Essential Life Functions: An Overview of Respiration and Excretion

One life function is respiration, in which we convert chemical energy stored in foods to a form that the cells can use more easily. The organs and tissues have adapted to absorb oxygen. The nasal cavity is composed of a series of channels where outside air is admitted to the body's inside. It is lined with mucus and hair to filter, warm, and moisten the air for the lungs. Next, the pharynx is the area in the back of the oral cavity where it joins the nasal cavity. Here, the epiglottis opens and closes to stop food from "going down the wrong tube." The trachea, or windpipe, is a cartilage-ringed tube used to get air from the pharynx deeper. These rings make the open condition of the trachea. Also, like the nose, the trachea is lined with ciliated tissues to stop dust particles. After this, two bronchi come from the end and lead to the lungs. They are ringed with cartilage and are lined with ciliated mucous membrane also.

Bronchioles are small tubes that come from the ends of the bronchi, gradually decreasing in size as it goes farther away from the bronchi, though they lack cartilage rings. On these, alveoli, tiny air sacs, are found. They are lined with cells that make up the actual respiratory surface of the lung. Capillaries surround the alveoli, carrying away oxygen to be transported. The lungs are composed of all the bronchi, bronchioles, alveoli, and their supporting tissues. Their functional unit is the alveoli. To move air efficiently, there is the mechanical process of breathing. The diaphragm and rib cage help this by raising and decreasing pressure. As it decreases, air is forced into the lungs, and as it increases, gases are expelled. In the alveoli, gas exchange is done by diffusion. Oxygen in the bloodstream combines with hemoglobin to form oxyhemoglobin. When this process is reversed, oxygen is released, which is called aerobic respiration. Carbon dioxide is formed as an end product of this, which diffuses into the blood and is carried in plasma as bicarbonate iron. It then goes back to the alveoli for removal. When this process occurs without molecular oxygen, its called anaerobic respiration.

The next life function is excretion, how we remove metabolic wastes from their cells and release them into the environment. If not removed, they can be harmful to the part where they were produced. The lungs emit carbon dioxide and water vapor, byproducts of respiration, through breathing. The liver recycles worn-out red blood cells and produces urea, which results through deamination. Sweat glands of the skin excrete water, salts, and urea from the bloods as perspiration. Heat is also removed, and as the water evaporates, it carries the heat with it, cooling your system down. Kidneys are in the urinary system, and they regulate chemical composition of the blood and the chemical composition of the body's tissues.

Two arteries branch off the aorta to carry blood that needs to be filtered to the kidney, then branching into many capillary networks known as a glomerulus. It is a cup-shaped structure found inside Bowman's capsule, where soluble blood components are absorbed from diffusion. It is part of the nephron, the functional unit of the kidney. Here, active transport is used to reabsorb most of the soluble nutrients, mineral ions, and some water. They are then returned to the blood by veins to the vena cava. This concentrated mixture of waste materials in the nephron is known as urine. The two ureters, small tubes, conduct urine to the urinary bladder, which collects urine and stores it for excretion. The urethra is a small tube that leads from the urinary bladder to the outside of the body.

In conclusion, although it is not necessary for the individual cell living deep inside the body, the body has other organ systems that aid it in functioning properly. Since they are not perfectly apt to the question, I will go over them briefly. Regulation is the function in which human beings control and coordinate other life functions to maintain existence. It is comprised of both nervous system regulation and endocrine system regulation. They both use chemical messengers to affect other living tissues. In the nervous system, neurons transmit nerve impulses. There are three structurally and functionally different neurons: sensory neurons, interneurons, and motor neurons. Sensory neurons receive stimuli and transmit this to the central nervous system for interpretation. Interneurons interpret these stimuli. Motor neurons carry impulses to the organs where a response is initiated. Nerves are bundles of neurons and conduct the impulses.

The brain is composed of interneurons that regulates just about everything. The spinal cord is attached to the brain and extends down and coordinates reflexes. There are two types of peripheral nervous systems, somatic and autonomic. The endocrine regulation delivers hormones, and contains the hypothalamus, pituitary gland, thyroid gland, parathyroid gland, adrenal gland, Islet of Langerhans, and gonads. These all produce hormones for various reasons. Locomotion is how human beings move from place to place. The skeletal system and the muscular system make this happen. The skeletal system is comprised of bones, joints, and cartilage, while the muscular system is flexors and extensors, ligaments, and tendons that work to allow you to move. Although these systems are necessary to the cell, they are necessary to the human being. Cells are also necessary to the human being, so their needs must be met, as they are small structural and functional units that make us up.

Sources: Glencoe Science Biology