Structure and Development of the Nervous System Flashcards
What words are used to refer to the head end?
➤ Cranial
➤ Cephalic
➤ Rostral
➤ Anterior (four legged animals and embryos)
What words are used to refer to the tail end?
➤ Posterior
➤ Caudal
What words are used to refer to the foot end?
Caudal
What words are used to refer to the back?
➤ Dorsal
➤ Posterior (humans)
What words are used to refer to the belly?
➤ Ventral
➤ Anterior (humans)
What words are used to refer to things that are higher vertically?
➤ Superior
➤ Dorsal (four legged animals and embryos)
What words are used to refer to things that are lower vertically?
➤ Inferior
➤ Ventral (four legged animals and embryos)
What word is used to refer to things that are close to origin?
Proximal
What word is used to refer to things that are far from the origin?
Distal
What are the sectional planes of the brain?
➤ Coronal
➤ Longitudinal
➤ Axial or horizontal
What is the coronal plane of the brain?
➤ Frontal plane
➤ Brain is split into front and back
What is the longitudinal plane of the brain?
➤ Sagittal plane
➤Brain is split into left and right
What is the axial or horizontal plane of the brain?
➤ Transverse plane
➤ Brain is split into top and bottom
What does the central nervous system include and its function?
➤ Brain and spinal cord
➤ Integrative and control centres
What does the peripheral nervous system include and its function?
➤ Cranial nerves and spinal nerves
➤ Communication lines between between the CNS and the rest of the body
What does motor (efferent) division include and its function?
➤ Motor nerve fibers
➤ Conducts impulses from the CNS to effectors (muscles or glands)
What does the sensory (afferent) division include and its function?
➤ Somatic and visceral sensory nerve fibers
➤ Conducts impulses from receptors to the CNS
What does the somatic nervous system include and its function?
➤ Somatic motor (voluntary)
➤ Conducts impulses from the CNS to the skeletal muscles
What does the autonomic nervous system include and its function?
➤ Visceral motor (involuntary)
➤ Conducts impulses from the CNS to cardiac muscles, smooth muscles and glands
What is the function of the sympathetic division?
Mobilises body systems during activity (fight or flight)
What is the function of the parasympathetic division?
➤ Conserves energy
➤ Promotes “housekeeping” functions during rest
Why do we have a nervous system?
➤ Respond to a stimulus
➤ Process the stimulus
➤ Make a decision regarding movement
What type of nervous system do primitive animals (e.g. jellyfish) have?
Nerve net (not really a nervous system)
What is the difference between vertebrates and arthropods regarding nervous system?
Arthropods have a ventral nerve cord whereas vertebrates have a dorsal nerve cord
When did the vertebrate brain appear?
In amphioxus (cephalochordate)
What brain divisions do all vertebrates have?
➤ Olfactory bulb
➤ Cerebral hemispheres
➤ Cerebellum
➤ Optic tectum (visual processing centre)
➤ Medulla oblongata (brain stem)
What are the four regions of the brain in vertebrates?
➤ Forebrain
➤ Midbrain
➤ Hindbrain
➤ Spinal cord
What are the subdivisions of the forebrain?
➤ Telencephalon
➤ Diencephalon
What structures does the telecephalon contain?
➤ Cortex
➤ Olfactory bulb
What structures does the diencephalon contain?
➤ Thalumus
➤ Hypothalamus
What makes up the brain stem?
➤ Midbrain
➤ Hindbrain
What are the subdivisions of the brain stem?
➤ Mesencephalon
➤ Rhombencephalon
What structures does the mesencephalon contain?
➤ Tectum
➤ Tegmentum
What structures does the rhombencephalon contain?
➤ Pons
➤ Medulla
➤ Cerebellum
What happens when the ectoderm is specialised?
➤ One region becomes the epidermis (on the sides) and the other becomes the neural plate (in the middle) separated by an neural plate border
➤ Border regions move together which results in the neural plane folding and fusing the form the neural tube
➤ Continuous layer of epidermis formed with neural tube underneath it and with neural crest cells between them
What does the neural tube become?
Central nervous system
What do the neural crest cells become?
Peripheral nervous system
How does the neural tube close?
➤ Closing starts at the middles
➤ Closing progresses to the anterior and posterior end
➤ End up with a neural pore at the end of the each tube
What can go wrong if the anterior end pore does not close?
➤ Brain would not develop
➤ Leads to anencephaly: incompatible with life
What can go wrong if the posterior end pore does not close?
➤ Condition called spina bifida
➤ Worst case: gap in the vertebral column and a portion of the spinal cord poking out of the baby’s back
➤ Likely that the baby’s leg would be paralysed
How can neural tube effects be prevented?
Supplementing diet with folic acid in the early stages of pregnancy
What drugs increase the risk of spina bifida?
Antilepsy/bipolar drugs e.g. sodium valproate used to treat epilepsy and bipolar disorder
How does the development of the brain begin?
Three swellings at rostral end of the neural tube become the primary vesicles
What are the primary vesicles of the brain?
➤ Prosencephalon (forebrain)
➤ Mesencephalon (midbrain)
➤ Rhombencephalon (hindbrain)
What does the prosencephalon differentiate to?
➤ Telencephalon which becomes the cerebrum
➤ Diencephalon which becomes the thalamus, hypothalamus and epithalamus
➤ Structures for the eye
What does the rhombencephalon differentiate to?
➤ Metencephalon which becomes the pons and cerebellum
➤ Myelencephalon which becomes the medulla oblongata
