Chapter 10
Anatomy and Physiology
of Farm Animals
Reasons to Learn
Anatomy and Physiology
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To describe animals in judging
Selection of animals for breeding purposes
Improved husbandry
Improved health care
Definitions
• Gross anatomy: structures can be seen with
unaided eye
• Microscopic anatomy: tissues are studied
using a microscope (magnification of 401000 times), also called histology
• Comparative anatomy: comparisons
between species
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
Terms to Describe Location
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Dorsal: top or back of a tetrapod
Ventral: belly or underside of a tetrapod
Cranial (anterior): towards the front
Caudal (posterior): towards the rear
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
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
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)
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
Types of Joints
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Ball-and-socket (shoulder)
Hinge (elbow)
Pivot (neck)
Gliding (vertebrae)
Ligaments span joints outside the joint
capsule, within the capsule is synovial fluid
The Muscular System
• Voluntary (striated)
– Skeletal muscles (connect to bones via tendons)
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Extensor (straighten)
Flexor (bend)
Abductor (move away from midline)
Adductor (move towards midline)
• Involuntary (smooth or striated)
– Digestive, urogenital, respiratory system walls
– Cardiac (heart)
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”)
Circulatory System Components
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Heart
Veins, arteries, capillaries
Lymph vessels and lymph nodes
Spleen
Red marrow (bone marrow)
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
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
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)
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
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
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
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
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
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)
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
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
Human Blood Types (continued)
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AA and Aa combinations = Type A
BB and Ba combinations = Type B
AB combination = Type AB
aa combination = Type O
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)
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)
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)
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
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
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
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
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)
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)
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)
White Blood Cells (continued)
• Lymphocytes
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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
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
The Respiratory System
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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 Nervous System
• Provides animals with ability to react or
adjust to stimuli
• Coordinates physical activities
• Provides pathways for the actions of all
senses
The Nervous System
• Central Nervous System
– Brain
– Spinal cord
• Peripheral Nervous System
– Somatic nerves (serve muscles, skin)
– Autonomic nerves (serve the visceral organs)
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
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
Gross Anatomy of the Brain
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Cerebrum
Cerebellum
Pons
Medulla oblongata
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
The Urinary System
• Kidney Shapes
– Lobulated: cattle, chicken
– Heart-shaped: horse
– Bean-shaped: pigs, sheep
• Kidney architecture
– Cortex
– Medulla
– See Figure 10.20
The Urinary System
• Excretory products
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See Figure 10.21
Salts
Urea (most mammals)
Uric acid (birds, reptiles, Dalmatian dogs,
humans)