Neurobiology A.1 – A.3 Allison Bynum

A.1 Neural Development Allison Bynum

A.1 – The neural tube of embryonic chordates is formed by infolding of ectoderm followed by elongating of the tube. Neural folds converge Neural plate elongates and thickens The neural crest forms as the tube is forming Neural tube is formed and the outer layer of the ectoderm becomes the epidermis

A.1 – Neurons are initially produced by differentiating in the neural tube. Neuron differentiation Neurons – carry the messages by electrical impulses Glial cells – provide structural and nourishing support for neurons (also act as insulators(Myelin Sheath))

A.1 – Immature neurons migrate to a final destination. Glial cells provide a way for the immature neurons to travel to destinations. Maturation of the neurons occurs after the migration.

A.1 – An axon grows from each immature neuron in response to chemical stimuli. Axon growth CAMs help to attract axons to their targets CAMs are released into the extracellular space. Some signals from CAMs interfere with other axons and repel them.

A.1 – Some axons extend beyond the neural tube to reach other parts of the body. Motor neurons – extend beyond the CNS to become the peripheral nervous system for voluntary movements

A.1 – A developing neuron forms multiple synapse. Neurons try to form synapses with nearby target cells and test the connection. The synapse is eliminated if it isn’t successful. (neural pruning)

A. 1 – Synapse that are not used do not persist. A A.1 – Synapse that are not used do not persist. A.1 – Neural pruning involves the loss of unused neurons. Neural pruning – the elimination of unused or unnecessary synapses

A.1 – The plasticity of the nervous system allows it to change with experience. Brain plasticity – is the brain’s ability to change and adapt as a result of experience Brain plasticity is higher in younger children and decreases with age. The adult brain is more resistant to change.

A.2 The Human Brain

A.2 – The anterior part of the neural tube expands to form the brain. Nerve cells migrate to the outer edge of the neural tube and cause the walls to thicken. The neural tube develops into the brain and spinal cord. The anterior end of the tube expands to form the cerebral hemispheres of the brain, while the posterior end forms the spinal cord and the other parts of the brain.

A.2 – Different parts of the brain have specific roles. Part of the Brain Function Cerebral hemispheres Higher complex functions/problem solving Hypothalamus Maintains hormone homeostasis and the pituitary gland Cerebellum Coordinates unconscious functions(not vital)/balance and movement Medulla Oblongata Controls automatic vital functions(heart beat and breathing) Pituitary Gland Hormone storage and secretion/controlled by hypothalamus

A.2 – The autonomic nervous system controls involuntary processes in the body using centers located in the brainstem. Autonomic nervous system – is part of the peripheral nervous system; controls involuntary functions; regulates gland activities, smooth muscles, and the heart The sympathetic and parasympathetic systems are divisions of the ANS. Sympathetic Parasympathetic Important for emergencies Returning to normal “Fight or Flight” response Relaxing Noradrenaline Acetylcholine Excitatory Inhibitory

A.2 – The cerebral cortex forms a larger portion of the brain and is more highly developed in humans than other animals. Cerebral cortex – the thin layer of grey matter covering the cerebral hemispheres; contains 75% of the body’s neurons Responsibilities include: Reasoning Language Complex thought Visual processing Motor movement Remembering Speech

A.2 – The human cerebral cortex has become enlarged principally by an increase in total area with extensive folding to accommodate it within the cranium The folds in the brain help to increase the surface area of the cerebral cortex to allow more neurons. Parts of the cerebral cortex have specific functions.

A.2 – The cerebral hemispheres are responsible for higher order functions. The cerebrum is responsible for the problem solving and higher thinking

A.2 – The left cerebral hemisphere receives sensory input from sensory receptors in the right side of the body and the right side of the visual field in both eyes, and vice versa for the right hemisphere. Left hemisphere receives sensory info from: Right eye Right field of vision(some parts will cross over with left field of vision) Right side of body Right Hemisphere receives sensory info from: Left eye Left field of vision(some parts will cross over with right field of vision) Left side of body

A.2 – The left cerebral hemisphere controls muscle contraction in the right side of the body, and vice versa for the right hemisphere. The motor neurons for the left cerebral hemisphere connect to the muscles on the right side and vice versa.

A.2 – Brain metabolism requires large energy inputs. Glucose is needed constantly for the brain because neurons cannot store it. The energy is used up very rapidly because of the mental activity. Carbohydrates like fruits, vegetables, grains and dairy are some of the best sources for glucose.

A.3

Receptors detect changes in the environment.

Rods and cones are photoreceptors located in the retina.

Rods and cones differ in their sensitivities to light intensities and wavelengths.

Bipolar cells send the impulses from the rods and cones to ganglion cells.

Ganglion cells send messages to the brain via the optic nerve.

The information from the right field of vision from both eyes is sent to the left part of the visual cortex and vice versa.

Structure in the middle ear transit and amplify sound.

Sensory hairs of the cochlea detect sounds of specific wavelengths.

Impulses caused by sound perception are transmitted to the brain via the auditory nerve.

Hairs in the semicircular canals detect movement of the head.

Resources http://www.bodbot.com/Cognitive_Health.html http://www.dreamstime.com/royalty-free-stock-images-motor-neuron-vector-diagram-structure-include-dendrites-cell-body-nucleus-axon-myelin-sheath-nodes-ranvier-end-image35181499 http://www.neurosignallab.com/ http://america.pink/synaptic-pruning_4248821.html http://womenoutandabout.net/summer-musings-pruning-by-christine-c-cantrell/ https://1mkturin.wordpress.com/category/science-of-music/page/2/ http://www.sunscientific.com/What-is-ANS.html http://zzanatomy.yolasite.com/ http://scicurious.scientopia.org/2011/02/23/cell-phones-coming-for-your-brain-cells-since-well-maybe-not/