NERVOUS SYSTEM

- the nervous system is the body’s fast pacing control system. It consist of the brain, spinal cord, nerves, and sensory receptors, the body must be able to respond to irritants or stimuli coming from the outside of the body (such as light, sound, or changes in temperature) and from inside the body (such as decreases in oxygen or stretching of tissue). The sensory receptors detects changes and send messages (via electrical signal called nerve impulses) to the central nervous system (brain and spinal cord) so that is constantly informed about what is going on. The central nervous system then assesses this information and responds by activating the appropriate body effectors (muscles or glands).

BRAIN- a very clever or intelligent person is often spoken of as a “brainy” individual. This expression suggest that reasoning, remembering, learning and thinking ahead are in some way centered in a person’s brain. This is true. However, the brain is also concerned with activities other than these higher processes. It is involved in some way with everything that happens in or to a person’s body.  Man is able to see, hear, taste, and touch because his brain receives sensory impulses and make him respond to them. The brain coordinates the physical activities involved in talking, walking, running, or lifting. It is also plays a role in vital processes such as respiration, circulation, and digestion.

The brain may be described as the master control mechanism of the body’s vast and complex communication network-the nervous system. To better understand the brain, one should first know something about nerves. These are the structures which carry sensory and motor impulses between the brain and other body parts.

NERVES­- nerves course throughout the body in much the same way that railroad lines cross a country. The brain can be considered as a complicated but orderly switchyard. Some nerves bring impulses to the brain from body parts such as the skin, joints, muscles and sense organs. These are the sensory nerves. Others, the motor nerves, transmit impulses from the brain to the muscles, such motor impulses cause the muscles to contract. Thus all bodily movements are controlled by motor nerve impulses. The organ and system of organ which carry out vital processes such as respiration, circulation, and digestion are regulated by autonomic nerves.

SPINAL CORD- most nerves connect with a cable like structures, the spinal cord. It routes their impulses to or from the brain, it runs through a tunnel of bone, the vertebral column, or backbone, and is thus well protected. The spinal cord is made up of many tightly bound nerves fibers. These fibers extend the length of the cord. Specific groups of them are bundled together to form special pathways. Such as bundles of nerve fibers are called nerve tract

NERVE TRACT IN THE SPINAL CORD- when a sensory nerve enters the spinal cord, it joints its special nerve tract. This tract carries its impulses to the brain. It is called a sensory nerve tract. It is also known as an ascending nerve tract, because it carries impulses “upward” or to the brain. Other nerve tracts carry impulses from the brain. These are the motor nerve tracts. Because they transmit impulses “downward,” or away from the brain, they are also called descending tracts. At a point just above the neck region the spinal cord thickens. This marks the area where the cord merges with the brain. Here fibers from each ascending tract fan out from the cord and end in special collections of cells called sensory nerve centers. The general function of such a center is to receive and redirect the specific sensory impulses. Other nerve centers are the areas of origin, rather than the ends, of certain nerve tract. These are the motor nerve centers. They give rise to the motor nerve tracts. Instead of fanning out, as a sensory fibers do when they leave the cord and enter the brain, the motor nerve tract converge when they reach their point of entry from the brain into spinal cord.

PREPARED BY: JULLENA V. DE LEON

THE URINARY SYSTEM

also known as the renal system, consists of the kidneys, ureters, bladder, and the urethra. Each kidney consists of millions of functional units called nephrons. The purpose of the renal system is to eliminate wastes from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood ph. The kidneys have extensive blood supply via the renal arteries which leave the kidneys via the renal vein. Following filtration of blood and further processing, wastes (in the form of urine) exit the kidney via the ureters, tubes made of smooth muscle fibre’s that propel urine towards the urinary bladder, where it is stored and subsequently expelled from the body by urination (voiding). The female and male urinary systems are very similar, differing only in the length of the urethra. Urine is formed in the kidneys through a filtration of blood. The urine is then passed through the ureters to the bladder, where it is stored. During urination, the urine is passed from the bladder through the urethra to the outside of the body.

800-2000 millilitres (mL) of urine are normally produced every day in a healthy human. This amount varies according to fluid intake and kidney function.

There are several functions of the Urinary System:

·         Removal of waste product from the body (mainly urea and uric acid)

·         Regulation of electrolyte balance (e.g. sodium, potassium and calcium)

·         Regulation of acid-base homeostasis

·         Controlling blood volume and maintaining blood pressure

     KIDNEYS-are bean-shaped organs that serve several essential regulatory roles in vertebrates. They remove excess organic molecules from the blood, and it is by this action that their best-known function is performed: the removal of waste products of metabolism. Kidneys are essential to the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and regulation of blood pressure (via maintaining the salt and water balance). They serve the body as a natural filter of the blood, and remove water-soluble wastes which are diverted to the bladder. In producing urine, the kidneys excrete wastes such as urea and ammonium. They are also responsible for the reabsorption of water, glucose, and amino acids. The kidneys also produce hormones including calcitriol and erythropoietin. An important enzyme renin is also produced in the kidney which acts in negative feedback.

Located at the rear of the abdominal cavity in the retroperitoneal space, the kidneys receive blood from the paired renal arteries, and drain into the paired renal veins. Each kidney excretes urine into a ureter which empties into the bladder.

Renal physiology is the study of kidney function, while nephrology is the medical specialty concerned with kidney diseases. Diseases of the kidney are diverse, but individuals with kidney disease frequently display characteristic clinical features. Common clinical conditions involving the kidney include the nephritic and nephrotic syndromes, renal cysts, acute kidney injury, chronic kidney disease, urinary tract infection, nephrolithiasis, and urinary tract obstruction. Various cancers of the kidney exist. The most common adult renal cancer is renal cell carcinoma. Cancers, cysts, and some other renal conditions can be managed with removal of the kidney. This is known as nephrectomy. When renal function, measured by the glomerular filtration rate, is persistently poor, dialysis and kidney transplantation may be treatment options. Although they are not normally harmful, kidney stones can be extremely painful.

URETERS-In human anatomy, the ureters are tubes made of smooth muscle fibre’s that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually 25–30 cm (10–12 in) long and ~3–4 mm in diameter. Histologically, the ureter contains transitional epithelium and an additional smooth muscle layer in the more distal one-third to assist with peristalsis. The ureters are a component of the urinary system. Urine, produced by the kidneys, travels along the ureters to the bladder.

URINARY BLADDER is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible (or elastic) organ, the bladder sits on the pelvic floor. Urine enters the bladder via the ureters and exits via the urethra. There is no exact measurement for the volume of the human bladder, but different sources mention 500 mL (~17 oz.) to 1000 mL (~34 oz.). Urine, excreted by the kidneys, collects in the bladder before disposal by urination. The urinary bladder usually holds 300-350 ml of urine. As urine accumulates, the rugae flatten and the wall of the bladder thins as it stretches, allowing the bladder to store larger amounts of urine without a significant rise in internal pressure.

URETHRA- In anatomy, the urethra is a tube that connects the urinary bladder to the urinary meatus for the removal of fluids from the body. In male placental mammals, the urethra travels through the penis, and carries semen as well as urine. In female placental mammals, the urethra is shorter and emerges at the female external urethral orifice above the vaginal opening. Female placental mammals use their urethra only for urinating, but male placental mammals use their urethra for both urination and ejaculation. The external urethral sphincter is a striated muscle that allows voluntary control over urination.

NEPHRON- is the basic structural and functional unit of the kidney. Its chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine. A nephron eliminates wastes from the body, regulates blood volume and blood pressure, controls levels of electrolytes and metabolites, and regulates blood ph. Its functions are vital to life and are regulated by the endocrine system by hormones such as antidiuretic hormone, aldosterone, and parathyroid hormone. In humans, a normal kidney contains 800,000 to 1.5 million nephrons.

PREPARED BY: ALLEN DALE Q. VELACRUZ MW 2:30-4:00

RESPIRATORY SYSTEM

           the job of respiratory system is to keep the body constantly supplied with oxygen and to remove carbon dioxide. The respiratory system consists of the nasal passages, pharynx, larynx, trachea, bronchi and lung. Within the lungs are tiny air sacs. It is though the thin walls of these air sacs that gas exchanges are made to and from the blood.

The Nasal Cavities- Air makes its initial entrance into the body through the openings in the nose called the nostrils. Immediately inside the nostrils, located between the roof of the mouth and the cranium, are the two spaces known as the nasal cavities. These two spaces are separated from each other by a

Partition, the nasal septum. The septum and the walls of the nasal cavities are constructed of bone covered with mucous membrane. From the lateral (side) walls of each nasal cavity are three projections called the conchae. The conchae greatly increase the surface over winch air must travel on its way

Through the nasal cavities.

The Pharynx- The muscular pharynx (throat) carries air into the respiratory tract and foods and liquids into the digestive system. The upper portion located immediately behind the nasal cavity is

Called the nasopharynx, the middle section located behind the mouth is called the oropharynx, and the lowest portion is called the laryngeal pharynx. This last section opens into the larynx toward the front and into the oesophagus toward the back.

The Larynx- The larynx (voice box) is located between the pharynx and the trachea. It has a framework of cartilage that protrudes in the front of the neck and sometimes is referred to as the Adam’s

Apple. The larynx is considerably larger in the male than in the female; hence, the Adam’s apple is much more prominent in the male. At the upper end of the larynx are the vocal cords, which serve in the production of speech. They are set into vibration by the flow of air from the lungs. A difference in the

Size of the larynx is what accounts for the difference between the male and female voices; because a man’s larynx is larger than a woman’s, his voice is lower in pitch. The nasal cavities,

The sinuses and the pharynx all serve as resonating chambers for speech, just as the cabinet does for a stereo speaker. The space between these two vocal cords is called the glottis,

And the little leaf-shaped cartilage that covers the larynx during swallowing is called the epiglottis. The epiglottis helps keep food out of the remainder of the respiratory tract. As the

Larynx moves upward and forward during swallowing, the epiglottis moves downward, covering the opening into the larynx. You can feel the larynx move upward toward the epiglottis during this process by placing the flat ends of your fingers on your larynx as you swallow. The larynx is lined with ciliated mucous membrane. The cilia trap dust and other particles, moving them upward to the pharynx to be expelled by coughing, sneezing, or blowing the nose.

The Trachea (Windpipe) -The trachea is a tube that extends from the lower edge of the larynx to the upper part of the chest above the heart. It has a framework of cartilages to keep it open. These cartilages, shaped somewhat like a tiny horseshoe or the letter C, are found along the entire length of the trachea. All the open

Sections of these cartilages are at the back so that the esophagus can bulge into this section during swallowing. The purpose of the trachea is to conduct air between the larynx

And the lungs.

The Bronchi and Bronchioles -The trachea divides into two bronchi which enter the lungs. The right bronchus is considerably larger in diameter than the left and extends downward in a more vertical direction. Therefore, if a foreign body is inhaled, it is likely to enter the right lung. Each bronchus enters the lung at a notch or depression called the hilus or hilum. The blood vessels and nerves also connect with the lung in this region

The Lungs -The lungs are the organs in which external respiration takes place through the extremely thin and delicate lung tissues. The two lungs, set side by side in the thoracic cavity, are constructed in the following manner:

Each bronchus enters the lung at the hilus and immediately subdivides. Because the subdivision of the bronchi resembles the branches of a tree, they have been given the common name bronchial tree. The bronchi subdivide again and again, forming progressively smaller divisions, the smallest of which

Are called bronchioles. The bronchi contain small bits of cartilage, which give firmness to the walls and serve to hold the passageways open so that air can pass in and out easily. However, as the bronchi become smaller, the cartilage decreases in amount. In the bronchioles there is no cartilage at all; what remains is mostly smoothly muscle, which is under the control of the autonomic nervous system. At the end of each of the smallest subdivisions of the bronchial tree, called terminal bronchioles, is a cluster of air sacs, resembling a bunch of grapes. These sacs are known as alveoli. Each alveolus is a single-cell layer of squamous (flat) epithelium. This very thin wall provides easy passage for the gases entering and leaving the blood as it circulates through millions of tiny capillaries of the alveoli. Certain cells

In the alveolar wall produce surfactant, a substance that prevents the alveoli from collapsing by reducing the surface tension (“pull”) of the fluids that line them. There are millions of alveoli in the human lung. Because of the many air spaces, the lung is light in weight; normally a piece of lung tissue

Dropped into a glass of water will float.

PREPARED BY: HAZEL MAE VILLEJO MW 2:30-4:00

ENDOCRINE SYSTEM

                     like the nervous system, the endocrine system controls body activities, but it acts much more slowly. The endocrine glands produce chemical molecules called hormones and release them into the blood to travel to relatively distant target organs.The endocrine glands include the pituitary, thyroid, parathyroid, adrenals, thymus, pancreas, pineal, ovaries (female), and testes (male). The endocrine glands are not connected anatomically in the same way that parts of the other organ system are. What they have in common is that they all secrete hormones, which regulate other structures. The body functions controlled by hormones are many and varied, involving every cell in the body. Growth, reproduction, and food use by cells are all controlled (at least in part) by hormones.

PITUITARY GLAND- the pituitary gland is approximately the size of the grape. It hangs by a stalk from the inferior surface of the hypothalamus of the brain, where it is snugly surrounded by the “Turk’s saddle” of the sphenoid bone. It has two functional lobes- the anterior pituitary (glandular tissue) and the posterior pituitary (nervous tissue).

GROWTH HORMONE (GH)- is a general metabolic hormone. However, its major effects are directed to the growth of skeletal muscles and long bones of the body, and thus it plays an important role in determining final body size. GH is a protein sparing and anabolic hormone that causes amino acids to be built into proteins and stimulates most target cells to growth in size and divide. At the same time, it causes fats to be broken down and used for energy while it spares glucose, helping to maintain blood sugar homeostasis.

THYROID GLAND- the thyroid gland is a hormone producing gland that Is familiar to most people primarily because many obese individuals blame their overweight condition on their “glands” (meaning the thyroid) actually, the effect of thyroid hormones on the body weight is not as great as many believe to it to be. The thyroid gland is located at the base of the throat, just inferior to the Adam’s apple, where it is easily palpated during physical examination. It is a fairly large gland consisting of two lobes joined by a central mass, or isthmus. The thyroid gland produces two hormones, one called thyroid hormone, and the other called calcitonin. Internally, the thyroid gland is composed of hollow structures called follicles, which store a sticky colloidal material. Thyroid hormone is derived from this colloid.

PARATHYROID GLANDS- the parathyroid glands are tiny masses of glandular tissue most often found on the posterior surface of the thyroid gland. Typically there are two glands on each thyroid lobe; that is, a total of four, but as many as eight have been reported, and some may be in other regions of the neck. The parathyroid secretes parathyroid hormone (PTH), or parathormone, which is the most important regulator of calcium ion homeostasis of the blood. When blood calcium blood levels drop below a certain level, the parathyroid release PTH, which stimulate bone destruction cells (osteoclasts) to break down bone matrix and release calcium into the blood. Thus, PTH is a hypercalcemic hormone (that is, it acts to increase blood levels of calcium), whereas calcitonin is a hypercalcemic hormone as they control blood calcium level. Although the skeleton is the major PTH target, PTH also stimulates the kidneys and intestine to absorb more calcium (from urinary filtrate and foodstuffs, respectively).

ADRENAL GLANDS- the two bean-shaped adrenal glands curve over the top of the kidneys. Although the adrenal glands looks like a single organ, it is structurally and functionally two endocrine organ in one. Much like the pituitary gland, it has glandular (cortex) and neural tissue (medulla) parts. The central medulla region is enclosed by the adrenal cortex, which contains three separate layers of cells.

·         ADRENAL MEDULA- it produces hormone called epinephrine and norepinephrine which raise blood glucose level; increase rate of metabolism; constrict certain blood vessels.

·         ADRENAL CORTEX- it produces glucocortoids which increase blood glucose and mineralocorticoids which promote reabsorption of sodium and excretion of potassium in kidneys.

PANCREATIC ISLETS- the pancreas, located closed to the stomach in the abdominal cavity, is a mixed gland. Probably the best-hidden endocrine glands in the body are the pancreatic islets, formerly called the islets of Langerhans. These little masses of hormone-producing tissue are scattered among the enzyme-producing acinar tissue of the pancreas. The exocrine (enzyme producing) part of the pancreas, which acts as part of the digestive system. It produces insulin which reduces blood glucose and glucagon which raises blood glucose.

PINEAL GLAND- the pineal body also called the pineal gland, is a small, cone-shaped gland found in the roof of the third ventricle of the brain. The endocrine function of this tiny gland is still somewhat of a mystery. Although many chemical substances have been identified in pineal gland, only the hormone melatonin appears to be secreted in substantial amounts. The levels of melatonin rise and fall during the course of the day and night. Peak levels occur at night and make us drowsy; the lowest level occurs during daylight around noon. Melatonin is believed to be a “sleep trigger” that plays an important role in establishing the body’s day and night cycle. In some animals, melatonin also helps regulate mating behaviour and rhythms. In some humans, it is believed to coordinate the hormones of fertility and to inhibit the reproduction system (specially the ovaries of females) so that sexual maturation is prevented from occurring before adult body size has been reached.

THYMUS GLAND- the thymus gland is located in the upper thorax, posterior to the sternum. Large in infants and children, it decreases in size throughout adulthood. By old age, it is composed mostly of fibrous connective tissue and fat. The thymus produces hormone called thymosin, and during childhood the thymus acts as an incubator for the maturation of a special group of white blood cells that are important in the immune response. 

 GONADS- the female and male gonads produce sex hormone that are identical to those produced by adrenal cortex cells, the major differences are the source and relative amounts produced.

·         TESTIS (male)- it produce hormone called androgen's which support sperm formation; development and maintenance of male secondary sex characteristics.

·         ESTROGENS (female)-  it produce hormone called estrogens which stimulate uterine lining growth; development and maintenance of female secondary characteristics, and progesterone which promote growth of uterine lining. 

PREPARED BY: LEOMIDEE BUENDIA MW 2:30-4:00

THE DIGESTIVE SYSTEM

Your digestive system is uniquely designed to turn the food you eat into nutrients, which the body uses for energy, growth and cell repair. here's how it works.

MOUTH- food enters the digestive tract

 through the mouth or oral cavity.

PHARYNX- from the mouth, food passes posteriorly into the oropharynx and laryngopharynx, both of which are common passageways for food, fluids and air. The pharynx is subdivided into the nasopharynx, part of the respiratory passageway; the oropharynx, posterior to the oral cavity; and the laryngopharynx, which is continuous with the esophagus below.

ESOPHAGUS- the esophagus or gullet runs from the pharynx through the diaphragm to the stomach. About 25cm (10 inches) long, it is essentially a passageway that conducts food to the stomach.

STOMACH-The stomach is a muscular organ located on the left side of the upper abdomen. The stomach receives food from the esophagus. As food reaches the end of the esophagus, it enters the stomach through a muscular valve called the lower esophageal sphincter. The stomach secretes acid and enzymes that digest food. Ridges of muscle tissue called rugae line the stomach. The stomach muscles contract periodically, churning food to enhance digestion. The pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.

SMALL INTESTINE- the small intestine is the body’s major digestive organ. Within its twisted passageways, usable food is finally prepared for its journey into the cells of the body. The small intestine is a muscular tube extending from the pyloric sphincter to the ileocecal valve. It is the longest section of the alimentary tube, with an average length of 2.5 to 7 meters (8-18 feet) in a living person. Except for the initial part of the small intestine (the duodenum), which mostly lies in a retroperitoneal position, the small intestine hangs in sausage like coils in the abdominal cavity, suspended from the posterior abdominal wall by the fan-shaped mesentery. The large intestine encircles and frames it in the abdominal cavity.

LARGE INTESTINE- the large intestine is much larger in diameter than the small intestine (thus its name, the large intestine) but shorter in length. About 1.5 meters (5 feet) long, it extends from the ileocecal valve to the anus. Its major function is to dry out the indigestible food residue by absorbing water and to eliminate these residues from the body as feces. 

RECTUM- The rectum (Latin for "straight") is an 8-inch chamber that connects the colon to the anus. It is the rectum's job to receive stool from the colon, to let you know there is stool to be evacuated, and to hold the stool until evacuation happens. When anything (gas or stool) comes into the rectum, sensors send a message to the brain. The brainthen decides if the rectal contents can be released or not. If they can, the sphincters (muscles) relax and the rectum contracts, expelling its contents. If the contents cannot be expelled, the sphincters contract and the rectum accommodates, so that the sensation temporarily goes away.

ANUS-The anus is the last part of the digestive tract. It consists of the pelvic floor muscles and the two anal sphincters (internal and external muscles). The lining of the upper anus is specialized to detect rectal contents. It lets us know whether the contents are liquid, gas, or solid. The pelvic floor muscle creates an angle between the rectum and the anus that stops stool from coming out when it is not supposed to. The anal sphincters provide fine control of stool. The internal sphincter keeps us from going to the bathroom when we are asleep, or otherwise unaware of the presence of stool. When we get an urge to go to the bathroom, we rely on our external sphincter to keep the stool in until we can get to the toilet.

PREPARED BY: JOSE CARLO D. RAMORES MW 2:30-4:00