The brain and nervous system Flashcards
Neurons
Basic cells of the nervous system. Communicate cell to cell. Has soma/ cell body with dendrites that receive messages, axon that carries message coated with myelin sheath/ fatty insulation for efficient transmission. Axon sends messages through terminal buttons which contain neurotransmitters in synaptic vesicles. These chemical messages are received by receptors, not all neurotransmitters and receptors are compatible.
Resting potential
Neuron’s resting voltage (not firing), polarised with (-) in cell membrane and (+) outside of cell membrane.
Graded potential
Neurons stimulate other neurons either depolarising or hyperpolarising. Spreading voltage changes along the cell membrane excited by another neuron. They accumulate to a threshold before neurons fires.
Action potential
Nerve impulse. Neuron fires and releases neurotransmitters.
Steps of neuron communicating
- Resting state. Na+ (sodium) cannot enter or is pumped out. Cell is (-) charged.
- Depolarisation. Na+ enters dendrites and cell body, cell is less (-) charged.
- Graded potential. Change in cell voltage passed down dendrites and cell body.
- Action potential. If change in axon voltage surpasses threshold, axon lets in surge of Na+.
- Neurotransmitter released. The action potential causes terminal buttons to release neurotransmitters into the synaptic cleft.
- Chemical message transmitted. Depending if neurotransmitter is facilitating or inhibitory, voltage of cell membrane receiving depolarises or hyperpolarises.
Glial cells
Holds neurons in place. Manufactures nutrient chemicals and absorbs toxins and waste.
Cell membrane
Separates inner neuron from surrounding fluid. Substances can pass through ion channels. Inner ion (-) charged more and outside (+) charged more. Sodium (Na+) flows in depolarises, potassium (K+) flows out repolarises. Chloride (Cl-) inside cell.
Absolute refractory period.
Neuron wont fire until returns to negative polarisation.
Modulatory neurotransmitters
Can increase or reduce impact of other neurotransmitters at synapse.
Nucleus
Contains chromosomes and determines how neurons will manipulate inputs from dendrites contained in the soma.
Glutamate
Plays excitatory role (glutamic acid) for most neurons. Involved in learning and memory. Abnormally high excitotoxicity linked to Huntington’s and Alzheimer’s.
GABA gamma-aminobutyric acid
Plays inhibitory role. 33% of neurons use it. Important for regulating anxiety.
Dopamine
Involved in motivation, involuntary movement, emotional arousal, learning memory, pain, and pleasure. Undersupply linked to Parkinson’s and depression. Oversupply linked to schizophrenia. Key role in addiction and rewards system.
Serotonin
Regulates mood, sleep, appetite, arousal, social behaviour, pain suppression, and impulse control. Undersupply results in depression, eating disorders. Oversupply results in OCD.
ACh Acetylcholine
Involved in learning, memory, muscle movement, attention, muscle construction, sleeping. Depleted ACh linked to Alzheimer’s disease.
Endorphins
Elevate mood, reduce pain. Natural painkiller. increased with exercise, yoga, meditation, and acupuncture.
Epinephrine (Adrenaline is hormone)
Emotional arousal and memory. Increase metabolism of glucose for energy release.
Norepinephrine (Noradrenaline is hormone)
Attention, arousal, wake cycle, eating, learning, memory, dreaming, emotion, and stress. Low causes depression, high causes agitation, stress, panic, and manic states. Excitatory or inhibitory.
Endocrine system
Collection of glands that produce hormones that can be released into the blood stream to activate many cells in the body with compatible receptors simultaneously.
Pituitary gland
Master gland. Hormones released stimulate and regulate other glands. Pea-sized in the brain.
Thyroid gland
Located in the neck, releases hormones to control metabolism, energy levels and mood.
Adrenal glands
located above the kidneys, secrete adrenaline and others in emergencies.