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
What are the part and functions of the brain stem?
Pons sends messages between the cerebellum and cortex; sleep,dreaming.
Medulla is responsible for basic life functions; breathing swallowing heartbeat.
Reticular Formation is responsible for arousal, attention, alertness.
What the cerebellum?
The Cerebellum is a cauliflower like structure meaning small brain. It aids in controlling and coordination of involuntary rapid fine motor movement and also voluntary movements that happen in rapid succession.
What is midbrain?
Midbrain is the segment of the brainstem that lies between hindbrain and forebrain. It integrates sensory processes, such as vision and hearing. One area is also involved in dopamine synthesis. Degradation of this area can lead to Parkinson’s which makes the body get stuck in this area; the medicine is what makes the patients spasm.
What is the limbic system?
The Limbic System is responsible for Homeostasis, olfactory, memory, and emotion which include the Thalmus, Hypothalmus, Hippocampus, and Amygdala.
What is the Thalmus?
Thalamus is a round structure in center of brain that acts as brain’s sensory switchboard, relaying incoming sensory information to the appropriate sensory areas in cortex, deals with all senses but smell and is Bilateral.
What is the hypothalmus?
The hypothalus lies below thalamus and is responsible for thirst, hunger, body temp, sleeping, waking, sexual behavior, and emotions. It controls pituitary gland so it is also important in endocrine system too.
What is the Hippocampus?
The Hippocampus plays a vital role in learning and memory. Acetylcholine activates the hippocampus (also skeletal muscle), bilateral.
What is the Amydgal?
The Amydgal is two almond-shaped neural clusters linked to emotion, especially fear, Bilateral.
What is the cortext?
Cortex is the outermost covering of the brain consisting of densely packed neurons; responsible for higher thought processes and interpretation of sensory input.
Corticalization is wrinkling of the cortex which allows a much larger area of cortical cells to exist in the small space inside the skull: Wrinkles called giri, Grooves called solci
Describe the frontal lobe?
The frontal lobe have a lot of solci pointing back to front except one which is the motor cortex. Frontal lobe is responsible for higher mental processes and decision making. Also contains the motor cortex on the solci running side to side
§ Phineas gage: metal rod penetrated through base of skull; lived but experienced changes in behavior experiencing frontal temporal dementia: degrading of cells in frontal and temporal lobe.
What is the parietal lobe?
The Parietal Lobe contains somatosensory cortex; area of neurons running down the front of the parietal lobes; responsible for processing information from skin and internal body receptors for touch, temperature, and body position. Also has a homunculus for somatosensory cortex.
What is the occiptal lobe?
Occipital Lobe contains primary visual cortex which processes visual information from the eyes.
Visual association cortex: Interprets or makes sense of visual information.
What is the Temporal lobe?
The Temporal lobe contains Primary auditory cortex which processes auditory information from ears, and Auditory association cortex which interprets or makes sense of auditory information. Some also responsible for language.
What are association cortices?
The association cortices are areas within different lobes that integrate different types of information.
Wernicke’s area (left temporal lobe) damage: inability to comprehend language, “get me some milk from the air conditioner”
Broca’s area (left frontal lobe) damage: can comprehend speech but unable to produce it in a meaningful way. Cot instead of clock
Prosopagnosia: inability to recognize faces;
usually due to damage to the right side
What are the cerebral hemispheres?
Cerebral Hemispheres are the two sections of the cortex on the left and right sides of the brain.
What us corpus callosum?
Corpus Callosum is the thick band of neurons that connects the right and left cerebral hemispheres.
What are the types of lateralization?
- Information transmitted to one side of the
- Taste and olefaction
- Information transmitted to both sides of the
- Hearing and vision
- The left half of the brain only getting messages from the right half of the body.
If we are writing with our right hand, the motor cortex in the left side of the brain is controlling that information coming from the senses. Split brain video where anything to the left of the point (which went to the right side of his brain) could not be vocalized due to the left side being responsible for language
What is deep brain stimulation?
Deep Brain Stimulation (DBS) is stimulation from the inside, Used as treatment for Parkinson’s, seizures, chronic pain, and some psychiatric disorders.
What is transcranial magnetic stimulation
Transcranial magnetic stimulation (TMS) is Noninvasive stimulation with copper wire coils over head. Used in studies of cognition such as memory retrieval and decision making.
What is Transcranial direct current stimulation (TDCS)
Transcranial direct current stimulation (TDCS) is when scalp electrodes pass very low amplitude direct current to the brain. Used in studies of cognition such as memory retrieval and decision making. Not electroshock (just less painful)
What is a CT scan?
Computed Tomography (CT) are series of X-rays aided by a computer. Show stroke damage, tumors, injuries, and abnormal brain structure.
What is Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging (MRI) are much more detailed, show effects of very small strokes
What is diffusion Tensor Imaging?
Diffusion Tensor Imaging (DTI) show Grey matter: cell bodies and unmyelinated axons, White matter: myelinated axons and uses MRI technology to measure connectivity in brain by imaging these white matter tracts.
What is an EEG?
An Electroencephalogram (EEG), Records electrical activity of the cortex just below the skull. Small metal disks or sponges placed directly on scalp may show stages of sleep, seizures, tumors
What us ERP?
Event Related Potential (ERP)
Multiple presentations of stimulus measured during eeg then averaged to remove variations in the ongoing brain activity
What is MEG?
Magnetoencephalography (MEG) is a helmet-like device used to differentiate dementia disorders and explore cognitive processes in autism.
What is a fMRI?
Functional Magnetic Resonance Imaging (fMRI) cpu tracks changes in oxygen levels of blood to create asort of movie of the brain, more detail and clearer than PET an dhas been used in predicting Alzheimer’s and helping schizophrenia patients learn to control their brains.
What is PET?
Positron Emission Tomography (PET) is the Injection of radioactive glucose that tracks which cells are using the glucose during different tasks. Related to SPECT which measures brain blood flow
Why use on method over the other?
Most interested in measuring a fast response, use EEG. If you most interested in knowing exactly where the signal is coming from use fMRI. Also, cost and other factors plays a role and choosing methods.
Parts of the brain?