Self Directed Learning Neurons: The Nervous System

1. what is a zygote: - fertilized egg which divides by binary fission into 2,4,8... - cell progressive cleavage 2. what is a blastula: hollow sphere of cells produced during development of an embryo by repeated cleavage of a fertilised egg 3. what is blastoderm and blastocoel: - the blastoderm is the epithelial layer formed by the blastula cells - the blastoderm encloses a fluid like cavity called the blastocoel 4. what is the gastrulation process: - the embryo transforms from one dimensional layer of epithelial cells into a multilayered and multidimensional structure called the gastrula 5. how many layers are there of the blastula: 3 - the cells at one pole of the blastula start to move inwards to form a second layer of cells inside the hollow ball - the primitive streak allows cells from the outer layer into the gap between the outer layer and inner layer of cells - this results in an outer layer of cells on the outside of the gastrula 6. what are the cell layers of a gastrula called: germ layers - outer layer: ectoderm - inner layer: endoderm - centre layer: mesoderm 7. what is the ectoderm: - the germ layer covering the embryo's surface (outer layer) - forms epidermis, mouth, teeth, hair, nostrils, nails, nervous system 8. what is the endoderm: - innermost germ layer - forms Gi tract, respiratory system, liver, pancreas, thymus, thyroid, bladder 9. what is the mesoderm: - middle germ layer - forms muscle, heart, connective tissue, blood vessels, some organs 10. explain neural tube formation: - neural tissue forms from an areas of the ectoderm - area thickens and becomes neural plate - under the influence of notochord (flexible rod like structure of mesoderm) the neural plate dips into the mesoderm layer and forms the neural groove - there are crests either side of the groove called neural crests - the descending of neural groove into mesoderm causes the neural crest cells to 1/5 fuse over the top - now the ectoderm is one layer fused over the top and the neural groove cells fuse together to form the neural tube structure which lies in the middle of the mesoderm - this tube is the CNS 11. what happens if the neural crest does not fuse together: - leads to conditions like spina bifida 12. what are the two cells of the nervous system: - principle cells - glia cells 13. explain principle cells of the nervous system: - make up 10% of nervous tissue cells two types - projections neurons: communicate to other places in the body - interneurons: communicate locally 14. explain glia cells of the nervous system: - make up 90% of nervous tissue cells - located in CNS and PNS - provide physical and metabolic support to neurons 4 types - astrocytes: star shaped. provide metabolic and structural support for neurons - microglia: act as macrophages and remove damaged neurons and infections - schwann cells: (PNS) provide structural support myelination - oligodendrocytes: (CNS) do the same thing as schwann cells but in the CNS 15. what is the central nervous system: - consists of the brain and spinal cord - role: process sensory input and generate motor output 16. What is the peripheral nervous system: - consists of neurons that connect CNS to rest of body - sensory neurons (afferent neurons) are nerve fibres responsible for bringing info from receptors to brain - motor neurons (efferent neurons) are nerve fibres responsible for carrying signals from brain to PNS in order to initiate action - contain cranial and spinal nerves 17. explain the cranial nerves of the PNS: - set of 12 pairs of nerves - come directly from brain and send signals between brain, face, neck, torso - help you taste, smell, hear, feel sensations, facial expressions, blink, move tongue 18. explain the spinal nerves of the PNS: - set of 31 pairs of nerves - emanate from spinal cord - send electrical signals between brain, spinal cord and rest of the body 2/5 19. what are the meninges: - membranes that surround the brain and spinal cord - protection - made up of 3 layers of membrane - outer layer closest to skull = dura mater - middle layer = arachnoid mater - between arachnoid mater and last layer there is a subarachnoid space - last layer is the layer closets to brain: pia mater 20. what is the subarachnoid space: - space between arachnoid and pia mater - contains extracellular fluid called cerebrospinal fluid which cushions the brain and spinal cord whilst providing nutrients and removing waste through blood vessels 21. describe the spinal cord structure: grey matter: - areas of no myelination of cells - receives info from sensory afferent neurons and distributes info to other parts of the spinal cord/brain via motor efferent neurons 22. describe the spinal cord structure: dorsal root: - also known as posterior, sensory root - made up of sensory afferents from the periphery into the grey matter - root contains a ganglion (swelling of root) which contains the cell bodies of the sensory afferent neurons bringing in the info 23. describe the spinal cord structure: ventral root: - also known as anterior, motor root - is made up of motor efferents coming from the grey matter - root then joins with the dorsal root to make the spinal nerve 24. describe the spinal cord structure: white matter: - bundles of myelinated axons travelling up and down cord - motor neurons go down - sensory neurons go up 25. describe the brain structure: hindbrain: - first part of brain above spinal cord located at the lower back part of brain - contains medulla oblongata and pons-bridge connecting brainstem to cerebral cortex - responsible for basic survival functioning: breathing, sleeping, blood pressure, heart rate, wakefulness 26. describe the brain structure: midbrain: - above hindbrain - contains thalamus, hypothalamus, pituitary gland - role in motor movement, auditory/visual processing, endocrine control, thrist, hunger 3/5 27. describe the brain structure: cortex or forebrain: - above midbrain - contains neocortex and cerebellum - role in motor function, consciousness, thinking, memory, motor skills 28. describe the roles of the 4 lobes of the brain: - frontal: cognition, memory, emotions, problem solving - parietal: sensation, hearing, taste - occipital: vision - temporal: processes auditory info and encodes memory 29. what is the cerebellum: At the back, responsible for muscle contraction & balance 30. what is the medulla oblongata: the posterior part of the brain that controls autonomic functions - controls: swallowing, taste, breathing, heart function... 31. what is the pons: the part of the brainstem that links the medulla oblongata and the thalamus. - works with medulla oblongata to generate the respiratory rhythm of breathing 32. what is the cerebrum: The cerebrum is the part of the brain that controls memory, senses, consciousness, and reasoning - largest part of the brain 33. what is the hypothalamus: - controls homeostasis and pituitary gland 34. what is the thalamus: - Sensory "relay station." - Sensory info. such as visual/auditory information evaluated here and relayed to cerebral cortex 35. what is the pituitary gland: It is the master gland. It produces many hormones that regulate homeostasis 4/5 36. What is the somatic nervous system?: - division of the peripheral nervous system - conscious control - input from sense organs - output to skeletal muscles 37. What is the autonomic nervous system?: - division of the peripheral nervous system - subconscious control - input from internal receptors - output to smooth muscles and glands 38. what is the sympathetic nervous system: "Fight or flight" Blood pressure/heart rate increase, digestive slowing. - neurotransmitter = noradrenaline 39. What is the parasympathetic nervous system?: "Rest and digest" Blood pressure/heart rate decrease, digestive increases. - neurotransmitter = acetylcholine 5/5