Discuss the role of major body systems of small animals

Objective 5.01

Basic Anatomy terminology for small animals

• Cheek- the fleshy side of the face below the eye and above and to the side of the mouth

• Dewlap- the loose fold of skin under the chin of an animal, most prominent in female rabbits

• Elbow- the upper joint of the front leg just below the shoulder

• Flank- the fleshy part of the side between the ribs and the rump (croup)

• Foot pad- the part of the foot that the animal walks on• Forearm- the part of the front limb just below the elbow

Basic Anatomy terminology for small animals

• Guard hairs- the longer, coarse hairs above the shorter under-fur of an animal that protects the animal and under-fur from rain and cold

• Hock- the tarsal joint or large joint halfway up the hind limb

• Muzzle- the projecting jaw that contains the nose and mouth in some animals

• Nose pad- the tip of the nose that may be sensitive and useful for investigating food, water, or unfamiliar objects (called nose leather in cats)

• Rump- the upper rounded part of the hindquarter (also called the croup)

Basic Anatomy terminology for small animals

• Shoulder- the part of an animal’s body just above the elbow of the foreleg• Stifle- the joint next above the hock in the

hind leg of a four footed animal• Thigh- the hind limb extending from the

rump to the hock• Whiskers- the long projecting hairs or bristles

growing near the mouth of an animal

Basic Anatomy terminology for birds

• Crown- the topmost part of the head• Ear covert- the feathers covering the ears• Mandible- the upper or lower segment of

a bill of a bird• Nape- the back of the neck• Orbital ring- a ring encircling the eye of

many birds

Basic Anatomy terminology for fish, Amphibians, and Reptiles

• Brille- the transparent layer permanently covering the eye that serves as the eyelid for snakes

• Fins- the web of skin supported with bone or cartilage rods that enable a fish to move through the water

• Gills- The major organ of the respiratory system of fish that allows them to breath without lungs

• Scales- extensions of the epidermal layer of skin that have been modified to provide protection. (Fish and reptiles may have some type of scales)

• Scutes- epidermal scales found on turtles

Skeletal Anatomy

• Skeletal System- Bones– Axial skeleton- vertebral column, ribs, sternum, and

skull– Pectoral limb- front limbs including shoulders, legs

and feet. Bones are scapula(shoulder blade), humerus (arm), radius and ulna (forearm), carpals, metacarpals and phalanges (toes)

– Pelvic limb- rear legs and pelvic bones including hooks, pin bones, femur (upper leg bone), tibia and fibula (lower leg bones), tarsals (hocks), metatarsals (feet), and phalanges (toes)

Skeletal system-Structure and Purpose

• Purposes- protect vital body organs and give form or shape to body–Skull protects brain, ribs protect lungs and

internal organs–Spinal column or backbone protects the spinal

cord and provides shape to the animal• Structure consist of bones, cartilage and

joints

Birds have some unique bones unlike mammals

–Most birds have a skull bone that elongates toward the front of the head– Some birds have a skull with an upper beak

fused to it while other birds have hinged on both upper and lower (mandibles) giving it more flexibility

Internal Anatomy• Heart- major organ in the circulatory system–Made up of 3 muscle layers myocardium- second

layer muscle that makes up the thickness of the heart, endocardium- thin layer inside myocardium, and epicardium- thin cover over the myocardium–Other parts of the circulatory system are the arteries,

capillaries, veins and blood. They all move nutrients, metabolic waste, and oxygen around. Another important role of the circulatory system plays is protection against microbes and injury.

Internal Anatomy• Kidneys and bladder-part of the excretory

system that rids the body of waste. In addition, the kidneys maintain chemical composition, volume of blood, and tissue fluid

• Stomach and intestines- major part of digestive system, which breaks the food down into smaller pieces to be used by the body. Nutrients are gleaned from these food materials

Internal Anatomy• Lungs- part of the respiratory system

where the oxygen is taken in by the nose, passed on to the lungs and then goes into the blood• Brains, spinal cord, and nerves make up

the nervous system. The coordinator of all body activities, regulates other systems, and controls memory and learning.

Internal Anatomy• Ovaries (female) and testes (male) make

up the reproductive system to produce new individuals of the same species. Ovaries produce eggs and testes produce sperm• Muscles make up the muscular system

that gives the body its movement, posture, support, and produces heat

Digestive system• Non-ruminants are referred to as single-stomached or

mono-gastric animals• The digestive system of rabbits and birds are classified

as non-ruminants even though their system is slightly different– Rabbits have a digestive system similar to a horse in that they have

a large cecum (place where small and large intestines join) with bacteria present• Therefore, rabbits can eat more high-quality roughage material than

other small animals and convert them to nutrients• Rabbits must maintain levels of bacteria in the cecum for digestive

process and health. Rabbits eat undigested feces (coprophagy) to help bacterial action

Digestive System• Birds have a unique system for breaking

down the seed and food they eat–Birds do not have teeth. Saliva is added to

assist with swallowing, but very little breakdown of food occurs in the mouth– The largest organ is the ventriculus or

gizzard. The gizzard grinds and crushes food before passing it into the small intestine

Digestive Process• Food is broken down in the mouth (except

birds), stomach (gizzard in birds), and then passed into the small intestine, the primary site for digestion and absorption of carbohydrates, fats and proteins

• Undigested food passes from the small intestine into the large intestine where the main activity is the absorption of water from the undigested food and addition of lubricating mucus to aid in passage of waste

Digestive Process• Digestive systems of FISH vary somewhat– Type of feed fish eat is largely determined by the

type of teeth they have– Some fish swallow prey whole while others chew

up their food

Reproduction in small animals• Sexual reproduction is the union of egg and sperm to

produce a new animal– Two parents required: male furnishes sperm (spermatozoa or male animal

sex cell) and female supplies egg or ovum (female sex cell)– Natural insemination is the process of male depositing semen into female

reproductive tract• Sexual Terminology

– Conception- creation of new life by fertilization of an egg– Estrus is the heat period when female is receptive to male and will stand

for mating– Fertilization is the union of the egg and sperm– Gestation- period of pregnancy that begins with conception and ends with

parturition – Ovulation- releasing an egg for fertilization– Parturition- process of giving birth to young– Pregnant- stage of baby development in reproductive tract

Female reproductive anatomy• Ovary- primary reproductive organ produces the egg (female

gamete)• Gamete- sex cell that unites with other sex cells• Embryo (developing young) goes to the uterus in mammals

after 3-5 days• Uterus- the place of embryo growth and development• The cervix is the part of the uterus that contains rings and

cervical mucus to seal the uterus to keep out contaminants during pregnancy

• The vagina is the reproduction passageway and place of urine excretion

• The vulva is the external opening to the reproductive tract

Male reproductive anatomy• Testicle- primary reproductive organ and

produces the male gametes (sperm)• Two testicles are held externally in the

scrotum or sac that helps control the temperature so that the testicles remain cooler than the body

• Sheath- a fold of skin that is a protective covering for the penis

Gestation length• Cats- 51-65 days• Dogs- 56-70 days• Rabbits- 30-32 days• Hamsters- 16 days• Gerbils- 24-26 days• Rats/Mice- 21-24 days• Guinea pigs- 56-74 days• Ferrets- 42 days

General Characteristics of Gestation

• Gestation is usually identified by an increase in the female’s breast and abdominal size, weight, and appetite at various stages of the gestational period

• Restlessness is a usual sign that the gestation period is coming to an end and parturition (birthing) is about to take place.

• A nesting box of straw, shavings, paper, etc. may be provided for pocket pets and rabbits. Care should be taken not to excite animals at birthing as most do not need assistance.

• Dogs and cats should be given a birthing box in a quiet location one to three weeks prior to parturition so that they may get comfortable with the setting.