FOUNDATION STUDIES PROGRAMME BIOLOGY LABORATORY 2

FB 1031

DIGESTIVE SYSTEM & RESPIRATORY SYSTEM

Prepared by: Name : Siti Sarah RosliMatriculation number : FIS 1505-5784Group : 10AInstructor : Sir Mahathir Mohamed Azahari

Rat Dissection

In this experiment, the anatomy of the rat will be examined in detail. The rat is a vertebrate mammal, which means that many aspects of its structural organization are common with humans. The similarity of structures among related organisms shows evidence of common ancestry. In a way, studying the rat is like studying a human. As the leading theme of this lab observe every structure in the rat, there is an equivalent structure in your own body

INTRODUCTION

The digestive system is responsible for obtaining and processing food for the all of the cells in an organism. Structurally it is closely associated with the respiratory system and usually these two system will be studied together. Each system is composed of a series of tubular structures through which materials pass. In the case of the digestive system the raw materials are food particles that are broken into simple molecules as they pass through the system. Material that is not broken down is removed from the system. In the case of the respiratory system the major materials moving through it are oxygen and the waste product carbon dioxide.

The digestive and respiratory system share some common spaces. The digestive system is composed of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum and anus. There are also a number of glands that lie outside the system that contribute to its function. These include the salivary glands, liver and pancreas. The respiratory system is composed of the mouth or external nares, the pharynx, glottis, trachea, bronchi, bronchioles and alveoli. The latter three structures are in the lung.

OBJECTIVE

• Identify the organs of the digestive system of rat• Label the structure of digestive system• Define the terms used to described general planes,

surfaces and anatomy of vertebrae• Identify external mammalian feature of male and female

rat • Identify the organs of the respiratory system of rat• Label the structure of respiratory system

Rat Internal AnatomyBe careful not too cut to deeply keep the tip of your scissors pointed upwards.

Do not damage the underlying structures.

• Pin the rat down by placing the rat ventral side up.• Lift the abdominal skin with a forceps, and cut through it with the scissors.

Close the scissor blades and insert them under the skin. Moving in a cephalic direction, open and close the blades to loosen the skin from the underlying connective tissue and muscle.

• Once this skin-freeing procedure has been completed, cut the rat along the body midline, from the pubic region to the lower jaw.

• Make a lateral cut about halfway down the ventral surface of each limb. Complete the job of freeing the skin with the scissor tips.

• Pin the flaps to the tray.• Notice that the muscles are packaged in sheets of pearly white connective

tissue called fascia, which protect the muscles and bind them together.• Carefully cut through the muscles of the abdominal wall in the pubic region,

avoiding the underlying organs. To do this, hold and lift the muscle layer with a forceps and cut through the muscle layer from the pubic region to the bottom of the rib cage, in a similar way you did with the skin.

PROCEDURE

Ventral view of a female rat.Dashed line indicate incisions for removing the skin

MATERIAL / APPARATUS

MATERIAL / APPARATUS

• Lab rat• Dissecting tray• Dissection scissors • Dissecting needle• foreceps• probe• Magnifying glass• Scalpel• Plastic bag• Mask• paper towel • latex glove

RESULT

SpleenColon

Mouth

Anus Rectum

Large IntestineCaecum

Liver

Small intestine

Stomach

Lung Heart

trachea

heart

lung

esophagus

liver

stomach

DISCUSSION

Rat External Anatomy

The rat's body is divided into six anatomical regions:

• cranial region - head• cervical region - neck• pectoral region - area where foreleg (front) legs attach• thoracic region - chest area• abdomen - belly• pelvic region - area where the hind (back) legs attach

External mammalian FeatureMale Rat Female Rat

Anatomy Glossary of Terms• Proximal: near to the point of reference• Distal: far from the point of reference• Caudal: toward the tail end• Pectoral: relating to the chest and shoulder region• Pelvic: relating to the hip region• Dermal: relating to the skin• Longitudinal: lengthwise• Right & Left: refers to the specimen's right and left, not

yours• Abdominal Cavity: related to the area below (posterior)

the ribcage• Thoracic Cavity: related to the area above (anterior) the

ribcage

• Dorsal : toward the back• Ventral : toward the belly• Lateral : toward the sides• Median : near the middle• Anterior: toward the head• Posterior: toward the hind end (tail)• Superficial: on or near the surface• Deep : some distance below the surface• Sagittal : relating to the midplane which

bisects the left and right sides• Transverse: relating to the plane separating

anterior and posterior• Horizontal: relating to the plane separating dorsal

and ventral

DIGESTIVE SYSTEM

Structure Function

Mouth(oral cavity) Initial processing of food.

Pharynx Nasopharynx Oropharynx Laryngopharynx

Pathway for only airPathway for air and food Point where food meets air that has entered through the nose

Esophagus Connects the pharynx and stomach.

Stomach

Produces mucus, hydrochloric acid, and pepsin (a protease). Together they initiate the breakdown of proteins. The highly acid stomach deactivates the salivary enzymes that were initiating the breakdown of carbohydrates.

Pyloric valve Regulates movement of material out of the stomach

Small intestine (duodenum jejunum , ileum)

Receives ducts from gall bladder and pancreas. Breakdown of fats, carbohydrates and proteins is completed in this organ.

Major structures of the digestive system listed in sequence.

Structure Function

Caecum

A large blind pouch located between the small intestine and the colon. It contains bacteria that produce cellulase, which facilitates the breakdown of the cellulose found in plant material. Breakdown products are then absorbed into the bloodstream. Since rat mainly eat food that has source from plant, therefore their caecum is bigger

Colon(ascending, transverse, descending) Reabsorption of ions and water and production of mucus to lubricate material as it passes towards the rectum.

Rectum A muscular portion of the digestive tract that completes water reabsorption.

Anus Controls the removal of feces

Structures accessory to the digestive tractStructure Function

Liver Processes glucose and stores it as glycogen, detoxifies other products delivered by the circulatory system, and produces bile.

Bile Duct

Transports bile from ducts in the liver to the deuodenum. Bile helps neutralize the partially digested material entering the deuodenum and the bile salts help to emulsify fats. In humans the bile is stored in the gal bladder before transport to the deuodenum.

Pancreas

Lies in the mesentary near the deuodenum and stomach. This gland produces enzymes responsible for protein digestion. It is also an endocrine organ that releases insulin and glucagon into the circulatory system to regulate blood glucose levels.

SpleenThis organ is responsible for the production of lymphocytes and the breakdown of old red and white blood cells.

RESPIRATORY SYSTEM

RESPIRATORY SYSTEM

Upper respiratory tract:

• This includes the nose, mouth, and the beginning of the trachea (the section that takes air in and lets it out).

Lower respiratory tract:

• This includes the trachea, the bronchi, broncheoli and the lungs (the act of breathing takes place in this part of the system).

• The organs of the lower respiratory tract are located in the chest cavity. They are delineated and protected by the ribcage, the chest bone (sternum), and the muscles between the ribs and the diaphragm (that constitute a muscular partition between the chest and the abdominal cavity).

Structure Function

Trachea the tube connecting the throat to the bronchi.

Bronchi the trachea divides into two bronchi (tubes). One leads to the left lung, the other to the right lung. Inside the lungs each of the bronchi divides into smaller bronchi.

Broncheoli The - the bronchi branches off into smaller tubes called broncheoli which end in the pulmonary alveolus.

Pulmonary alveoli

– tiny sacs (air sacs) delineated by a single-layer membrane with blood capillaries at the other end.

The exchange of gases takes place through the membrane of the pulmonary alveolus, which always contains air: oxygen (O2) is absorbed from the air into the blood capillaries and the action of the heart circulates it through all the tissues in the body. At the same time, carbon dioxide (CO2) is transmitted from the blood capillaries into the alveoli and then expelled through the bronchi and the upper respiratory tract.

The inner surface of the lungs where the exchange of gases takes place is very large, due to the structure of the air sacs of the alveoli.

Lung

a pair of organs found in all vertebrates.

The structure of the lungs includes the bronchial tree – air tubes branching off from the bronchi into smaller and smaller air tubes, each one ending in a pulmonary alveolus.

• Wear glove to maintain hygienity of hand• use Blunt- ended apparatus as blunt-ended forceps and

needles were the most effective and least hazardous for the process

• Be careful not too cut to deeply • keep the tip of scissors pointed upwards to make sure

not to damage the underlying structures.

PRECAUTIONARY STEP

CONCLUSION

Digestive and respiratory system of rat had been identified to be slightly similar with human digestive and respiratory system . The respiratory system of rat is exactly the same with the respiratory of human. Besides, all the digestive organ of rat is the same as human's digestive but only have a difference on the size of caecum.Therefore , rat is a good model for human anatomy and this experiment has exposed students to the internal system of digestive and respiratory practically. Last but not least, precautionary step had been taken during the experiment to ensure the successfulness of this dissection.

REFERENCES

• Digestive system. (2016, July 2010) Retrieved from

http://biology.kenyon.edu/courses/biol10/110pdfs/10Digestive.pdf

• John R. Sowash (2016, May 2009) Rat Dissection.Retrieved from

https://jrsowash.wikispaces.com/file/view/rat.student.pdf