Draft Lesson
[Figure 1] The human brain. The “control center.” What does it control? Practically everything. From breathing and heartbeat to reasoning, memory, and language. And it is the main part of the central nervous system. Central Nervous System The nervous system has two main divisions: the central nervous system and the peripheral nervous system (see Figure below). The central nervous system (CNS) includes the brain and spinal cord (see Figure below). [Figure […]
Nerve Impulse
[Figure 1] How does a nervous system signal move from one cell to the next? It literally jumps by way of a chemical transmitter. Notice the two cells are not connected, but separated by a small gap. The synapse. The space between a neuron and the next cell. Nerve Impulses Nerve impulses are electrical in nature. They result from a […]
Neuron
[Figure 1] A close-up view of a spider web? Some sort of exotic bacteria? What do you think this is? This is actually a nerve cell, the cell of the nervous system. This cell sends electrical “sparks” that transmit signals throughout your body. The Nervous System A small child darts in front of your bike as you race […]
Nails and Hair
Would you believe this is a close-up of your hair and scalp? Well maybe not yours. But some other person’s. Hair is an integral part of the integumentary system. And although many people may lose some or all of the hair on top of their head, they still have hair on their arms and legs that […]
Skin
What is integumentary? Because the organs of the integumentary system are external to the body, you may think of them as little more than “accessories,” like clothing or jewelry. But the organs of the integumentary system serve important biological functions. They provide a protective covering for the body and help the body maintain homeostasis. The Skin The skin is the […]
Muscle Contraction
[Figure 1] What makes a muscle contract? It starts with a signal from the nervous system. So it starts with a signal from your brain. The signal goes through your nervous system to your muscle. Your muscle contracts, and your bones move. And all this happens incredibly fast. Muscle Contraction Muscle contraction occurs when muscle fibers get shorter. Literally, the muscle […]
Skeletal Muscles
[Figure 1] How do your bones move? By the contraction and extension of your skeletal muscles. Notice how the muscles are attached to the bones. The muscles pull on the bones, causing movement. Skeletal Muscles There are well over 600 skeletal muscles in the human body, some of which are identified in Figure below. Skeletal muscles vary considerably in size, from tiny muscles inside […]
Muscles
[Figure 1] What exactly are muscles? Does the word “muscle” make you think of the biceps of a weightlifter, like the man in pictured above? Muscles such as biceps that move the body are easy to feel and see, but they aren’t the only muscles in the human body. Many muscles are deep within the body. […]
Skeletal Diseases
[Figure 1] Do you think this would hurt? Why? That would probably hurt. And hurt a lot. Broken bones, or fractures, may be one of the more common problems of the skeletal system. And this one would probably need surgery to fix. But, in addition to broken bones, there are other problems and diseases of the skeletal system. […]
