Physiology of the Nervous System
The function of the Nervous System is to transmit and receive a constant series of messages via electrical impulses to and from the controlcentre situated in the brain. These messages are either those receiving "information" from various body tissues via the sensory nerves, or those initiating the function of other tissues such as organs, muscles, etc.
Nervous System:
A) Neuron:
1. Cell body: The
part of a neuron containing the nucleus, but not incorporating the axon and dendrites.
2. Dendrites: The branching extensions of neurons that carry electrical signals to the cell body: the receptive portion of a nerve cell.
3. Axon: Neuron process that carries impulses away from the nerve cell body; efferent process; the conducting portion of a nerve cell.
4. Axon Terminals: it is the part of the neuron that is used to continue the sgnal to the next neuron.
5. Myelin Sheath: The purpose is to allow impulses to transmit quickly and efficiently along the nerve cells. If myelin is damaged, the impulses slow down. This can cause diseases such as multiple sclerosis.
6. Node:periodic gap in the insulating sheath myelin on the axon of certain neurons that serves to facilitate the rapid
conduction of nerve impulses.
B) Nerve Impulses:
1. resting potential: difference in electrical charge between the insie and outside of a neuron; contains the potential energy needed to transmit the impulse.
2. action potential: fast, moving change in electrical charge across a neuron's membrane; also called an impulse
3. synapse: tiny gap between neurons through which chemical signals are sent
4. neurotransmitter: chemical that transmits a nervous system's signal across a synapse
C) Divisions of the Nervous System:
1. Central Nervous System: Part of the nervous system that interprets messages from other nerves in the body; includes the brain and spinal cord. It is composed of interneurons that interact with other nerves in the body .
a) Brain
-The Cerebrum or cortex is the largest part of the human brain, associated with higher brain function such as thought
and action
-The Cerebellum or "little brain", is similar to the cerebrum in that it has two hemispheres and has a highly folded
surface or cortex. The structure is associated with regulation and coordination of movement, posture, and balance.
-Limbic System is often referred to as the "emotional brain" and is found buried within the cerebrum.
b) Spinal Cord
2. Peripheral Nervous System: The collection of nerves that connects the CNS to all your other organ systems. The PNS uses sensory neurons to detect stimuli from inside and outside your body, and it uses motor neurons to carry signals from the CNS to ther parts of the body and stimulate your nuscles or other target organs.
a) Somatic Nervous System: the division of the PNS that regulates all of the movements over which you have voluntary cantrol. It connects the CNS to target organs.
b) Autonomic Nervous System: the division of the PNS that controls automatic functions that you do not have to think about. For example, involuntary muscles help you digest food by pushing it through your intestines. ANS is also important in maintaining homeostasis. It takes messages from the hypothalmus to organs in the circulatory, digestive, and endocrine systems.
i. Sympathetic Nervous System: part of the autonomic nervous system that prepares the body for action and stress. This is called the "fight or flight" response.
ii. Parasympathetic Nervous System: the division of the autonomic nervous system that calms the body and helps the body to conserve energy. It does this by lowering blood pressure and heart rate. It is active when the body is relaxed.
Nervous System:
A) Neuron:
1. Cell body: The
part of a neuron containing the nucleus, but not incorporating the axon and dendrites.
2. Dendrites: The branching extensions of neurons that carry electrical signals to the cell body: the receptive portion of a nerve cell.
3. Axon: Neuron process that carries impulses away from the nerve cell body; efferent process; the conducting portion of a nerve cell.
4. Axon Terminals: it is the part of the neuron that is used to continue the sgnal to the next neuron.
5. Myelin Sheath: The purpose is to allow impulses to transmit quickly and efficiently along the nerve cells. If myelin is damaged, the impulses slow down. This can cause diseases such as multiple sclerosis.
6. Node:periodic gap in the insulating sheath myelin on the axon of certain neurons that serves to facilitate the rapid
conduction of nerve impulses.
B) Nerve Impulses:
1. resting potential: difference in electrical charge between the insie and outside of a neuron; contains the potential energy needed to transmit the impulse.
2. action potential: fast, moving change in electrical charge across a neuron's membrane; also called an impulse
3. synapse: tiny gap between neurons through which chemical signals are sent
4. neurotransmitter: chemical that transmits a nervous system's signal across a synapse
C) Divisions of the Nervous System:
1. Central Nervous System: Part of the nervous system that interprets messages from other nerves in the body; includes the brain and spinal cord. It is composed of interneurons that interact with other nerves in the body .
a) Brain
-The Cerebrum or cortex is the largest part of the human brain, associated with higher brain function such as thought
and action
-The Cerebellum or "little brain", is similar to the cerebrum in that it has two hemispheres and has a highly folded
surface or cortex. The structure is associated with regulation and coordination of movement, posture, and balance.
-Limbic System is often referred to as the "emotional brain" and is found buried within the cerebrum.
b) Spinal Cord
2. Peripheral Nervous System: The collection of nerves that connects the CNS to all your other organ systems. The PNS uses sensory neurons to detect stimuli from inside and outside your body, and it uses motor neurons to carry signals from the CNS to ther parts of the body and stimulate your nuscles or other target organs.
a) Somatic Nervous System: the division of the PNS that regulates all of the movements over which you have voluntary cantrol. It connects the CNS to target organs.
b) Autonomic Nervous System: the division of the PNS that controls automatic functions that you do not have to think about. For example, involuntary muscles help you digest food by pushing it through your intestines. ANS is also important in maintaining homeostasis. It takes messages from the hypothalmus to organs in the circulatory, digestive, and endocrine systems.
i. Sympathetic Nervous System: part of the autonomic nervous system that prepares the body for action and stress. This is called the "fight or flight" response.
ii. Parasympathetic Nervous System: the division of the autonomic nervous system that calms the body and helps the body to conserve energy. It does this by lowering blood pressure and heart rate. It is active when the body is relaxed.
D) The Brain:
1. cerebrum: the part of the brain that interprets signals from your body and forms responses such as hunger, thirst, emotions, motion, and pain. The cerebrum has right and left halves, or hemispheres. Each hemisphere controls the opposite part of your body.
2. cerebral cortex: the outer layer of the cerebrum that interprets information from your sensory organs and generates responses
3. cerebellum: the part of the brain that coordinates your movements. It helps maintain your posture and balance, and it automatically adjusts your body to help you move smoothly.
4. brain stem: it connects the brain to the spinal cord and controls the most basic activities required for life, such as breathing and heartbeat. The brain stem has three major parts:midbrain, pons, and medulla oblongata.
5. thalmus: it sorts information from your ensory organs and passes signals between the spinal cord and other parts of your brain
6. hypothalmus: it gathers information about body temperature, hunger, and thirst. Then it sends signals that hel the body adjust and maintain homeostasis.
1. cerebrum: the part of the brain that interprets signals from your body and forms responses such as hunger, thirst, emotions, motion, and pain. The cerebrum has right and left halves, or hemispheres. Each hemisphere controls the opposite part of your body.
2. cerebral cortex: the outer layer of the cerebrum that interprets information from your sensory organs and generates responses
3. cerebellum: the part of the brain that coordinates your movements. It helps maintain your posture and balance, and it automatically adjusts your body to help you move smoothly.
4. brain stem: it connects the brain to the spinal cord and controls the most basic activities required for life, such as breathing and heartbeat. The brain stem has three major parts:midbrain, pons, and medulla oblongata.
5. thalmus: it sorts information from your ensory organs and passes signals between the spinal cord and other parts of your brain
6. hypothalmus: it gathers information about body temperature, hunger, and thirst. Then it sends signals that hel the body adjust and maintain homeostasis.