lala

Central Nervous System (CNS):
- Main processing center for sensory information.
- Involves the spinal cord and brain.
Peripheral Nervous System (PNS):
- Includes all nerves outside the CNS.
- Responsible for transmitting sensory input and motor output; analogous to a computer's peripherals (mouse, keyboard, monitor).

Structure of a Neuron:
- Cell Body (Soma): Contains the nucleus.
- Axon: Transmits signals away from the cell body.
- Axon Terminals: Where signaling to another neuron occurs via neurotransmitter release.
- Myelin Sheath: Insulating layer that increases the speed of signal transmission along the axon.

Support neurons; outnumber neurons approximately 100 to 1.
Oligodendrocytes: Produce myelin in the CNS.
Schwann Cells: Produce myelin in the PNS.
Astrocytes: Provide support and nutrients; assist in transmission of information.
Microglia: Act as the immune cells in the CNS, specifically adapted to avoid damaging neurons due to their inflammatory responses.

Frontal Lobe:
- Contains the motor cortex (controls voluntary movements), prefrontal cortex (decision-making, planning), and Broca's area (speech production).
- Develops up to age 25.
Temporal Lobe:
- Involved in processing auditory information; key for understanding speech.
Parietal Lobe:
- Contains the somatosensory cortex, which handles sensory information such as touch.
Occipital Lobe:
- Primary visual processing center.
Cerebellum:
- Controls balance and coordination of movements.

Resting Membrane Potential:
- At rest, neurons have a potential of approximately -70 mV.
- Inside of the cell is more negative compared to the outside; high concentrations of potassium inside and sodium outside.
Sodium-Potassium Pump:
- Pumps 3 sodium ions out for every 2 potassium ions in, contributing to the negative potential inside the cell.
Action Potentials:
- Triggered when the membrane potential reaches a threshold (around -55 mV), resulting in a rapid depolarization of the cell.
- Sequence of voltage-gated sodium channels opening allows sodium to flow in, leading to a rapidly positive membrane potential.
- After reaching around +40 mV, potassium channels open, bringing membrane potential back down during repolarization.
- This process is an all-or-nothing response; any stimulus must exceed the threshold for true action potential generation.
Refractory Period:
- The phase after action potential during which the neuron is less excitable; another action potential cannot be generated.

Graded Potentials: Triggered by synaptic inputs prior to reaching threshold for action potentials.
Hyperpolarization: Makes the neuron less likely to fire by making it more negative (moving away from 0).
Depolarization: Makes the neuron more likely to fire, towards reaching the threshold.
Summation of Potentials:
- Temporal Summation: Rapid signals from the same synapse.
- Spatial Summation: Simultaneous signals from multiple synapses.

Process of brain changing and reorganizing itself in response to learning and experience.
- Long-Term Potentiation (LTP): Strengthening of synapses based on recent patterns of activity.
- Influence of repeated firing connections, leading to long-lasting enhancements in signal transmission.

Acetylcholine: Associated with muscle activation, learning, and memory.
Amino Acid Neurotransmitters:
- GABA (gamma-aminobutyric acid): Main inhibitory neurotransmitter.
- Glutamate: Primary excitatory neurotransmitter, involved in many cognitive functions.
Biogenic Amines:
- Dopamine: Involved in reward-motivated behavior and motor control. Degeneration leads to Parkinson's disease.
- Serotonin: Regulates mood, anxiety, and happiness.
- Norepinephrine: Involved in alertness and arousal; functions similarly to adrenaline.
Neuropeptides: Short chains of amino acids that modulate neurotransmitter effects.
Endocannabinoids: Signal molecules that influence synaptic transmission and neuroplasticity.

Depression: Mood disorder linked to imbalances in neurotransmitters like serotonin.
Bipolar Disorder: Characterized by alternating episodes of mania and depression due to neurotransmitter fluctuations.
Schizophrenia: Affects perception of reality, often connected to dopamine dysregulation.
Alzheimer's Disease: Neurodegenerative disease characterized by accumulation of amyloid plaques leading to cognitive decline.
Parkinson's Disease: Motor function disorder due to loss of dopamine-producing neurons; treated with dopaminergic medications.

Skeletal Muscle Structure: Comprised of muscle fibers containing actin and myosin.
Troponin and Tropomyosin: Proteins that regulate muscle contraction; calcium ions facilitate interaction between myosin and actin.
Contractile Cycle: Myosin heads attach to actin, using ATP for energy to pull the actin filaments (power stroke).

Vision: Caused by light waves within specific wavelengths (400-700 nm); involves photoreceptors (rods and cones).
- Rods: Black and white vision.
- Cones: Color vision, with specific types sensitive to red, green, and blue light.
- Photopsins: Light-sensitive proteins in cone cells that begin the signal transduction for vision.
Hearing: Involves sound waves creating vibrations within the cochlea, stimulating hair cells that send signals to the brain.
Chemical Senses: Involve binding of molecules (odorants or tastants) to receptors, initiating signals for taste and smell.
- Taste Buds: Detect different tastes using specialized receptors on papillae.
- Olfactory Bulb: Directly processes smell signals; unique in that it bypasses the thalamus.

The sensory input is processed in the CNS, leading to appropriate motor responses through the effector neurons (efferent pathways).
Examples include voluntary muscle actions triggered through reflex arcs or conscious decision-making frameworks involving different systems (somatic and autonomic).