Chapter Five Organs and Organ Systems
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Organs and Organ Systems • Techniques are based on anatomy & physiology. • Restraint, injection and blood collection techniques, are described by anatomic terminology. • Functional aspects of organ systems are the basis of many diagnostic, nutritional and experimental manipulations seen in the facility environment.
Integumentary System • Skin covers & protects from outside environment. • Protection maintains metabolic functions & prevents entry of pathogenic organisms. • Skin is composed of several layers, each many cells thick. • There are integumentary differences among species. • Fishes have scales. • Birds have feathers & scale on the legs, feet, beak. • Mammals have hair.
Skeletal System • Framework = skeleton • Invertebrates: exoskeleton • Vertebrate: endoskeleton • Determines shape, provides support and protection and helps it move • Protection - cranium encases brain; sternum, ribs and vertebrae surround heart and lungs. • Movement by providing attachment for muscles. • Bones are attached at joints by ligaments, and muscles are attached to bones by tendons. • Muscle contractions result in movement of joints by lever-like actions.
Skeletal Tissues • Bone = living cells in a nonliving calcified matrix. • Matrix provides rigidity, cells provide ability to grow & repair. • Calcium incorporates into cartilage & forms bone. • Permanent cartilage is not calcified. • ribs, ears, intervertebral discs, joint surfaces, larynx & trachea • Four types: • Long bones: femur, tibia, fibula, humerus, radius, ulna & phalanges • Short bones: carpals and tarsals (wrist, ankle) • Flat bones: ribs, scapula and parts of the cranium • Irregular bones: vertebrae, mandible and parts of the pelvis • Two main groups of bones: • Axial skeleton makes up central trunk of body. • Appendicular skeleton = limbs & are attached to axial skeleton.
Muscular System • Muscle is found in almost every part of the body. • Muscle contraction and relaxation = movement. • Movement = locomotion, posture, working of the digestive system, the circulatory system and focus of the eye. • Muscle cell activity = body’s heat produced. • Contracts when signals received from a nerve. • Voluntary muscle contractions = limb movement. • Involuntary muscle contractions = respiration, blood circulation or digestion.
Circulatory System • Cells depends on O2 and nutrients and removal of CO2 and other waste products. • Primary function of circulatory system • Gases, nutrients & other substances diffuse through capillary walls to extracellular fluid. • Plasma ~ 55% total blood volume. • 45% blood volume = erythrocytes, leukocytes & thrombocytes. • Heart pumps blood to lungs. • Red blood cells receive O2 & release CO2. • Blood returns to heart & is pumped to rest of body.
Blood Vessels • 3 types of blood vessels: • Arteries carry blood away from heart. • Veins return blood to heart. • Blood capillaries connect arteries and veins. • Arteries are thicker walled than veins because they carry blood under higher pressure. • Largest artery is the aorta, which carries blood from heart to body. • Blood capillaries, the smallest blood vessels, are distributed throughout body tissues.
Lymphatic System • Lymphatic system is filter mechanism of body. • A major defense against pathogenic organisms • An extension of circulatory system • Transports lymphatic fluid and helps regulate fluid balance between tissues and blood plasma. • Fluid moves to heart, through lymph nodes. • Fluid is filtered in nodes to remove dead cells, bacteria and other foreign material. • Fluid is returned to heart via lymph vessels.
Respiratory System • Respiration is exchange of O2 & CO2. • Air inhaled into lungs releases O2 into capillaries. • This O2 is carried to tissues via bloodstream. • CO2 is taken back to lungs via bloodstream where it is exhaled. • Fishes & larval amphibians respire with gills while adult amphibians get part of their oxygen supply directly through their skin. • All terrestrial vertebrates respire through lungs. • The principle is the same—gas exchange by diffusion. • Respiration also aids vocalization, temperature regulation and water elimination.
Digestive System • There are three basic feeding types: • Carnivores are flesh or meat eaters. • Omnivores eat both plant matter and meat. • Herbivores eat only plant matter. • Digestive tract depends on type of food eaten. • Carnivores = simple stomach w/ 1 compartment. • Herbivores & omnivores eat more roughage. • requires adaptations to break down & use • GI tract has evolved into a “fermentation vat,” which aids the digestion of roughage by bacteria. • goats, cows and sheep = rumen • rabbits, horses & rodents = cecum
Urinary System • Homeostasis depends heavily on urinary system. • Kidneys filter blood & remove unwanted chemicals. • Wastes are eliminated from body as urine. • Normal urine is clear and light yellow in color. • Normal rabbit urine is cloudy and sometimes reddish-brown in color. • The urine of birds & reptiles is white.
Reproductive System • Sexual reproduction principally under hormonal control by pituitary gland and the gonads. • In mammals, reproductive organs differ between sexes. • Female gonads are called ovaries and male gonads are called testes. • Eggs produced by the ovaries are fertilized by sperm produced by the testes. • Fertilized egg begins to divide in uterus of female & a new organism is formed.
Nervous System • Brain, spinal cord and the nerves • Proper nerve function is required for all voluntary movements and involuntary movements. • Required for 5 senses: • sight, hearing, touch, taste, & smell • Connected to spinal cord • spinal cord connected to brain • Brain evaluates information received from nerves, and communicates necessary response, via nerves, to body.
Endocrine System • Made up of glands that produce one or more specific types of hormones. • Hormones are secreted directly into bloodstream by diffusion across cell walls and through walls of the capillaries. • Hormones are chemical substances that regulate functions of digestion, metabolism, growth, puberty, reproduction and aging.
Additional Reading Frandson, R.D. Anatomy and Physiology of Farm Animals, 5th Edition. Lea and Febiger, Philadelphia, PA. 1992.