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.
Pancreas
Near stomach, produces hormones to control blood sugar levels.
Gonads
Influences sexual development and behaviour. Male testes in testicles produce testosterone. Female ovaries produce estrogen. Both control sex drive.
Peripheral nervous system
Carry information to and from central nervous system.
Autonomic nervous system
Controls basic life processes such as heart, digestive, and breathing. Has two systems: Sympathetic and Parasympathetic.
Sympathetic nervous system
Activates in response to threats. Stops digestion, send blood to muscles for fight or flight. Increase heart rate, dilates pupils, and erects hairs.
Parasympathetic nervous system
Regulates blood sugar levels, secretes saliva, regulates heart rate, and pupil size. Resumes normal functioning when emergency passes.
Somatic nervous system
Transmits sensory information to central nervous system and carries out motor commands (voluntary commands). Also has reflex arcs.
Central nervous system
Brain and spinal cord. Soinal cord carries out reflexes and transmits sensory messages to brain and messages to muscles and organs.
Hind brain
Lowest part of brain, has brainstem, medulla, pons, cerebellum and reticular formation (spreads form lower medulla to upper midbrain).
Mid brain
Reticular formation, tectum, and tegmentum. Small joining of hind brain and forebrain.
Forebrain
Majority of brain. Cerebrum which is outer cortex layers and subcortical structures. Also has hypothalamus and thalamus.
Cerebellum
Discriminates stimuli from one another, coordinating smooth movements, balance, amd maintaining posture.
Pons
Respiration, waking, sleep, dreaming, movement (top of brain stem).
Medulla oblongata
Heart beat, circulation, respiration, blood pressure (vasomotor), vomiting. The link between the spinal cord and brain (lower brain stem).
Reticular formation
Lower medula to upper mid brain. Maintains consciousness, regulates arousal levels, modulates activity of neurons throughout central nervous system. Help screen incoming messages to the brain. Blocks some messages e.g. sleep quality control.
Tectum
Involved with vision and hearing. Orients human to visual and auditory stimuli. Also involved in linking unpleasant feelings or punishment to behaviours to avoid or escape them.
Tegmentum
Includes parts of the reticular formation. Serves functions in movements. Also includes substantia nigra, which deteriorates in Parkinson’s. Also involved on experience of pleasure or reward. Crucial for learning with positive consequences.
Thalamus
The switch board that sorts and relays sensory messages to correct cortex. Located above hypothalamus. Issues can result in confusing stimuli and cause hallucinations.
Hypothalamus
Regulates emotions and drives for hunger, thirst, sex, aggression, and sleep. Connected to pituitary gland.
Cerebrum
The major structure of the brain, has two hemispheres that wrap around the brainstem. Hemispheres are connected with a thick band of axons called the corpus callosum. Includes outer layer (cerebral cortex, convolutions are 75% of surface area. High points are gyrus, low points are sulcus) and subcortical structures (limbic system and basal ganglia).
Basal ganglia
The structure includes the putamen and caudate nucleus. Involved in movement and judgements that require minimal conscious thought. Mood and memory too. Substantia nigra in midbrain supplies basal ganglia with dopamine to function. Involved in Parkinson’s.
Septal area (limbic system)
Purpose not entirely known. appears to have similiar function to mid brain (tectum and tegmentum). Linking punishment and reward to behaviour, also responds in environmental stressors.
Amygdala (limbic system)
Almond shaped, involved in many emotional processes, especially learning and memory of emotionally significant events. Recognises emotion, particularly fear.
Hippocampus (limbic system)
Forming and retrieving memories. Not all memories involve the hippocampus.
Primary areas of cortex
Process raw sensory information (in frontal lobes, initiates movement).
Association areas of cortex
Silent areas, complex mental processes - forming perception, ideas and plans.
Occipital lobes
Specialised for vision. Polysensory areas combine with auditory or tactile.
Parietal lobes
Involved in touch. Detects movement in environment, experience own body, locating objects. Primary area is somatosensory cortex which each section receives sensation from specific body parts (face and fingers most, back and legs least).
Frontal lobes
29% of brain. Involved in movement, attention, planning, social skills, abstract thinking, memory, and personality. Primary area initiates movement. Primary motor cortex communicates with same parts of body as somatosensory for voluntary movement.
Prefrontal cortex
Executive functions direct behaviour to goals. Broca’s area in left hand frontal lobe for speech production.
Temporal lobes
Hearing and language. contains Wernicke’s area in left hand side for speech comprehension.
Cognitive neuropsychologist
Studies people with damaged brains to learn how normal brains function. Studies perception, attention, learning, memory, processing of written and spoken language, thinking, and reasoning.
Cognitive neuroscientist
Focuses on neural mechanisms that underlie cognition.
