Human Physiology Study Guide for McGraw-Hill's ASVAB
Physiology is the branch of biology that deals with the parts of the body, their functions, and the various bodily processes. Human physiology deals with the human body.
Cells, Tissues, Organs, and Organ Systems
In the human body, there are many different kinds of cells. Each kind is specialized for the primary function it performs. Examples are fat cells, skin cells, muscle cells, bone cells, and nerve cells. Groups of cells arrange themselves into tissues, and various tissues work together to form organs, such as the skin, liver, heart, gallbladder, and intestines. Organs work together to form organ systems. Organ systems include the muscular system, skeletal system, skin or integumentary system, respiratory system, digestive system, circulatory system, lymphatic system, immune system, excretory system, nervous system, endocrine system, and reproductive system.
The muscular system allows movement and locomotion. The muscular system helps you make body movements and supports the body in its activities. Muscles are involved in breathing, your heart beating, and the working of your digestive system.
Some actions are controlled by voluntary muscles, such as making a face, showing your biceps, or walking. Other muscle systems are involuntary, such as those that control breathing, your heart beating, and your digestive process.
Skeletal muscles help move the bones. They are attached to the bone by bands of tissue called tendons. Skeletal muscles work in pairs; when one muscle of the pair contracts, the other muscle relaxes. Cardiac muscle is found in the heart. Smooth muscles are found in some of your internal organs, such as your intestines and bladder.
The skeletal system is a living system that provides shape and support to your body. It is built to protect your inner organs and to provide attachment points for muscles. The skeletal system provides a rigid framework for movement. It supports and protects the body and body parts, produces blood cells, and stores minerals. In lower animals, such as a grasshopper, the skeleton might be on the outside. This is called an exoskeleton.
Vertebrates have developed an internal mineralized endoskeleton. The endoskeleton is made up of bone and cartilage. Muscles are on the outside of the endoskeleton. Although our endoskeleton is mostly bone, some parts of our body are made of cartilage, such as the trachea, nose, and ears. The skeleton and muscles function together as the musculoskeletal system. Calcium and phosphorus are important components of bone; these elements make bone hard. Osteoblasts are bone-forming cells.
Places where your bones come together are called joints. Joints are held together by bands of tissue called ligaments. Bones move at the joints. There are three major types of joints: ball and socket joints, like the shoulder and hip; pivot joints, like the elbow; and hinge joints, like the knee. These joints, working with the muscles and tendons, allow the body to move in certain ways.