The trachea is a tube which runs from the throat down into the chest cavity; within the chest, the trachea divides into two smaller tubes. These are the bronchi; these divide again, into the bronchial tubes. The bronchial tubes lead down into the lungs, where they split into many very small tubes which connect to tiny, air-filled sacs of spongy tissue (the alveoli). Most adults have around 600 million alveoli, which are surrounded by capillaries. Inhaled oxygen moves into the alveoli and diffuses into arterial blood through the capillaries; at the same time, the veins release carbon dioxide directly into the alveoli, and the carbon dioxide is removed from the lungs upon exhaling. The diaphragm is the muscle which inflates and deflates the lungs, moving air into and out of them.
Digestive system
The digestive system is responsible for taking whole foods and turning them into energy and nutrients to allow the body to function, grow, and repair itself. The six primary processes of the digestive system include: 1) Ingestion of food; 2) Secretion of fluids and digestive enzymes; 3) Mixing and movement of food and wastes through the body; 4) Digestion of food into smaller pieces; 5) Absorption of nutrients; and 6) Excretion of wastes.
Ingestion
The first function of the digestive system is ingestion, or the intake of food. The mouth is responsible for this function, as it is the orifice through which all food enters the body. The mouth and stomach are also responsible for the storage of food as it is waiting to be digested. This storage capacity allows the body to eat only a few times each day and to ingest more food than it can process at one time.
Secretion
In the course of a day, the digestive system secretes around 7 litres of fluids. These fluids include saliva, mucus, hydrochloric acid, enzymes, and bile. Saliva moistens dry food and contains salivary amylase, a digestive enzyme that begins the digestion of carbohydrates. Mucus serves as a protective barrier and lubricant inside of the GI tract. Hydrochloric acid helps to digest food chemically and protects the body by killing bacteria present in our food. Enzymes are like tiny biochemical machines that disassemble large macromolecules like proteins, carbohydrates, and lipids into their smaller components. Finally, bile is used to emulsify large masses of lipids into tiny globules for easy digestion.
Mixing and Movement
The digestive system uses 3 main processes to move and mix food: swallowing, peristalsis, and segmentation.
Swallowing is the process of using smooth and skeletal muscles in the mouth, tongue, and pharynx to push food out of the mouth, through the pharynx, and into the oesophagus.
Peristalsis is a muscular wave that travels the length of the GI tract, moving partially digested food a short distance down the tract. It takes many waves of peristalsis for food to travel from the oesophagus, through the stomach and intestines, and reach the end of the GI tract.
Finally, segmentation occurs only in the small intestine as short segments of intestine contract like hands squeezing a toothpaste tube. Segmentation helps to increase the absorption of nutrients by mixing food and increasing its contact with the walls of the intestine.
Digestion
Digestion is the process of turning large pieces of food into its component chemicals.
Mechanical digestion is the physical breakdown of large pieces of food into smaller pieces. This mode of digestion begins with the chewing of food by the teeth and is continued through the muscular mixing of food by the stomach and intestines. Bile produced by the liver is also used to mechanically break fats into smaller globules. While food is being mechanically digested it is also being chemically digested as larger and more complex molecules are being broken down into smaller molecules that are easier to absorb.
Chemical digestion begins in the mouth with salivary amylase in saliva splitting complex carbohydrates into simple carbohydrates. The enzymes and acid in the stomach continue chemical digestion, but the bulk of chemical digestion takes place in the small intestine thanks to the action of the pancreas. The pancreas secretes an incredibly strong digestive cocktail known as pancreatic juice, which is capable of digesting lipids, carbohydrates, proteins and nucleic acids. By the time food has left the duodenum, it has been reduced to its chemical building blocks – fatty acids, amino acids, monosaccharides, and nucleotides.
Absorption
once food has been reduced to its building blocks, it is ready for the body to absorb. Absorption begins in the stomach with simple molecules like water and alcohol being absorbed directly into the bloodstream. Most absorption takes place in the walls of the small intestine, which are densely folded to maximize the surface area in contact with digested food. Small blood and lymphatic vessels in the intestinal wall pick up the molecules and carry them to the rest of the body. The large intestine is also involved in the absorption of water and vitamins B and K before faeces leave the body.
Excretion
The final function of the digestive system is the excretion of waste in a process known as defecation. Defecation removes indigestible substances from the body so that they do not accumulate inside the gut. The timing of defecation is controlled voluntarily by the conscious part of the brain, but must be accomplished on a regular basis to prevent a backup of indigestible materials.
Urinary system
One of the major functions of the Urinary system is the process of excretion. Excretion is the process of eliminating, from an organism, waste products of metabolism and other materials that are of no use. The urinary system maintains an appropriate fluid volume by regulating the amount of water that is excreted in the urine. Other aspects of its function include regulating the concentrations of various electrolytes in the body fluids and maintaining normal pH of the blood. Several body organs carry out excretion, but the kidneys are the most important excretory organ. The primary functions of the kidneys are to maintain a stable internal environment (homeostasis) for optimal cell and tissue metabolism. They do this by separating urea, mineral salts, toxins, and other waste products from the blood. They also do the job of conserving water, salts, and electrolytes. At least one kidney must function properly for life to be maintained.
Nervous system
Functions of the Nervous System
The nervous system has 3 main functions: sensory, integration, and motor.
Sensory: The sensory function of the nervous system involves collecting information from sensory receptors that monitor the body’s internal and external conditions. These signals are then passed on to the central nervous system (CNS) for further processing by afferent neurons (and nerves).
Integration: The process of integration is the processing of the many sensory signals that are passed into the CNS at any given time. These signals are evaluated, compared, used for decision making, discarded or committed to memory as deemed appropriate. Integration takes place in the grey matter of the brain and spinal cord and is performed by interneurons. Many interneurons work together to form complex networks that provide this processing power.
Motor: Once the networks of interneurons in the CNS evaluate sensory information and decide on an action, they stimulate efferent neurons. Efferent neurons (also called motor neurons) carry signals from the grey matter of the CNS through the nerves of the peripheral nervous system to effector cells. The effector may be smooth, cardiac, or skeletal muscle tissue or glandular tissue. The effector then releases a hormone or moves a part of the body to respond to the stimulus.
Endocrine system
The endocrine system works alongside of the nervous system to form the control systems of the body. The nervous system provides a very fast and narrowly targeted system to turn on specific glands and muscles throughout the body. The endocrine system, on the other hand, is much slower acting, but has very widespread, long lasting, and powerful effects. Hormones are distributed by glands through the bloodstream to the entire body, affecting any cell with a receptor for a particular hormone. Most hormones affect cells in several organs or throughout the entire body, leading to many diverse and powerful responses.
Reproductive system
The male reproductive system enables a man to have sexual intercourse and to fertilize ova (eggs) with sperm (male sex cells). Sperm and the male sex hormones are produced in the testes. This is a pair of oval-shaped glands which are suspended in a pouch of skin; this pouch is called the scrotum. The sexual organs of the male are only partly visible; the other organs are hidden within the body. The visible parts are the penis and the scrotum. Inside the body are the prostate gland and seminal vesicles
The female reproductive system includes the ovaries, fallopian tubes, uterus, vagina, vulva, mammary glands and breasts. These organs are involved in the production and transportation of gametes and the production of sex hormones. The female reproductive system also facilitates the fertilization of ova by sperm and supports the development of offspring during pregnancy and infancy
Lymphatic system
The lymphatic system is important to the body's defence mechanisms. It filters out organisms that cause disease, produces certain white blood cells and generates antibodies. It is also important for the distribution of fluids and nutrients in the body, because it drains excess fluids and protein so that tissues do not swell up. Lymph is a milky body fluid that contains a type of white blood cells, called lymphocytes, along with proteins and fats. Lymph seeps outside the blood vessels into the spaces of body tissues and is then stored in the lymphatic system to flow back into the bloodstream. Through the flow of blood in and out of arteries, and into the veins, and through the lymph nodes and into the lymph, the body is able to eliminate the products of cellular breakdown and bacterial invasion. It is through the actions of this system - which includes the spleen, the thymus, lymph nodes and lymph ducts - that our body is able to fight infection. Lymph plays an important role in the immune system and in absorbing fats from the intestines.
The lymphatic vessels are present wherever there are blood vessels; they transport excess fluid to the end vessels without the assistance of any pumping action, such as is found in the cardiovascular system. There are more than 100 lymph nodes in the human body; these tiny, oval structures are mainly in the neck, groin and armpits, but there are several scattered all along the lymph vessels. They act as barriers to infection by filtering out and destroying toxins and germs. The largest body of lymphoid tissue in the human body is the spleen.
Skeletal system
Support and Protection
The skeletal system’s primary function is to form a solid framework that supports and protects the body's organs and anchors the skeletal muscles. The bones of the axial skeleton act as a hard shell to protect the internal organs—such as the brain and the heart from damage caused by external forces. The bones of the appendicular skeleton provide support and flexibility at the joints and anchor the muscles that move the limbs.
Movement
The bones of the skeletal system act as attachment points for the skeletal muscles of the body. Almost every skeletal muscle works by pulling two or more bones either closer together or further apart. Joints act as pivot points for the movement of the bones. The regions of each bone where muscles attach to the bone grow larger and stronger to support the additional force of the muscle. In addition, the overall mass and thickness of a bone increase when it is under a lot of stress from lifting weights or supporting body weight.
Immune system
The immune system is a complex system of biological structures and processes within the human body which protects a person from disease by locating, identifying and destroying infectious agents (called pathogens) and tumour cells. The immune system can identify a number of different disease agents: everything from viruses and bacteria to parasitic worms. It efficiently differentiates between these invaders and the body’s own healthy tissues and cells. This process of detection is quite complicated due to the rapid evolution of most pathogens; they quickly adapt so they can avoid the body's immune system and continue to infect their hosts.
The immune system includes the body's white blood cells, antibodies, T cells and other cells which identify and attack pathogens and tumour cells.
Health and Social Care level 3
Unit 5 P3