Questions
- Skeletal SystemThe skeletal system consists of bones, cartilages, and ligaments. It provides support for the body and protection for vital organs like the heart, lungs, and brain.
- Muscle SystemMuscles of the body form the muscle system. Skeletal muscles are attached to bones by tendons to form levers that enable movement when the muscles contract. About half of the body weight consists of skeletal muscles.4. Nervous SystemThe nervous system consists of the brain, spinal cord, cranial nerves, spinal nerves, and sensory receptors. The formation and transmission of neural impulses enable the nervous system to provide rapid perception of environmental changes and coordination of body functions. Self-awareness, intelligence, will, and emotions are functions of the human brain.
- Cardiovascular SystemThe cardiovascular system consists of the heart, blood vessels, and blood. As it is pumped by the heart through blood vessels, blood is the transporting medium that carries materials throughout the body. Blood also provides a primary defense against invasion by disease-causing microorganisms.
- Lymphatic SystemLymphatic vessels, spleen, tonsils, and lymph nodes compose the lymphatic system. Extracellular fluid is collected by lymphatic vessels; filtered through lymph nodes, where microorganisms and cellular debris are removed; and then returned to the blood. The lymphatic system plays an important role in immunity.
- Respiratory SystemThe respiratory system consists of the lungs and the air passages. The lungs are gas-exchange organs, where atmospheric air is separated from blood by thin membranes, enabling oxygen in the air to diffuse into the blood and carbon dioxide in the blood to diffuse into the air in the lungs. The air passages through which air enters and leaves the lungs are the nasal cavity, pharynx, larynx, trachea, and bronchi.
- Digestive SystemThe digestive system consists of the alimentary canal, through which food passes, and the accessory digestive glands. The parts of the alimentary canal are the mouth, pharynx, esophagus, stomach, small intestine, large intestine or colon, rectum, and anus. The digestive glands are the salivary glands, pancreas, and liver. The function of the digestive system is to convert large, non-absorbable food molecules into small, absorbable nutrient molecules.
- Urinary SystemThe urinary system removes metabolic wastes and excessive minerals from the body as urine. Wastes and excessive minerals are removed from the blood by the paired kidneys, and are then carried through ureters to the urinary bladder for temporary storage, and voided from the body through the urethra.
- Endocrine SystemThe endocrine system consists of hormone-producing endocrine glands: pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, pineal, ovaries, and testes. Hormones are chemical messengers that provide a relatively slow-acting, but long-lasting, coordination of body functions.
- Reproductive SystemThe function of the male and female reproductive systems is the production of offspring. The male reproductive system consists of sperm-producing testes located in the scrotum, the exterior pouch; two vas deferens, two tubes carrying sperm to the urethra; accessory glands providing fluid for sperm transport; and the penis, the male copulatory organ. The female reproductive system consists of egg-producing ovaries; two oviducts that carry eggs and, after egg-sperm fusion, early embryos to the uterus, where prenatal development occurs; accessory glands that secrete lubricating fluids; and the vagina, the female copulatory organ and birth canal.C. BODY CAVITIESMany organs are located in body cavities. There are two body cavities that are named for their location. See Figures 1-3. The ventral body cavity is the larger cavity, and is located near the anterior (front) of the body. It is divided by a dome-shaped sheet of muscle, the diaphragm, into the thoracic cavity and the abdominopelvic cavity. The thoracic cavity is further subdivided into left and right pleural (lung) cavities containing the lungs and the pericardial cavity containing the heart. The abdominopelvic cavity is further subdivided into an abdominal cavity and a pelvic cavity. The dorsal body cavity is the smaller cavity, and it consists of the cranial cavity containing the brain and the spinal cavity containing the spinal cord. Note that the dorsal body cavity is surrounded by bones. Figure
- The ventral body cavities.Figure
- Male torso with the anterior body wall removed to expose the thoracic and abdominopelvic organsFigure
- Female torso with some anterior organs removed to expose the deeper organsD. TISSUESOrgans of the body are formed of two or more tissues, and each tissue is formed of similar cells that are specialized to perform their particular functions. There are four basic types of tissues in the body. Epithelial tissue - Covers surfaces and lines cavities; forms secretory portions of glands; functions include protection, secretion, and absorption.Connective tissue - Binds tissues together; provides protection and support for organs and body.Muscle tissue - Specialized for contraction enabling body movements.Nerve tissue - Transmission of neural impulses enabling rapid coordination of body functions.In this section, your task is to learn the recognition characteristics of body tissues and their general functions, and to correlate their microscopic structure with their functions.Epithelial TissuesThe cells of epithelial tissues are tightly packed together, forming single or multiple sheet like layers. The innermost layer is attached to underlying connective tissue by a very thin, non-cellular basement membrane. The tissue surface opposite the basement membrane is always exposed, i.e., it is not attached to other tissues.Epithelial tissues are named according to (1) whether they have only one layer (simple epithelium) or more than one layer (stratified epithelium) of cells, (2) the shape of the cells in the outermost cell layer, and (3) the presence or absence of cilia.
1. have thick walls and are resilient.2. expand to accommodate sudden increase in blood volume that results after heart contraction.3. divide into small arterioles.B. Arterioles constriction and dilation are regulated by nervous system to regulate blood pressure.C. Capillaries are microscopic blood vessels with a wall formed of one layer of simple squamous cells.
1. Capillary beds are so prevalent that, in humans, all cells are within 60–80 µm of a capillary.2. Capillaries are so narrow that red blood cells must pass through them in single file.3. Gas, nutrient, and waste exchange occurs across the thin walls.D. The venules are vessels that take blood from capillaries and join to form a vein.E. Veins transport blood toward the heart.
1. Wall of a vein is much thinner than that of arteries; there is low blood pressure.2. One-way valves open in direction of heart; close to prevent backflow. Capillary Blood Flow:As blood enters capillaries, molecules small enough to cross the thin walls follow their concentration gradients in or out of the bloodstream. The blood pressure at the arteriole end forces water out across the walls. Osmotic pressure of the blood causes most of the water to move back in by osmosis by the time the blood enters the venule.