Essential Human Anatomy & Physiology I w/Lab - 2023A: Human Body Systems Overview PDF

1.1: Overview of Physiology and Major Systems of the Body 10:26 Anatomy and physiology are studies of how the human body works. Anatomy focuses on the structure of the body and how it is designed, and physiology looks at how the body functions. The physiology of the body depends on the a...

1.1: Overview of Physiology and Major Systems of the Body 10:26 Anatomy and physiology are studies of how the human body works. Anatomy focuses on the structure of the body and how it is designed, and physiology looks at how the body functions. The physiology of the body depends on the anatomy of the body. The physiology of how the organs function depends on the structure of the bones, which are hard structures made of mineral deposits that protect the organs from damage. It is important to study anatomy and physiology together because they are so closely related. The human body has many levels of organization (Figure 1.1). Studying the human body at the chemical level is to look at atoms, which are the smallest building blocks of matter. Atoms combine to form molecules, which then combine to form macromolecules (such as proteins and nucleic acids). Macromolecules combine to form organelles (working structures) inside of each human cell. Examples of organelles are the nucleus and mitochondria of the cell. The cells are the smallest units of living organisms and comprise the cellular level of structural organization. There are many different types of cells in the body that perform various functions; together, they form the tissue level. Figure 1.1 Levels of organization in the human body Tissues are groups of cells that perform a common function. The four basic tissue types in the human body are epithelium, muscle, connective, and nervous tissue, each of which is made up of specific cell types that perform specific functions. Epithelial tissue (Figure 1.2) covers the body surface and lines the cavities of the body. The cells that make up epithelial tissue are specialized for tasks such as secretion and absorption. The structure of epithelial tissue contains closely packed cells with very little matrix (layer outside the cells). Epithelial tissue can be found as one layer or in many layers. These cells are under constant cell division to replace dead cells that shed away. Figure 1.2 Epithelial tissue lining the cavities inside the body shown in pink Muscle tissue enables us to move (Figure 1.3). The cells that make up muscle tissue are specialized for muscle contraction. Figure 1.3 Anterior view multiple layers of muscular tissue (visible in context with skeleton, internal organs, arteries, and veins) Connective tissue (Figure 1.4) offers support and protection of body organs and includes bones, tendons, blood, and ligaments. Connective tissue cells are specialized to bind tissues together and play a supportive role. Figure 1.4 View various types of connective tissue in context (bones, blood, tendons, ligaments) Nervous tissue (Figure 1.5) is responsible for the communication between the cells of the body by forming a system of electrical impulses that communicate very rapidly. Nerves are like the “wiring” of the body. Figure 1.5 Nervous tissue (nerves) in yellow Together the tissues make up the organ structure level of the body (Figure 1.1). The organs of the body perform very specific functions. Examples of organs that we will study are the liver, brain, lungs, heart, and kidneys. Organs carry on extremely complex functions. Organs will work together to accomplish necessary functions. An example of this is how the heart and the blood vessels that make up the cardiovascular system circulate blood continuously to carry oxygen and nutrients to all the cells that make up the body. The next level is that of organ systems. Examples of organ systems we will study are the cardiovascular system, integumentary system, skeletal system, muscular system, nervous system, endocrine system, lymphatic system, respiratory system, digestive system, urinary system, and reproductive system. These systems are extremely complex and function in an amazing way without us even knowing the functions are occurring. These organ systems form the organism, a living thing. As we study each of these tissues and organs in detail, it is truly amazing and miraculous to see the intricate design of life. So, what are some of the necessary functions that keep us alive? We are multicellular organisms requiring all organs functioning at full capacity to keep us alive. This is an overview of the organ systems. We will be studying some of these organ systems in this course, and the rest are discussed in Anatomy and Physiology II. 1. Integumentary system: See Figure 1.6 to view the layers that make up our “skin.” Skin is made up of the epidermis (outer layer), dermis (middle layer), and the hypodermis (inner, also called subcutaneous tissue layer). The hypodermis is a layer made mostly of fat that helps anchor the dermis to a layer of fat cells. Adipocytes (fat cells) help to insulate and regulate body temperature. Skin forms the external body covering and protects the deeper tissues from injury. The integumentary system produces vitamin D and contains the pain receptors and pressure receptors used in our protection. Our skin (Figure 1.6) plays an important role in protecting our internal organs from extreme temperature changes. Sweat glands and oil glands can also be found here. If the integumentary system is damaged and microbes or chemicals make their way into the body, it is the lymphatic system that is responsible for mounting the attack to defend our internal environment. Figure 1.6 Skin Layers 2. Skeletal System: (Figure 1.7) Serves as the framework for the muscular system and supports the body organs. The skeletal system also provides protection for internal organs and houses blood cells as well as stores minerals. The skeletal system provides the framework for which the muscles attach. Figure 1.7 Layers of a long bone of Figure 1.7 the skeletal system (femur) 3. Muscular System: (Figure 1.8) Allows for movement of the body. Muscles attach to bones to bring movement to the skeletal system. Groups of muscles contract and relax in complex coordination to allow us to perform all our daily activities. Figure 1.8 Three types of muscle fibers (cardiac, skeletal, smooth) from gross anatomical view to microscopic view 4. Nervous System: (Figure 1.9) Provides internal communication among the cells of the body. Our nervous system uses electrical impulses to communicate within the body and enable the body to respond to the internal and external environments. Figure 1.9 Key components of the nervous system: Brain (in pink), spinal cord, and nerves (in yellow) 5. Digestive System: (Figure 1.10) Breaks down food into small molecules. Those molecules enter the bloodstream through the small intestine and supply the body with nutrients. Figure 1.10 Alimentary canal (from mouth to anus) with view of its four tissue layers (mucosa, submucosa, muscularis, serosa) 6. Endocrine System: Made up of glands (Figure 1.11) that make hormones, which regulate the reproductive system and the metabolism of the body. Figure 1.11 Primary endocrine organs: thyroid gland, adrenal glands (hypothalamus, pituitary gland, pineal gland all inside the brain) Metabolism is all the chemical reactions that take place in the body that enable us to function. Catabolism is the breakdown of substances into their simpler building blocks. Anabolism is the synthesizing of more complex structures from simpler ones. Cellular respiration uses these more complex structures along with oxygen to make ATP (Figure 1.12). ATP is a very energy-rich molecule that powers cellular activities, allowing cells to have the energy needed to carry out their functions. First, the body breaks down a glucose molecule (with six carbon atoms) into 2 pyruvic acid molecules, creating two ATP molecules. Next, in the citric acid cycle the body breaks down the pyruvic acid molecules to create 2 more ATP molecules and release electrons. Finally, in the electron transport chain the body uses electrons to produce most of its ATP. Figure 1.12 depicts how ATP is created from a glucose molecule: Figure 1.12 The Creation of ATP: Step 1: glycolysis, Step 2: citric acid cycle, Step 3: electron transport system. In total, this process can create up to 38 ATP from one glucose molecule to fuel cellular processes. 7. Cardiovascular System: (Figure 1.13) Made up of blood vessels that move blood, oxygen, and nutrients throughout the body. Figure 1.13 Anterior view of arteries and veins (arteries in red, veins in blue) 8. Lymphatic System: (Figure 1.14) Responsible for immunity and fighting off disease. The lymphatic system is also a part of the circulatory system. It has a complex network of vessels and nodes that allow for the excess fluid to drain back to the heart. Figure 1.14 Major organs of lymphatic system: thymus, spleen (lymph vessels and lymph nodes in green) 9. Respiratory System: (Figure 1.15) Involved in excretion of the waste CO2, which is a byproduct of metabolism. The respiratory system also keeps the blood supplied with oxygen. Figure 1.15 Anterior view of lower respiratory structures 10. Urinary System: (Figure 1.16) Involved in excretion of waste from the body. The urinary system also intricately regulates the water and electrolyte balance in the blood. The cardiovascular system, digestive system, and urinary system help to move nutrients and waste through the body. The actual ability to remove waste from the body is known as excretion and is carried out by the digestive, urinary, and respiratory systems. Figure 1.16 Internal anatomy of the kidney: Blood flow through the nephron (This is the functional unit of the kidney. Nephrons process blood plasma to form urine for excretion.) 11. Male and Female Reproductive Systems: Responsible for creating new life. The reproductive system involves cellular reproduction in which the original cell divides, producing two identical daughter cells that are often used for body growth or repair. In human reproduction (Figure 1.17), a male sperm cell unites with an oocyte (egg) and fertilizes it to form a baby within the mother's uterus. The reproductive system is controlled by hormones from the endocrine system. Figure 1.17 Gametes to zygote: (male and female sex cells, sperm and oocyte, come together to form a new cell called a zygote. This new cell carries the entire genetic code necessary to form a baby.)