1. Animal, Plant & Soil Science
Lesson C2-4
The Integumentary, Muscular, and
Urinary Systems

2. Interest Approach
Begin by asking students if they have ever eaten muscle tissue. Show students a piece of raw meat, and ask them to identify the type of muscle (or even the animal the meat came from). Most students eat meat, but the thought of raw muscle tissue is not very appetizing. Lead into a discussion of the skin, muscle, and urinary systems of livestock animals.

3. Objectives
Explain the integumentary system, and describe the two layers of skin.
Examine the muscular system, describe the three types of muscle tissue, and explain how muscles contract to create movement.
Describe the creation and utilization of energy for muscle contractions.

4. Objectives
Identify common muscles found in livestock and companion animals.
Identify components of the urinary system, examine its role, and describe the function of the kidneys, ureters, urinary bladder, and urethra.

5. Terms abdominal obliques actin adenosine triphosphate aerobic
anaerobic
biceps brachii
biceps femoris
bladder
cardiac muscle
dermis
epidermis
gluteals
integumentary system
keratin
kidney
lattisimus dorsi
masseter

6. Terms myosin pectorals sebaceous glands serratus ventralis
skeletal muscle
tendon
trapezius
triceps brachii
urea
ureters
urethra
urine

7. What is the integumentary system, and what are the two layers of skin?
The integumentary system (skin) is the largest organ of the body.
Its main function is to protect the body from foreign substances, such as bacteria, but it also keeps fluids and nutrients in the body.
In addition, the integumentary system helps regulate body temperature through hair, fur, and/or sweat glands.
Directing blood flow to and from skin can also regulate body temperature.

8. What is the integumentary system, and what are the two layers of skin?
Skin consists of two layers: the epidermis and the dermis.
The epidermis is composed of hard, flattened dead cells.
Beneath the epidermis are larger cells that are living.
Larger and more round cells are found in the deeper layers of skin.
At the bottom layer, new cells are growing and pushing toward the surface.
As cells are pushed toward the surface, they become flattened and lose most of their water content.

9. What is the integumentary system, and what are the two layers of skin?
A. The epidermis is the outer layer of epithelial cells.
It is the protective layer of skin, but it is also the thinnest skin layer.
The epidermis produces hair, nails, beaks, and feathers.
The skin of all mammals is covered with hair.
Sweat glands are found in the epidermis of many animals.
In addition, keratin is produced in the epidermis.
Keratin is a fibrous protein used to produce horns, hooves, nails, hair, feathers and the outer sheath of beaks and claws.

10. What is the integumentary system, and what are the two layers of skin?
B. The dermis is the thick and sturdy inner layer of skin that is composed of dense connective tissue.
The dermis contains lymph and blood vessels, nerves, muscle cells, sweat and sebaceous glands, and hair follicles.
The sebaceous glands secrete oily substances that lubricate the hair and skin.
The dermis layer composes about 90 percent of the skin’s thickness, which varies with species, breed, sex, and body location.
For example, skin is thinnest in the eyelids and thickest at the soles of the feet.

11. What is the integumentary system, and what are the two layers of skin?

12. In addition, muscles can be classified as voluntary or involuntary.
What is the muscular system, what are the three types of muscle tissue, and how do muscles contract to create movement?
The muscular system creates bodily movement, maintains posture, and produces heat.
It consists of three types of muscle tissue: skeletal, smooth, and cardiac.
In addition, muscles can be classified as voluntary or involuntary.
Voluntary muscles are under the control of the animal; involuntary muscles are not.

13. What is the muscular system, what are the three types of muscle tissue, and how do muscles contract to create movement?
A. Skeletal muscle, or striated voluntary muscle, contracts to produce bodily movement.
Skeletal muscles are the largest component of red meat animal products and are usually attached to bones by tendons.
A tendon is connective tissue that attaches muscle to bone.
Movement is made possible when muscles shorten.
A muscle shortens because its cells are shortening, and a muscle cell shortens because basic units of contraction within the cell (sarcomeres) are shortening.

14. Sarcomeres contain two types of protein filaments: myosin and actin.
What is the muscular system, what are the three types of muscle tissue, and how do muscles contract to create movement?
Sarcomeres contain two types of protein filaments: myosin and actin.
Myosin is a thick filament, and actin is a thin filament.
During muscle contraction, the actin filaments slide past the myosin filaments, causing the sarcomere to shorten.
A muscle consists of thousands of muscle fibers, or muscle cells, in bundles.
An entire muscle fiber is called a myofiber, and the sarcomeres are found within the myofibers.

15. What is the muscular system, what are the three types of muscle tissue, and how do muscles contract to create movement?
B. Smooth muscle, or unstriated involuntary muscle, is located in reproductive, digestive, and urinary organs.
The contraction of smooth muscle is involuntary and is necessary for proper functioning of internal organs.
For example, smooth muscle contractions in the intestines permit the movement of food products.

16. C. Cardiac muscle is striated muscle found only in the heart.
What is the muscular system, what are the three types of muscle tissue, and how do muscles contract to create movement?
C. Cardiac muscle is striated muscle found only in the heart.
Contraction of the cardiac muscle is involuntary and is essential for proper blood circulation.

17. What is the muscular system, what are the three types of muscle tissue, and how do muscles contract to create movement?

18. How is energy created and utilized for muscle contractions?
All cells require adenosine triphosphate (ATP).
ATP is an energy source for cells; ATP is broken down into adenosine diphosphate (ADP) and a phosphate radical, releasing energy.
In muscle cells, ATP provides the energy for muscle contractions.
At the beginning of muscle contractions, the cells only have small amounts of ATP and, therefore, must rely on aerobic (in the presence of oxygen) and anaerobic (in the absence of oxygen) reactions to supply further ATP.

19. How is energy created and utilized for muscle contractions?
A. A quick but short-term source of ATP is available from creatine phosphate, which is a storage form of high-energy phosphate.
An enzyme transfers phosphate from creatine phosphate to ADP to create ATP in an anaerobic reaction.
Once all of the creatine phosphate is depleted, mitochondria should be producing enough ATP for muscle contractions.
If that is not the case, a temporary anaerobic source is made through a fermentation process that breaks down muscle glycogen into lactic acid and produces ATP.

20. How is energy created and utilized for muscle contractions?
B. During moderate exercise, aerobic respiration can typically provide the necessary ATP for muscle contractions.
The muscle cell receives its energy from glucose from the bloodstream and from the breakdown of glycogen in cells.

21. What are the common muscles found in livestock and companion animals?
Many muscles can be found that are common to livestock and companion animals.
Knowledge of these muscles is important to an effective health care and production management plan.
A. The masseter is the superficial muscle of the cheek that aids in chewing and biting movements.
B. The trapezius is the superficial, triangular muscle of the shoulder that helps move front appendages.

22. What are the common muscles found in livestock and companion animals?
C. The latissimus dorsi is a long muscle that connects the humerus bone of the forearm to the back of the animal.
D. The abdominal obliques are large muscles that run along the sides of the animal and help support the internal organs of digestion and reproduction.
E. The gluteals are the large muscles in the upper hind quarter region of the animal that aid in rear leg movement.

23. What are the common muscles found in livestock and companion animals?
F. The biceps femoris is a large muscle found in the rear leg of an animal.
G. The biceps brachii is the muscle responsible for the flexing of the front legs (elbow joint) of an animal.
H. The triceps brachii is the muscle responsible for the extension of the front legs (elbow joint) of an animal.

24. What are the common muscles found in livestock and companion animals?
I. The pectorals are large muscles that run across the chest of the animal and are responsible for the primary movement of the front legs.
J. The serratus ventralis are muscles that connect the forelimbs (or front legs) to the trunk of the animal.

25. What are the components and role of the urinary system
What are the components and role of the urinary system? What are the functions of the kidneys, ureters, urinary bladder, and urethra?
The urinary system is probably one of the most underappreciated organ systems in the animal body.
Without the removal of wastes from the bloodstream, the accumulation of toxins would quickly poison the body, causing sickness and eventually death.
The role of the urinary system is to filter the blood and rid the body of excess nitrogen, which is a byproduct of cellular functions.

26. The solution of ammonia in water is called uric acid (urea).
What are the components and role of the urinary system? What are the functions of the kidneys, ureters, urinary bladder, and urethra?
This nitrogen is commonly bound with hydrogen to create ammonia, which dissolves in water.
The solution of ammonia in water is called uric acid (urea).
This urea is excreted as a white paste in birds in order to conserve water.
In most mammals, however, urea is mixed with more water and excreted as urine.

27. What are the components and role of the urinary system
What are the components and role of the urinary system? What are the functions of the kidneys, ureters, urinary bladder, and urethra?
There are four main components of the urinary system: kidney, ureter, bladder, and urethra.
A. The kidney is the organ responsible for filtering wastes from the blood.
There are two kidneys working together to filter wastes while reabsorbing water back into the bloodstream.
B. The ureters are muscular tubes that use a contracting action to move urine from the kidneys to the bladder.

28. What are the components and role of the urinary system
What are the components and role of the urinary system? What are the functions of the kidneys, ureters, urinary bladder, and urethra?
C. The bladder is a holding sac for the temporary storage of urine before it is expelled from the body.
The bladder has a muscular lining that can contract to expel the urine.
The bladder will indicate a feeling of “fullness” when it is actually half full of urine.
D. The urethra is the tube that carries the urine from the bladder to outside of the animal body.

29. Review
What is the integumentary system, and what are the two layers of skin?
What is the muscular system, what are the three types of muscle tissue, and how do muscles contract to create movement?
How is energy created and utilized for muscle contractions?

30. Review
What are the common muscles found in livestock and companion animals?
What are the components and role of the urinary system? What are the functions of the kidneys, ureters, urinary bladder, and urethra?