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Questions and Answers
The nervous system has billions of __________.
The nervous system has billions of __________.
neurons
One function of the nervous system is controlling __________ and glands.
One function of the nervous system is controlling __________ and glands.
muscle
The Central Nervous System is responsible for interpreting incoming __________ information.
The Central Nervous System is responsible for interpreting incoming __________ information.
sensory
The __________ is the primary center for regulating and coordinating body activities.
The __________ is the primary center for regulating and coordinating body activities.
The __________ carries impulses to and from the spinal cord.
The __________ carries impulses to and from the spinal cord.
Neuroglia nourishes the __________ cells in the brain and spinal cord.
Neuroglia nourishes the __________ cells in the brain and spinal cord.
Meninges are the membranes that cover the __________.
Meninges are the membranes that cover the __________.
An __________ is an agent that directly influences an activity by exciting a sensory organ.
An __________ is an agent that directly influences an activity by exciting a sensory organ.
Each pair of spinal nerves is connected to a segment of the cord by two pairs of attachments called ______.
Each pair of spinal nerves is connected to a segment of the cord by two pairs of attachments called ______.
The 8 cervical nerves supply the ______, neck and diaphragm.
The 8 cervical nerves supply the ______, neck and diaphragm.
The 12 thoracic nerves supply the muscles of the ______ and back.
The 12 thoracic nerves supply the muscles of the ______ and back.
The 5 lumbar nerves supply the lower ______ and some parts of the lower limb.
The 5 lumbar nerves supply the lower ______ and some parts of the lower limb.
The olfactory cranial nerve is responsible for the sense of ______.
The olfactory cranial nerve is responsible for the sense of ______.
The vagus nerve stimulates digestive organs, internal organ functions such as heart rate and respiratory ______.
The vagus nerve stimulates digestive organs, internal organ functions such as heart rate and respiratory ______.
The somatic sensory fibers deliver impulses from skin, skeletal muscles and ______.
The somatic sensory fibers deliver impulses from skin, skeletal muscles and ______.
The motor division of the Peripheral Nervous System carries impulses away from the ______.
The motor division of the Peripheral Nervous System carries impulses away from the ______.
The autonomic nervous system controls the activity of smooth and ______ muscles.
The autonomic nervous system controls the activity of smooth and ______ muscles.
The ______ state is characterized by calming responses and maintaining homeostasis.
The ______ state is characterized by calming responses and maintaining homeostasis.
The basic structural and functional unit of the brain and nervous system is called a ______.
The basic structural and functional unit of the brain and nervous system is called a ______.
The brain is protected by the skull and ______.
The brain is protected by the skull and ______.
During embryonic development, the prosencephalon is also known as the ______.
During embryonic development, the prosencephalon is also known as the ______.
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Study Notes
Overview of the Nervous System
- Small yet complex, comprising billions of neurons.
- Weighs approximately 2 kg (3% of total body weight) and controls communication within the body.
Functions of the Nervous System (C.R.I.M.E.)
- Controlling muscle and glands.
- Receiving sensory input from the environment.
- Integrating information for processing and response.
- Maintaining homeostasis, or stable internal conditions.
- Establishing and maintaining muscle activity.
Key Terms
- Neuropeptide: Specialized protein messengers involved in mental functions.
- Neuroglia: Cells that nourish and support neurons in the brain and spinal cord.
- Meninges: Membranes covering the brain, providing protection.
- Myelinated: Neurons surrounded by a myelin sheath for faster impulse transmission.
- Neuron: Basic nerve cell responsible for receiving and transmitting impulses.
- Nerve: Bundle of neuron fibers outside the central nervous system (CNS).
- Instinct: Immediate awareness without reasoning or discovery.
- Stimulus: Agent influencing activity, evoking sensory responses or muscular contractions.
- Impulse: Wave of excitation transmitted by nerve fibers and muscles.
Divisions of the Nervous System
-
Central Nervous System (CNS): Main control center interpreting sensory information and coordinating responses.
- Brain: Primary regulatory center for body activities, processing information.
- Spinal Cord: Conducting pathway for reflex actions and information between the brain and the body.
-
Peripheral Nervous System (PNS): Transmits impulses to and from the CNS.
- Spinal Nerves: 31 pairs connecting to specific spinal cord segments, facilitating impulse transmission.
- Cervical Nerves: Supply limbs, neck, and diaphragm.
- Thoracic Nerves: Supply muscles of chest and back.
- Lumbar Nerves: Supply lower abdomen and parts of the lower limbs.
- Sacral Nerves: Supply reproductive organs.
- Spinal Nerves: 31 pairs connecting to specific spinal cord segments, facilitating impulse transmission.
Cranial Nerves (12 pairs)
- Olfactory: Responsible for sense of smell.
- Optic: Responsible for vision and visual acuity.
- Oculomotor: Controls eyelid opening and pupil constriction.
- Trochlear: Governs oblique eye movement.
- Trigeminal: Related to facial sensation and mastication.
- Abducens: Manages lateral eye movement.
- Facial: Controls facial expressions and tear production.
- Vestibulocochlear: Involved in hearing and balance.
- Glossopharyngeal: Responsible for taste and swallowing.
- Vagus: Stimulates internal organ functions, including the heart and digestive organs.
Functional Classifications of the PNS
-
Sensory Division (Afferent): Nerve fibers conveying information from sensory receptors to the CNS.
- Somatic Sensory Fibers: Deliver impulses from skin, muscles, and joints.
- Visceral Sensory Fibers: Transmit information from internal organs and blood vessels.
-
Motor Division (Efferent): Carries impulses away from the CNS to initiate actions.
- Somatic Nervous System: Controls voluntary movements of skeletal muscles.
- Autonomous Nervous System: Regulates involuntary actions of smooth and cardiac muscles.
- Parasympathetic Division: Promotes a calming state, supporting digestion and energy conservation; lowers heart rate and blood pressure.
Neurons
- Basic structural and functional units of the nervous system.
- Cell Body (Perikaryon): Central portion responsible for metabolism and gene expression.
- Dendrites: Tree-like structures conducting impulses to the cell body.
- Axon: Transmits nerve impulses away from the cell body.
The Brain
- Control center of the nervous system, weighing about 3 pounds, with a structure that is soft, spongy, and pinkish gray.
- Composed of over 100 billion neurons and demands continuous oxygen and glucose supply.
- Major components include:
- Brain Stem
- Cerebrum
- Cerebellum
Brain Development
- Begins during the 4th week of embryonic development, forming three major vesicles:
- Prosencephalon (Forebrain): Divides into Telencephalon (cerebrum) and Diencephalon (thalamus, hypothalamus).
- Mesencephalon (Midbrain)
- Rhombencephalon (Hindbrain): Divides into Metencephalon (cerebellum, pons) and Myelencephalon (medulla oblongata).
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