Chapter 11, Lesson 1 Notes

*Every minute of the day, no matter what a person is doing, the body is busy at work.  Each part of the body has a specific job to do.  All the parts work together to keep the body functioning smoothly and effectively.  The organization of the body is in part responsible for this smooth functioning.

*The levels of organization in the human body consist of cells, tissues, organs, and organ systems.  A cell is the basic unit of structure and function in a living thing, or organism.  Almost all cells in the human body have the same basic parts.

*The cell membrane forms the outside border of a cell. 

*The nucleus directs the cell’s activities and holds information that controls a cell’s function.

*The cytoplasm, which forms the rest of the cell, is a clear, jellylike substance that contains many cell structures, each of which has a specific job to perform.

*A group of similar cells that perform the same function is called a tissue.  Muscle tissue is made up of muscle cells.  Muscle tissue contracts and thus makes body parts move.

*Nervous tissue directs and controls body processes.  Electrical signals are carried between the brain and the rest of the body by nervous tissue.

*Connective tissue provides support for the body and connects all its parts.  Connective tissue can be made up of bone cells and fat cells.

*Epithelial tissue covers both the internal (inside) and external (outside) surfaces of the body.

*A group of different types of tissue performing a specific function is called an organ.  Each type of tissue in an organ does its specific job and in that way contributes to the organ’s function.  Each organ is part of an organ system, or group of organs that work together to perform a major function.  Organ systems also work together, forming the next level of organization, the organism.

Chapter 11, Lesson 2 Notes

*The skeletal system, or skeleton, includes all the bones in the body.  The muscular system is made up of all the muscles in the body.

*Muscles and bones work together to make your body move.  The nervous system tells your muscles when to act.

*The muscles that are attached to the bones of the skeleton are skeletal muscles.  They provide the force that moves the bones.  Muscles can contract and relax.  When a muscle contracts, it pulls on the bones to which it is attached.

*A joint is a place where two or more bones meet.  Movement occurs at joints by the action of muscles on bones.  The nervous system controls when and how the muscles act on bones.

*The respiratory, digestive, circulatory and excretory systems play key roles in moving materials within your body.

*The circulatory system- heart, blood vessels, and blood- brings essential materials to all cells of the body and carries away cell wastes.  One of those essential materials is oxygen, and one of the wastes is carbon dioxide.

*The respiratory system moves oxygen into the body and carbon dioxide out of the body.  Air that is inhaled goes into the lungs, an organ of the respiratory system, where oxygen from the air moves into the bloodstream.

*The circulatory system delivers oxygen to all body cells and carries back carbon dioxide to the lungs, where it is eliminated when air is exhaled.  Oxygen is needed by the cells to release energy from sugar molecules.

*The digestive system breaks down foods into nutrients, substances that the body needs to carry out its functions, which then move into the bloodstream through absorption.  The circulatory system delivers the nutrients to all body cells.

*The nervous system and the endocrine system work together to control body functions.  Information gathered by the senses in the form of a stimulus travels through nerves to the brain or spinal cord and produces a response, often involving other body systems.

*Glands of the endocrine system produce hormones, chemicals released directly into the bloodstream and transported throughout the body.  Hormones affect many body processes.

Chapter 11, Lesson 3 Notes

*Although conditions outside the human body may change, conditions inside the body stay stable.  Such conditions include chemical makeup of the cells, their water content, and body temperature.  The condition in which an organism’s internal environment is kept stable in spite of changes in the outside environment is called homeostasis.  Homeostasis is necessary for an organism’s proper functioning and survival.

*All of your body systems working together maintain homeostasis and keep the body in balance.  Body responses that maintain homeostasis in the face of changes in external conditions include shivering, sweating, being hungry, and being thirsty.  In each of these cases, the nervous and endocrine systems respond to a change in the body’s internal environment and control the responses.  They also signal other body systems to play a role in the response.  Homeostasis is never the responsibility of only one system; it relies on the interaction of many body systems.  Maintaining body balance in terms of position involves structures in the inner ear that sense the position of the head and send messages to the brain.

*Stress is the reaction of the body to possibly threatening, challenging, or uncomfortable events.  Some stress is normal and healthy, and once the stress is over, the body returns to a healthier condition.  However, too much negative stress can be unhealthy.  Homeostasis can be disrupted by ongoing stress.  Thus managing stress is important to having a healthy lifestyle.  When homeostasis is maintained, a person is healthy.  Bacteria and viruses can upset homeostasis and make a person sick.  The body’s immune system helps fight disease.

Chapter 11, Lesson 4 Notes

*Your inner framework, or skeleton, is made up of all the bones in your body.  Your skeleton has five major functions.  It provides shape and support, enables you to move, and protects your organs.  It also produces blood cells and stores minerals and other materials until your body needs them.

*Your skeleton is made up of hundreds of bones of different shapes and sizes.  A total of 26 small bones, or vertebrae, make up your backbone in the vertebral column.

*Most of the body’s bones are associated with muscles, which pull on the bones to make them move.  The skull’s protection of the brain is an example of bones’ protection of organs.

*A joint is a place where two bones come together.  Joints allow bones to move in different ways.

*You have two types of joints.  Immovable joints connect bones but allow little or no movement.  Movable joints allow the body to make many different movements.  The bones in movable joints are held together by ligaments, which are made of strong connective tissue.

*Bones are complex living structures that grow, develop, and repair themselves.  Bones are made up of bone tissue, blood vessels, and nerves.

*A thin, tough outer membrane covers all of a typical bone except the ends.  Beneath the membrane is a thick layer of compact bone.  This bone is hard and dense but not solid; it contains minerals such as phosphorus and calcium that strengthen it.  Bone can absorb more force without breaking than concrete or granite, yet it is far lighter than those materials.

*Spongy bone has small spaces within it, making it lightweight but still strong.  Bone has soft connective tissue called marrow, which is responsible for producing most blood cells and for storing fat.

*Bones form new bone tissue as you grow.

*Cartilage is a strong connective tissue that is more flexible than bone.  At birth, human beings’ bones are mostly cartilage.  Gradually most cartilage is replaced with bone.  Some cartilage still protects the ends of your bones.  A combination of a balanced diet and regular exercise helps build and maintain strong, healthy bones.  As you grow older, your bones start to lose some minerals, leading to osteoporosis, a condition in which bones become weak and break easily.

Chapter 11, Lesson 5 Notes

*Involuntary muscles, which are muscles that you cannot control, perform essential activities in your body, such as keeping your heart beating and moving food through your digestive system.

*By contrast, voluntary muscles allow you to move parts of your body in different ways when you want to.

*Your body has skeletal, smooth, and cardiac muscle tissue.  Some of these tissues are in involuntary muscle, and some are in voluntary muscle.

*Skeletal muscles are voluntary muscles that provide the force that moves your bones.  A strong connective tissue called a tendon attaches skeletal muscles to a bone.

*The tissue called cardiac muscle is found only in the heart.

*Skeletal muscle and cardiac muscle are sometimes referred to as striated muscle, because of their banded appearance.  The inside of many internal body organs contain smooth muscle tissue that is not striated.  Both smooth muscle and cardiac muscle are involuntary.

*Skeletal muscles do their work by contracting, or becoming shorter and thicker.  Each time you move, more than one muscle is involved.

*Skeletal muscles work in pairs.  Muscle cells can only contract, not lengthen.  While one muscle in a pair contracts, the other muscle in the pair reflexes to its original length.

*Regular exercise is important for maintaining the strength and flexibility of muscles.  Exercise makes individual muscle cells grow bigger, so the whole muscle becomes thicker and stronger.

*Sometimes, muscles can become injured.  A muscle strain occurs when muscles are overworked or overstretched.

*After a long period of exercise, a skeletal muscle can cramp, or contract and stay contracted.  After injuring a muscle, it is important to follow medical instructions and rest the injured area so it can heal properly.

Chapter 11, Lesson 6 Notes

*The skin is part of the integumentary system, which also includes hair, nails, sweat glands, and oil glands.

*The skin has two layers that protect the body.  Skin helps regulate body temperature, eliminate wastes, gather information about the environment, and produce vitamin D.

*The skin forms a barrier that keeps harmful substances outside the body.  Also, the skin keeps important substances such as water and other fluids inside the body.

*Skin helps the body maintain a steady temperature through perspiration and the enlarging of blood vessels.

*Perspiration is also responsible for eliminating some waste materials from the body.  Nerves in the skin gather information from the environment about pressure, temperature, and pain.

*Some skin cells produce vitamin D in the presence of sunlight.  Together an outer layer and an inner layer perform all the skin’s functions.

*The epidermis is the outer layer of the skin, which helps protect your skin.  Some cells deep in the epidermis produce melanin, a pigment that colors the skin.

*The dermis is the inner layer of the skin, which includes nerves, blood vessels, sweat glands, hairs, and oil glands.

*Pores are openings that allow sweat to reach the surface.  Strands of hair grow within the dermis in follicles.  Oil produces in glands around the follicles keep the surface of the skin moist and the hairs flexible.