The nervous system Flashcards
Central nervous system and Peripheral nervous system
CNS: Brain and spinal cord
PNS: Cranial nerves (12 pairs)
Spinal nerves (31 pairs)
Oligodendrocytes
- Are the myelinating cells of the CNS
- Oligodendrocytes can myelinate serveral axons
- Myelin is tightly wrapped cell membrane
- Cell membrane is a billipid layer, so myelin essentially represent fat
Gray matter of the CNS
-Is composed of less myelinated-axons (higher density axons)
Brain: superficial gray matter: cortex
Deep gray matter: Basal nuclei
Gray matter is deep and located in horns
The white matter of the CNS
Fat is pale/yellow characterizing area of CNS with higher myelination as ‘‘white matters’’
Brain: Much white matter is deep
Spinal cord: Much white matter is superficial
The Brain
Forebrain: Presencaphalon, Cerebrum (telencephalon), Thalmus and hypothalmus
Midbrain: Mesencephalon, narrow connection of forebrain to hindbrain
Hindbrain: Rhombencephalon, medulla oblongata, pons and cerebellum
Brainstem: midbrain, pons and medulla oblongata
Midbrain
Tectum: Visual and auditory processing
- Superior colliculus (reflex to stim e.g. light)
- Inferior colliculus (reflex to auditory stim e.g. loud)
- The 4 colliculi= corpora quadrigemina
Tegmentum- subconscious control of upper limb position and muscle tone
- Red nucleus
- Substantia nigra
Pons
Is the bridge linking the cerebellum with the mesencephalon, diencephalon, cerebrum and spinal cord
- Nuclei of cranial nerves (v, vi)
- Nuclei involved in respiration-control
- Nuclei that relay info to and from the cerebellum
- Nuclei that interconnect ascending and descending tracts of the CNS
Cerebellum
Monitors all proprioceptive, visual, tactile, balance and auditory sensations. Its primary functions are:
- Automatic control of postural muscles of the body
- Programming and fine-tuning conscious and unconscious movements
Medulla Oblongata
connects the brain to the spinal cord and is responsible for complex autonomic reflexes and control of visceral functions:
- CVD centres
- Cranial nerve nuclei
- Relay stations for sensory and motor pathways
Spinal cord and meninges
Pia matter: Closest layer to brain, follows all irregularities of brain surface
Arachnoid mater: Subdural layer with projections to Pia (forms subarachnoid space for CSF)
Dura mater: External dense connective tissue (protection)
Dural Folds and Cerebrospinal fluid
- Divides the cranial cavity and help to hold the brain in place and house the venous sinuses
CSF - Clear fluid
- Supplies nutrients and removes waste products
- Floats brain and buffers against knocks
Special features of vertebrae
Cervical= C1,C2,C7
- Bifid spine
- Transverse foramen
- Triangular and wide vertebral canal
- Small oval body
Thoracic: T1, T10, T11,T12
- Inferiorly projecting spine
- Large transverse processes
- Circular small vertebral canal
- Triangular body
- Articular facets for ribs
Lumbar
- Small stumpy spine
- Small transverse processes
- Small triangular vertebral canal
- large round body
Cranial nerves (12 pairs)
CN 1: Olfactory nerve
CN 2: Optic nerve
CN 3: Oculomotor nerve
CN 4: Trochlear nerve
CN 5: Trigeminal nerve
CN 6: Abducens nerve
CN 7: Facial nerve
CN 8: Vestibulocochlear nerve
CN 9: Glossopharyngeal nerve
CN 10: Vagus nerve
CN 11: Accessory nerve
CN 12: Hypoglossal nerve
Spinal nerves and rami
Ventral rami
- Supply main component of trunks and limbs
- Gives rises to the major nerves
- Little branching from T1-T12
Dermatomes
- The area of skin innervated by a single spinal nerve
Autonomic Nervous system
Autonomic NS
Sympathetic:
- Preparation for an emergency: fight or flight
Parasympathetic
- Conserving/ restoring energy: Rest and digest
Control: Involuntary
Efferents: 2 neurons from brain stem/ spinal cord, 1st cell body in lateral grey horn in the brain stem. 2nd cell body in peripheral ganglia
Effector organs: Smooth and cardiac muscle; Secretory glands
Effect: Excitation or inhibiton