Structure of Living Organisms and Their Function
Introduction Anatomy is the study of the structure of living organisms and physiology is the study of their function. A diver must understand the basics of these to escalate the increased demands that are enforced on the human body by the underwater environment.
Cells and the Internal Environment
- The body is made up of billions of cells that get the energy they require to live by using up food and oxygen. In the progression, they produce carbon dioxide, water, heat, and waste materials. Food and oxygen must be available in acceptable amounts, and the waste products disposed of, for the cells in the body to live.
- To breathe underwater, humans essentially take a supply of oxygen with them. Survival is encouraged by understanding how the body familiarizes with the increased pressure, which is imposed by being underwater.
The Body Systems
The body is composed of several organ systems that work together constantly to maintain, as nearly as possible, a constant internal environment. These systems are summarized 👇
- The Musculoskeletal System. (Muscles and Skeleton) provides the rigid structure of the body and imparts the capability to move.
- The Nervous System. (The brain, spinal cord, and nerves) is made of highly specialized cells, which use electrical signals to control and coordinate the muscles, glands, and blood vessels. The nervous system is also responsible for receiving and processing information from the outside world via the sensory organs.
- The brain and spinal cord make up the Central Nervous System (CNS) and the remainder is known as the Peripheral Nervous System (PNS). The Autonomic Nervous System is a part of the PNS, which unconsciously (automatically) controls internal organs such as the heart, lungs, and bowel.
- The Digestive System. (Mouth, throat, stomach, small and large intestine, salivary glands, pancreas, liver, and gall-bladder) converts swallowed food into a resolvable form which can be immersed into the bloodstream for transport to and used by the cells of the body. Material that is not digested leaves the body as feces.
- The Urinary System. The kidneys receive about a quarter of the blood pumped by the heart. They filter out cellular excess products, which are dissolved in the blood, and convert them into the urine. This is carried by the ureter to the bladder for excretion via the urethra at an appropriate time.
- The Endocrine System. (Pituitary, thyroid, parathyroid, adrenal glands, pancreas, and testes or ovaries) releases chemical messengers, known as hormones, into the bloodstream. These hormones control functions as diverse as sexual development, airway diameter, and blood salt levels.
- The Circulatory System. (Heart, vessels, and blood) carries nutrients, oxygen, and hormones to the cells of the body and removes the carbon dioxide and other excess products which they produce.
- The Respiratory System. (Lungs and air passages) allows the exchange of gases such as oxygen and carbon dioxide between the air and blood.
Conclusion:
The structure and function of living organisms are crucial for divers to understand the demands imposed by the underwater environment. Key topics covered are cells, and internal environment, body systems (musculoskeletal, nervous, digestive, urinary, endocrine, circulatory, and respiratory).
