The Human Organism: An Overview Chapter 27

Structure and Function  This is one of the central themes of biology  Studying the human body can be broken down into studying its structures and the functions of those structures:  Anatomy: the study of the structures of an organism (the parts)  Physiology: the study of what structures do and how they do it (how the parts work, and why we use them)

Structure and Function  The concept: when you change what a structure looks like, you change what it can do.  Here, adding Ca 2+ and ATP to the muscle fibers makes them change position and cause you to flex/relax

Levels of Organization  The most basic unit of all living things: CELLS!!!!!

Levels of Organization  Cells can be organized into TISSUES  A tissue is a cooperating unit of many similar cells that perform a specific function

Levels of Organization  Tissues can be organized in ORGANS  An organ consists of several tissues that together perform a specific task

Levels of Organization  Organs can be organized together to form an ORGAN SYSTEM  An organ system consists of multiple organs that together perform a vital body function

Levels of Organization  Organ systems can be organized together to create an ORGANISM

Human Organ Systems  Integumentary System: covers the body (a.k.a the skin)  Has a protective role  Involved in temperature regulation  Makes Vitamin D  Provides sensory input to the nervous system (touch, pain, hot, and cold)

Human Organ Systems  Muscular System: enables body movement  Tendons attach muscles to bone

Human Organ Systems  Skeletal system: provides support and structure  Stores Calcium  Bone marrow makes blood cells (rbc, wbc)  Ligaments attach bone to bone  Cartilage acts as shock absorbers

Human Organ Systems  Nervous system: coordinates body’s activities by detecting stimuli and directing the body’s responses  CNS vs. PNS (central vs. peripheral)  Sympathetic vs. Parasympathetic divisions

Human Organ Systems  Endocrine System: secretes hormones that regulate the activities of the other organ systems

Human Organ Systems  Circulatory System: delivers oxygen and nutrients to body cells and transports carbon dioxide to the lungs and waste products to excretory system  The heart pumps blood throughout body

Human Organ Systems  Lymphatic System (Immune system): supports the function of the circulatory system by returning fluid to the blood near the heart  Supports the immune system  Lymphocytes: B and T cells

Human Organ Systems  Immune System: defends against infections and cancer  Specific vs. nonspecific  Lymphocytes: B & T cells  Pathogens are organisms that cause disease (bacteria, protists, fungus, viruses)

Human Organ Systems  Respiratory System: exchanges carbon dioxide and oxygen gases with the environment  The site of gas exchange is called the alveoli, located at the ends of the branched bronchioles

Human Organ Systems  Digestive System: ingests and breaks down food to deliver nutrients to the cells  Mechanical vs. chemical digestion  Villi in small intestine increase surface area for digestion  Eliminates undigested material (solid waste)

Human Organ Systems  Excretory System: removes waste products from the body—sodium (Na), urea (ammonia), toxins  Kidneys also help regulate blood viscosity(thickness) by retaining water and therefore impact blood pressure

Human Organ Systems  Reproductive System: produces gametes  The female reproductive system also provides the organs to support the developing embryo  Closely related to the endocrine system

Tissue Types  Epithelial tissue: closely packed cells that cover the entire surface of the body and form the lining of the internal organs

Tissue Types  Connective Tissue: holds together and supports other tissues  Examples:  tendons  ligaments  bone  cartilage  blood  adipose (fat) tissue  loose connective tissue

Tissue Types  Nervous Tissue: allows for quick, short-term long- distance communication

Tissue Types  Muscle Tissue: allows humans to move and aid in digestion and circulation  Three Types:  skeletal muscle (voluntary movement)  smooth muscle (involuntary movement)  cardiac (heart) muscle

Homeostasis  ‘steady state’  Your body tries to maintain a steady internal environment to maximize function  Temperature  Blood pH  Glucose concentration in blood and tissues