Meeting the Body’s Basic Needs Chapter 23
Meeting the Body’s Basic Needs Imagine that your running a race. The muscles in your legs spring into action when you hear the starting pistol. Your feet hot the ground as you move ahead of the other runners. You breathe deeply as air moves into and out of your lungs. Your heart pounding. You begin to sweat. Different systems in your body work together to make all this possible.
How the Body Moves Chapter 23: Section 1
The Skeletal System The 206 bones of the human body make up the skeletal system. Bones have several functions. First, bones support the body. They give the body shape. Bones form a framework that supports the softer tissue of the body. Second, bones protect organs. The rib cage protects the heart and lungs. Vertebrae protect the spinal cord. Vertebrae are the 33 bones that make up the backbone. The pelvis protects reproductive organs. The skull protects the brain.
The Skeletal System A third function of bones is to allow movement. Muscles attach to bones and move them. The body has big bones, small bones, flat bones, wide bones, and unusually shaped bones. The variety of bones helps a person move in different ways. Fourth, bones are the place where blood cells are formed. Bones contain spongy material called red marrow. Red marrow has special cells that make blood cells. Fifth, bones store minerals, such as calcium, phosphorus, and magnesium.
The Skeletal System
Cartilage to Bone Most bones start out as cartilage. Cartilage is a thick, smooth tissue. It is not as hard as bone. Before birth, the entire skeleton is cartilage. It is gradually replaced by bone. A baby is born with more than 300 bones. Over time, some of the bones join so that a person ends up with 206 bones.
However, some parts of the body continue to have cartilage. Cartilage to Bone However, some parts of the body continue to have cartilage. The end of your nose is cartilage and will never become bone. Your outer ear contains cartilage. Inside your body, cartilage surrounds your trachea.
How Bones Change Bones are organs that are made of tissue. They are always changing. Bones are built up and broken down throughout life. This is a normal process. Example: Enzymes break down bone tissue when the body needs calcium.
How Bones Change Calcium is released in the bloodstream. However, if calcium is not placed properly, a person can develop osteoporosis. The bones of people with this disease become less solid and break more easily than before. Osteoporosis most often affects older people. Regular exercise and diet higher in calcium can help prevent osteoporosis.
Joints Bones come together at joints. Cartilage covers bones at the joints. This cartilage acts like a cushion.
Joints
The Knee Joint
The Muscular System
The Muscular System
The Muscular System
The Muscle System
Kinds of Muscle Tissue
Kinds of Muscle Tissue
Kinds of Muscle Tissue
How the Body Digests Food Chapter 23: Section 2
Digestion
Digestion
Digestion Begins Inside your Mouth
The Esophagus
The Stomach
The Stomach
The Small Intestine
The Small Intestine
The Small Intestine
The Small Intestine
Villi
The Large Intestine
The Large Intestine
How Materials Move to and from Cells Chapter 23: Section 3
How Materials Move to and from Cells
The Heart
Heart
The Heart
How Blood Circulates
How Blood Circulates
Blood Vessels
Blood Vessels
Blood Vessels
Blood Vessels
Blood Pressure
Blood and Its Parts
Blood and Its Parts
Blood and Its Parts
Blood and Its Parts
Blood and Its Parts
Blood and Its Parts
Blood Types
How we Breathe Chapter 23: Section 4
The Respiratory System
How Air Moves to the Lungs
Respiration
Respiration
Respiration
Breathing
Breathing
The Respiratory System
How the Body gets Rid of Wastes Chapter 23: Section 5
How the Body gets Rid of Wastes
Perspiration
Three Layers of Skin
The Excretory System
The Excretory System
The Excretory System