Understanding the Nervous System

Nervous System

• A network of cells, tissues, and organs
• Controls thoughts, movement, and life processes quickly
• Neuron: A specialized cell that produces and transmits signals

Structure of Neurons

• Cell Body: contains the nucleus and organelles
• Dendrites: Receives messages from neighboring cells
• Axon & Axon Terminals: Carries messages to other cells
• Myelin Sheath: An insulator of axons that guides messages

Other Terminologies

• Stimulus: Any factor that triggers a nerve impulse
• Nerve Impulse: Transmitted electrochemical signal
• Neurotransmitters: Stimulated chemicals carry information at the end of axons
• Synapse: is a space between neurons

Types of Neurons

• Sensory Neuron/Afferent: Detects stimuli and transmits signals to the brain and spinal cord
• Interneuron: Processes and relays signals between sensory and motor neurons through the brain and spinal cord
• Motor Neuron/Efferent: Passes messages from the nervous system to the rest of the body

Parts of the Nervous System

• Central Nervous System (CNS): Main processing center composed of interneurons
  • Brain: Located in the skull, organizes information and protected by meninges
  • Cerebellum: Coordinates muscle movement while regulating balance and posture
  • Brain Stem/Medulla: Controls involuntary functions that connects the brain to the spinal cord
  • Spinal Cord: Controls involuntary movements called reflexes, serves as a channel for signals
• Cerebral Cortex: Outer layer of the cerebrum that interprets information from the sensory organs
• Left Hemisphere: Controls sensory stimulus and motor control on RIGHT and is for speech and abstract thinking
• Right Hemisphere: Controls sensory stimulus and motor control on LEFT while processing images and spatial awareness
• Peripheral Nervous System (PNS): Contains the sensory and motor neurons to transmit information between CNS and body

Somatic and Autonomic Systems

• Somatic System: Uses skeletal muscles for voluntary movements with 31 pairs of spinal nerves and 12 pairs of cranial nerves
• Autonomic System: Uses smooth and cardiac muscles to regulates involuntary actions with the Sympathetic preparing the body for action and stress, and the Parasympathetic calming and conserving energy

Common Neurotransmitters

• Serotonin: Influences mood, hunger, and some muscle functions
• Dopamine: Influences emotional behavior, stress, and some voluntary muscle functions
• Glutamate: Affects learning, memory, and brain development
• Acetylcholine: Involves learning and memory
• Gamma Amino Butyric Acid: Prevents neurons from generating impulses

Intervention of Drugs

• Affects the amount of neurotransmitters in synapses
• Leads to behavioral changes, pain sensitivity, and addiction
  • Stimulants: Increase neurotransmitters
  • Depressants: Reduce neuron synapse ability, relaxing, and tiring the body

Diseases and Disorders of the Nervous System

• Alzheimer’s Disease: It degenerates neural connections, deteriorating various cognitive abilities with progressive memory decline
• Cerebral Palsy: Abnormal brain development/damage during the first years of life, characterized by paralysis
• Epilepsy: A chronic disorder with abnormal neurosignals causing sudden recurrent seizures
• Multiple Sclerosis: Damages myelin sheath, disrupting communication between CNS and body parts
• Parkinson’s Disease: Degenerative disorder with tremor onset, muscle rigidity, slow movement, and stooped posture

Endocrine System

• This is a system of glands that produces hormones, slowly changing and developing the body to maintain homeostasis
• Glands: Secrete and release hormones into the bloodstream
• Hormones: Chemical signals equivalent to neurons and can be of two types
  • Steroid Hormones: alter DNA in the nucleus to make proteins
  • Non-steroid Hormones: stimulate a messenger cell in the cytoplasm to start a series of chemical reactions which activate enzymes
• Homeostasis: The internal environment is in equilibrium/balance
• Hormone Process

Glands and their Hormones and Functions

• Hypothalamus: Controls the functions of other glands, except the hypothalamus, and links the nervous system to control glands and homeostasis as the master gland
• Pineal Gland: This isn't part of test
• Pituitary: Stimulates growth by growth hormones
• Thyroid: Increases body metabolism/digestion (thyroxin) and regulates calcium/bone formatin as calcitonin
• Thymus: Produces antibodies/maturation of white blood cells (thymosin)
• Adrenal: Handles stress response through regulating heart rate, blood pressure, and breathing due to epinephrine
• Pancreas: Decreases sugar levels in the bloodstream thanks insulin, and increases sugar levels in the bloodstream by glucagon
• Reproductive: Controls maturation and characteristics of male (testis) and female (ovaries)

Feedback System

• Negative Feedback: Too much hormone production triggers a change that reduces hormone production for self-regulation
• Positive Feedback: Release of hormone that triggers additional release, like an increase in blood clotting and/or contractions during breathing

Sex related Diseases

• Pituitary Dwarfism: Hyposecretion of growth hormone leads to shortness and slow development
• Gigantism: Hypersecretion of growth hormone causes an abnormal increase in weight/height, happening at acromagelia (a later stage)
• Hypothyroidism: Weight gain, slowed heart rate, muscle/joint pain, and depression
  • Cretinism: iodine deficiency causing dwarfism and mental retardation.
  • Myxedema: a decreased function in adults
• Hyperthyroidism: causes weight loss, irregular heartbeat, nervousness, Graves' Disease causes bulging eyes
• Diabetes: hyposecretion of insulin, which causes either type 1 genetic variation, or type 2 minimal production due to lifestyle
• Hypoglycemia: cycling hypersecretion of insulin due to consumption of carbs

Reproductive System

• This involves the glands/hormones for making individuals
• Gonads: Glands secreting testosterone (male) or estrogen (female)
  • Testosterone: which develops male characteristics and is an activator
  • Estrogen: which develops femaleness while preparing the uterus

Important Reproductive Hormones

• Oxytocin: which stimulates labor contractions & behavior
• Progesterone: which prepares the uterus lining for growth and implantation of the zygote
• Puberty: Sexual maturation for having fertility

Male Reproductive System

• It doesn't produce sperm until puberty and then makes millions each day
  • Testis: which produces sperm cells (through spermatogenesis)
  • Scrotum: which protects the testis -Epididymis: where sperm matures until use or reabsorbed -Vas Deferens: Its for carrying sperms -Urethra: which links to carry sperm/urine -Seminal Vesicle: Which energizes
  • Prostate Gland: which nourishes -Bulbourethral / Cowper’s Gland: A clear mucus cleaning

Sperm Part

• Acrosome which eats membrane with enzymes
• Nucleus which contains pairs
• Mitochondria which supplies power
• Tail for propulsion

Female Reproductive System

• It produces eggs even before birth which leads to only a month being fertile, which involved the creation of eggs
• Ovary: Makes eggs with a sac called the "Follicle", and the Luteum temporary cell masses.
• Fallopian Tube: a passageway for eggs
• Uterus the egg implantation zone
• Cervix: The lower region
• Vagina: Which mates

Embryo phases

• Ova for eggs
• A cycle divides unevenly, with with nutrients

Menstrual Phase

• Estrogen increases during the menstrual phase in order to start vessel building
• In pregnancy, the cell joins and implanted as blastocyst
• In the cycle, the average is roughly twenty eight days from the start with a flow and increase
• Then follicle hormone for making the follicle stimulate

Cell Development

• Sperm joins egg, and begins to split to create vessels while growing for the next step
• Implants as cell layers to eventually build a endoderm/mesoderm/ectoderm
• The growing zone in the Blastocyst is now and Embryo for the baby
• This continues for the next 10 weeks to make a Fetus and then its almost a month

Things that protect the Fetus

• Amniotic Sac: Protects fetus under pressure and temperature
• Placenta: Supplies cord, blood, oxygen, and also nutrients through the cord
• The phase depends on the part, the organ starts to develop and detect heartbeat/sex

Time development

-In trimesters of three months each the baby continues to develop -Then they start the head down position and stronger bones, eventually leading into the Three Stages of Birth where the cervix dialates

Disorders

• With certain positions the development isn't always done correctly and some things can move like Inguinal Hernia
• The body might also refuse to move them either, like in Cryptorchidism

DNA

• DNA; Molecule carrying genetic info.
• nucleotides which are in a base to hold Deoxyribose which is with Phosphate Group in the sugar to help move

Protein Phase

• Protein synthesis: cells produce protein by amino acids
• Transcription phases transfer DNA to RNA
• Ribonucleic: acid, single-stranded, has three types, for moving with the DNA of the Ribonucleic acid

Codes

• In the strands will either replicate or split depending on what section
• Replicates before the division so strands separate again
• Has 3 codes in them, and one of which could transfer information for all the acids and parts to be coded

Process phases

• RNA has mutations to alter it, and you must be able to identify those factors by looking at a codon (a group of three bases) to determine which it's likely linked too

Engineering

• In terms of mutations, the body in itself, at least somatically can't exactly pass something that helps with the reproductive state
• A genetic change will happen for the DNA or gene synthesis, with Deletion, a Duplication or an Inversion of the Gene

GMO development

• The code to create the protein is affected and can be altered by adding certain things to change how the body operates from removing parts and inserting them
• As a result more and more test started happen as development started, with now even animals being genetically made to a similar standard
• Although it leads and could develop to create super species, it also could mean more damage to individuals or environments in themselves

Evolutionary Phase

• In the natural belief it studies how things change and are formed slowly over development
• This could lead to different forms and the factors that follow, which can then lead into the phases that come after
• Some organisms will live in favorable changes while others won't, leading to the death and or mutations of certain species while others adapt

Genetic Change

• Change might lead to better or worse in the long run, making certain directional or adrift based on an organism

Evidence and reasons for extinction

-Over time most of the changes will take longer and lead to various different functions depending on whats there -Certain points can have limited impact on the current system from the amount of species as well as the various different structures that change the system either at birth or as it develops naturally to the environment

Explore the structure and function of the nervous system. Learn about neurons, their components, and different types. Discover how nerve impulses transmit messages throughout the body.