Structure And Development Of NS Flashcards
What are the primary functions of the nervous system?
Stimulus processing, decision making, and movement control
What type of nervous system do sponges and jellyfish (Invertebrates) possess?
Nerve net
They have a ventral nerve cord compared to dorsal nerve cords (nerve cord in the back) in vertebrates
List the brain divisions common to all vertebrates.
- Olfactory bulb
- Cerebral hemispheres
- Cerebellum
- Optic tectum
- Medulla oblongata
What is the small central collection of neuronal control circuits in Amphioxus called?
Primitive brain
What are the two main parts of the forebrain?
- Diencephalon - thalamus and hypothalamus
- Telencephalon - cortex and olfactory bulb
What does the central nervous system (CNS) develop from?
The walls of the neural tube
The neural plate folds and fuses to form the neural tube
What is spina bifida?
Failure of the posterior neural tube to close
This forms a gap in the vertebral column and portion of the spinal cord pokes out of the back = paralysis down to legs
How can the incidence of neural tube defects be reduced?
Supplementing diet with folic acid in early pregnancy
What are the three layers of cells in the developing nervous system?
- Endoderm (lining of organs; viscera)
- Mesoderm (bones and muscles)
- Ectoderm (nervous system and skin)
What do the dorsal roots of the spinal cord contain?
Sensory, afferent neurons
Sensory information enters the spinal cord through these
Located at the back of the
What do the ventral roots of the spinal cord contain?
Motor, efferent neurons
Motor information leaves the spinal cord through these
What is the primary channel for messages between the brain and the body?
Spinal cord
Messages from skin, joints and muscles to the brain and from the brain to the periphery
What are the two types of matter in the spinal cord?
- Grey matter = neuron cell bodies
- White matter = myelinated axons
Which part of the brainstem is important for controlling blood pressure and respiration?
Medulla = important in ANS
What role does the pons play in the brain?
Important relay between cortex and cerebellum
Swells out from ventral surface of brain stem
What is the function of the thalamus and hypothalamus?
In the Diencephalon (located above midbrain)
Thalamus = Relay and gating roles in sleep and conscious movement
Hypothalamus = homeostasis and reproduction
What is the function of the Midbrain?
Located above brain stem
Linkages between components of motor systems, eye movement, sleep and temperature regulation
What is the cerebellum primarily responsible for?
Movement control centre
Extensive connections to cerebrum and spinal cord
Disease includes ataxias = aberrant movement coordination (drunk-like movement)
What structure separates the two halves of the cerebral cortex?
Sagittal fissure
What is the neocortex?
The more complex 6-layer structure of the cortex in mammals
List the cortical lobes of the cerebral cortex in clockwise order from the front.
- Frontal
- Parietal
- Occipital
- Temporal
What anatomical feature increases the processing power of the brain?
Cortical neurons
True or False: The cerebellum contains at least as many neurons as both cerebral hemispheres combined.
True
Fill in the blank: The brain is hollow and bathed in _______.
Cerebrospinal fluid (CSF)
What anatomy does Dorasal - Ventral describe?
Back and belly
What anatomy does Cranial - Caudal describe?
Head end to tail end
What anatomy does proximal - distal describe?
Close to far —> one end to the other
Name the sectional plane of the brain
Coronal = frontal plane
Longitudinal = Sagittal plane
Axial/ horizontal = transverse plane
What is meant by decussation?
To become crossed
Means the brain is lateralised
What is a brain division specific to mammals?
The neocortex (processes complex information)
What 4 regions is the CNS split into?
- Forebrain
- Midbrain (makes up brain stem)
- Hindbrain (makes up brain stem)
- Spinal cord
What is the part in the Midbrain known as?
Mesencephalon = Tectum and tegmentum
What is the part in the Hindbrain known as?
Rhombencephalon = Pons, medulla and cerebellum
What does the peripheral nervous system (PNS) develop from?
Derives from neural crest
What causes spina bifida?
Some antiepilepsy/ bipolar drugs interfere with folate metabolism and increase risk of SB
This can be prevented through a supplementing diet with folic acid in early pregnancy (at the 3-4 week stage) = reduces by 90%
What is key about development differentiation in embryos?
Three swellings at the rostral end (leads to brain) of the neural tube become the primary vesicles
Describe the differentiation of the Forebrain
Forebrain (prosencephalon) splits into the Diencephalon (develops into eye cup, thalamus, hypothalamus and epithalamus) & the Telencephalon (develop into the cerebrum)
Describe the differentiation of the midbrain
Mesencephalon (midbrain) stays as mesencephalon and forms Midbrain
Describe the differentiation of the Hindbrain
Hindbrain (rhombencephalon) splits into the Metencephalon (develops into Pons and cerebellum) & the Myelencephalon (develops into medulla oblongata)
What is the spinal cord protected by?
The spinal cord deals with motor & sensory information
Protected by spinal column, surrounded by meninges (tough membranes) and cerebrospinal fluid (CSF) which helps cushion it
What do the Dorsal and Ventral roots join to form?
A nerve
What is the dorsal root ganglion?
A collection of fibres from sensory neurons with the cell body of the neurons in the ganglion
These have an axon that splits into 2:
- One goes to the periphery to pick up sensory information
- Other enters spinal cord to relay the sensory information to the CNS
What makes up the brain stem?
The midbrain = movement, sensory input from eyes and ears
The hindbrain:
- pons
- medulla
- cerebellum (not involved in brain stem function)
What makes up the brain stem?
The midbrain = movement, sensory input from eyes and ears
The hindbrain:
- pons
- medulla
- cerebellum (not involved in brain stem function)
What is the consequence of brain stem damage ?
- Hydrocephalus (excess CSF)
- Haemorrhage (bleeding into cranial cavity)
- Severe cases lead to ‘coning’ (brain is pushed downwards and brain stem is pushed into an opening at the base of the brain called the foramen magnum) = damage to medulla = respiratory arrest
