ANIMAL HUSBANDRY I

Learn about Animal Physiology and Anatomy

Lesson Structure

There are 11 lessons in this course:

1. Introduction, cells and tissues
2. The Digestive System
3. The Circulatory System
4. The Urinary System
5. The Nervous System
6. Respiration
7. The Reproductive System
8. Muscles and Meat
9. The Skeleton
10. Animal Growth, Development, and the Endocrine System
11. Comparing Different Animals

Aims

• Explain the structure of animals, including bones, organs, cells and tissues.
• Explain the digestion of animals.
• Explain the circulatory system of animals.
• Explain the structure and function of the animal urinary system.
• Explain the nervous system of animals.
• Explain the respiratory system of animals.
• Explain the animal reproductive system.
• Explain the muscular system in animals.
• Explain the skeletal system of a typical mammal.
• Explain biological mechanisms underlying the growth and development of animals.
• Explain the endocrine system of animals.
• Explain differences between different types of animals, in terms of both structure and function.

Learn about Animal Structure and Function.

Learn what the different parts of a body are their structure and purpose, and how they all interact to function as one whole animal. 

Understanding this is the foundation for understanding animal health and well being; and knowing how to manage animals whether pets, wildlife or livestock on a farm.

Every animal body is made up of different types of tissues.

 There are two types of tissue in the body – epithelial tissue and connective tissue. Epithelial tissue can be found anywhere in the body where two different environments meet. Its functions are protection, secretion, absorption, and transport.

Connective tissue is a diverse tissue type and encompasses blood, bone, adipose tissue and connective tissue proper. It has a range of functions which depend on the tissue in question. Further detail connective tissue is not covered in this module; however, the integumentary system is comprised of both. 

In mammals, the skin is the largest organ of this system and is made up of multiple layers of tissue. These tissues are organised into two layers - the epidermis and the dermis. These two layers sit on the hypodermis, a layer of connective tissue lying deep in the dermis.  

Epidermis

The epidermis is comprised of four or five layers of tissue, dependent on their location.
These layers are:

• Stratum corneum
• Stratum lucidum (only in areas of thick skin, such as soles of the feet in humans and  foot pads in dogs)
• Stratum granulosum
• Stratum spinosum
• Stratum basale

About 95% of cells in the skin are keratinocytes. These cells are produced constantly, migrate to the surface, die and are worn away, being replaced by newly-produced cells. The life of a keratinocyte is about 7 to 10 days from production to attrition.

Dermis

The dermis is divided into two regions - the papillary region and the reticular region. Loose areolar connective tissue comprises the majority of the papillary region. Fingerlike projections called papillae extend from this region into the epidermis, giving a much larger area for absorption of nutrients and immune surveillance between the external and internal environment. It also acts as an anchor between the two skin sections, creating a more secure attachment.

The reticular region is situated deep to the papillary region. It is composed of dense irregular connective tissue and has been named for its concentration of collagenous, elastic, and reticular fibers woven through it. These fibers give the dermis elasticity, strength and extensibility. 
The roots of the hair, sebaceous and sweat glands, receptors, nails, and blood vessels are also located within the reticular region and the hypodermis.

Claws, Nails and Spurs

Claws are keratinized structures which wrap around the bones at the end of digits and have been adapted to assist with the catching and holding of prey. Similar structures which are not sharp are referred to as nails and structures such as this found on other parts of the body are known as spurs.

These structures have a hard tip, upper and lateral surface (known as the unguis) and a soft underside (the subunguis). The unguis is the external layer, and consists of keratin fibers arranged in a direction perpendicular to that of growth and in oblique layers. The subunguis is soft and flaky, and the grain runs parallel to the direction of growth. 

Nails consist of a hard outer layer and a soft cuticle in the center housing a nerve and a blood vessel. The cuticle may also be referred to as the "quick". 

On light-colored nails, the quick is easy to see. However, many animals have black or dark nails, making seeing the quick difficult. Regardless of the color, nail anatomy remains the same. When trimming nails, the best place to cut is 2-3 millimeters from the quick. If the quick is cut, the nail will bleed and the animal will feel pain. This is important to remember when trimming and grooming nails etc.

Claws, nails and spurs grow outward from a structure known as the nail matrix. This structure lies at the base of the unguis. The subunguis grows thicker and travels across the nail bed. The unguis grows at a faster outward rate than the subunguis and results in a curve.  A sharp point is produced by the thinner sides of the claw wearing away faster than their thicker middle.

Hair

All mammals have hair on their skin to some degree and it is a distinct mammalian feature. This includes marine mammals which at times appear to be hairless. 

A cross section of a hair reveals two or three layers. The ‘core’ of the hair is called the cortex. This contains the pigment of the hair. The outside layer is called the cuticle. This layer is a set of microscopic overlapping scales. The size, shape and pattern of these scales differ between species and breeds to the point where an individual hairs may be identified by the cuticle pattern. Some hairs may also have a medulla, which may be described as an area of dead cells and air spaces.

Hair has attachments to nerves and muscles. The tiny smooth muscles which are attached to the hair make the hair stand up when contracted. This accounts for goose-pimples in humans. It is also the mechanism for our hair standing on end and animals puffing up their coats when cold. Contraction of these papillary muscles and the subsequent increase in the density of the coat creates an insulation effect and assists to conserve heat in furred animals.

Fur is dense hair. It augments the insulation qualities of the skin but can also act in other roles, such as secondary sexual characteristics or as a camouflage tactic. 

WHO SHOULD DO THIS COURSE?

• Anyone who wants to better understand animals in order to properly care for them
• Hobby farmers, farm managers, farm workers
• Animal owners or carers - people who work in animal health or welfare,
• Students of agriculture, or anyone with a passion for animals