Lecture 20. Neurons and Nervous Systems Flashcards
What does the nervous system do?
- Receive and interpret information about the internal and external environments of the body (sensory system)
- To make decisions about this information (integrating system)
- To organise and carry out action (motor system)
What does the sensory system include?
Sense organs, sensory nerves, central sensory areas
What is the integrating system used for?
Making decisions from sensory input and stored record of previous experience (memories)
What does the motor system include?
Motor neurones, central motor areas, all muscles and ducted glands of the body
What is the motor system used for?
Control of movement - conscious and unconscious
What are the units of the brain?
Neurons
What is a neuron made up of?
Dendrites
Axon
Myelin
Node of Ranvier
Terminals
What do dendrites do?
Increase surface area receive inputs
What do axons do?
Carry information over distances
What does myelin do?
Coats axon improves conduction
What are Nodes of Ranvier do?
Breaks in myelin sheath
What are terminals?
Output region transmitter release synapse with other neurones
What is anterograde transport (WGA-HRP)?
From soma, down axon to terminals
Two kinds: rapid: 300-400 mm/day (up to 1 μm/s) and slow: 5-10 mm/day
What is retrograde transport (HRP)?
From terminals to soma
Worn out mitochondria, SER
Rapid: 150 - 200 mm/day
What is required for axonal transport?
Hydrolysis of ATP
Microtubules
What do microglial cells do?
Act as scavengers
Clean up cellular debris
Launch immune response
What do oligodendrocytes do?
Form myelin sheath in Central NS
What do astrocytes do?
Supporting role
Mop up transmitters
Correct ionic environment
Release gliotransmitters (ATP, glutamate, D-serine)
Provide metabolic fuel for neurones
How do nervous systems form?
Nerve nets → Nerve ring → Ganglia → Fusion of ganglia
What occurs after the fusion of the ganglia?
Fusion of ganglia → Brain and Nerve cord → Vertebrates encephalisation
What makes up the central nervous system (CNS)?
Brain and Spinal Cord
What makes up the peripheral nervous system (PNS)?
Automatic (involuntary) Nervous System and Somatic (voluntary) Nervous System
What are the segments of the spinal cord?
Cervical
Thoracic
Lumbar
Sacral
How are brain structures defined?
By embryology
What parts of the brain develop after 4 weeks?
Prosencephalon (Forebrain)
Mesencephalon (Midbrain)
Rhombencephalon (Hindbrain)
What parts of the brain develop after 6 weeks?
Prosencephalon (Diencephalon and Telencephalon)
What does the diencephalon contain?
Thalamus and Hypothalamus
What does the telencephalon contain?
Cerebrum
Basal ganglia
Hippocampus
What does the midbrain mesencephalon?
Inf. Colliculus
Sup. Colliculus
Ret Formation
What does the hindbrain rhombencephalon contain?
Medulla
Cerebellum
Pons
What are the meninges?
Surround the CNS
Brain suspended in jacket of cerebrospinal fluid
3 layers 1) Tough outer layer Dura mater 2) Arachnoid mater 3) Pia mater
What is the ventricular system?
Principle source of CSF: choroid plexuses in ventricles
About 150 ml CSF
Renewed ~ 4-5 times in 24 hrs
Removes waste products
Supplies brain & sp cord with nutrients
Buffers changes in blood pressure and protects brain
Supplies brain with fluid during dehydration
Allows the brain to remain buoyant
What links the two hemispheres of the brain?
Corpus callosum
What are the functions of the midbrain?
Visual, auditory information, motor control, sensation
What is the function of the pons and where are they located?
Links with cerebellum, modifies medulla output
What are the functions of the medulla?
Respiration and cardiovascular function
What are the functions of the cerebellum?
Balance, gait, fine movement, posture
What is the function of the hypothalamus?
Integrates sensory information (LGN vision, MGN hearing)
What is the function of the hypothalamus?
Autonomic control, appetitive drives reproductive behaviour, homeostasis, endocrine control
