The nervous system

Question 1

Central nervous system and Peripheral nervous system

Answer 1

CNS: Brain and spinal cord
PNS: Cranial nerves (12 pairs)
Spinal nerves (31 pairs)

Question 2

Oligodendrocytes

Answer 2

• 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

Question 3

Gray matter of the CNS

Answer 3

-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

Question 4

The white matter of the CNS

Answer 4

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

Question 5

The Brain

Answer 5

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

Question 6

Midbrain

Answer 6

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

Question 7

Pons

Answer 7

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

Question 8

Cerebellum

Answer 8

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

Question 9

Medulla Oblongata

Answer 9

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

Question 10

Spinal cord and meninges

Answer 10

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)

Question 11

Dural Folds and Cerebrospinal fluid

Answer 11

• 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

Question 12

Special features of vertebrae

Answer 12

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

Question 13

Cranial nerves (12 pairs)

Answer 13

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

Question 14

Spinal nerves and rami

Answer 14

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

Question 15

Autonomic Nervous system

Answer 15

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

Question 16

Somatic Nervous system

Answer 16

Control: Voluntary
Efferents: 1 neuron from the spinal cord, cell body in ventral grey horn brainstem
Effector organs: Skeletal muscle
Effect: Excitation

Question 17

Sympathetic

Answer 17

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

Question 18

Parasympathetic

Answer 18

Heart: Decreased heart rate and decreased blood pressure
Eye: Constrict pupil
Airways: Decreased Airway diameter
Blood vessels: Not innervated
GIT glands: Stimulation

Question 19

Postganglionic fibre and sympathetic chain

Answer 19

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

Question 20

Collateral ganglion

Answer 20

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

Question 21

Adrenal medulla and Hypothalamus

Answer 21

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