Friday, February 13, 2009

Nerves

There are twelve pairs of cranial nerves. Cranial nerves eight and twelve are only carry afferent impulses.Olfactory nerves relay information from high in the nasal cavity. When the brain is removed the olfactory lobe on the brain gets ripped off. The olfactory foramina is where the nerves go through cranial nerve I. The ganglion is a collection of cell bodies outside the central nervous system. A cell body found inside the central nervous system is a nucleus cell. Cervical three, four, and five stimulates the breathing, they go through thoracic diagram to keep your negative and positive pressure.The median nerve controls your thumb and if it is severed you will never be able to use it again.The sciatic nerve is the largest nerve in the body it controls the back muscles of the legs.
The muscles of the eyeball stimulate the oculomotor nerves, trochlear nerves, and abducens. The trochlear nerve is the central nerve number four. The central nerve VI is the abducens it is a motor nerve, sends efferent impulses. The trochlear nerve controls the superior oblique. The ascending oblique attaches and connects to the lateral rectus.
Nerve three, four, and six all pass through the superior orbital fissure. There are two parts to the autonomic nervous system, the sympathetic and the parasympathetic. The parasympathetic nerves system stimulates the muscles of the eyeball that cause the eyeball to constrict. The sympathetic nerves system stimalates the muscles of the eye to dilate.

Friday, February 6, 2009

The Circle of Willis and Cranial Nerves

The Circle of Willis is a ring of arteries at the base of the brain. The Circle of Willis contains five aortic archs, there is the posterior communicating, posterior cerebral,middle cerebal, anterior cerebral, and anterior communicating. It is the brains major blood flow and has two main arteries. The Circle of Willis has a backup artery in case one artery gets clogged and the other one will flow.
There are twelve pairs of Cranial Nerves. The twelve pairs are known as Olfactory, Optic, Oculomotor, Trochlear, Abducens, Trigeminal, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Spinal, and Hypoglossal. Three of the pairs of nerves are consider sensory: Olfactory, Optic, and Vestibulocochlear. The rest of the nerves are considered mixed. The mixed nerves have a sensory portion and motor portion, these mixed nerves have the sensory and motor part mixed together.

Friday, January 30, 2009

The Brain and the Spinal Cord

There are three types of Dura, the epidural space, dura mater, and subdural space. The epidural space is the space external to the sac of the spinal dura mater within the vertebral canal. The dura mater is the outermost of the meningeal layers covering the brain and spinal cord. The dura has a hard leathery outside. The subdural space is a fluid-filled space or potential space between the dura mater and the arachnoid. The arachnoid has no blood supplies and is web-like. The sub-arachnoid space is the cerebra spinal fluid.The pia mater is the delicate membrane that lies on surface of the brain and spinal cord.
Vessels are confluence like, two or more vessels will met and flow together with the same amount of blood. The vessels full of blood flow from the lungs where they become oxygenated to the left atrium to the bicuspid-mistral value. After the bicuspid-mistral value then to left ventricle to the semi lunar value then ascends to the aora then to the aortic arch. From the aortic arch the blood descends to the aorta.The blood also flows through the aortic arch to the right brachiocephalic to the right subclavian, and finally right common caryatid.

Friday, January 23, 2009

Metric Conversation, Some Neuroglial Cells

Schwanns Cells can wrap only one axon. Oligodendrocyte Cells can wrap many axons. Schwanns Cells go through the process of mitosis and produce many cells. This process of making Schwanns Cells will occur until the number of cells reaches the target cell. Schwanns cells are in the PNS, peripheral nervous system. Aster is star like and is the blood brain barrier. Astrocytes filter ammo acids. Astrocytes have a lot of rough and smooth er. Capillaries have the smallest diameter. They have simple squamous epitheliums.
When doing metric conversations, the trick is to remember that there are many steps that need to be done. When going from ounces to grams, you need to go from ounces to pounds to grams. There is no straight conversation from ounces to grams. There are many conversations that need to be done with multiply steps, they are the ones that go from one unit of measurement to another.

Sunday, January 18, 2009

Neurons

There are many parts to a neuron. The cell body is called the soma. Inside the cell body is where the nucleus is. On the edges of the soma, there are objects that look like tree branches from a truck those are called dendrites. The dendrites are known as neurotransmitters. They collect information and send it through the body of the neuron and down the axon, which is covered with a myelin sheath, to the terminal button. The information travels from the terminal buttons of one neuron across a space known as a synapse to the dendrites of another neuron.
The neurons can be in three stages one is known as resting potential which is when the neuron is inactive or resting. Another stage is the action potential which is when the neurons is actively firing the messages through the axon to pass the message on. The last one is the local potential which is the graded potential receptor.
Channels have gates that are closed at a resting state, sodium ions that are positively charged move inward. The sodium channels are the first int the depolarization phase. Then the potassium channels open , allowing the potassium to flow out, producing repolarizing phase. Together the depolarization and repolarization phase last about one millisecond in a normal neuron.