Science Lecture for Unit 22: Human Anatomy I
- Topic area: Body System
- Terms and concepts to know: cells, tissues, organs, organ systems, skeletal system, muscle system
- See historical period(s): Leonardo da Vinci
The Study of Anatomy
Human Anatomy: Introduction to Skin, Bones, and Muscles
Anatomy looks at the organs and systems of the body in terms of structure. An anatomist tries to identify the different organs from their appearance and location. The ability to do this more accurately, thanks to the illustrations in texts like those of Leonardo and Vesalius (whom we study in the next unit), made it possible for scientists in different areas to compare and communicate their observations. As their observations became more detailed, they also became more interested in how the different organs and tissues of the body function. This study of function is physiology.
The modern approach to learning about the human body usually starts with cell theory, then goes on to discuss how cells come together to form tissues with specialized functions, which are then combined into organs and organ systems. The function of the systems is the study of physiology; the identification of the systems and their structure, especially in comparison to similar organisms in other animals, is anatomy. Since historically, the progression was from anatomy to physiology, tissue studies, and cell theory, we will be learning the subject "out of order", from the middle up, then top down, rather than the bottom up. Because of this, we need to keep in mind that ultimately, all the organs of the body do rely on the basic structures and functions of cells, but we will cover those details later.
Modern biologists identify four kinds of tissue that make up the organs of the different organ systems.
- Epithelial tissue is tissue that covers surfaces. The lining of the nose and throat, the inside of your lungs, and the outer layer of skin are all epithelial tissue.
- Muscular tissues make up muscles!
- Nervous tissues are used for sensory perception and transmission of information throughout the body.
- Connective tissue, the most common kind of tissue, supplies support, joins parts of the body and different organs together, and distributes nutrients throughout the body. Blood and bone are both connective tissue.
Study J. Kimball's diagram of the different types of Animal Tissue cells.
- How are the shapes of the cells different in different kinds of tissue?
- Notice that the epithelial tissue is only one cell layer deep? Why is this necessary if the epithelial tissue is used in the surface lining of the stomach?
Organs and organ systems
Now we can take a closer look at anatomy, the identification of organ systems and organs within the human body. The early anatomists divided the human body into four regions: the head, the neck, the trunk, and the extremities. The head houses the brain and most of the sensory organs, the eyes, ears, nose, and tongue. The neck is a connector filled with tubes carrying air, blood, and messages. The trunk houses the organs which process food (the digestive system) and air (lungs and bronchial passages) and supply the body with nutrients (heart and circulatory systems). These vital organs are protected from injury by special bones (the rib cage and hip bones). The muscles and bones of the appendages--the arms and legs--are primarily for movement and support.
The major systems are:
- The integumentary system, which includes skin, hair, and nails
- The skeletal system, all bones and cartilage of the body
- The muscular system, including not only the muscles that help us move, but also muscles of the heart and internal systems, such as the esophagus
- The nervous system, which often includes the sensory organs
- The endocrine system, which includes glands like the pineal, thyroid, thymus, pituitary, hypothalamus, adrenals, pancreas, and that excrete controlling hormones.
- The circulatory system, the heart (a muscle) and all blood vessels
- The lymphatic system, the body's cleaning system
- The respiratory system, mouth, larynx, tracheae, bronchial tubes, lungs, and diaphragm (a muscle)
- The digestive system, mouth, pharynx, esophagus, stomach, intestines, rectum, anus, and various glands (liver, gall bladder, salivary glands)
- The urinary (excretory) system, with its kidneys and bladder
- The reproductive systems, with different organs in the male and female body
Notice that these systems are not completely separate and distinct, but overlap. We find muscles with functions dedicated to a single system, and glands that produce hormones affecting multiple systems.
Study the skeletal, muscle, and nervous systems Think Quest's Tour of the Human Body. This is a student-developed website with basic information on each of the body's systems. For this week, concentrate on bones, muscles, and nerves.
- Study the main bones of the skull, shoulder, rib cage, arm, hip, leg, hand and foot and be able to identify the cranium, clavicle, scapula, sternum, ribs, humerus, vertebrae, radius, ulna, phalanges, pelvis, femur, tibia, and fibula.
- What are the three layers of bone? What is the purpose of each?
- What connects two bones together?
- How does a ball and socket joint like the shoulder work?
- What is a hinge joint like the elbow work?
- Ligaments are tough connective tissue that join bones together: are they elastic?
- Why does your body have immovable joints?
- What is cartilage?
- How is bone itself structured?
- What are the three kinds of muscle tissue?
- Where is each kind found?
- What connects muscles to bones?
- How does a muscle contract?
- Why do muscles work in pairs to move your arms, legs, and fingers?
- Where is the central nervous system? What does it do?
- Where is the peripheral nervous system? What does it do?
- What are the "five senses"?
- How does the brain receive information through your senses?
- How does the brain control different parts of your body?
- What are the parts of a nerve cell?
- How does the nervous system and the endocrine system work together to control your body?
- What are the main body systems?
- In each system, what are the characteristics of the tissues of that system?
- How are the organs of each system connected?
- Which systems transport something through the body?
Further Study/On Your Own
- You can find links to more sites on the human body's different organ systems at KidInfo
- You can study the different systems at Human Anatomy Online, which has some good animations.
© 2005 - 2021 This course is offered through Scholars Online, a non-profit organization supporting classical Christian education through online courses. Permission to copy course content (lessons and labs) for personal study is granted to students currently or formerly enrolled in the course through Scholars Online. Reproduction for any other purpose, without the express written consent of the author, is prohibited.