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Nervous System - Coggle Diagram
Nervous System
Neurons
Dendrite - Receives electrical impulses from other neurons and allows the transmission of the impulse to the cell body
Cell Body - Contains the nucleus of the neuron
Axon - Tube like structure that carries the impulse from the cell body to the axon terminal to then pass the impulse on to another neuron.
Myelin Sheath - Allows quick and efficient transmission of electrical impulses. Damage can cause mild shocking sensations.
Structure
here
Schwann Cells - They play essential roles in the development, maintenance, function, and regeneration of peripheral nerves.
Brain
Midbrain
Midbrain functions involve movement of the body and head, as it provides passage for downward pathways for the cerebral cortex. It is a channel for the spinal cord transmitting stimuli (sensory) from the head and body to the direct brain.
Colliculi
Tegmentum
Cerebral Peduncles
The corpus callosum is the largest set of commissural fibers in the brain. The corpus callosum serves as the major connection between the hemispheres and conveys neural information from one hemisphere to the other.
Hindbrain
The hindbrain coordinates functions that are fundamental to survival, including respiratory rhythm, motor activity, sleep, and wakefulness.
Cerebellum - cerebellum is part of your brain that helps coordinate and regulate a wide range of functions and processes in both your brain and body
Medulla Oblongata - where your brain and spinal cord connect, making it a key conduit for nerve signals to and from your body. It also helps control vital processes like your heartbeat, breathing and blood pressure
Pons - handles unconscious processes and jobs, such as your sleep-wake cycle and breathing.
Forebrain
The forebrain plays a central role in the processing of information related to complex cognitive activities, sensory and associative functions, and voluntary motor activities.
Cerebral Cortex - Cerebral cortex is responsible for the higher-level processes of the human brain, including language, memory, reasoning, learning, decision-making, emotion, intelligence.
Hippocampus - Hippocampus is a complex brain structure embedded deep into temporal lobe. It has a major role in learning and memory. It is a plastic and vulnerable structure that gets damaged by a variety of stimuli.
Hypothalamus - Its main function is to keep your body in a stable state called homeostasis. It does its job by directly influencing your autonomic nervous system or by managing hormones.
Lobes
Frontal
The frontal lobe is responsible for higher cognitive functions, such as decision-making, problem-solving, and personality expression.
Occipital
The occipital lobe is primarily dedicated to visual processing and interpretation.
Temporal
The temporal lobe plays a crucial role in auditory processing, language comprehension, and memory formation.
Parietal
The parietal lobe processes sensory information, including touch, temperature, and spatial awareness.
Brain Scanning Techniques
CT (Computerized Tomography)
The individual is placed in a donut shaped X-Ray machine that moves around the individual generating a 2D X-Ray. A CT of the side of the individual can be taken to create a 3D image.
Advantages
Can detect brain damage and blood flow in the brain while the individual is conducting an activity to measure brain functionality.
Non-invasive & Painless
Disadvantages
High dose of radiation
MRI (Magnetic Resonance Imaging)
The subject is placed on a moveable bed that is inserted into a giant circular magnet. Images of sections of the brain are obtained through the use of "gradient magnets" which alter the main magnetic field in a very precise area while the magnetic force is being applied. The MRI technician can pick exactly what area of the individuals brain they need an image of.
Advantages
No tracer required
Painless, non-invasive
MRI show brain anatomy, fMRI shows anatomy & function
Disadvantages
Expensive
Patients with metallic implants cannot scan
Patients must lie still
EEG (Electroencephelography)
An EEG is a recording of electrical signals from the brain. Electrodes, hooked up to the subject’s scalp, pick up electric signals naturally produced by the brain and send them to galvanometers (instruments that detect and measure small electric currents). The galvanometers are hooked up to pens, which trace the signals onto the graph paper.
Advantages
Observes brain function
Disadvantages
Does not display anatomy of brain
PET (Positron Emission Tomography)
The subject is injected with a very small quantity of radioactive glucose. The PET then scans the absorption of the radioactivity from outside the scalp.
Advantages
Provides an image of brain activity.
Allows researchers to look at cross-sectional "slices" of the brain, and observe deep brain structures, which earlier techniques like EEGs could not.
Disadvantages
Expensive
Uses radioactive tracer
Types of Neurons:
Relay Neurons: Relays information from sensory neurons to the brains, receives response and transmits action potential to motor neurons.
Motor Neurons: Convey information from brain to the effector and response is made.
Sensory: Transmits sensory information from sensory organs to relay neurons.
Synapse
The meeting point between two neurons. Two neurons are never touching, but have a microscopically small distance between them known as the synaptic cleft.
Neurotransmitters are packaged into small sacks known as vesicles. When the presynaptic neuron is excited by an action potential (electrical impulse). The vesicles fuse with the presynaptic membrane and release the neurotransmitters into the synaptic cleft.
The neurotransmitters interact with the receptors on the post-synaptic neuron. They bind with the receptors. This makes the post-synaptic neuron fire an action potential.
Parts of Nervous System
PNS (Peripheral Nervous System)
The PNS is the nervous system that lies outside of the brain and the spine. The role of the PNS is to send information from your brain to the body and to relay sensory information to the brain. The PNS is divided into autonomic and somatic nervous system.
Somatic - Conscious, Voluntary
Autonomic - Subconscious, Involuntary
CNS (Central Nervous System)
The CNs comprises of the brain and spine. It is protected by membranes know as meninges as well as cerebrospinal fluid. The CNS is divided into grey and white matter.
White Matter - Axons
Grey Matter - Dendrites and glial cells
Voluntary & Involuntary Actions
Involuntary actions are not under our conscious control and are carried out by the autonomic, sympathetic and parasympathetic nervous system.
Reflexes, Heart Rate, Digestion
Voluntary actions are under our conscious control and are carried out by the somatic nervous system
Walking, Talking, Writing
Eyes
Structure of the EYE
Sclera - The main function of the sclera is to protect the delicate internal structures of the eye, such as the retina, choroid, and optic nerve. It helps shield the eye from mechanical injuries, UV radiation, and excessive light.
Cornea - Clear outer layer present outside the eye that focuses light onto the retina to form clear image. Provides structural integrity to the eye as well protects the iris and pupil.
Iris - Colored part of the eye which contains the muscle that controls the pupil. Helps expand and contract the pupil between changes in light intensity.
Pupil: The part of the eye which regulates the amount of light entering the eye. Expands or contracts based on the light intensity of the surrounding environment,
Retina - Layer of tissue at the back of the eye that contains photoreceptors known as rods and cones. Converts light into electrical impulses to be carried by the optic nerve to the brain
Rods - Allow us to see black and white in low light environments
Cones - Allow us to see color in environments with sufficient light
Disorders of the Eye:
Myopia (Nearsightedness): Myopia is a refractive error where close objects are seen clearly, but distant objects appear blurry. It happens when the eyeball is longer than normal or the cornea is too curved, causing light to focus in front of the retina instead of on it.
Presbyopia: Presbyopia is an age-related condition where the natural lens of the eye loses its flexibility, making it difficult to focus on close objects. It typically begins around the age of 40 and gradually worsens. People with presbyopia may require reading glasses or multifocal lenses to improve near vision.
Hyperopia (Farsightedness): Hyperopia is a refractive error where distant objects appear clearer than nearby objects. It occurs when the eyeball is shorter than normal or the cornea is flatter, causing light to focus behind the retina rather than directly on it. This results in blurred vision up close.
Astigmatism: Astigmatism is a common refractive error that occurs due to an irregularly shaped cornea or lens. It causes blurred vision at any distance as the light entering the eye is not evenly focused. Astigmatism can be corrected with glasses, contact lenses, or refractive surgery.
Cataracts: Cataracts refer to the clouding of the natural lens of the eye, leading to blurry or hazy vision. It often occurs with age but can also result from injury, certain medications, or underlying medical conditions. Cataracts can be treated with surgery, where the cloudy lens is replaced with an artificial intraocular lens (IOL) to restore clear vision.