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
Somatic Nervous system
Control: Voluntary
Efferents: 1 neuron from the spinal cord, cell body in ventral grey horn brainstem
Effector organs: Skeletal muscle
Effect: Excitation
Sympathetic
Heart: Increased heart rate, increased blood pressure
Eye: Dilate pupil
Airways: Increased airway diameter
Blood vessels: Decreased GIT blood flow, increased skeletal muscle blood flow
GIT glands: Inhibition
Parasympathetic
Heart: Decreased heart rate and decreased blood pressure
Eye: Constrict pupil
Airways: Decreased Airway diameter
Blood vessels: Not innervated
GIT glands: Stimulation
Postganglionic fibre and sympathetic chain
Postganglionic fibre: Is a nerve fibre that extends from an autonomic ganglion to innervate target tissues or organs, transmitting signals away from the ganglion in the ANS
Sympathetic chain= Is a series of ganglia located on either side of the vertebral column that serve as a major component of the sympathetic division of the ANS
Collateral ganglion
Collateral ganglion: Is a type of autonomic ganglion located outside the sympathetic chain, typically found in proximity to major arteries and involved in the relay of autonomic signals to target organs in the ab and pelvic region
Adrenal medulla and Hypothalamus
Adrenal medulla: This is an endocrine gland located within the adrenal gland that releases hormones contributing to the body’s responses to stress and regulation of SNS activity
Hypothalamus: Is a region in the brain that regulates numerous bodily functions e.g. temp, hormone secretion and control of basis behaviours such as hunger and thirst
