Anatomy and Physiology / Unit 1: Body Organization and Homeostasis
1.2 Organ Systems and Necessary Life Functions
Notes
Humans have 11 organ systems (integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, reproductive). They carry out the necessary life functions.
- Maintaining boundaries: the skin and cell membranes separate inside from outside.
- Movement: of the body, of substances (blood, food) and of cells.
- Responsiveness (irritability): detecting and reacting to changes.
- Digestion: breaking food into absorbable molecules.
- Metabolism: all chemical reactions in the body, including catabolism (breaking down) and anabolism (building up).
- Excretion: removing wastes. Reproduction: making new cells or new people. Growth: increase in size of cells or the body.
- Survival also needs nutrients, oxygen, water, normal body temperature and appropriate atmospheric pressure.
Practice
Building a large protein from amino acids is an example of:
Anabolism builds larger molecules from smaller ones. Catabolism breaks them down.
A hand jerks away from a hot pan. Which necessary life function is this?
Detecting a change in the environment and reacting to it is responsiveness.
Which organ system is mainly responsible for removing nitrogen-containing wastes from the blood?
The kidneys filter wastes such as urea from the blood, and the urinary system removes them in urine.
Ready for more? Take the Unit 1 test.