout, “Ouch!”

The BrainThe Brain

The brain consists of three major regions: The brain consists of three major regions:

1)1) The hindbrainThe hindbrain

2)2) The midbrainThe midbrain

3)3) The forebrainThe forebrain

Our forebrain is most important in those Our forebrain is most important in those aspects of life that are most relevant to aspects of life that are most relevant to psychology (e.g. perception, memory, psychology (e.g. perception, memory, thinking and social behavior).thinking and social behavior).

The HindbrainThe Hindbrain

The hindbrain controls some basic functions such as The hindbrain controls some basic functions such as breathing and heart rate. It is also important in breathing and heart rate. It is also important in attention, sleep, alertness, body movement, and attention, sleep, alertness, body movement, and balance. The primary structures of the hindbrain balance. The primary structures of the hindbrain are the following:are the following:

1)1) The cerebellum coordinates motor behavior, muscle The cerebellum coordinates motor behavior, muscle coordination, and balance.coordination, and balance.

2)2) The medulla regulates unconscious functions such The medulla regulates unconscious functions such as breathing and circulation. as breathing and circulation.

3)3) The pons connects the brain stem to the cerebellum The pons connects the brain stem to the cerebellum and is involved in sleep and arousal as well as and is involved in sleep and arousal as well as transmits information about body movement. transmits information about body movement.

4)4) The reticular formation controls arousal and The reticular formation controls arousal and attention.attention.

The MidbrainThe Midbrain

The midbrain plays a role in vision, The midbrain plays a role in vision, hearing, motor movements, hearing, motor movements, attention, and sleep. For our attention, and sleep. For our purposes, the midbrain is a purposes, the midbrain is a conduction and switch center that conduction and switch center that serves as a link between the serves as a link between the hindbrain and the forebrain. hindbrain and the forebrain.

The ForebrainThe ForebrainThe The primary structures of the forebrainprimary structures of the forebrain are: are:

1)1) ThalamusThalamus – relay station that receives and – relay station that receives and relays sensory information to the appropriate relays sensory information to the appropriate area of the cerebral cortex (e.g. sensory info. area of the cerebral cortex (e.g. sensory info. from the eyes)from the eyes)

2)2) HypothalamusHypothalamus – regulates autonomic nervous – regulates autonomic nervous system, motivation and emotion. It also system, motivation and emotion. It also controls eating, drinking, sexual behaviors and controls eating, drinking, sexual behaviors and aggression.aggression.

3)3) Limbic SystemLimbic System – includes the amygdala, – includes the amygdala, hippocampus and parts of the hypothalamus. hippocampus and parts of the hypothalamus. The amygdala is involved in aggression and fear The amygdala is involved in aggression and fear responses. The hippocampus is important in responses. The hippocampus is important in learning and memory.learning and memory.