BMSC11002 Lecture Notes - Lecture 7: Axon Terminal, Lipid Bilayer Fusion, Endoplasmic Reticulum
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WEEK 7: INTRODUCTION TO THE NERVOUS SYSTEM
12.1 NERVOUS SYSTEM: HOMEOSTASIS AND INTEGRATION OF BODY CAVITIES
• Sensory function – sensory receptors detect internal stimuli, such as an increase in blood acidity,
and external stimuli, such as a raindrop landing on your arm
o This sensory information is then carried into the brain and spinal cord through cranial and
spinal nerves
• Integrative function – the nervous system processes sensory information by analysing and storing
some of it, and making decisions for appropriate responses
• Motor function – once sensory information is integrated, the nervous system may elicit an
appropriate motor response, by activating effectors (muscles and glands)
o Through cranial and spinal nerves
o Stimulation of effectors causes muscles to contract and glands to secrete
12.2 NERVOUS SYSTEM CLASSIFICATION INTO CENTRAL AND PERIPHERAL NERVOUS
SYSTEMS
CENTRAL NERVOUS SYSTEM
The central nervous system is made up of the brain and spinal cord, which process sensory
input and provide instructions to the body.
• The central nervous system (CNS) and the peripheral nervous system (PNS) comprise the
entirety of the body's nervous system, which regulates and maintains its most basic functions.
• The CNS is the main control center of the body—it takes in sensory information, organizes and
synthesizes this input, then provides instructions for motor output to the rest of the body.
• The CNS is made up of the brain and spinal cord.
• The brain is the main data center of the body, consisting of the cerebrum (which regulates higher-
level functioning such as thought) and the cerebellum (which maintains coordination).
• The brain stem includes the midbrain, pons, and medulla, and controls lower-level functioning
such as respiration and digestion.
• The spinal cord connects the brain and the body's main receptors, and serves as a conduit for
sensory input and motor output.
Terms
• brain stem
The part of the brain that connects the spinal cord to the forebrain and cerebrum.
• cerebellum
Part of the hindbrain in vertebrates. In humans it lies between the brainstem and the
cerebrum, and plays an important role in sensory perception, motor output, balance,
and posture.
• spinal cord
A thick, whitish cord of nerve tissue that is a major part of the central nervous system.
It extends from the brain stem through the spine, with nerves branching off to various
parts of the body.
• cerebrum
In humans it is the largest part of the brain and is the seat of motor and sensory
functions, as well as the
higher mental functions such as consciousness, thought, reason, emotion, and memory.
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The central nervous system (CNS) is one of the two major subdivisions of the nervous system. The CNS
includes the brain and spinal cord, which together comprise the body's main control center. Together
with the peripheral nervous system (PNS), the CNS performs fundamental functions that contribute to
an organism's life and behavior.
Activity of the CNS
The nervous system has three main functions: gathering sensory information from external stimuli,
synthesizing that information, and responding to those stimuli. The CNS is mainly devoted to the
"information synthesizing" function. During this step in the process, the brain and spinal cord decide on
appropriate motor output, which is computed based on the type of sensory input. The CNS regulates
everything from organ function to high-level thought to purposeful body movement. Thus, the CNS is
commonly thought of as the control center of the body.
Structure of the Central Nervous System
The CNS is comprised of the brain, brain stem, and spinal cord.
Brain
The brain is found in the cranial cavity and consists of the cerebrum and cerebellum. It houses the nerve
centers responsible for coordinating sensory and motor systems in the body. The cerebrum, or the top
portion for the brain, is the seat of higher-level thought. It is comprised of two hemispheres, each
controlling the opposite side of the body. Each of these hemispheres is divided into four separate lobes:
• the frontal lobe, which controls specialized motor control, learning, planning, and speech;
• the parietal lobe, which controls somatic or voluntary sensory functions;
• the occipital lobe, which controls vision;
• the temporal lobe, which controls hearing and some other speech functions.
The cerebellum is located underneath the backside of the cerebrum, and governs balance and fine motor
movements. Its main function is maintaining coordination throughout the body.
Brain Stem
The brain stem is connected to the underside of the brain. It consists of the midbrain, pons, and medulla.
The midbrain is found in between the hindbrain and the forebrain. It regulates motor function and allows
motor and sensory information to pass from the brain to the rest of the body. The pons houses the
control centers for respiration and inhibitory functions. The medulla also helps regulate respiration, as
well as cardiovascular and digestive functioning.
Spinal Cord
The spinal cord connects the brain and brain stem to all of the major nerves in the body. Spinal nerves
originate from the spinal cord and control the functions of the rest of the body. Impulses are sent from
receptors through the spinal cord to the brain, where they are processed and synthesized into
instructions for the rest of the body. This data is then sent back through the spinal cord to muscles
and glands for motor output.
PERIPHERAL NERVOUS SYSTEM
The peripheral nervous system (PNS) is one of the two major components of the body's nervous system.
In conjunction with the central nervous system (CNS), the PNS coordinates action and responses by
sending signals from one part of the body to another. The CNS includes the brain, brain stem, and spinal
cord, while the PNS includes all other sensory neurons, clusters of neurons called ganglia, and connector
neurons that attach to the CNS and other neurons.
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The nervous system
The human nervous system, including both the central nervous system (in red: brain, brain stem, and
spinal cord) and the peripheral nervous system (in blue: all other neurons and receptors).
Divisions of the Peripheral Nervous System
The PNS can also be divided into two separate systems: the autonomic nervous system and the somatic
nervous system.
Autonomic Nervous System
The autonomic nervous system regulates involuntary and unconscious actions, such as internal-organ
function, breathing, digestion, and heartbeat. This system consists of two complementary parts: the
sympathetic and parasympathetic systems. Both divisions work without conscious effort and have similar
nerve pathways, but they generally have opposite effects on target tissues.
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Document Summary
12. 2 nervous system classification into central and peripheral nervous. The part of the brain that connects the spinal cord to the forebrain and cerebrum. cerebellum. In humans it lies between the brainstem and the cerebrum, and plays an important role in sensory perception, motor output, balance, and posture. spinal cord. A thick, whitish cord of nerve tissue that is a major part of the central nervous system. It extends from the brain stem through the spine, with nerves branching off to various parts of the body. cerebrum. In humans it is the largest part of the brain and is the seat of motor and sensory functions, as well as the higher mental functions such as consciousness, thought, reason, emotion, and memory. The central nervous system (cns) is one of the two major subdivisions of the nervous system. The cns includes the brain and spinal cord, which together comprise the body"s main control center.
