The Nervous System and Brain Ana Cendejas Period:7 (Action Potential…
The Nervous System and Brain
Ana Cendejas Period:7
Major Functions of Spinal Cord
Sensory-detects changes (stimuli) within body and outside the body
Integrative-It analyzes sensory information, stores some aspects and makes decisions regarding appropriate behavior's
Major parts and
functions of the spinal cord
Spinal Cord- Connection between the brain and brainstem to the rest of the body
Anatomy of Spinal Cord
Two deep longitudinal grooves divide the cord into the right and left halves. White matter is a butterfly shaped core of gray matter housing interneurons and cell bodies. The gray matter divides the white matter into 3 regions anterior, lateral and posterior funiculi. The gray commissure is where fibers cross from side to side.
Motor-It may respond to stimuli by initiating muscular contractions or glandular secretions
Major Divisions of NS
Central Nervous System (CNS)-Receives incoming sensory information ,issue instructions,integration of information,thoughts, and emotions. Nerve impulses that influence effect-or organs begins in CNS.
Peripheral Nervous System-Spinal nerves carry impulses to and from spinal cord, and cranial nerves carry impulses to and from cranium.
Sensory (afferent) Nerves- Relays information from skin,muscles, and glands to CNS
Motor (efferent) Neuron- Carry instructions away from CNS to target or effector organs of the body
Somatic- Senses and responds to external environment
Automatic- Responds to internal environment
Major Parts of the Brain
Cerebrum- Largest part of the brain and associated with higher mental function
Diencephalon- Processes sensory input and controls many homeostatic process
Brainstem- Coordinates and regulates visceral activities
Cerebellum- Coordinates muscular activity
Names of the Lobes of the Brain
Frontal Lobe-Part of the brain that controls emotional expressions,problem solving,memory,language,judgment, and sexual behavior's. It;s located near the forehead.
Parietal Lobe-Processes sensory information regarding the location of the parts of the body. It's located near the center of the brain.
Temporal Lobe-Controls memory,sensory input,language, and comprehension.It's located behind the ears.
Occipital Lobe-Controls vision, color determination, face recognition, and face recognition. It's located rear portion of the skull.
Diseases and Brain injuries
Concussion- Shaking of the brain, no permanent damage, results of swelling
Contusion- Causes tissue destruction, permanent damage
Intracranial hemorrhage- Bleeding in the skull
Alzheimer, Parkinson disease and multiple sclerosis
Drugs that affect the brain
Heroine activates receptors in the brain. This causes greater amounts of dopamine to be released into reward system making an intense short lived rush
Ecstasy blocks the reuptake pumps for certain neurotransmitters and it increases their levels in synaptic gap and effects on the post synaptic neurons receptors
Tetrahydrocannabinol is the active ingredient in marijuana. It activates a specific receptor in the brain called cannabinoid. When it activates these receptors it interferes with the normal functioning of many areas of the brain
Methamphetamine causes the release of neurotransmitters dopamine, norepinephrine. The release of neurotransmitters activates the heart rate and increases the blood pressure
Automatic Nervous System
Controls involuntary responses
Somatic Nervous System
Controls voluntary movements
Structure of Neurons
Dendrite- portion of neuron that receives impulse and sends signals to the cell body
Cell body- Contains nucleus and other organelles is the metabolic center
Axon- The portion that conducts signal away from body cell
Myelin- Fatty substance that surrounds axon, and insulates signal
Node of Ranvier- Spaces between myelin and schwann cells
Synapse- The junction between two communicating neurons
Classifications of Neurons
Multipolar- Many dendrites and one axon
Bipolar- One dendrites and one axon (sensory)
Unipolar- Fused axon and dendrites (sensory)
Layers of meninges of the Brain
Dura Mater- The outer layer, tough, white dense connective tissue and contains many blood vessels
Arachnoid Mater- The middle layer, very thin, lacks blood vessels
Pia Mater- The inner layer, it covers every fold of the brain
Endoeurium- surrounds individual fibers within a nerve
Perineurium- Surrounds a fascicle
Fascicle- A group of nerve fibers
Epineurium- Surrounds the entire nerve
Resting Membrane Potential: Membrane at rest has polarized fewer potassium ions inside and more sodium ions outside
Stimulus begins depolarization-Strong stimulation or nerve impulse causes sodium ion gates to open. Then sodium ions rush into cell causing depolarization.
Threshold Potential- If a strong depolarization occurs, it reaches the threshold potential (-55mv).
Action Potential occurs- When the threshold is achieved it causes and action potential, where a nerve is transmitted.
Repolarization- Once repolarization begins K plus rushes out of neuron after Na plus rushes in.
Resting State- After depolarization stage the Na plus gates open, then close going into an inactive conformation until the repolarization goes to it's normal resting potential and is ready to repeat the process again.
Sensory/ afferent neuron- sends signals to CNS
Synapse/ Interneuron Integration center- Connection between sensory neuron and motor efferent neuron
Sensory receptor- afferent nerve ending detects stimulus
Motor/ efferent neuron- delivers response to target organ
Effector- targets organ responds to signal