Body Regulation and Homeostasis

The Body Regulation

• The nervous system is essential for responding to stimuli and performing functions like mental activities, data processing, body regulation, homeostasis, and environmental interaction.
• Mental Activities serves as the center for learning, memory, thinking, and speech.
• Data Processing receives, examines, and processes information to initiate appropriate responses.
• Body Regulation controls and regulates all bodily activities and coordinates the functions of other organs.
• Homeostasis, along with the endocrine system, maintains internal equilibrium.
• Environmental Interaction keeps us connected to the external environment.
• Homeostasis and Control Systems employ several internal control systems to maintain a stable internal environment despite external changes with the nervous and endocrine systems as primary mechanisms.
• The neuron is the fundamental unit of the nervous system, transmitting impulses, with three types: sensory (afferent), motor (efferent), and interneurons.
• Sensory (afferent) neurons receive information and send impulses to the spinal cord or brain.
• Motor (efferent) neurons conduct impulses from the brain or spinal cord to muscles or glands.
• Nissl bodies are sites of protein synthesis within the neuron.
• The axon transmits impulses to motor neurons.
• The myelin sheath surrounds the axon and it varies in thickness.
• A nerve fiber consists of an axon and its myelin sheath, surrounded by neurilemma outside the CNS (central nervous system).
• A fiber tract refers to bundled nerve fibers extending within the spinal cord or brain.
• A nerve is bundles of nerve fibers outside the CNS, surrounded by epineurium and supported by blood vessels.
• A dendrite is a short extension of the cell body, increasing surface area for impulse reception.

Transmission of Nerve Impulses

• Nerve impulses are transmitted between neurons across a synapse where an axon branches into synaptic knobs connecting to another axon, dendrite, or cell body.

Neurotransmitter Functions

• Acetylcholine carries signals from motor neurons to skeletal muscles.
• Norepinephrine impacts stress response.
• Dopamine is related to muscular activity.
• Serotonin influences mood, consciousness, and emotions.
• Melatonin regulates sleep-wake cycles.

Synapse Structure

• In the presynaptic neuron, the axon terminal releases neurotransmitters.
• In the postsynaptic neuron, the dendrite receives neurotransmitters.
• A reflex is an involuntary, automatic response to a stimulus.
• Touching a hot pan triggers sensory receptors to send an impulse to the spinal cord.
• Interneurons in the spinal cord direct motor neurons to move the hand via a reflex arc, bypassing the brain initially.
• The impulse then travels to the spinal cord and then to the brain's cerebral cortex, with pain felt only after the reflex action.

Divisions of the Nervous System

• The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS).
• The Central Nervous System consists of the brain and spinal cord.
• The Peripheral Nervous System connects the brain and spinal cord to the rest of the body, consisting of 12 pairs of cranial nerves and 31 pairs of spinal nerves.
• The brain contains around 100 billion non-regenerating neurons, is protected by the skull, while the spinal cord is protected by the vertebral column.
• Both the brain and spinal cord are covered by meninges and bathed in cerebrospinal fluid.
• The spinal cord serves as a connector for spinal reflexes and a link between the peripheral nervous system and the brain, through which sensory and motor information pass through.
• The Somatic nervous system controls skeletal muscles, skin, and internal organs.

Autonomic Nervous System Mechanisms

• The sympathetic mechanism dominates during stress, initiating the "fight-or-flight" response.
• The parasympathetic mechanism restores the body to normal after stress, promoting digestion and elimination.

Endocrine System

• The endocrine system works with the nervous system to coordinate body cell activities.
• The endocrine system secretes hormones that control metabolism, reproduction, growth, and development.
• Hormones are released into the bloodstream and travel to target cells, where they activate receptors.
• The circulatory system aids hormone transport.

Hormone Action

• Hormones travel short or long distances and specific hormones affect specific target cells.
• Target cells have receptors for specific hormones.
• Hormones are released from secreting cells and bind to receptors on target cells.
• Nontarget cells do not have these receptors.

The Negative Feedback Mechanism

• Endocrine glands regulate hormone production through negative feedback.
• Low thyroid hormone stimulates the hypothalamus to release TSH (thyroid-stimulating hormone).
• TSH then stimulates the thyroid gland to produce thyroid hormones.
• Encountering a threatening situation triggers the sympathetic nervous system to initiate the "fight-or-flight" response.
• The adrenal medulla releases epinephrine (adrenaline) and norepinephrine (noradrenaline) into the bloodstream.
• Physiological changes include increased heart rate and blood pressure, pupil dilation, shutdown of non-essential systems, and increased blood glucose.
• Insulin, produced by the pancreas, regulates blood glucose levels with glucagon working with insulin to maintain glucose balance.
• When carbohydrates are consumed, they convert to glucose, raising blood glucose levels and triggering insulin release causing excess glucose is stored as glycogen in the liver and muscles.
• If glycogen stores are full, insulin converts excess glucose to fat for energy reserve and promotes protein storage when proteins and fats are consumed.
• The glycemic index (0-100) reflects how food affects blood glucose.
• Refined sugars and husk-less grains, or refined carbohydrates, cause rapid insulin secretion and fat deposition.
• Unrefined carbohydrates (fruits, vegetables, whole grains, dried beans) cause controlled insulin release, less fat synthesis and storage, and weight gain.
• Exercise depletes muscle glycogen, allowing.
• Hormonal imbalance includes over/underproduction of hormones which can cause diabetes, gigantism, dwarfism, hyperthyroidism, hypothyroidism.
• Endocrine Gland Injury/Tumor can cause thyroid nodules, goiter, adrenal cancer, pancreatic cancer, ovarian cancer, pituitary tumors

The Human Reproductive System

• Reproduction is the method by which genetic material is transferred from one generation to the next.
• Both the female's egg and the male's sperm are necessary for this procedure.
• The joining of a female ovum and a male sperm to create a fertilized egg, or zygote, is known as fertilization.
• The endocrine system is composed of glands that secrete different types of hormones that affect almost every cell, organs, and function of our body.
• It is essential in regulating growth and development, metabolism as well as reproductive processes and mood.
• Endocrine glands secrete chemicals known as hormones into the bloodstream.
• When a hormone in the blood reaches the target organ, it produces a notable effect.

Endocrine Glands and Their Hormones:

• Pituitary gland: Located at the base of the brain, controls the functions of other glands.
• Thyroid gland: Located below the voice box, regulates body metabolism and causes storage of calcium in bones.
• Parathyroid gland: Located in the neck, controls calcium levels in the body and normalizes bone growth.
• The thymus gland is in front of the heart and it enables the body to produce certain antibodies.
• The adrenal gland is on top of the kidneys to prepares the body for action and controlls heart rate.
• The pancreas gland is between the kidneys regulating blood sugar levels.
• The testes are located in the lower abdomen controlling maturation and male characteristics.
• The ovaries are in the lower abdomen influencing female traits, and support reporductive function.

Male Reproductive System

• The male reproductive system is made up of accessory glands, a network of ducts, and the testes where sperm are created.
• Sperm is carried by the urethra, ejaculatory duct, deferent duct, and epididymis.
• Semen is composed of secretions produced by the prostate gland, bulbourethral glands, and seminal vesicles.
• The scrotum is the loose pouch-like sac of skin that covers the testes and controls temperature, maintaining it at about 96°F.
• The penis delivers sperms into the vagina of the female reproductive tract and it is covered with the prepuce (or foreskin).
• The testis or testicle is the male reproductive gland that produces sperm and androgens.
• The epididymis is the coiled tube in the male reproductive system where sperm matures, is stored, and transported.
• The urethra is the tube that carries urine from the bladder to outside of the body.
• The seminal vesicles are sac-like pouches that produce a fructose-rich fluid, providing energy for sperm motility.
• The prostate gland is located below the urinary bladder and secretes semen to permit sperm motility.
• The rectum is the final segment of the large intestine which stores feces.
• The urinary bladder is a hollow, muscular organ that stores urine before it is expelled from the body.
• The vas deferens is a muscular tube that transports mature sperm from the epididymis to the urethra during ejaculation.
• The pubic bone is known as the pubis, is one of the three main bones that make up the pelvis.
• Testosterone is the main male sex hormone secreted by the testes, responsible for the development of the male reproductive system and the maturation of sperm cells with the help of follicle-stimulating hormone (FSH).
• Testosterone is also responsible for male muscular strength.

Sperm Cells

• Sperm cells are made in the testes.
• The head contains the genetic material located in the nucleus containing 23 chromosomes with acrosome containing enzymes to help penetrate the egg.
• The body contains mitochondria which provide energy.
• The tail allows the sperm to move and propel along to reach the egg.
• This mature egg is swept by the tiny fingerlike projections of the oviducts or fallopian tubes and moves with the help of cilia.
• The uterus is an inverted pear-shaped muscular organ where the embryo may attach to the endometrium.
• The vagina is the muscular canal that leads from external genitalia (vulva) to the cervix.
• The cervix acts as a gateway between the vagina and the uterus and produces cervical mucus, which changes consistency throughout the menstrual cycle to help or hinder sperm.
• The urethra is the opening through which urine exits the body.
• The clitoris is a small, sensitive organ located at the top of the vulva.
• The Mons Pubis is the rounded area of fatty tissue that covers the pubic bone.
• The pubic symphysisis joint that connects the left and right pubic bones
• The ovaries produce eggs (ova) and the hormones estrogen and progesterone
• The oviduct (Fallopian Tube) transports the egg from the ovary to the uterus where Fertilization occurs.
• The uterus provides a nurturing environment for the growing fetus. The Urinary Bladder stores urine.
• The anus is the opening at the end of the digestive tract through which stool exits the body.
• The large bowel absorbs water from stool.
• The tailbone (coccyx) is the small, triangular bone at the bottom of the spine.
• The female sex hormones control the secondary sex characteristics and the ovarian and uterine cycles.
• Females also secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH) as directed by the pituitary gland during puberty.
• A female experiences bodily changes even before the first menstruation (called menarche).
• Menstrual cycle changes typically takes 28 days.
• Menstruation occurs every month
• The pituitary gland releases follicle stimulating hormone (FSH) in response to the ovary on day 14.
• Then the egg moves to the oviduct.
• Menstrual cramps are the result of strong contractions of the uterine wall that occur before and during menstruation.

Ovarian Cycle:

• Ovulation usually occurs on the fourteenth day of the cycle.
• The egg is viable for fertilization within 24 hours from its release.
• Still under the influence of LH, the cells of the ruptured follicle develops into a yellow body
• luteum is a yellow body then produces more estrogen and another female sex hormone, progesterone
• While events take place in the ovary, a series of hormone influenced changes also happens in the uterus. With low levels of
• With low levels of progesterone, the surface of the endometrium or uterine wall begins to disintegrate and the blood vessels rupture.
• Blood and some accompanying endometrial tissues flow out of the vagina in a process called menstruation,

Common STDS

• Gonorrhea: can cause discharge, pain during urination, swollen testicles, anal itching. Discharge, pain during urination, swollen testicles, anal itching.
• Trichomoniasis: causes Discharge, strong odor, vaginal itching, painful urination.
• Chlamydia: causes Discharge, pain during menstruation.
• Genital herpes: causes Small, red bumps, blisters, ulcers, pain, or itching in genital area, buttocks, and thighs.
• HIV/AIDS: causes Fever, headache, sore throat, swollen lymph glands, rash, fatigue, rapid weight loss, cough, shortness of breath, pneumonia, chronic diarrhea, persistent headaches.
• Genital warts: causes Flesh-colored or gray swellings, cauliflower-shaped warts, genital itching or discomfort, bleeding during intercourse.
• Syphilis: causes Painless ulcers, fever, warts in groin, swollen lymph nodes, weight loss.