Laboratory Activity No. 9: The Frog Respiratory System

Laboratory Activity No.
9: The Frog Respiratory System
Respiration is the process by which animals take in oxygen and gives of carbon dioxide.
Two types of respiration can be observed among animals, direct and indirect.
Direct respiration is when the cell exchange oxygen and carbon dioxide directly with the
surrounding environment, and usually, no respiratory system is necessary, which is true for a
lower form of animals. Indirect respiration takes place in higher animal forms and used
specialized respiratory organs like gills, lungs, and skin.
External respiration is the exchange of gases between the external environment and the
blood through the respiratory organs. Internal respiration is the exchange of gases between the
blood and the body cells where oxygen will be used for cellular respiration.
Respiration is based on the principle that gases pass through moist permeable membranes
from the area of more significant pressure to lesser pressure.
Frogs have three respiratory surfaces that aid in gas exchange. A frog’s respiratory
surfaces are its skin, lungs, and the thin membranes lining its mouth and pharynx.
Structure of the Buccal Cavity of the Frog

- External and internal nares are the head region's opening, commonly called nostrils, and
are guarded by valves. The external nares are continuous with the internal nares inside
the cavity.
- The buccal cavity is the space that lies posterior to the mouth. It consists of the following
parts:
• The upper lip fold borders the margin of the upper jaw.
• Lower lip folds borders the margin of the lower jaw.
• Maxillary teeth are the conical teeth along the edges of the upper jaw.
• Sulcus marginalis is the deep grove at the inner margin of the two rows of maxillary
teeth.
• Median subrostal fossa is the tiny, shallow depression at the tip of the upper jaw,
which is immediately posterior to the premaxillary teeth.
• Pulvinar rostale are low elevations situated on the sides of the median subrostal fossa.
• Lateral subrostal fossa is another depression lateral to the pulvinar rostale.
• Vomerine teeth are small clusters of teeth at the antero-median portion of the root of
the mouth.
• Internal nares are small opening, which is anterolaterally located to the vomerine
teeth.
• Eyeball prominence is two rounded bulges at the posterior half of the roof of the
mouth.
• The Eustachian tubes' opening is opening just laterally below the eyeball prominence
and the jaw's median angles.
• The tongue is a structure that significantly occupies the floor of the buccal cavity.
• Tuberculum prelinguale is an elevation at the lower jaw tip, which is immediately
anterior to the tongue.
• Laryngeal prominence is a small, hardened oval elevation at the medial portion of the
floor of the buccal cavity and posterior at the tongue at its center is a short vertical
slit, the glottis.
- The opening of the esophagus is a wide transverse slit that is posterior to the laryngeal
prominence.
- The pharynx is the most posterior part of the buccal cavity leading to the stomach. The
opening of the vocal sacs is found only in male frogs. These are slit-like opening located
at the lower jaw's postero-medial sides, lateral to the posterior portion of the tongue.
- The larynx, commonly called the voice box, is located below the pharyngeal cavity
supported by the hyoid cartilage, a mylohyoid's flat structure cord.
- The vocal cords are thin membranous folds found inside the larynx and attached to the
arytenoids. The vibration of the vocal cords produces the croaking of the frog.
- The lungs are a pair of thin-walled sacs situated dorsally to the lover. The bubble-shaped
chambers of the inner surface are called alveoli or air sacs.
Frogs can breathe through their skin while they are in wet places. They can also exchange
gases between the blood vessels in it and with its outer environment. There are mucus glands in
the skin that keep the skin moist, and skin absorbs a lot of dissolved oxygen from the
surrounding atmosphere. The second respiratory surface is the thin membranes lining its mouth
and pharynx. The third respiratory surface is the lungs, which are thin, elastic, lightweight organs
that inflate and deflate rhythmically while the frog is at rest. Adult frogs have poorly developed
lungs and are used on dry land while the frogs are active.
Frogs breathe very similarly to humans. The frog inhales. When the frog breathes, the air
enters the mouth. The floor of the mouth drops, and the external nares open. When a frog
breathes, the floor of the mouth rises and falls in a rhythmic pattern. These movements are
interrupted by a rapid expansion and contraction of the body wall's sides at less frequent
intervals. For each breath taken, the floor of the mouth will fall twice and rise twice. The body
wall will only contract once. At rest, frogs usually breathe through the lining of the mouth. This
process only fills the lung occasionally. This is because the lungs, which only adults have, are
poorly developed.
Learning Objectives: At the end of this activity, I can:

1. familiarized the different parts and functions of frog respiratory system; and
2. know how the process of respiration happens in animals.
Instruction:
1. Pith and dissect the frog, pinning back the skin's flaps and feet on the dissecting pan.
Then review the buccal cavity which you studied in the digestive system. Pay particular
attention to the external nares, which are continuously attached to the internal nares
inside the cavity. Look also for the glottis and the pharynx.
2. Put the digestive organs into one side to expose the lungs. Observe how these expand and
relax. Notice the alveoli, or small packets separated into groups by ridges. Observe the
wall of the lungs, the pleura, which is richly covered with blood capillaries.
3. Take pictures of the specimen showing all the respiratory parts mention above.
4. For the submission of activity no. 9, the number of photos allowed is a maximum of two
only, following the format below. The deadline for submission is on November 24, 2020,
until 6:00 PM.
Name: Maricris Guillermo Date: November 24, 2020
Course/Year/Section: BSBIO1A Laboratory Teacher: Ma’am Krystel Grace Padilla
Laboratory Activity Sheet No. 9: The Respiratory System of a Frog

1. Photo of the actual frog specimen showing the labeled external and internal nares,
pharynx, glottis, and lungs.
External nares
Internal nares
pharynx
glottis
lungs
2. Draw and label the human respiratory system.
3. Name the five respiratory diseases in a man? Give their symptoms and causes.
Asthma symptoms comprise tightness of chest, shortness of breath, wheezing and dry cough
that naturally came from either allergic reaction triggered by the environment or even genetic
patterns and lack of nutrition at a young age.
Chronic obstructive pulmonary disease (COPD) signs are coughing too much with
phlegm or sputum, wheezing and blue lips or fingernails it came from long-term exposure to
the materials such as pollutants in the air and smoke from cigarettes that may damage our
lungs.
Lung cancer often appears with coughing with blood, hard breathing, and chronic coughing
and came from exposure to cigarette smoke or second-hand smoke.
Pneumonia symptoms are difficulty in breathing, coughing with phlegm or mucus,
exhausted and no appetite, fever or chills, and shortness of breath. it usually came from the
common cold, flu, certain bacteria, or virus.
Influenza symptoms can include fever, chills, and body aches that naturally came from one
person that has this disease or those who are a carrier of this virus or flu.
4. Why is smoking bad for health.
Smoking is bad for our health because cigarette sticks contain chemicals that badly affects
our organs particularly our lungs, inhaling cigarette smoke or tobacco-like sticks will surely
affect our lungs. Smoking leads our body not to work properly and may result in death.
5. State the principal functions of the larynx, glottis, and lungs.
Larynx enables the air to pass through the respiratory organs for gas exchange and prevents
food and water or liquids from entering the respiratory system while the glottis acts as the
gate of air or allows the air to enter and leave to the pharynx and the lungs are responsible for
body’s respiration where it brings oxygen to the bloodstream.

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Laboratory Activity No.

9: The Frog Respiratory System

Structure of the Buccal Cavity of the Frog

Learning Objectives: At the end of this activity, I can:

Laboratory Activity Sheet No. 9: The Respiratory System of a Frog

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