Understanding the Nervous System

• The nervous system coordinates the body's activities.

Parts of the Nervous System

• The central nervous system (CNS) processes information.
• The gray matter processes information.
• The white matter connects the gray matter to other parts of the nervous system.
• The brain is protected by the skull, with gray matter on the outside and white matter on the inside.

Brain Divisions

• Forebrain is at the front.
• Midbrain is in the middle.
• Hindbrain is at the back.
• The cerebrum manages thinking, voluntary movements, and cognitive functions such as thinking, reasoning, memory, and decision-making, and controls voluntary muscle movements via the motor cortex.
• The diencephalon regulates processes like sleep and body temperature.
• The thalamus is a relay station that transmits sensory and motor signals to the cerebral cortex and regulates consciousness, sleep, and alertness.
• The brain stem controls basic functions like breathing and involuntary movements, essential life-sustaining functions such as heart rate, breathing, and blood pressure, and automatic reflexes like swallowing, coughing, and sneezing.
• The cerebellum coordinates balance, muscle activity, and voluntary movements, is involved in learning motor skills and fine-tuning movements, and is located in the hindbrain.

Spinal Cord

• The spinal cord is protected by the spinal column.
• The white matter is on the outside, and the gray matter (butterfly-shaped) is on the inside.
• The spinal column is comprised of:
  • Cervical column in the neck.
  • Thoracic column in the thorax/throat.
  • Lumbar column in the stomach/abdomen.
  • Pelvic column in the pelvis/hipbone.
  • Sacral and Coccygeal column for the degenerated tail.

Neuron

• Neurons, or nerve cells, are the basic unit of the nervous system.
• Neurons transmit impulses or information.
• Sensory neurons receive and send information to the brain and spinal cord.
• Motor neurons conduct information from the brain and spinal cord.
• Interneurons relay information from sensory to motor neurons.
• The Synapse is the end of axon and tip of dendrite.
• Mechanoreceptors detect touch.
• Photoreceptors detect light.
• Nociceptors detect pain.

Brain Diseases

• Parkinson's Disease involves dopamine-producing neurons dying off in the basal ganglia and causes difficulty initiating movement.
• Huntington's Disease is a genetic mutation which causes excess glutamate and kills neurons in the basal ganglia, leading to uncontrollable movements.
• Alzheimer's Disease involves unusual proteins building up around neurons in the neocortex and hippocampus, causing memory loss and impaired ability to perform everyday tasks.

Peripheral Nervous System

• The peripheral nervous system (PNS) connects the central nervous system (CNS) to other body parts.
• It comprises nerves and ganglia and transmits information between the CNS and other body parts
• The Somatic Nervous System consists of the cranial and spinal nerves.
• The Autonomic Nervous System controls involuntary body movement.
• The Sympathetic nervous system activates when the body is in a dynamic role or stress and increases heart rate, elevates beating, and dilates pupils.
• The Parasympathetic nervous system maintains body functions and restores the body to a normal or relaxed state.

Endocrine System

• The endocrine system is a network of glands that produce and release chemical messengers called hormones.
• It works with the nervous system to maintain homeostasis (internal balance).
• Functions:
  • Cell growth and division.
  • Appetite suppression.
  • Acid secretion.
  • Calcium absorption.
  • Red and white blood cell production.
• Hormones transmit signals from one cell to another via the bloodstream and control or regulate biological processes.
• Glands synthesize and secrete hormones.
• Epinephrine is produced during emergencies, provides more energy and ATP signals to cells, and is also known as adrenaline.
• Exocrine glands secrete substances on the body surface through a duct.
  • The Liver secretes or produces bile with salt and digestive substances.
  • Mammary Glands secrete breast milk.
  • Sweat Glands release salty water through perspiration.
  • The Pancreas secretes pancreatic juice with digestive enzymes into the stomach.
  • Salivary Glands secrete saliva with digestive enzymes.
• A receptor is a specific site on a cell that recognizes and accepts a specific hormone.
• Hormones circulate to all tissues but are only active with specific target cells, they must have specific receptors.
• Receptors may be intracellular or on the plasma membrane.

Major Endocrine Glands

• Pituitary Gland regulates other endocrine glands and secretes growth hormone.
  • It is also known as the hypophysis gland or master gland.
  • The hormones it secretes are:
    • Growth Hormone (GH) stimulates growth and cell reproduction, increases muscle mass and promotes fat breakdown.
    • Prolactin (PRL) stimulates milk production in the mammary glands.
    • Luteinizing Hormone (LH) triggers ovulation and stimulates testosterone production in males.
    • Follicle-Stimulating Hormone (FSH) stimulates growth of ovarian follicles in females and sperm production in males.
    • Thyroid-Stimulating Hormone (TSH) stimulates the thyroid gland to produce thyroid hormones Triiodothyronine (T3) and Thyroxine (T4).
• The Hypothalamus links the endocrine and nervous systems and regulates the pituitary gland and homeostasis.
  • It is where the pituitary gland is and is like a canal area of the brain.
  • Hormones secreted:
    • Oxytocin stimulates uterine contractions during childhood and milk ejection during breastfeeding.
    • Antidiuretic Hormone (ADH) regulates water balance by promoting water reabsorption in the kidneys.
• The Pineal Gland receives information about the light-dark cycle from the environment, and conveys this by the production and the secretion of melatonin.
  • Hormones secreted:
    • Melatonin regulates sleep-wake cycle and circadian rhythms.
    • Circadian Rhythm is influenced by external cues such as light, temperature, food, stress, physical activity, and social environment.
• The Thymus is in the chest between the lungs behind the breastbone, assists in the development of the immune system.
  • Hormones secreted:
    • Thymosin stimulates development and maturation of T cells (T lymphocytes).
• The Thyroid regulates metabolic rate, metabolism, growth, and development and produces thyroxine (T4) and triiodothyronine (T3).
  • T3 and T4 maintain metabolism, body temperature, mood, excitability, a pulse rate, a heart rate, and digestion.
    • The secreted hormones are:
      • Thyroxine (T4).
      • Triiodothyronine (T3) is more potent/stable than T4.
      • Calcitonin lowers blood calcium levels by inhibiting osteoclast activity and promoting calcium deposition in bones.
    • The negative feedback mechanism involves the brain signaling the thyroid to stop producing osteoclasts.
• The Pancreas helps regulate blood sugar.
  • The secreted hormones:
    • Insulin reduces blood sugar by increasing glucose uptake.
    • Glucagon increases blood sugar.
• The Adrenal Gland regulates fluid and sodium balance and is an emergency warning system under stress and is located on top of kidneys.
• The Ovary and Testis control the development of secondary sex characteristics and the functioning of sex organs.
• Secondary Sex Characteristics are physical traits that distinguish males and females but aren't directly involved in reproduction and are developed during puberty due to hormonal changes.
  • Examples in Males:
    • Facial hair, mustache and beard.
    • Chest hair.
    • Increased body hair.
    • Adam's apple
    • Deep voice.
    • Lean body mass.
  • Examples in females:
    • Breasts.
    • Widened hips.
    • Pubic hair.
    • Thicker head hair.
    • Rounded hips and figure.
    • Increased body fat consumption.
    • Menstrual cycle.
    • Ability to nurse children.

Endocrine Diseases

• Acromegaly occurs when the body produces too much growth hormone (GH).
• Cushing's Syndrome occurs when the body produces too much cortisol over a long period of time.
• Hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormone.
• Polycystic Ovary Syndrome (PCOS) is a set of symptoms related to hormonal imbalance in women.
  • It has a set of symptoms related to hormonal imbalance in women.
  • Absence of ovulation, leading to irregular menstrual cycle or no periods at all.
  • High levels of androgen.
  • Abnormal growth on one or both ovaries.

Reproductive System

• Reproduction is the process of producing offspring that are biologically or genetically similar to the parent organism.

Male Reproductive System

• Testicles (Testes) paired oval-shaped organs in a pouch called the scrotum.
  • They responsible for the production of sperm and the male hormone testosterone.
    • Producing testosterone - male sex hormone.
    • Producing sperm - a carrier of man's genes.
• Spermatogenesis is the production of sperm cells.
• The scrotum houses the testicles and maintains their temperature.
• Vas Deferens are muscular tubes where sperms get matured and pass to the urethra.
• Accessory Glands:
  • Seminal vesicles secrete a thick fluid that contains nutrients.
  • The prostate gland secretes a thick, milky alkaline fluid which is alkaline to counteract the acidic environment.
  • The Bulbourethral or Cowper's gland produces a lubricating effect.
• The penis is a cylindrical tube that serves as both a reproductive and excretory organ, and delivers sperm into the vagina during sexual intercourse.
  • Ejaculation is the release of semen.
  • The prepuce is the outer part and the glans is the head of the penis.
  • The penis is flaccid (soft) when sperms are not yet ejected.
• The Urethra is a tube-like structure that connects the bladder and carries urine and sperm.
• The sperm pass through epididymis and reaches the back of the testes where they mature and swim.
• Testosterone is the main male sex hormone.
• Mitochondria provide a lot of ATP to the cell.
• Parts of a sperm:
  • The tail provides a lot of energy.
  • The head targets the egg cell.
  • During sexual intercourse, the middle piece and tail are lost.

Female Reproductive System

• Oogenesis describes the production of the female reproductive cell (egg cell).
• Coitus is a term used for sexual intercourse.
• The vulva is the external part of the female reproductive system.
• The mons pubis is where pubic hair is located.
• The Labia Majora are major lips that enclose and protect the external reproductive organs.
  • It contains hair growth which contains sweat and oil-secreting glands.
• The Labia Minora are the inner lips which lie under the labia majora surrounding the openings to the vagina and urethra.
• The Clitoris, where the two labia minora meet, is a comparable penis that is covered by a prepuce and very sensitive to stimulation.
• The Vaginal opening is where menstruation comes out.
• The Urethral opening is where urine leaves the body.
• In the Hymen, the tissue covers or surrounds the part of your vaginal opening.

Internal System

• The Fallopian Tubes (Oviduct) connect the ovaries to the uterus and transport fertilized eggs from the ovaries to the uterus.
• The Ovaries, located on each side of the uterus in the pelvic cavity, produce eggs, and hormones, release an egg.
• The uterus(womb) is a three layered pear organ, which produce estrogen and progesterone like hormones.
• The Cervix produces cervical mucus to help the sperm move up to the reproductive tracts.
• The Vagina a muscular organ extends from the vulvar vestibule to the cervix.
• The Menstrual cycle, around 28 days is when hormonal changes that make a woman fertile.

Ovarian Cycle

• The pituitary will secrete follicle-stimulating hormone(FSH) and will allow the ovarian follicles to mature.
• Estrogen is the female sex hormone produced when follicle cells develop.
• The pituitary gland will secrete luteinizing hormone(LH).
• The follicle's final maturation culminates in ovulation (release of a mature egg)
• The yellow body will develop and will produce progesterone.

Phases

• Follicular phase - 10 days
• Luteal phase - around 14 th day
• Formation Phase - formation of follicles - 10 days
• Luteal Phase - pregnancy on the 14th day
• Cesarean Section (CS) involves cutting the abdominal area and moving the intestine, and will breach when the baby's head is not in the cervix
• Normal delivery involves cervix moving and widening.
• Postpartum is the period after childbirth.

Deoxyribonucleic Acid (DNA)

• The cell is the basic unit of life.
• Nucleus and Organelles are parts of a cell - contains mitochondria which produces energy.
• The cell membrane covers animal cells and the cell wall covers planted.
• Cytoplasm in the fluid substance.
• Protein, carbohydrates, fats/lipids and nucleic acids are four types of Biomolecules.
• Nucleotides are components of DNA, and consist of sugar, phosphate, and nitrogenous bases.
  • DNA contains cytosine, guanine, adenine, and thymine.
  • RNA contains cytosine, guanine, adenine, and uracil.
• Lock and Key determine base pairing:
• Adenine is for Thymine (DNA)
  • Adenine is for Uracil (RNA)
• Three main types of RNA include:
  • Messenger RNA (mRNA) copies DNA in the nucleus for replication.
  • Ribosomal RNA (rRNA) synthesizes proteins in ribosomes for transcription.
  • Transfer RNA (tRNA) carries amino acids in the cytoplasm for translation.
• Protein Synthesis include:
  • Replication copying genetic information in the DNA
  • Transcription genetic code in DNA into mRNA
  • Translation codons which are then translated into amino acids

Mutation

• Mutation is the permanent change in the genes within the gene or chromosomes of a cell
• Types of mutation:
  • Substitution (exchanges one base for another),
  • Insertion (extra base pairs are inserted),
  • Deletion (a section of DNA is lost),
  • Frameshift (insertion and deletion can alter a gene so that its message is no longer correct)