Chapter 10 Anatomy and Physiology of Farm Animals

1. Chapter 10Anatomy and Physiology of Farm Animals

2. Reasons to Learn Anatomy and Physiology • To describe animals in judging • Selection of animals for breeding purposes • Improved husbandry • Improved health care

3. Definitions • Gross anatomy: structures can be seen with unaided eye • Microscopic anatomy: tissues are studied using a microscope (magnification of 40-1000 times), also called histology • Comparative anatomy: comparisons between species

4. Definitions (continued) • Embryology: study of development in utero or within the egg (e.g. birds) • Morphology: pertaining to structure • Physiology: pertaining to body-organ function, individually and collectively in systems

5. Terms to Describe Location • Dorsal: top or back of a tetrapod • Ventral: belly or underside of a tetrapod • Cranial (anterior): towards the front • Caudal (posterior): towards the rear

6. Cutaneous Anatomy • Skin consists of two layers: epidermis (outer layer of epithelial cells) and dermis (corium, composed of connective tissue and vessels) • Glands of the skin include sebaceous (oily) and sweat (sudoriferous) glands • The dermis also contains sensory nerves and arrector pili muscles

7. Cutaneous Anatomy (continued) • Hair is produced by hair follicles in the skin of cattle, goats, horses and swine • Sheep produce wool (finer texture, soft and curly) • Birds are covered with feathers

8. The Skeletal System • Mammals and birds have an endoskeleton consisting of the long bones of the legs, ribs, vertebrae, and skull • The outer layers of bones consist of calcium and mineral while the inner core is a soft tissue known as bone marrow (red marrow is a site of blood cell production while yellow marrow is primarily fat)

9. The Skeletal System (continued) • Epiphyses are the ends of bones • Diaphysis is the shaft of a long bone • Growth occurs in the epiphysial-diaphysial cartilage • The epiphysial-diaphysial cartilage gradually becomes calcified and replaced by bone, once it is totally ossified bone growth stops

10. Types of Joints • Ball-and-socket (shoulder) • Hinge (elbow) • Pivot (neck) • Gliding (vertebrae) • Ligaments span joints outside the joint capsule, within the capsule is synovial fluid

11. The Muscular System • Voluntary (striated) • Skeletal muscles (connect to bones via tendons) • Extensor (straighten) • Flexor (bend) • Abductor (move away from midline) • Adductor (move towards midline) • Involuntary (smooth or striated) • Digestive, urogenital, respiratory system walls • Cardiac (heart)

12. Muscle Metabolism • Aerobic • ATP breaks down to ADP releasing energy • Muscle glycogen breaks down to generate more ATP, produces lactic acid which is oxidized to carbon dioxide and water producing energy which liver can use to resynthesize glycogen • Muscle glycogen can also be converted anaerobically to lactic acid but without oxygen cannot be converted back to glycogen (build up of an “oxygen debt”)

13. Circulatory System Components • Heart • Veins, arteries, capillaries • Lymph vessels and lymph nodes • Spleen • Red marrow (bone marrow)

14. Heart • Typical human heart pumps 60,000 miles of blood through blood vessels each day • By 70 years of age a human heart will have beaten over 2.5 trillion times and pumped more than 435,000 tons of blood

15. Vessels of Circulatory System • Arteries • Thick muscular walls • Carry blood away from heart • Veins • Thin walled with valves • Carry blood towards heart • Capillaries • Tiny, one-cell thick

16. Systemic Circulation • Heartbeats are coordinated by the sinoatrial node (pacemaker of the heart) • Systemic circulation refers to the heart and vessels that move oxygenated arterial blood from the left atrium and ventricle throughout the body and then returns it via veins into the right atrium (from which it goes into the right ventricle and then the pulmonary circulation)

17. Portal Circulation • This is a subset of the systemic circulation located in the abdominal cavity • Takes venous blood from the stomach, pancreas, small intestines and spleen through the liver for filtering and processing of nutrients prior to return to the heart

18. Pulmonary Circulation • The pulmonary artery receives unoxygenated blood from the right ventricle and carries it into the pulmonary circulation • Within pulmonary capillaries associated with alveoli of the lungs, oxygen diffuses into the blood while carbon dioxide is released into the airways • Pulmonary veins then return the now oxygenated blood to the left atrium

19. Lymphatic System • Lymph vessels collect tissue fluids, are filtered through lymph nodes and then returned to veins of the circulatory system • Lymph nodes filter out foreign cells and materials and produce lymphocytes • Lymphocytes produce antibodies and also destroy foreign and infectious cells

20. Blood Composition • 50-65% of blood volume is plasma • Contains 90% water • 10% solids include salts, proteins, enzymes, antibodies, hormones, vitamins, minerals, glucose, clotting factors, etc. (clotting of plasma leaves a fluid called serum) • 35-50% blood cells • Red blood cells (erythrocytes) • White blood cells (leukocytes) • Platelets

21. Hemoglobins • Hemoglobin within erythrocytes gives them their red color • Consists of heme (an iron-containing porphyrin) and a globin (a protein) • Readily absorbs oxygen forming oxyhemoglobin

22. Abnormalities in Hemoglobin • Anemia = inadequate amount of hemoglobin (or decreased #s of erythrocytes) • Sickle-cell hemoglobin (result of a gene mutation, common in some races of people)

23. Blood Types • Antigens are substances capable of producing an immunological response, usually in the form of specific antibodies directed against the antigen • Red blood cells can have a variety of cell surface antigens coded for by different genes • Different antigens = Different blood types

24. Blood Types • Antibodies against cell surface antigens will agglutinate cells (clumping) • Humans: A, B, O series (genes A, B, a) • Gene A produces antigen A • Gene B produces antigen B • Gene a does not produce antigens

25. Human Blood Types (continued) • AA and Aa combinations = Type A • BB and Ba combinations = Type B • AB combination = Type AB • aa combination = Type O

26. Human Blood Antibodies • Individuals of Blood type A have B antibodies • Individuals of Blood type B have A antibodies • Individuals of Blood type AB do not have antibodies • Individuals of Blood type O have both A and B antibodies (but no antigens on their own blood cells)

27. Human Transfusions • Type A can receive type A or type O blood • Type B can receive type B or type O blood • Type AB can receive any blood (universal recipient) • Type O can only receive type O blood (but can donate to anyone, universal donor)

28. Human Rh Factor • Another type of antigen on human erythrocytes is the Rh factor • If have Rh factor are called Rh positive • If lack Rh factor are called Rh negative (and will produce antibodies against Rh positive cells if received from a transfusion or during birth of an Rh positive baby to an Rh negative mother---do not occur naturally)

29. Erythroblastosis Fetalis • When an Rh positive baby is born to a mother previously sensitized and producing antibodies to Rh, these antibodies can cross the placenta and agglutinate the erythrocytes of the baby resulting in severe anemia or death • Sensitization can often be prevented by treating an Rh negative mother with an anti-Rh gamma globulin immediately after the birth of each Rh positive baby

30. Neonatal Isoerythrolysis in Animals= Hemolytic Disease of the Newborn • In farm animals and horses, antibodies to erythrocytes are transferred in colostrum rather than across the placenta • When the offspring is of a blood type to which the dam has produced antibodies, absorption of colostrum will be followed by destruction of the neonatal animals red blood cells (isoerythrolysis) and its death

31. Neonatal Isoerythrolysis (Hemolytic Disease of the Newborn) • This condition is most common in Arabian horses but can occur in other horse breeds and less often in other species • Prevent by checking to see if the plasma of the dam agglutinates red cells of the sire, if so the foal may be at risk and should not be allowed to consume colostrum from the mare until its blood has also been checked

32. Hemolytic Disease of the Newborn • Affected animals are normal at birth but become weak and jaundiced after nursing • Treatments involve blood transfusions and feeding a milk replacer while milking out the dam until she is no longer producing colostrum

33. Blood Typing • Blood typing tests for cell surface antigens • Useful in parentage testing • Certain blood types are associated with superior performance (e.g. egg hatchability and egg production in chickens), others with genetic disease (e.g. PSS and PSE in swine) • Useful in avoiding problems of blood incompatibility (for transfusions and breeding of domestic animals)

34. White Blood Cells (Leukocytes) Cells of bone marrow origin, segmented nuclei • Neutrophils (phagocytic; increase with stress and with bacterial infections, decrease with some viral infections) • Eosinophils (granules stain red with eosin dye; are phagocytic; increase with parasitic infections and allergies) • Basophils (phagocytic; increase with some parasitic infections)

35. White Blood Cells Cells of bone marrow origin continued • Monocytes (single non-lobed nucleus; phagocytic; increase with chronic infections) • Thrombocytes (platelets; non-nucleated particles function in hemostasis)

36. White Blood Cells (continued) • Lymphocytes • Produced in lymph nodes, spleen, thymus • Single large nucleus • Some produce antibodies • Others are involved in immune surveillance and destruction of foreign materials and tumor cells • Can be cultured and used in chromosome studies

37. The Digestive System • Species differences • Ruminants have four compartments to stomach: rumen, reticulum, omasum, abomasum • Poultry have a crop, proventriculus, ventriculus • Horses have a large cecum • Accessory organs • Liver, pancreas, salivary glands • See chapter 19 for more detail

38. Nostrils (paired) Nasal Cavity Pharynx Epiglottis Larynx Primary bronchi Bronchioles Respiratory bronchioles Alveoli Birds also have a voice box syrinx and air sacs Respiratory center (in medulla of brain) The Respiratory System

39. The Nervous System • Provides animals with ability to react or adjust to stimuli • Coordinates physical activities • Provides pathways for the actions of all senses

40. The Nervous System • Central Nervous System • Brain • Spinal cord • Peripheral Nervous System • Somatic nerves (serve muscles, skin) • Autonomic nerves (serve the visceral organs)

41. Nerve Cells and Pathways • Neurons (nerve cells) • Axon (single long fiber of a nerve) • Dendrites (branches off axon), receive stimuli from a receptor organ or another nerve, conduct impulses to other nerves via synapses

42. Peripheral Nerves • Bundles of neurons bound together form a nerve trunk, these may be covered with myelin forming a medullary sheath • A bundle of nerve cell bodies found together outside the CNS is called a ganglion • Neurons receiving stimuli are termed sensory or afferent neurons • Neurons conducting impulses are called motor or efferent neurons

43. Gross Anatomy of the Brain • Cerebrum • Cerebellum • Pons • Medulla oblongata

44. Spinal Cord • Located within the vertebral column • Main line between the brain and each part of the body • Sensory (afferent) impulses come in through dorsal roots of the spinal nerves • Motor (efferent) impulses are transmitted through the ventral roots of the spinal nerves

45. The Urinary System • Kidney Shapes • Lobulated: cattle, chicken • Heart-shaped: horse • Bean-shaped: pigs, sheep • Kidney architecture • Cortex • Medulla • See Figure 10.20

46. The Urinary System • Excretory products • See Figure 10.21 • Salts • Urea (most mammals) • Uric acid (birds, reptiles, Dalmatian dogs, humans)