2 - APP - Unit 3.1 - Nervous System Flashcards
The nervous system
Controls and coordinates the functions of the other systems of the body so they work harmoniously and efficiently.
Composed of: brain + spinal cord + peripheral nerves
The nervous system - Types of cells
- Neurons
- Neuroglia
The nervous system - Neurons
Responsible for most special functions attributed to the nervous system:
- sensing
- thinking
- remembering
- controlling muscle activity
- regulating glandular secretions
The nervous system - Neuroglia
Support, nurture and protect neurons and maintain homeostasis of the fluid that bathes neurons
Neurons & nerves - Neuron composition
A cell body
Its outgrowth of projections (=neuronal fibers)
Neurons & nerves - Types of neuronal fibers
- Numerous multi-branched dendrites that connect with other neurons to receive information
- A single Axon that conducts impulses away from the cell body
Neurons & nerves - Cell body
Stores energy and nutrients that are used by the cellular projections to receive and conduct nerve impulses throughout the body
Neurons & nerves - Synapse
Junction at which impulses are passed from one neuron to another
Neurons & nerves - Neurotransmitter
When an impulse reaches the end of an axon, a chemical neurotransmitter is released at the synapse that acts on the membrane of the receptive neuron to pass the impulse along.
Neurons & nerves - Neurons are classified according to…
… the direction in which they transmit nerve impulses and the type of information carried.
Neurons & nerves - 3 types/classifications of neurons
- Sensory neurons
- Motor neurons
- Interneurons
Neurons & nerves - Sensory neurons
AKA Afferent Neurons
Originate in the periphery of the body
Carry incoming information (impulses or messages from sense organs) to the brain & spinal cord where sensations of touch, cold, heat, sight, hearing, taste or pain are interpreted and experiences
Neurons & nerves - Motor neurons
AKA Efferent Neurons
Carry outgoing motor information (nerve impulses) from the brain/spinal cord to the muscles or glands that they control
Neurons & nerves - Interneurons
AKA Central or Connection neurons
Located in the brain and spinal cord
Carry impulses from one neuron to another
Neurons & nerves - Nerve cell bodies & fibers location
Almost all nerve cell bodies are contained in the brain and spinal cord
Fibers extend outward to make up the nerves
Neurons & nerves - Nerve
A group of neuronal fibers (axons and/or dendrites) found in the peripheral portions of the nervous system bundled together by connective tissue like the strands of a cable
Neurons & nerves - Myelin
Fatty insulating material wrapping individually the fibers found within the nerve
Divisions of the Nervous System - 2 divisions
- Central nervous system
- Peripheral nervous system
Divisions of the Nervous System - Central nervous system (CNS)
CNS = Brain + Spinal Cord
- incoming sensory information are integrated and correlated
- thoughts and emotions are generated
- memories are formed and stored
Originate in the CNS: most nerve impulses that stimulate muscles to contract & glands to secrete
CNS communicates with rest of the body through PNS
Divisions of the Nervous System - Brain
Principle nerve center
Body’s largest & most complex nerve tissue containing in excess of ten billion neurons and innumerable nerve fibers
Located in & protected by cranium
Controls sensations, muscles, glandular activity & the power to think and feel (emotions)
Divisions of the Nervous System - Brain - Diencephalon
2 parts:
- Thalamus - the “sensory brain”
- Hypothalamus - the principal link between endocrine and nervous systems
Divisions of the Nervous System - Brain - Cerebrum
Largest portion making up the front and top of the brain Presides over complex activities / mental activities as: - speech - sensation - communication - memory - reasoning - emotions
Divisions of the Nervous System - Brain - Cerebellum
Smaller part of the brain
Located below the cerebrum & at the back of the cranium
Helps maintain body balance, coordinates voluntary muscles & makes muscular movement smooth and graceful
Divisions of the Nervous System - Peripheral nervous system (PNS)
PNS = All the nerves that connect the central nervous system to the rest of the body
Includes cranial nerves, spinal nerves and their branches
Divisions of the Nervous System - Brain - Diencephalon -Thalamus
Provides the sense of touch / pressure, pain & temperature
Provides functions in emotions & memory
Divisions of the Nervous System - Brain - Diencephalon -Hypothalamus
Principal link between the endocrine & nervous system
Regulates the pituitary gland
Functions in rage & agression, controls normal body temperature, food intake, thirst & help maintain the waking state and sleep cycles
Divisions of the Nervous System - Brain - Brain Stem - Midbrain
Contains main nerve pathways connecting cerebrum & lower nervous system
Contains certain visual and auditory reflexes that coordinate head and eye movement with things seen and heard
Divisions of the Nervous System - Brain - Brain Stem - Pons
Located between midbrain & medulla oblongata
Relays nerve impulses:
- between cerebrum & medulla oblongata
- from cerebrum to cerebellum
Divisions of the Nervous System - Brain - Brain Stem - Medulla oblongata
Enlarged continuation of spinal cord extending from the foramen magnum to the pons
Connects the brain & the spinal cord
Regulate heart rate, rate and depth of respiration & tonicity of blood vessels (+ digestion ?)
Divisions of the Nervous System - Limbic system
AKA “emotional” brain
Ring of structures on the inner border of the cerebrum & floor of the diencephalons, encircling the brain stem
Functions in:
- emotional aspects of behavior related to survival
- Primary function in emotions: pleasure, pain, anger, rage, fear, sorrow, sexual feelings, docility & affection
- memory (hippocampus + portions of cerebrum)
Divisions of the Nervous System - Limbic system - Hippocampus
Portion of the limbic system
Works with portions of the cerebrum functions in memory
Divisions of the Nervous System - Spinal cord
Extends downwards from the brain
Housed in and protected by the vertebral column
31 segments, each being the site of attachement of a pair of spinal nerves.
Functions as:
- a conduction pathway for nerve impulses traveling to & from the brain
- a reflex center between incoming & outgoing peripheral nerve fibers
Divisions of the Nervous System - Types of connective tissues surrounding and protecting the brain and spinal cord nervous tissue
- Cranial bones
- Vertebrae
- Meninges
- Layer of cerebrospinal fluid
Divisions of the Nervous System - Meninges
3 connective tissue layers that encircle the brain and spinal cord:
- Dura mater
- Arachnoid layer
- Pia mater
Divisions of the Nervous System - Meninges - Dura mater
Most superficial layer and durable layer
Compose of very thick and strong connective tissue
Divisions of the Nervous System - Meninges - Arachnoid layer
Middle layer
Avascular covering
“Spider web” arrangement of delicate collagen fibers
Divisions of the Nervous System - Meninges - Pia mater
Innermost layer
Thin transparent connective tissue layer that adheres to the surface of the spinal cord and brain.
Contains many blood vessels that supply nutrients and oxygen to the brain & spinal cord
Divisions of the Nervous System - Cerebrospinal fluid (CSF)
Nourishes and protects brain and spinal cord against chemical & physical injury
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To be completed
Divisions of the Nervous System - Cerebrospinal fluid (CSF)
Nourishes and protects the CNS (Central Nervous System = brain + spinal cord) against chemical & physical injury by acting as a shock absorber for the delicate nervous tissue.
Continuously circulates around the brain and spinal cord inside the subarachnoid space found between the arachnoid layer and pia mater.
Carries nutrients to the nerve tissue and carries waste away
Divisions of the Nervous System - Peripheral nervous system (PNS)
PNS = All the nerves that connect the central nervous system to the rest of the body
Includes cranial nerves, spinal nerves and their branches
Divisions of the Nervous System - Cranial nerves - Definition
12 cranial nerves
Connect directly to some part of the brain surface and pass through openings on the sides and base of the cranium
Divisions of the Nervous System - Cranial nerves - Classifications
- Motor
- Sensory
- Mixed nerves - containing both motor and sensory fibers
Divisions of the Nervous System - the 12 Cranial nerves
CN I. Olfactory nerve - Sense of smell
CN II. Optic nerve - Sense of sight
CN III. Oculomotor nerve - Controls eye movements
CN IV. Trochlear nerve - Controls eye movements
CN V. Trigeminal nerve - Controls face sensations & jaw movements. 3 branches: Mandibular branch / Maxilary Branch / Ophtalmic branch
CN VI. Abducent nerve - Sense of hearing
CN VII. Facial nerve - Controls facial muscles of expression & some neck muscles
CN VIII. Auditory Nerve - Sense of hearing
CN IX. Glossopharyngeal nerve - Sense of taste
CN X. Vagus nerve - Controls sensations & muscular movements relating to talking, heart action & digestion (longest cranial nerve - MBLEX)
CN XI. Spinal accessory nerve - Controls neck muscles movement (incl. trapezius & sternocleidomastoid)
CN XII. Hypoglossal nerve - Controls movement of the tongue
Divisions of the Nervous System - Spinal nerves - Definition
31 pairs of spinal nerves emerge from the spinal cord
All mixed nerves (contain sensory and motor nerve fibers) to provide 2-way communication between CNS and body
Divisions of the Nervous System - Spinal nerves - Emergence
Spinal nerves emerge from the spinal cord in the following order:
- 8 pairs attached to cervical segments
- 12 pairs attached to thoracic segments
- 5 pairs attached to lumbar segments
- 5 pairs attached to sacrospinal segments
- 1 pair attached to coccygeal segment
Divisions of the Nervous System - Spinal nerves - Branching
After spinal nerves exit from spinal cord segments they branch to form many peripheral nerves of the truck & limbs