The Respiratory System

The function of the respiratory system is to move air in and out of the lungs in a process known as ventilation, respiration, or breathing. The exchange of oxygen and carbon dioxide in the lungs is called external respiration. The same exchange within the hemoglobin of red blood cells is internal respiration. The larynx contains the vocal cords, which stretch between the thyroid and cricoids cartilages. The muscles of the lower vocal cords stretch and relax to produce different sounds which allow you to sing. The lungs contain connective tissue, the bronchial tree, nerves, lymphatic vessels and blood vessels. The left lung consist of two lobes, upper and lower and the right lung consist of three lobes, upper, middle, and lower. Within each lung are the primary, secondary, and tertiary branches of the bronchi, the bronchioles, and the alveoli.  The lungs are covered by, and the chest cavity is line with the pleura. The outer membrane is the parietal pleura and the inner membrane is the visceral pleura.

During inspiration, the diaphragm contracts and the intercostals muscles raise the ribs, increasing the space in the thoracic cavity. This decreases the pressure within the cavity so that the air outside the body passively flows into the thoracic cavity. During expiration, the diaphragm relaxes, pushing up into the thoracic cavity, and the intercostals muscles lower the rib, forcing the air flow out of the body.  Breathing is controlled by the respiratory center of the brain, located in the pons and medulla oblongate. 

Thoracic- chest cavity 

The Ear

Everyone knows the function of ears are, and that's to hear, but do you know what parts make up the ear?

There are three parts to the ear. The external ear includes the auricle or pinna and the external auditory canal to the tympanic membrance. The middle ear begins at the typanic membrance and ends at the oval window and includes the ear ossicles. The inner ear is composed of the labyrinth and contains the organ of Corti as well as perilymph and edolymph, the fluids of hearing. The semicircular canals are vestibule in the inner ear function in the equilibrium and balance of the body, sending impulses to the vestibular nerves, which brings information to the cerebrum (to your brain)  for interpretation. The outer ear collects sounds waves and channels then to the tympanic membrance, which then vibrates. The vibrations are amplified by the ear ossicles and enter the inner ear and cochlea. The movements of the hairs in the cochlea trigger nerve impulses that are transmitted by the auditory never to the brain. 

Aging causes the eardrum to shrink. The joints between the ossicles degenerate so there is less freedom of movement, which decrease in hearing acuity.

The types of hearing loss are conductive hearing lost which is the result of sound wave transmission interruption as with cerumen impaction and tumors or infections.

Another type is sensorineural hearing loss which is the result of nerve damage so that the brain cannot perceive sound waves as sounds. Also there is tinnitus, which is an abnormal constant ringing in your ears, suggests damage to the auditory nerve.

Integumentary System

People are often interested in the appearance of their skin but rarely consider its functions. The integumentary system serves many purposes, including these important functions:

·         Protection- as long as the skin is intact and not inflamed; it is our first line of defense against the entry of bacteria and viruses. It also protects underlying structures from ultraviolet radiation and dehydration.

·         Body temperature regulation- skin plays a major role in regulating body temperature. When a person is hot, dermal blood vessels are more dilated so more blood pass through the skin. This is beneficial because blood carries a lot of the heat in the body. When the blood gets close to the skin the skin, the heat can escape. If someone is cold, the dermal blood vessels constrict, preventing the heat in the blood from escaping.

·         Vitamin D production- when exposed to sunlight, the skin produces a molecule that is turn into vitamin D. The body needs vitamin D for calcium absorption.

·         Sensation- the skin is packed with sensory receptors that can detect touch, heat, cold, and pain.

·         Excretion- small amounts of waste products, such as water and salts, are lost through skin when a person perspires. This is why hydration is so important when exercising or during exposure to high temperature, when the amount of perspiration increased and higher amounts of water and salts are lost.

The topmost layer of the skin is the epidermis. The dermis is the complex middle layer. The innermost layer attaching the skin to muscle is subcutaneous layer. The most common cell type in the epidermis is the keratinocyte. Keratin is a durable protein that makes the epidermis waterproof and resistant to bacteria and viruses.  Another cell type is the melanoctye , which makes the pigment of melanin and the amount of melanin you have in your skin makes up your skin color. The dermis contains sudoriferous (sweat) glands, sebaceous (oil) glands, hair follicles, the arrector pili muscles, collagen fibers, elastin fibers, nerve fibers, and many blood vessels. The subcutaneous layer of the skin or hypodermis, is largely made of adipose and loose connective tissue.

Digestive System

The digestive system uses mechanical and chemical mechanisms to break down food into forms that the body's cell can use. The pathway of food through alimentary canal starts with the mouth through the pharynx, esophagus, stomach, small intestine, large intestine, and anal canal. The mouth takes in food and the teeth assist in reducing its size through chewing the tongue mixes food and holds it between the teeth.The salivary glands produce saliva to assist in moistening and breaking down food. The pharynx is a long muscular tube extending form behind the nose to the esophagus  connecting to oral and nasal cavities, it also acts to push food into the esophagus. The soft palate rise, closing the opening between the nasal and oral cavities. The epiglottis covers the laryngeal opening  food is forced into the oropharynx by the tongue and the pharynx contract, pushing food to the esophagus. The esophagus is a muscular tube that pushes food toward the stomach through muscular contractions. At the end of esophagus is the cardiac sphincter, the entrance  to the stomach. The stomach receives foods, mixes it with gastric juices to start protein digestion, and moves food into the small intestine. The stomach has for regions: cardiac region, funds, body, and pylorus. The small intestine carries out most of the nutrient absorption. The sections of the small intestine are in order, duodenum, jujunum, and ileum. They secretes peptiases to digest protein; sucrase, maltase, and lactase to digest sugars; and intestinal lipase to digest fats. The components of the large intestine are the cecum with its vermiform appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anal canal, ending in the anus. The large intestine's primary's job is to get rid of the body's solid waste by defecation. The liver stores vitamins and iron and produces macrophages to flight infections. the gallbladder stores the bile produce by the the liver. The pancreas produces pancreatic juices that assist in carbohydrate, lipid, and protein digestion. Nutrients absorbed by the body include carbohydrates, proteins, lipids, vitamins, minerals, and water. Most of the absorption takes place in the small intestine.

EYES and their functions

 

The eye is a complicated machine in itself with many parts. The eye works by refracting light rays to the retina. The light rays are adjusted through muscles and certain parts to create the right amount of light refracted to the retina. When light arrives at the retina it is converted to both chemical and electrical energy before being sent through optic nerves to the brain. In the retina, millions of rods containing rhodopsin that are responsible for night vision and convert the light into electrical impulses sent to the brain. The retina also contains millions of cones that contain iodopsin that are used for bright light vision, visual perception, and color perception. Light is transformed here also and sent to the brain through optic nerves. The brain translates what it receives through optic nerves so that we understand what we see.

Cornea

The cornea is the dome shape outer covering of the eye. It is like the windows of the car. It allows you to see but around you but protects you as well. The cornea is where most of the focusing of light occurs. It consists of many layers including the epithelium which is the tough outer layer that regenerates fairly quickly. The epithelium is usually removed or cut during many refractive procedures where the cornea is reshaped to focus light better.

Sclera

The Sclera is the outer white part of the eye that you can see. It provides protection and structure for the inner parts of the eye.

Conjunctiva and Lacrimal Glands

The conjunctiva is a mucus layer that keeps the eye moist. Infections to this area are known as the popular “pink eye.” Lacrimal glands are found on the outer part of each eye and are producers of tears.

Vitreous Humor and Aqueous Humor

The Vitreous Humor is gel like substance in the back part of the eyeball which provides the shape of the eyeball. The Aqueous Humor is the watery region in the form of the eye ball. It is separated into two regions, the anterior chamber in front of the iris and the posterior chamber behind it. The canal of Schlemm drains water in this region and is sometimes blocked off leading to the disease known as glaucoma or other complications.

Sclera

The Sclera is the outer white part of the eye that you can see. It provides protection and structure for the inner parts of the eye.

Iris and Pupil

The Pupil is the dark, black circle of the eye. It contracts with brightness and expands during darkness allowing light to better transmit. The iris is the colored part of the eye. This coloring is due to pigment cells in tissue in the iris. The iris contains the sphincter pupillae, a muscle used to narrow the pupil, and the dilator pupillae, a muscle used to widen the pupil.

Lens

The lens is a clear layer behind the pupil that does just what a regular lens does. The lens main purpose is to focus light by changing its shape. The ciliary body are muscles attached to the lens that help the lens change it shape to better focus light to the retina.

Retina

The retina is the inner most layer of sensitive tissue. When light is transmitted here images can clearly be transmitted to the brain. The retina consists of many layers including layers of rods and cones. Many cells in the retina transform light into chemical and electrical energy that is transferred to optic nerves. The back center of the retina contains themacula. The Macula is a highly sensitive part of the retina. It is responsible for our detailed vision. The center of the macula is called thefovea which has a major role in detailed perception. When there is damage to the macula, we are unable to see finer details.

FUN FACTS

• The human eye blinks an average of 4,200,000 times a year.
• It's impossible to sneeze with your eyes open.
• Our eyes are always the same size from birth, but our nose and ears never stop growing.
• Our body has some natural protection for our eyes. Our eyelashes help to keep dirt out of our eyes. Our eyebrows are made to keep sweat from running into our eyes.
• The shark cornea has been used in eye surgery, since its cornea is similar to a human cornea.
• The number one cause of blindness in adults is diabetes.
• The eyeball of a human weighs approximately 28 grams.
• The eye of a human can distinguish 500 shades of the gray.
• The cornea is the only living tissue in the human body that does not contain any blood vessels
• People generally read 25% slower from a computer screen compared to paper.
• Men are able to read fine print better than women can.
• All babies are colour blind when they are born.
• Babies' eyes do not produce tears until the baby is approximately six to eight weeks old.

Muscles

Muscles are one of those things that most of us take completely for granted, but they are incredibly important for two key reasons: Muscles are the “engine” that your body uses to propel itself.  Muscles turn energy into motion just like a car engine or an electric motor would do. It would be impossible for you to do anything without your muscles. Absolutely everything that you conceive with your brain is expressed as muscular motion. The only ways for you to express an idea are with the muscles of your larynx, mouth and tongue to speck words and the muscles of your fingers when taking with your hands or even dancing, or running.

When most people think of “muscle,” they think about the muscles that we can see. For example, most of us know about the biceps muscles, abs muscles. But there are three unique kinds of muscles in the human body, which are skeletal muscles, smooth muscle, and cardiac muscle. Skeletal muscle is the type of muscle that we can see and feel. When a body builder works out to increase muscle mass, skeletal muscle is what is being exercised. They attach to the skeleton and come in pairs, one muscle to move the bone in one direction and another to move it back the other way. These muscles usually contact voluntarily.  Smooth muscle is found in your digestive system, blood vessels, bladder, airways, and in a female, the uterus. Smooth muscle has the ability to stretch and maintain tension for long period of time. Smooth muscles also contracts involuntarily, meaning that you do not have to think about contracting it because your nervous system controls it automatically. Lastly, the cardiac muscle is found only in your heart, and its big features areenduracne and consistency. It can stretch a limited way, like smooth muscle, and contract with the force of a skeletal muscle. It is a twitch muscle and only contracts involuntarily.

Smooth                                                   skeletal                                                  cardiac 

             

The Skeletal System

The skeletal system is made up of bones and teeth. The normal human body has 206 bones which are needed for variety of functions within the body. The role of bones extends beyond the function of giving your body its shape. There are many reasons why bones are important to the body.  One of the most important functions that bones have in our body is providing support and structure. Bones are the hardest and most rigid structures in our body. The skeletal system also plays an important role in the protection of the vital organs throughout the body. The skull and the backbone protect the central nervous system. This protective role is especially important because the central nervous system controls the rest of your body and is very fragile. The ribs also protect the vital organs in the chest, such as the lungs and heart.  The skeletal system is also closely interacts with the muscles system. Bones are necessary because the muscles need something to attach to in order to contract and cause motion. Bones are also important as a center for the production of blood cells.  Lastly, the bones are responsible for the regulation of calcium levels. Calcium levels in the blood have to be kept in a narrow range to make sure the nerves and muscles are about to properly work. Much of the calcium is stored in the bones. When the body needs more calcium, bone tissue can be broken down to increase the blood’s supply and excess calcium can be stored in bone tissue for later.

Some interesting facts about the skeletal systems are:

1. Babies are born with 300 bones.

2. We are about 1 cm taller in the morning than in the evening.

3.The tooth is the only part of the human body that can't repair itself.

4.The feel account for one quarter of all the human body's bones.

5. Some bones are stronger than steel.