Lab 7: Introduction to Rat Dissection, Digestion, Gas Exchange & Nutrition

Dissecting

To expose to view.

Scalpel

A tool used to make initial cuts through epidermis or to excise an organ.

Scissors

The primary cutting instrument used in dissection.

Forceps

A tool used for manipulation and lifting structures.

Blunt probe

A tool used for lifting, pushing, freeing, tracing, and feeling.

Teasing Needle

A tool useful for careful punctures or when a sharp point is necessary.

Cranial region

The head region of the rat.

Cervical region

The neck region of the rat.

Pectoral region

The area where the front legs attach.

Thoracic region

The chest area of the rat.

Abdominal region

The belly area of the rat.

Pelvic region

The area where the back legs attach.

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 mid-plane which bisects the left and right sides.

Transverse

Relating to the plane separating dorsal and ventral.

Frontal

Relating to the plane separating dorsal and ventral.

Proximal

Near to the point of reference.

Distal

Far from the point of reference.

Caudal

Toward the tail end.

Cranial (anatomy)

Toward the head.

Pectoral

Relating to the chest and shoulder region.

Pelvic

Relating to the hip region.

Dermal

Relating to the skin.

Longitudinal

Lengthwise.

Right and Left

Refers to the specimen’s right and left, not yours.

Abdominal Cavity

Related to the area below the diaphragm.

Thoracic Cavity

Related to the area above the diaphragm.

Vibrissae

Sensory hairs (whiskers) used in vital processes in nocturnal rats.

Pinna

The external part of the ears.

Nares

Used to sense chemicals in the air (smell).

Eyes

Large pupils relative to body size.

Nictitating membrane

Found in the inside corner of the eye for protection.

Manus

Forefoot of the rat.

Pes

Hindfoot of the rat.

Digitigrades

Animals that walk with the heel elevated off the ground (e.g., rats).

Plantigrade

Animals that walk with heel and digits resting on the ground (e.g., humans).

Urinary aperture

Posterior to the last pair of teats.

Vaginal orifice (Vulva)

Situated behind the urinary aperture.

Mammea

Refers to mammary glands; females have 12.

Scrotal Sacs

Contain testes in male rats.

Prepuce

Anterior to scrotal sacs, bulge of skin surrounding the penis.

Urogenital orifice

End of penis where urine and sperm exit.

Dental formula for rat

1 0 0 3 x2 = 16 (for incisors, canines, premolars, and molars).

Epiglottis

Gate-like structure preventing food from entering the lungs.

Peristalsis

The wave-like movements throughout the digestive tract.

Salivary Glands

Glands in the rat that produce saliva.

Parotid Glands

Large, thin glands located between ear, shoulder, and lower jaw.

Mandibular Gland

Large, oval gland lying ventral to the parotid gland.

Sublingual Gland

Small gland overlying the mandibular gland.

Lymph nodes

Circular glands lying anterior to the salivary glands, pressed against jaw muscles.

Extraorbital lacrimal gland

Flat, spleen-shaped gland below the ear.

Buccal Cavity

Contains the oral cavity and teeth.

Esophagus

Soft, muscular tube on the dorsal surface of the trachea.

Greater Curvature (of stomach)

Outer margin of the stomach.

Lesser Curvature (of stomach)

Inner margin of the stomach.

Fungus (of stomach)

Blind sac extension to the left of the cardiac region.

Pylorus (of stomach)

Thickened area near the junction with the small intestine.

Greater omentum

Sac extending from the greater curvature used for fat storage.

Duodenum

First section of the small intestine where chyme enters.

Ileum

Part of the small intestine where water and nutrients are absorbed.

Jejunum

Part of the small intestine for further digestion and absorption.

Pancreas

Gland producing insulin and enzymes to break down food.

Liver functions

Produces bile and aids in digestion.

Caecum

Sac for fermentation of fibrous plant material.

Ascending colon

Part of the large intestine that moves upward.

Transverse colon

Part of the large intestine that moves across.

Descending colon

Part of the large intestine that moves downward.

Defecation

The process of excreting waste from the anus.

Trachea

Long tube composed of cartilaginous rings.

Bronchial tubes

Branches from the trachea entering the lungs.

Larynx

Protrusion toward the cranial end of the trachea, known as the voice box.

Alveoli

Tiny air sacs in the lungs where gas exchange occurs.

Negative breathing

Breathing mechanism where the lungs expand through negative pressure.

Parietal Pleura

Covers the outer layers of the chest wall.

Intercostal muscles

Muscles between ribs that assist in lung respiration.

Tidal Volume (TV)

Amount of air inhaled or exhaled with each breath (500mL).

Inspiratory reserve volume (IRV)

Amount of air that can be forcefully inhaled after a normal tidal volume inhalation (3100mL).

Expiratory reserve volume (ERV)

Amount of air that can be forcefully exhaled after a normal tidal volume exhalation (1200mL).

Vital Capacity (VC)

Maximum amount of air that can be exhaled after maximal inspiration (4800mL).

Spirometer

Device used to measure respiratory volumes.

Wet spirometer

Type of spirometer that measures air volume using water.

Handheld dry spirometer

Portable spirometer that measures air volume without water.