04 The Body Systems
The seven anatomical systems of the human body are:
- Musculoskeletal System
- Nervous System
- Respiratory System
- Circulatory System
- Digestive System
- Lymphatic System
- The Skin
All body cells need a constant supply of food to provide energy and the building blocks needed to manufacture body substances. Food as we take it in is however, too large to enter the cells. It must first be broken down into particles small enough to pass through the cell membrane. This process is known as digestion. After digestion, food must be carried to the cells in every part of the body by the circulatory system; the transfer of food into the circulation is called absorption. Digestion and absorption are the two chief functions of the digestive system. The main organs of the digestive system are the Mouth, Pharynx, Oesophagus, Stomach, Liver, Small Intestine, Large Intestine, and Rectum.
The Skin protects the body from the environment while the nervous system responds to the signals from all systems to keep the body functioning correctly. If the skin feels cold a message is sent to the brain via the nerves to indicate that it is cold and the nervous system may adjust the blood flow in the circulatory system to adjust the body temperature. If you touch something hot the nervous system responds by causing the muscles to move the hand away quickly.
Musculoskeletal System
The Musculoskeletal System comprises of the Muscles and Skeleton which provide structural support and movement for the body.
There are three types of muscle:
- Skeletal muscle or "voluntary muscle" is anchored by tendons to bone and is used to affect skeletal movement such as locomotion and in maintaining posture. Though this postural control is generally maintained as a subconscious reflex, the muscles responsible react to conscious control like non-postural muscles. An average adult male is made up of 40-50% of skeletal muscle and an average adult female is made up of 30-40%.
- Smooth muscle or "involuntary muscle" is found within the walls of organs and structures such as the esophagus, stomach, intestines, bronchi, uterus, urethra, bladder, and blood vessels, and unlike skeletal muscle, smooth muscle is not under conscious control.
- Cardiac muscle is also an "involuntary muscle" but is a specialized kind of muscle found only within the heart.