MP2 Quarterly Study Guide- Use This Information, Your Quarterly Review Webquest, and Your

MP2 Quarterly Study Guide- use this information, your Quarterly Review Webquest, and your class handouts to study for the test.

CELL STRUCTURES

The nucleus is the organelle that directs most cell activities. Mitochondria are the cells powerhouse, converting glucose and oxygen into energy that the cell needs for repairs, reproduction and normal cell activity. The cell membrane gives the cell shape and allows oxygen, glucose, and water to diffuse into the cell, and waste products to diffuse out.

HOMEOSTASIS

Homeostasis is the body’s ability to regulate, and maintain, a balanced internal environment despite external changes. All body systems and functions contribute to maintaining homeostasis. The body needs to keep the amounts (or ratios) of water, salt, glucose, temperature, etc., within the proper limits in order for the body to function at its best.

MUSCULAR SYSTEM

Muscles work by contracting, or shortening, and then relaxing. Muscles never push, they only pull. There are three types of muscle tissue. * Cardiac muscle is found only in the heart. It is a striated (striped) muscle that never tires. One of the factors that makes it able to constantly work is that each cell contains many mitochondria to provide the energy it needs. It is also known as an involuntary muscle, because it does not require any conscious thought to operate. * Smooth muscle tissue is another kind of involuntary muscle. It is found around all of your internal organs, like the stomach and intestines. It has fewer mitochondria per cell than cardiac muscle, but can still work for long periods of time before it tires. Smooth muscle tissue is not striated (no stripes). * Skeletal muscles are attached to bones and allow you to move when they contract. Skeletal muscles have to work in pairs (like your biceps and triceps). When your biceps contracts, the triceps relaxes, and you bend your arm at the elbow. To reverse the action, the triceps contracts, while the biceps relaxes, and the arm straightens. Skeletal muscles are striated (striped) like cardiac muscles. They have the fewest number of mitochondria in their cells, and tire quickly when working. Skeletal muscles are voluntary… you can control their actions.

SKELETAL SYSTEM

Your 206 bones give shape to your body, provide support, store minerals (like calcium), make blood cells, protect internal organs, and allow you move (when they work with your muscles). Bones are living organs, capable of growth, and able to repair themselves from injuries.

As you can see from this diagram bones have a thin outer covering, called the periosteum. Beneath that is a dense, hard layer of compact bone. At the center is a web of spongy bone, the spaces of which are filled with bone marrow (the marrow is where new blood cells are produced and fat is stored). This unique design is what allows bones to be incredibly strong, yet relatively lightweight and flexible.

The places where any two bones meet are called joints. Some joints allow bones, and underlying organs, to grow and then later fuse together to become immovable structures. Other joint allow our limbs to move in various directions with various degrees of motion. Ball and socket joint have the greatest range of motion, while gliding joints can move in many different directions, but only for short distances. Use the following diagram to memorize the five types of joints and examples of each type. Then use your own body to examine how those joints move.

INTEGUEMENTARY SYSTEM (SKIN)

Skin is an effective barrier between the body and the outside world. It keeps bacteria, viruses, and contaminants from entering the body, allows excess moisture and waste products to leave the body, and helps to maintain body temperature in response to changes in the environment.

Use the diagram to memorize the layers of skin, and its structures

The outer layer of skin is the epidermis. Those cells are dead and are constantly being shed and replaced by new cells created in the living, lower layer called the dermis.

Skin produces the pigment melanin. Melanin production increases, and decreases in response to the amount of available sunlight. Melanin is able to reduce the harmful effects of UV radiation exposure.

There are a variety of sensory nerves in the skin. They respond to pain, pressure, heat, cold, texture, etc. and provide an enormous amount of information about the environment to the brain.

Many of the skin structures help the body with thermoregulation. When environmental temperatures increase, the skin reddens because more blood is channeled toward the surface through vasodilation, (when the blood vessels expand). At the same time sweat glands excrete sweat through the pores to so that evaporation can help cool the surface. If temperatures drop skin becomes pale because blood is kept away from the surface due to vasoconstriction (shrinking of the blood vessels). Shivering starts to generate more heat, and erector pilli muscles contract and pull on hair follicles causing goosebumps in an attempt to trap an insulating layer of air next to the skin.

DIGESTIVE SYSTEM

The function of the digestive system is to break downnutrients into their simplest forms so that they can be absorbed into the body. These nutrients are the basic components that your body needs for cell growth, repair, and reproduction, and the fuel your cells need to make energy. The most important nutrient is water sinceno body process can take place without it. The primary organs of the digestive system are the mouth, esophagus, stomach, small intestine and large intestine. There are also accessory organs, such as the liver, gallbladder, and pancreas, which are important to the digestive process, but food does not actually pass through these organs.

*Digestion starts in the mouth with the teeth breaking the food into small fragments by mechanical digestion. Saliva contains the enzyme amylase. Amylase chemically digests carbohydrates, changing them into sugars (like glucose), their simplest forms.

*When you, swallow food moves through the esophagus, and the rest of the digestive system, by a rippling motion of the smooth muscles in the organ walls. This type of movement is known as peristalsis.

*When the food reaches the stomach hydrochloric acid provides the proper environment for the enzyme pepsin to begin changing proteins into their simplest form (amino acids). The stomach wall is protected from this strong acid by a mucus layer.

*The now liquid food (called chyme) leaves the stomach and enters the small intestine where the majority of chemical digestion, and nutrient absorption takes place. Bile, which is produced by the liver and stored in the gall bladder, enters the small intestine and emulsifies fats (breaks them into tiny droplets). The pancreas releases many types of enzymes into the small intestine to complete the chemical digestion of various proteins into amino acids, carbohydrates into simple sugars, and finally fats into fatty acids and glycerols (their simplest forms). The pancreas also neutralizes the stomach acid to create an alkaline environment in the small intestine. The walls of the small intestine are lined with countless tiny, fingerlike projections called villi. The enormous surface area of all these villi I greatly increases the efficiency of nutrient absorption, and diffusion, into the bloodstream.

*With all of the available nutrients absorbed by the small intestine, the remaining food residue enters the large intestine where excess water is reabsorbed back into the body, and the feces is prepared for elimination.