Body Systems Digestive Respiratory Nervous Endocrine Urinary Circulatory Musculoskeletal

Section 1: The Body’s Transport System What are the functions of the cardiovascular system? What is the function and structure of the heart? What path does blood take through the cardiovascular system? What are the functions and structures of arteries, capillaries, and veins?

The Cardiovascular System The cardiovascular system carries needed substances to cells and carries waste products away from cells. In addition, blood contains cells that fight disease.

The Heart The heart is a hollow, muscular organ that pumps blood throughout the body. The right side of the heart is completely separated from the left side by a wall of tissue called the septum. Each side has an upper chamber, or atrium, and a lower chamber, or ventricle.

The Heart As blood flows out of the heart and toward the lungs, it passes through a valve like the one here.

Two Loops Blood circulates through the body in two loops, with the heart at the center. In the first loop, blood travels from the heart to the lungs and then back to the heart. In the second loop, blood is pumped from the heart throughout the body and then returns to the heart.

Blood Vessels The walls of arteries and veins have three layers. The walls of capillaries are only one cell thick.

Artery and Vein In this photo, you can compare the wall of an artery with the wall of a vein.

Section 2: Blood and Lymph What are the components of blood? What determines the type of blood that a person can receive in a transfusion? What are the structures and functions of the lymphatic system?

Blood Blood consists of liquid plasma and three kinds of cells—red blood cells, white blood cells, and platelets.

Blood

Blood Types The marker molecules on your red blood cells determine your blood type and the type of blood that you can safely receive in transfusions.

Blood Type Distribution The circle graph shows the percentage of each blood type found in the U.S. population.

The Lymphatic System The lymphatic system is a network of veinlike vessels that returns the fluid to the bloodstream.

Section 3: The Respiratory System What are the functions of the respiratory system? What structures does air pass through as it travels to the lungs? What happens during gas exchange and breathing?

The Air You Breathe The air you breathe in contains several different gases, shown in the circle graph on the left. The air you breathe out contains the same gases, but in the amounts shown in the circle graph on the right.

The Air You Breathe

Respiratory System Functions Oxygen from the air and glucose from digested food are both carried to the cells by the blood. During respiration, oxygen reacts with glucose to release energy.

The Path of Air As air travels from the outside environment to the lungs, it passes through the following structures: nose, pharynx, trachea, and bronchi.

Gas Exchange After air enters an alveolus, oxygen passes through the wall of the alveolus and then through the capillary wall into the blood. Carbon dioxide and water pass from the blood into the alveoli.

Gas Exchange

How You Breathe When you breathe, the actions of your rib muscles and diaphragm expand or contract your chest. As a result, air flows in or out.

Breathing and Speaking Two vocal cords, folds of connective tissue that produce your voice, stretch across the opening of the larynx. Air moving over the vocal cords causes them to vibrate and produce sound.

Section 4: Cardiovascular and Respiratory Diseases What are some diseases of the cardiovascular system? How may tobacco smoke affect the body? What are some respiratory diseases that result from infections or other physical conditions?

Health Problems and Smoking Tobacco smoke damages the respiratory system and strains the circulatory system, resulting in such diseases as emphysema, cancer, and chronic bronchitis.

Health Problems and Smoking

Respiratory Diseases During an asthma attack, air passages narrow and breathing is more difficult.

Section 1: How the Nervous System Works What are the functions of the nervous system? What is the structure of a neuron and what kinds of neurons are found in the body? How do nerve impulses travel from one neuron to another?

The Neuron A neuron has a large cell body that contains the nucleus, threadlike extensions called dendrites, and an axon.

How a Nerve Impulse Travels For a nerve impulse to be carried along at a synapse, it must cross the gap between the axon and the next structure. The axon tips release chemicals that carry the impulse across the gap.

Section 2: Divisions of the Nervous System What are the structures and functions of the central nervous system? What are the structures and functions of the peripheral nervous system? What is a reflex? What are two ways in which the nervous system can be injured?

Central Nervous System The central nervous system is the control center of the body. It includes the brain and spinal cord.

The Brain There are three main regions of the brain that receive and process information. These are the cerebrum, the cerebellum, and the brain stem.

Peripheral Nervous System The peripheral nervous system consists of a network of nerves that branch out from the central nervous system and connect it to the rest of the body. The peripheral nervous system is involved in both involuntary and voluntary actions.

Reflexes A reflex is an automatic response that occurs very rapidly and without conscious control.

Reflexes

Reflexes A reflex is an automatic response that occurs very rapidly and without conscious control.

Section 3: Sight and Hearing How do your eyes enable you to see? How do you hear and maintain your sense of balance?

Vision You eyes respond to the stimulus of light. They convert that stimulus into impulses that your brain interprets, enabling you to see.

Vision

Vision Light coming from an object enters your eye and is focused by the lens. The light produces an upside-down image on your retina. Receptors in your retina then send impulses to your cerebrum, which turns the image right-side up.

Section 4: Smell, Taste, and Touch What are the functions of the nervous system? What is the structure of a neuron and what kinds of neurons are found in the body? How do nerve impulses travel from one neuron to another?.

Smell and Taste The senses of smell and taste work closely together. Both depend on chemicals in food or in the air. The chemicals trigger responses in receptors in the nose and mouth.

Alcohol Alcohol is a drug found in many beverages, including beer, wine, cocktails, and hard liquor. Alcohol is a powerful depressant and affects every system of the body.

Section 1: The Endocrine System How does the endocrine system control body processes? What are the endocrine glands? How does negative feedback control hormone levels?

Functions of Endocrine Glands The endocrine glands include the hypothalamus, pituitary, thyroid, parathyroid, adrenal, thymus, and pancreas.

Functions of Endocrine Glands The ovaries in females and testes in males are also endocrine glands.

Functions of Endocrine Glands The pituitary gland communicates with the hypothalamus to control many body activities.

Functions of Endocrine Glands

Negative Feedback Through negative feedback, when the amount of a particular hormone in the blood reaches a certain level, the endocrine system sends signals that stop the release of that hormone.