Nervous systems Flashcards
Nervous system
Senses environment and transfers information centrally for processing and response
What is cephalization?
The evolution of the brain where neurons supplying sensory clusters also grouped towards the front forming the brain
What is longitudinal centralization?
Aggregation of nerve cell bodies as individual ganglia. Co-ordinates the function of the body segment within that region and decentralizes the brain.
What are the 3 neurones in the nervous system?
Afferent (sensory), efferent (motor) and interneurons
What is the purpose of afferent/sensory neurones?
Information flow via axon towards control centre
What is the purpose of efferent/motor neurones?
Information flow via axon away from control centre
What is the purpose of interneurons?
Central connections (more common than other neurones)
What are the types of neurones?
Unipolar: branched axon and no dendrites
Bipolar: axon and a dendrite
Multipolar: axon and several dendrites
What is in the Central Nervous System (CNS)?
Brain, brainstem, spinal cord and millions of interneurons
What is in the Peripheral Nervous System?
Sensory and motor neurones, axons run together as peripheral nerves
How many spinal nerve pairs are there?
31: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal and 12 cranial nerves
Name the 12 cranial nerves
I- Olfactory (S)
II- Optic (S)
III- Oculomotor (M)
IV- Trochlear (M)
V- Trigeminal (B)
VI- Abducens (M)
VII- Facial (B)
VIII- Vestibulocochlear (S)
IX- Glossopharyngeal (B)
X- Vagus (B)
XI- Accessory (M)
XII- Hypoglossal (M)
What are the 2 functional divisions of the PNS?
Somatic nervous system and Autonomic nervous system (ANS)
Somatic nervous system vs Autonomic nervous system
Somatic: responds to external environment
Autonomic: responds to internal environment
Sensory receptors
Detect external and internal events which leads to action potentials in sensory neurones conducted to the CNS
