THE NERVOUS SYSTEM
BY: MR. JASTINE JASON J. CARO
FUNCTIONS
• Controls and coordinate all the different parts of
the body.
• Controls responses involving emotions, reasons, and
habitats.
MAIN PARTS
• Central Nervous System
(CNS) – consist of the brain
and the spinal cord.
• Peripheral Nervous System
(PNS) – consist of a network
of nerves and sense organs.
CENTRAL NERVOUS SYSTEM
• It is the control center of the body.
• It is protected by the skull and the
vertebrae of the spinal column.
• The brain and the spinal cord are
covered by layers of connective
tissues called meninges.
PERIPHERAL NERVOUS SYSTEM
• It consist of network of nerves connecting the CNS to the other
parts of the body.
• It carries messages between the CNS and the rest of the body.
• It includes the cranial nerves, spinal nerves, and ganglia
(contains nerve cell bodies).
CRANIAL NERVES
GANGLIA
PERIPHERAL NERVOUS SYSTEM
• The sensory division conducts impulses from the
sense organs to the CNS.
• The motor division conducts impulses from the CNS
to the effectors (muscles or glands) of the body.
MOTOR DIVISION (PNS)
• It consists of the somatic nervous system and the
autonomic nervous system.
• The somatic nervous system innervates skeletal muscles
and regulates voluntary activities.
• The autonomic nervous system is involuntary and
innervates glands, the heart, and smooth muscles.
AUTONOMIC NERVOUS SYSTEM
• It consists of the sympathetic and the parasympathetic
nervous system.
• The sympathetic system excites a particular organ while
the parasympathetic system inhibits it. (e.g. constriction
and dilation of the bronchial tubes)
NEURON
NEURON
• A neuron is the basic unit of structure and function of the nervous system.
• The cell body is the largest portion of a neuron which contains the
cytoplasm and nucleus.
- It integrates incoming stimuli or signals and receives impulses
from dendrites.
- It supports and maintains the functions of a neuron by producing
the protein needed.
NEURON
• The nucleus gives life to the cell body.
- It helps in maintaining the cell and keeps the neuron
functional.
• Dendrites are short, highly branched fibers that are specialized to
receive stimuli and send messages or nerve impulses to the cell
body.
- They increase the surface area of the body.
NEURON
• The axon is a long fiber that carries messages or nerve impulses away
from the cell body to another neuron or to a muscle gland.
• Myelin sheaths are thick, fatty coats that insulate and protect the axon.
- It aids in the speed of transmitting impulses.
• Nodes of Ranvier are gaps in the myelin sheaths wherein impulses jump
from node to the other.
- It increases the speed of transmitting impulses.
BASIC NEURON TYPES
• Sensory neurons receive messages from special receptors
and carries them to the CNS.
• Motor neurons carry messages from the CNS to the
effectors.
• Interneurons connect sensory and motor neurons. It integrates
information and sends appropriate signals to motor neurons.