The Central and Peripheal Nervous system
Overveiw of the nervous system
What is gray and white matter?
Neurons are gray matter (mostly) and receives and sends messages. The Glia are white matter which makes up 90% of the cells in our nervous system. Glia's have a supportive role providing nutrients, repairing damage, forming myelin, and gettig rid of waste.
What is an action potential?
Action Potential (All or nothing reaction) is how the signal is transmitted along the axo. Propagation of channels opening and ions coming in and out of the cell passing all along the axon. At rest, a neuron is polarized negatively, around -70 mV and no Na+ is allowed entrance, but once a stimulus is applied, it slowly begins to depolarize and sodium will flow in rapidly making it positive. Then potassium will leave to neutralize it. Sodium gets pumped out as well so its lower than -70 before it returns to normal.
How does the strength of the message gets coded in transmitting neurons?
By sending off multiple action potentials.
What is Synapse or Synaptic Gap
Synapse or synaptic gap is the tiny gap between the axon terminal and the dendrite or cell body of the receiving neuron. Neurotransmitters are either reabsorbed into sending neurons through reuptake, Diffused throughought, or Broken down by enzymes. This is the braking mechanism for actions.
What are neurotrasmitters?
Neurotransmitters are (chemicals) released from the sending neuron that travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing it. Neurotransmitter can have an excitatory or inhibitory effect.
What are the different types of neurotransmitters?
The Neurotransmitters are:
- Gaba-aminobutyric acid (GABA)
- Neuropeptides such as Endorphins
What is Glutamate?
Glutamate is a major excitatory neurotransmitter which is important role in learning and memory. Glutamate is involved in development of nervous system and synaptic plasticity. Over excitation can cause glutaate cells to die off.
What is Gaba-aminobutyric acid (GABA)
Gaba-aminobutyric acid (GABA) is an inhibitor of glutamate which can help calm anxiety. Alcohol enhances GABA.
What is serotonin?
Serotonin (5-HT) is is repsonsible for mood, hunger, sleep, and arousal. Most common treatment for depression inhibits reuptake of serotonin.
What is Acetylcholine?
Acetylcholine (Ach) is Responsible for muscle movement. Plays a role in learning and memory in CNS; found in hippocampus. Too much Acetylcholine, such as when bitten by a black widow, could result in convulsions and possible death because the venom is an agonist. Low levels could be linked to Alzheimer’s disease.
What is dopamine?
Dopamine (DA) influences the controls of movement and sensations of pleasure. Dopamine Can affect different things depending on exact location in brain. If too little released in certain areas, you get Parkinson’s. If too much is released in certain areas, it could lead to cluster of symptoms part of schizophrenia.
What are Neuropeptides?
Neuropeptides, Ex: endorphins (endogenous morphine), Can serve as neurotransmitters, hormones, or influence the action of other hormones.
What are agonist drugs?
Drugs that are Agonists increases the original message that the neurotransmiter was supposed to send. So if neurotransmitter had an inhibitory affect, it would be more inhibitory.
What are Antagonist drugs?
Drugs that are Antagonists blocks the original message that neurotransmitter was supposed to send by binding to receptor sites. Some drugs act by affecting the amount of NT available at the synapse.
The Spinal Cord reflex
Spinal Cord; reflex arc neurons
Afferent/sensory- from senses to spinal cord on an Ascending pathway.
Interneurons- connect afferent to efferent
Efferent/motor- from spinal cord to muscles; have a behavioral effect on a descending pathway.
What is the Somatic nervous system responsible for?
The Somatic Nervous system is responsible for Sensation and Voluntary muscle movement.
What is the Autonomic nervous system?
The Autonomic Nervous system is part of peripheal nervous system that controls the involuntary muscles, organs, glands, and reflexe.
Sympathetic section is responsible for Arouses and Fight or flight mode.
Parasympathetic section calms and helpd to rest and digest.
What is the endocrine system?
The Endocrine system release hormones through ducts into bloodstream, with effects that last longer than neurotransmitters.
What is the pitutary gland?
The Pituitary gland is the master gland of the endocrine system responsible for growth and control of other glands. Sometimes secreting some precursor hormone that tellssomething to secrete something else. Pitutary gland ssecretes oxytocin (Greek oxys meaning “rapid” and tokos meaning “childbirth”) which is involved in reproduction and parental behavior; stimulates uterus contractions and milk letdown reflex. It also secrets growth hormone and vasopressin which acts as diuretic.
What is the pineal gland?
The Pineal Gland, also part of the endocrine system is located directly above the brain stem. Its secretes melatonin which helps keep track of day length and seasons (influences seasonal behaviors such as molting and breeding in animals)
What is the thyroid?
The Thyroid is responsible for food, eating, and storage of fat. It Secretes thyroxin to regulate metabolism.
What us the parathyroid gland?
The parathyroid gland is responsible for calcium regulation, which is Important for bones and neurotransmitter transmission.
What are the adrenal glands?
The Adrenal glands are the Adrenal medulla and adrenal cortex.
What is the adrenal medula?
The adrenal medula releases epinephrine or norepinephrine when under stress.
What is the adrenal cortex?
The adrenal cortex produce over thirty different hormones called corticoids that regulate salt intake, help initiate and control stress reactions, and provide a source of sex hormones in addition to those provided by gonads. The adrenal cortex releases cortisol which is important in the release of glucose into bloodstream during stressful situations to provide energy.
What is the pancreas?
The Pancreas regulates blood sugar by secreting insulin and glucagon. Too little insulin leads to diabetes and too much leads to hypoglycemia
Brain stem and cerrebelum