Human Anatomy and Physiology II

In this lesson, you'll explore the topic of sensation as you learn about the sensations of touch, pressure, temperature, and pain. You'll discover the differences between free nerve endings, Merkel disks, Meissner corpuscles, root hair plexuses, and Pacinian corpuscles. The lesson will also talk about sensory adaptation and referred pain, and you'll learn where in the brain messages from sensory receptors end up. The lesson will end with a discussion of three disorders of cutaneous sensation—tactile defensiveness, congenital insensitivity to pain, and peripheral neuropathy.

In this lesson, you'll learn about sensory receptors (muscle spindles, Golgi tendon organs, and joint proprioceptors) that tell your brain how much tension is in your muscles and the position of your body parts. You'll learn why accurate information from these receptors is so important and how the brain uses their information to help you plan your movements. The lesson will also discuss your sense of equilibrium—that sense that lets you know if you're upright and if you're in danger of falling. You'll study the structures of the vestibular system and learn how they contribute to both static and dynamic equilibrium. At the end of the lesson you'll learn what happens when a person experiences proprioceptive or vestibular dysfunction.

Now it's time to learn about the physics of light and color and find out how light is bent and focused. In this lesson, you'll learn about the composition of the eyes, including their three coverings and the structures inside the eyeballs. The lesson will talk about special sensory receptors called rods and cones and how the information they receive is sent to the brain and analyzed. The lesson will conclude with a discussion about three common eye disorders—glaucoma, cataracts, and macular degeneration.

In this lesson, you'll discover the physics of sound. You'll learn why sounds differ in pitch and loudness, and you'll find out about a quality of sound called color. The lesson will then talk about the different structures that make up the outer ear, middle ear, and inner ear. You'll learn what happens when sound waves enter the ear and how information from the ear travels to the brain for analysis. The lesson will end with a discussion of hearing loss.

In this lesson, you'll finish up your study of the senses with a discussion on the senses of smell and taste. You'll learn about the structures that respond to chemicals of smell and taste, and how the sensations of smell and taste are perceived in the brain. The lesson will also talk about disorders of both of these senses, and you'll have an opportunity to perform a fun experiment to test the importance of smell to the perception of flavor.

This lesson will go over the fascinating topic of cellular metabolism—the chemical reactions that occur in your body's cells. You'll review the important concepts of homeostasis and negative feedback and learn that homeostasis is maintained by thousands of chemical reactions that occur every second. Those chemical reactions either build larger molecules from smaller ones or break apart larger molecules into smaller ones, so the lesson will discuss what happens in those two major types of reactions. You'll also learn about the capture and storage of energy, the role of enzymes in metabolic pathways, and disorders of cellular metabolism.

In this lesson, you'll continue your study of important chemicals in the human body. You'll start out by reviewing the differences between atoms and ions, and the differences between ionic and covalent bonds. You'll then move on to a study of water, its unique properties, and its important functions. You'll learn that water breaks apart molecules called electrolytes, and that the three major types of electrolytes include acids, bases, and salts. The lesson will also discuss the pH scale—a way to measure the degree of acidity in a substance, and you'll learn about the conditions called acidosis and alkalosis. You'll finish up the lesson with a discussion about imbalances of three important ions—sodium, potassium, and calcium.

In this lesson, you'll go over the wonders of prenatal development. You'll learn about the roles both men and women play in the creation of the zygote—the very first cell that starts a new human life. You'll then follow that new creature through the amazing changes that happen during the first eight weeks after fertilization (the embryonic period). The lesson will also discuss significant events that occur during the rest of the pregnancy (the fetal period). At the end of this lesson, you'll learn about some common causes of both male and female infertility.

In this lesson, you'll learn about pregnancy from the mother's point of view. The lesson will start with a discussion about the placenta and then talk about the way pregnancy affects the mother's different organ systems. It will also discuss the events of childbirth and what a mother experiences during the postpartum period. Many women choose to breastfeed (lactate), so it will also tell you how breasts prepare for lactation, how milk is produced, and how it's secreted. You'll end this lesson with a discussion of a complication of pregnancy called gestational diabetes.

In this lesson, you'll focus on the neonatal period, infancy, and childhood. The lesson will start with a discussion of normal circulation of blood in children and adults and compare that to circulation in the fetus. That's so you can understand the big changes that occur in the heart, blood vessels, and lungs as soon as a baby takes their first breath. The lesson will then talk about other changes in the first four weeks after birth (the neonatal period), and you'll move on to a discussion of reflexes and brain maturation during the first year and significant changes that occur during childhood. At the end of this lesson, you'll learn about a common developmental disorder in children called cerebral palsy.

In the final lesson, you'll go over puberty, adulthood, and old age. You'll learn how hormones work during puberty and what physical changes occur during that time. The lesson will also discuss changes that occur during young adulthood and middle age and spend some time on menopause. It will devote a chapter to the topic of senescence—the process of aging during the years 65 and over. In that chapter, you'll learn several reasons why getting older causes age-related changes. The lesson will end with a discussion of ways to slow down the aging process.