General Physiology I: Human Body Organ Systems

• General Physiology I, Unit 1: Human Body Organ Systems: An Orientation is presented by Keith Ncube.
• Contact Keith Ncube at [email protected].
• The textbook used is Saladin K.S. Anatomy and Physiology: The unity between form and function, 6th ED onwards.
• Mark allocations include 2 class tests, 1 semester test, and 1 assignment.
• A predicate mark is required for exam admission.
• If a test is missed, a valid medical certificate must be provided within 48 hours.
• Only ONE sick test will be written at the end of the year, covering all online work.
• Class attendance is very important.
• Class tests 1-4 are each worth 10%
• Written tests 1 and 2 are each worth 30%
• Tools for the class are Primal Pictures, online classes and study guides.
• Students should be able to discuss the terminology of general physiology throughout the module.

Assessment Criteria

• Define physiology and state the two major goals of physiology.
• Describe the six levels of organisation of the body and give the major characteristics of each level.
• List the 11 organ systems and give the major function of each.
• List six characteristics of life.
• Define homeostasis and explain why it is important.
• Describe a negative-feedback mechanism and a positive-feedback mechanism and their relationship to homeostasis.

Define Physiology

• Physiology is the study of function and is primarily an experimental science.
• The two major goals of physiology are to understand and predict the body's responses to stimuli.
• Another goal of physiology is understanding how the body maintains conditions within a narrow range of values in a continually changing environment.

Structural Organisation of Human Body

• The human structure is a hierarchy of complexity, from atoms, molecules and organelles, to cells, tissues, organs, organ systems, and the organism.
• Cells are made of molecules.
• Tissues are formed of similar cells that have a common function.
• There are four types of tissues: Epithelium, Muscle, Connective and Nervous tissues.
• Epithelium covers body surfaces and lines cavities.
• Muscle provides movement.
• Connective tissue supports and protects body organs.
• Nervous tissue facilitates rapid internal communication via electrical impulses.
• An organ is composed of at least two tissue types and performs a specific function. For example, the eye.
• An organ system consists of different organs that work together to accomplish a common purpose, such as the cardiovascular system.
• An organism is the sum total of structural levels working together to permit life.

Organ Systems

• The human body has 11 organ systems that work interdependently.

Integumentary System

• The integumentary system forms the external body covering.
• It is composed of the skin, sweat glands, oil glands, hair, and nails.
• The integumentary system protects deep tissues from injury and synthesizes vitamin D.
• It protects against mechanical injury, infections, and drying out.

Skeletal System

• The skeletal system is composed of bone, cartilage, and ligaments.
• It protects and supports body organs.
• Provides the framework for muscles.
• It also serves as a site of blood cell formation.
• It stores minerals.

Muscular System

• It is composed of muscles and tendons.
• It allows manipulation of the environment, locomotion, and facial expression.
• The muscular system maintains posture and produces heat.

Nervous System

• The nervous system is composed of the brain, spinal column, and nerves.
• It is the fast-acting control system of the body.
• It responds to stimuli by activating muscles and glands.

Cardiovascular System

• It is composed of the heart and blood vessels.
• The heart pumps blood.
• The blood vessels transport blood throughout the body.

Lymphatic System

• Composed of red bone marrow, thymus, spleen, lymph nodes, and lymphatic vessels.
• It picks up fluid leaked from blood vessels and returns it to the blood.
• Disposes of debris in the lymphatic stream.
• Houses white blood cells involved with immunity.

Respiratory System

• It is composed of the nasal cavity, pharynx, trachea, bronchi, and lungs.
• Keeps blood supplied with oxygen, removes carbon dioxide.

Digestive System

• The digestive system is composed of the oral cavity, esophagus, stomach, small intestine, large intestine, rectum, anus, and liver.
• It breaks down food into absorbable units that enter the blood.
• Eliminates indigestible foodstuffs as feces.

Urinary System

• Composed of kidneys, ureters, urinary bladder, and urethra.
• Eliminates nitrogenous wastes from the body.
• It regulates water, electrolyte, and pH balance of the blood.

Male Reproductive System

• This system is composed of the prostate gland, penis, testes, scrotum, and ductus deferens.
• The main function is to produce offspring.
• Testes produce sperm and male sex hormones.
• Ducts and glands deliver sperm to the female reproductive tract.

Female Reproductive System

• Composed of mammary glands, ovaries, uterine tubes, uterus, and vagina.
• The main function is the production of offspring.
• Ovaries produce eggs and female sex hormones.
• Remaining structures serve as sites for fertilization and development of the foetus.

Characteristics of Life

• The seven characteristics of life include responsiveness to the environment, growth and change, ability to reproduce, metabolism and breathing, homeostasis, being made of cells, and passing traits onto offspring.

Maintenance of Life

• Humans must maintain boundaries, movement, responsiveness, digestion, metabolism, and excretion to survive.
• Reproduction and growth are also important for life.
• To survive, humans need nutrients, oxygen, water, and an appropriate atmosphere.

Homeostasis

• Homeostasis: the body's ability to maintain relatively constant internal conditions and to return to those conditions if upset.
• Negative feedback is the main way the body returns to stable conditions.
• A thermostat controls a room's temperature which illustrates the process of negative feedback.
• Three steps are: receptor senses a change, the integrating centre makes a decision, and the effector carries out a corrective action.
• Human "thermostats" involve vasoconstriction or vasodilation of blood vessels to exchange heat with the outside environment.
• Positive feedback is a self-amplifying cycle; an example is the output of oxytocin and the stimulation of uterine contractions during labour and childbirth.
• Some pathogens trigger high fevers regulated by positive feedback designed to rid the body of the pathogen; this type of positive feedback can be life-threatening.