Proteins dictate cell function and gene expression, a cell is able to self-regulate by the amount of proteins produced. The body consists of many different types of tissue , defined as cells that act with a specialised function. The body consists of four main types of tissues — lining cells epithelia , connective tissue , nervous tissue and muscle tissue.
Cells that lie on surfaces exposed to the outside world or gastrointestinal tract epithelia or internal cavities endothelium come in numerous shapes and forms — from single layers of flat cells , to cells with small beating hair-like cilia in the lungs, to column-like cells that line the stomach. Endothelial cells are cells that line internal cavities including blood vessels and glands.
More in Sports
Lining cells regulate what can and can't pass through them, protect internal structures, and function as sensory surfaces. Organs , structured collections of cells with a specific function,  sit within the body. Examples include the heart , lungs and liver. Many organs reside within cavities within the body. These cavities include the abdomen which contains the stomach, for example and pleura , which contains the lungs. The circulatory system consists of the heart and blood vessels arteries , veins and capillaries.
The heart propels the circulation of the blood, which serves as a "transportation system" to transfer oxygen , fuel, nutrients, waste products, immune cells and signalling molecules i. Paths of blood circulation within the human body can be divided into two circuits: the pulmonary circuit , which pumps blood to the lungs to receive oxygen and leave carbon dioxide , and the systemic circuit, which carries blood from the heart off to the rest of the body.
The blood consists of fluid that carries cells in the circulation, including some that move from tissue to blood vessels and back, as well as the spleen and bone marrow. The digestive system consists of the mouth including the tongue and teeth , esophagus , stomach , gastrointestinal tract , small and large intestines , and rectum , as well as the liver , pancreas , gallbladder , and salivary glands.
It converts food into small, nutritional, non-toxic molecules for distribution and absorption into the body. These molecules take the form of proteins which are broken down into amino acids , fats , vitamins and minerals the last of which are mainly ionic rather than molecular. After being swallowed , food moves through the gastrointestinal tract by means of peristalsis : the systematic expansion and contraction of muscles to push food from one area to the next.
Digestion begins in the mouth , which chews food into smaller pieces for easier digestion. Then it is swallowed , and moves through the esophagus to the stomach. In the stomach, food is mixed with gastric acids to allow the extraction of nutrients.
What is left is called chyme ; this then moves into the small intestine , which absorbs the nutrients and water from the chyme. What remains passes on to the large intestine , where it is dried to form feces ; these are then stored in the rectum until they are expelled through the anus. The endocrine system consists of the principal endocrine glands : the pituitary , thyroid , adrenals , pancreas , parathyroids , and gonads , but nearly all organs and tissues produce specific endocrine hormones as well. The endocrine hormones serve as signals from one body system to another regarding an enormous array of conditions, and resulting in variety of changes of function.
The immune system consists of the white blood cells , the thymus , lymph nodes and lymph channels, which are also part of the lymphatic system. The immune system provides a mechanism for the body to distinguish its own cells and tissues from outside cells and substances and to neutralize or destroy the latter by using specialized proteins such as antibodies , cytokines , and toll-like receptors , among many others. The integumentary system consists of the covering of the body the skin , including hair and nails as well as other functionally important structures such as the sweat glands and sebaceous glands.
The skin provides containment, structure, and protection for other organs, and serves as a major sensory interface with the outside world.
The lymphatic system extracts, transports and metabolizes lymph, the fluid found in between cells. The lymphatic system is similar to the circulatory system in terms of both its structure and its most basic function, to carry a body fluid. The musculoskeletal system consists of the human skeleton which includes bones , ligaments , tendons , and cartilage and attached muscles.
It gives the body basic structure and the ability for movement. In addition to their structural role, the larger bones in the body contain bone marrow , the site of production of blood cells. Also, all bones are major storage sites for calcium and phosphate. This system can be split up into the muscular system and the skeletal system. The nervous system consists of the body's neurons , which together form the nerves and ganglia which in turn form the brain and related structures.
The brain is the organ of thought , emotion, memory , and sensory processing ; it serves many aspects of communication and controls various systems and functions. The special senses consist of vision , hearing , taste , and smell. The eyes , ears, tongue , and nose gather information about the body's environment. From a structural perspective, the nervous system is typically subdivided into two component parts: the central nervous system CNS , composed of the brain and the spinal cord ; and the peripheral nervous system PNS , composed of the nerves and ganglia outside the brain and spinal cord.
The CNS is mostly responsible for organizing motion , processing sensory information , thought, memory, cognition and other such functions.
From a functional perspective, the nervous system is again typically divided into two component parts: the somatic nervous system SNS and the autonomic nervous system ANS. The SNS is involved in voluntary functions like speaking and sensory processes. The ANS is involved in involuntary processes, such as digestion and regulating blood pressure. The nervous system is subject to many different diseases. In epilepsy , abnormal electrical activity in the brain can cause seizures. In multiple sclerosis , the immune system attacks the nerve linings , damaging the nerves' ability to transmit signals.
Amyotrophic lateral sclerosis ALS , also known as Lou Gehrig 's disease, is a motor neuron disease which gradually reduces movement in patients. There are also many other diseases of the nervous system. The reproductive system consists of the gonads and the internal and external sex organs. The reproductive system produces gametes in each sex, a mechanism for their combination, and in the female a nurturing environment for the first 9 months of development of the infant.
The respiratory system consists of the nose, nasopharynx , trachea , and lungs. It brings oxygen from the air and excretes carbon dioxide and water back into the air.
Introduction: The Human Brain | New Scientist
First, air is pulled through the trachea into the lungs by the diaphragm pushing down, which creates a vacuum. Air is briefly stored inside small sacs known as alveoli sing. Each alveolus]] is surrounded by capillaries carrying deoxygenated blood, which absorbs oxygen out of the air and into the bloodstream. For the respiratory system to function properly, there need to be as few impediments as possible to the movement of air within the lungs. Inflammation of the lungs and excess mucus are common sources of breathing difficulties.
- Flying Lessons: Feathers!
- When Somebody Loves You: Danger and romance abound in this gripping saga.
- The Most Important Body Parts - Thrillist!
Pneumonia occurs through infection of the alveoli, and may be caused by tuberculosis. Emphysema , commonly a result of smoking , is caused by damage to connections between the alveoli. The urinary system consists of the kidneys , ureters , bladder , and urethra. It removes toxic materials from the blood to produce urine, which carries a variety of waste molecules and excess ions and water out of the body. Human anatomy is the study of the shape and form of the human body. The human body has four limbs two arms and two legs , a head and a neck which connect to the torso.
The body's shape is determined by a strong skeleton made of bone and cartilage , surrounded by fat, muscle, connective tissue, organs, and other structures.
The body part that is the one of the most important, but also most ignored, for fitness and health
The spine at the back of the skeleton contains the flexible vertebral column which surrounds the spinal cord , which is a collection of nerve fibres connecting the brain to the rest of the body. Nerves connect the spinal cord and brain to the rest of the body.
All major bones, muscles, and nerves in the body are named, with the exception of anatomical variations such as sesamoid bones and accessory muscles. Blood vessels carry blood throughout the body, which moves because of the beating of the heart. Venules and veins collect blood low in oxygen from tissues throughout the body. These collect in progressively larger veins until they reach the body's two largest veins, the superior and inferior vena cava , which drain blood into the right side of the heart. From here, the blood is pumped into the lungs where it receives oxygen and drains back into the left side of the heart.
From here, it is pumped into the body's largest artery , the aorta , and then progressively smaller arteries and arterioles until it reaches tissue. Here blood passes from small arteries into capillaries , then small veins and the process begins again.
Top 10 Most Important Human Body Organs
Blood carries oxygen , waste products, and hormones from one place in the body to another. Blood is filtered at the kidneys and liver. The body consists of a number of body cavities , separated areas which house different organ systems. The brain and central nervous system reside in an area protected from the rest of the body by the blood brain barrier. The lungs sit in the pleural cavity. The intestines , liver , and spleen sit in the abdominal cavity. Height, weight, shape and other body proportions vary individually and with age and sex.
Body shape is influenced by the distribution of muscle and fat tissue. Human physiology is the study of how the human body functions. This includes the mechanical, physical, bioelectrical , and biochemical functions of humans in good health, from organs to the cells of which they are composed.
- Water Basics Photo Gallery.
- The Human Body: Anatomy, Facts & Functions | Live Science?
- What Is The Most Important Part Of Your Body? | Erin Mills Optimum Health.
- Monthly Magazine gokigen Julliet 2013 (French Edition).
The human body consists of many interacting systems of organs. These interact to maintain homeostasis , keeping the body in a stable state with safe levels of substances such as sugar and oxygen in the blood. Each system contributes to homeostasis, of itself, other systems, and the entire body. Some combined systems are referred to by joint names.