The Exterior, Nervous, Urinary, and Endocrine Systems of Domestic Animals Animal Science IMS 8646-F

Introduction An agricultural producer should be knowledgeable of that A&P of livestock. We will discuss 4 systems throughout these notes.

Nervous System Consists of two major parts: The Central Nervous System (CNS) Brain Spinal Cord The Peripheral Nervous System (PNS) Somatic Nerves Nerves that control voluntary movements Autonomic Nerves Nerves that control involuntary actions like the heart, intestines, and glands

CNS

PNS

Functions of the Nervous Sys. 1. To organize physical movement 2. Respond to the actions of all the senses, either internal or external

Nerves Consists of 2 parts: Neuron = nerve cell Axon = long fiber Dendrites = branched

Synapse Point at which the dendrite connects to the axon

Parts of the Brain Cerebrum Cerebellum Pons & Medulla Oblongata Largest part, relative to body size in smarter animals In charge of thinking process, reacts to sense stimuli Cerebellum Coordinates messages for transmission to the body Controls muscle performing activities, if damaged incoordination may result, but not paralysis Pons & Medulla Oblongata Together control reflex actions i.e. blinking, vomiting, breathing, swallowing Independent

Cow’s Brain

Sheep and Pig’s Brain

Human Brain

Spinal Cord The main avenue for message transferals Divided into 5 segments: what are they?

External Anatomy Skin is the largest organ! Hair, wool, horns, feathers, toenails, and hooves are modified extensions of the skin What is cloven hooves?

Functions of Skin To protect against disease and infection and to regulate body temperature. Contains glands for secretion and excretion and sensory nerves to help animals react to their environment.

Skin

Consist of two layers: Epidermis Dermis Outer layer of the skin and contain no blood cells Dermis Inner layer of the skin and contains blood vessels, lymph vessels, nerves, glands, hair follicles, and muscle fibers

Primary Glands Sweat glands Sebaceous glands Secrete oily substances to lubricate the skin and hair

Sweat Gland

Sebaceous gland

Urinary System Consists of: Kidneys Ureters Bladder Urethra

Kidneys Located in the abdominal cavity just under the lumbar vertebrae Consists of: Renal cortex = outer portion Renal medulla = inner protion

Kidneys

Functions of kidneys 1. Filter waste products form the blood 2. Regulate blood composition

Ureters Are tubules that connect the kidneys with the bladder and transport urine from to bladder as well.

Bladder An expandable sac that stores the urine until it is expelled from the animal’s body

Urethra Elastic tubule that carries urine from the bladder outside the body Chickens don’t have one.

Endocrine System Many cells in the animals body rely on the interaction of chemical substance that are secreted by the endocrine glands. The glands are small and located in various parts of the body. They secrete hormones into the bloodstream.

Pancreas In females releases oxytocin and that causes an immediate release of milk in lactating females

Hormones After being secreted in the bloodstream they perform specific duties including growth, fattening, reproduction, lactation, and egg laying. The animal production depends on the level of the correct hormones.

Pituitary gland Master Gland Anterior pituitary Controls hormones If removed the animal will not grow or reproduce. The other glands will then shrink and stop functioning.

Hypothalamus Located above the pituitary gland and regulates the functions. Hormones produced here are transported by means of portal blood vessels

Thyroid Located on either side of the trachea. Produces Thyroxine Controls growth and energy production. Calcitonin a hormone produced by the thyroid controls blood levels of calcium and bone density.

Vocabulary Terms Autonomic Nerves Hormones Somatic Nerve Glands