Nervous system structure and function Flashcards
What is gastrulation?
Defined as an early development process in which an embryo transforms from a 1D layer of epithelia cells (blastula) and reorganises into a multilayered and multidimensional structure called gastrula.
What is the primitive streak?
An elongated band of cells that forms along the axis of a developing fertilised egg early in gastrulation and is considered a forerunner of the neural tube and nervous system.
Primitive streak is a linear band of thickened epiblast that first appears at the caudal end of the embryo and grows cranially. At cranial end its cells proliferate to form the primitive knot (primitive node).
What is the germ layer formulation?
The germ layers form during the process of gastrulation, when the hollow ball of cells that constitutes the blastula begins to differentiate into more-specialized cells that become layered across the developing embryo.
What is the outermost layer of germ cells known as and when is it formed?
Ectoderm (outermost layer of germ cells) - 1 of the 3 primary germ layers formed in early embryonic development
What are the examples of ectoderm found in the body?
- Epidermis
- Mouth
- Teeth
- Nostrils
- Hair
- Nails
- Nervous system
What is the middle germ layer called and where is it devloped?
Mesoderm (middle layer of germ layer) - develops during gastrulation in very early development
What are the examples of mesoderm found in the body?
- Muscle
- Connective tissue
- Heart
- Blood vessels
- Some organs (kidneys)
What is innermost layer of germ cells called where is formed?
Endoderm (innermost layer of germ cells) - of an embryo in source of the epithelium of the digestive tract and the lower respiratory tract
What are the examples of endoderm found in the body?
- GI tract
- Respiratory system
- Liver
- Pancreas
- Thymus
- Thyroid
- Bladder
Where is neural tube formed?
Forms the early brain and spine - the CNS.
What happens when errors occur in the neural tube?
Errors in this process can lead to congenital anomalies such as neural tube defects.
What is the 2 most common neural tube defects?
The 2 most common neural tube defects are spinal bifda (a spinal cord defect) and anencephaly (a brain defect).
What happens when neural crest fusion fails?
Neurocristopathies are a group of diseases caused by the abnormal generation, migration or differentiation of neural crest cells.
Involve multiple organ systems in a single person, often familial - associated of neoplasms.
What cells make up 10% of the nervous system and what is its function?
Principle cells (10%)
- Neurons
- Projection, communication
What cells make up 90% of the nervous system and what is its function?
Gila (90%):
Astrocytes: specialised glial cells that outnumber neurons by over fivefold. They regulate blood flow, but also transfer mitochondria to neurons and supply the building blocks of neurotransmitters which fuel neuronal metabolism
Metabolic support
Where are interneurons found and what is its function?
Ones in between - connect spinal motor and sensory neurons
Found in brain/spinal cord - others within autonomic ganglia.
Function of interneurons is integration.
Local modulation
What is microglia, where is it found and what is its function?
Microglia are resident macrophages of the CNS.
Plays key role in brain development and physiology during life and aging.
What is the function of phagocytotic?
Phagocytotic: process for ingesting and eliminating particles larger than 0.5 um in diameter including microorganisms, foreign substances and apoptotic cells.
What is the structure and function of Oligodendrocyte (CNS)?
Function: in CNS oligodendrocytes assemble myelin, a multi-layered sheath of membrane, spirally wrapped around axonal segments and best known for its role in enabling fast saltatory impulse propagation.
Structure: have small amounts of cytoplasm’s surrounding rounded nuclei. 2 main types: satellites around neurons in the Gray matter. Myelin-forming cells in the white matter.
What is the function and structure of - Schwann cell (PNS) ?
Function: role in development, maintenance, function, and regeneration of peripheral nerves. Can be myelinating/non-myelinating cells.
Structure: form thick myelin sheath or an intended plasma membrane that folds around peripheral axons in the PNS. Schwann cell covers an axon, outer cell surface is called neurilemma - shields axon from interstitial.
