- The skin is often known as "the largest organ in the human body". This applies to exterior surface, as it covers the body, appearing to have the largest surface area of all the organs. Moreover, it applies to weight, as it weighs more than any single internal organ, accounting for about 15 percent of body weight. For the average adult human, the skin has a surface area of between 1.5-2.0 square meters, most of it is between 2-3 mm thick. The average square inch of skin holds 650 sweat glands, 20 blood vessels, 60,000 melanocytes, and more than a thousand nerve endings.
Functions:
- Protection: Skin gives an anatomical barrier between the internal and external environment in bodily defense; Langerhans cells in the skin are part of the immune system
- Sensation: Skin contains a variety of nerve endings that react to heat, cold, touch, pressure, vibration, and tissue injury; see somatosensory system and touch.
- Heat regulation: The skin contains a blood supply far greater than its requirements which allows precise control of energy loss by radiation, convection and conduction. Dilated blood vessels increase perfusion and heat loss while constricted vessels greatly reduce cutaneous blood flow and conserve heat. Erector pili muscles are significant in animals.
MUSCULAR SYSTEM
The human body contains more than 650 individual muscles which are attached to the skeleton, which provides the pulling power for us to move around. The main job of the muscular system is to provide movement for the body. The muscular system consist of three different types of muscle tissues : skeletal, cardiac, smooth. Each of these different tissues has the ability to contract, which then allows body movements and functions. There are two types of muscles in the system and they are the involuntary muscles, and the voluntary muscles. The muscle in which we are allow to control by ourselves are called the voluntary muscles and the ones we can't control are the involuntary muscles. The heart, or the cardiac muscle, is an example of involuntary muscle.
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- Another difference between skeletal and smooth muscles is that skeletal muscles are made of tissue fibers that are striated or striped. These alternating bands of light and dark result from the pattern of the filaments within each muscle cell. Smooth muscle fibers are not striated.
- The cardiac or heart muscle (also called myocardium) is a unique type of muscle that does not fit clearly into either of the two classes of muscle. Like skeletal muscles, cardiac muscles are striated. But like smooth muscles, they are involuntary, controlled by the autonomic nervous system. The longest muscle in the human body is the sartorius. It runs from the waist down across the front of thigh to the knee. Its purpose is to flex the hip and knee. The largest muscle in the body is the gluteus maximus. It moves the thighbone away from the body and straightens out the hip joint.
Skeletal Structure
CIRCULATORY SYSYTEM
The circulatory system is made up of the vessels and the muscles that help and control the flow of the blood around the body. This process is called circulation. The main parts of the system are the heart, arteries, capillaries and veins.
- The HeartThe human heart is one of the most fascinating and crucial organs in the human body. The main task that it carries out is the pumping of blood within the body, constantly receiving, purifying, and dishing out blood to various parts of the body.
-The LungsThere are 2 lungs in the human body, and their task is to supply oxygen to the heart. The intake of air while breathing is carried out by the lungs, and this oxygen is then added into the blood and then transported to the heart. Conversely, impure blood is transported to the lungs via the heart, and this blood is then oxygenated and the remaining components are released back into the air.
-Blood and Blood VesselsTechnically speaking these are not organs, but their presence is essential for the respiratory system and the circulatory system of the body. The blood vessels are stretched out to every single part of the body and there are hundreds of thousands of these vessels intertwined in an endless network within the body.
Organs in the Circulatory SystemPrimarily speaking, there are three basic components of the circulatory system. The heart, which serves as a pump; the blood vessels, which carry the blood throughout the body; and lastly, the blood, which is a vital component for the basic functioning of the human body, and which is processed after the intake of oxygen into the human lungs from the atmosphere.
DIGESTIVE SYSTEM
The digestive system breaks down proteins, fats and all carbohydrates (except glucose and fructose which can be absorbed as they are) into smaller molecules which can then be absorbed along with vitamins and minerals.
- MOUTH- The mouth is the beginning of the digestive tract; and, in fact, digestion starts here when taking the first bite of food. Chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form your body can absorb and use.
- ESOPHAGUS-Located in your throat near your trachea (windpipe), the esophagus receives food from your mouth when you swallow.
- STOMACH-The stomach is a hollow organ, or "container," that holds food while it is being mixed with enzymes that continue the process of breaking down food into a usable form.
- SMALL INTESTINE-Made up of three segments — the duodenum, jejunum, and ileum — the small intestine is a 22-foot long muscular tube that breaks down food using enzymes released by the pancreas and bile from the liver.
- PANCREAS-The pancreas secretes digestive enzymes into the duodenum, the first segment of the small intestine. These enzymes break down protein, fats, and carbohydrates. The pancreas also makes insulin, secreting it directly into the bloodstream. Insulin is the chief hormone for metabolizing sugar.
- LIVER-The liver has multiple functions, but its main function within the digestive system is to process the nutrients absorbed from the small intestine. Bile from the liver secreted into the small intestine also plays an important role in digesting fat.
- GALLBLADDER-The gallbladder stores and concentrates bile, and then releases it into the duodenum to help absorb and digest fats.
- LARGE INTESTINE-The colon is a 6-foot long muscular tube that connects the small intestine to the rectum. The large intestine is made up of the cecum, the ascending (right) colon, the transverse (across) colon, the descending (left) colon, and the sigmoid colon, which connects to the rectum.
- 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 the person know that there is stool to be evacuated, and to hold the stool until evacuation happens
- ANUS-The anus is the last part of the digestive tract. It is a 2-inch long canal consisting of the pelvic floor muscles and the two anal sphincters (internal and external).
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body.
Structures of the Nervous System
- Central Nervous System (CNS)
- Brain & Spinal Cord
- See interneurons
- Peripheral Nervous System (PNS)
- Contains all nerves outside of the brain & spinal cord.
- Somatic Nervous System (Voluntary)
- Two types: Sensory (or afferent) and motor (or efferent) nerves
- Autonomic Nervous System (Involuntary)
- Sympathetic
- Activated by stress
- Increase heart rate, breathing rate, pupil size, sweating
- Parasympathetic
- Maintains body functions; in control when relaxed.
- Restores body to pre-stress state
- Sympathetic
ENDOCRINE SYSTEM:
made up of glands that produce and secrete hormones. These hormones regulate the body's growth, metabolism (the physical and chemical processes of the body), and sexual development and function. The hormones are released into the bloodstream and may affect one or several organs throughout the body.
- The hypothalamus is the master organ, synthesizing and releasing hormones which exert control over the rest of the system. The pituitary gland also exerts some control over the endocrine system.
- The actual endocrine organs include the thyroid gland, the adrenal glands (specifically the adrenal cortex), the pancreas, the ovaries (female), and the testes (male).
- These are the traditional organs of the endocrine system. However, there are other organs that exert effects much like those listed above. The kidneys, for instance, produce erythropoietin, which stimulates the bone marrow to produce more red blood cells. They also release renin, which as an end result, causes the renal tubules to absorb sodium and water.
- The stomach and gastrointestinal systems also have endocrine-like functions - that results in enhanced digestion and absorption of nutrients.
The reproductive system or genital system is a system of organs within an organism which work together for the purpose of reproduction.
The major organs of the external genitalia (penis and vulva) as well as a number of internal organs including the gamete producing gonads (testicles and ovaries). Diseases of the human reproductive system are very common and widespread, particularly communicable sexually transmitted diseases.
Male reproductive system
Major secondary sexual characteristics includes: larger, more muscular stature, deepened voice, facial and body hair, broad shoulders, and development of an adam's apple. An important sexual hormone of males is androgen, and particularly testosterone.
Female reproductive system
The human female reproductive system is a series of organs primarily located inside of the body and around the pelvic region of a female that contribute towards the reproductive process. The human female reproductive system contains three main parts: the vagina, which acts as the receptacle for the male's sperm, the uterus, which holds the developing fetus, and the ovaries, which produce the female's ova. The breasts are also a reproductive organ during the parenting stage of reproduction. However, in most classifications breasts are not considered to be part of the female reproductive system.The vagina meets the outside at the vulva, which also includes the labia, clitoris and urethra; during intercourse this area is lubricated by mucus secreted by the Bartholin's glands. The vagina is attached to the uterus through the cervix, while the uterus is attached to the ovaries via the fallopian tubes. At certain intervals, typically approximately every 28 days, the ovaries release an ovum, which passes through the fallopian tube into the uterus. The lining of the uterus, called the endometrium, and unfertilized ova are shed each cycle through a process known as menstruation. when the reproduction takes place,the sperms of man fertilizes the egg and a new embroyo is formed.
The Human Respiratory System
The Pathway
- Air enters the nostrils
- passes through the nasopharynx,
- the oral pharynx
- through the glottis
- into the trachea
- into the right and left bronchi, which branches and rebranches into
- bronchioles, each of which terminates in a cluster of
- alveoli
The purpose of the respiratory system is to bring oxygen into the blood so it can distribute it to the body cells. It also turns oxygen into nutrients and removes carbon dioxide from the body.
1. To supply oxygen to the body.
2. To eliminate carbon dioxide in the body.
3. To regulate the body's pH balance
Excretory system
The excretory system is the system of an organism's body that performs the function of excretion, the bodily process of discharging wastes.
The main purpose of the excretory system is to get rid off the waste materials which can prove harmful to the body if stored.
- The kidneys are the major organs of the excretory system along with the skin and lungs.
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| The urinary system includes the kidneys, bladder and tubes. These organs control the amount of water and salts that are absorbed back into the blood and what is taken out as waste. This system also acts as a filtering mechanism for the blood. |
(1) Remove wastes from the body.
(2) Regulate levels of electrolytes in the body.
(3) Regulate hydration of the body.
(4) Maintain acid-base balance of the body.
(5) Maintain blood pressure.
IMMUNE SYSTEM
The immune system is the body's defense against infectious organisms and other invaders. Through a series of steps called the immune response, the immune system attacks organisms and substances that invade body systems and cause disease.
The immune system is made up of a network of cells, tissues, and organs that work together to protect the body. The cells involved are white blood cells, or leukocytes, which come in two basic types that combine to seek out and destroy disease-causing organisms or substances
The immune system, is made up of special cells, proteins, tissues, and organs, defends people against germs and microorganisms every day. In most cases, the immune system does a great job of keeping people healthy and preventing infections. But sometimes problems with the immune system can lead to illness and infection.
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