Frog Anatomy Laboratory 5, Part 1 PDF

________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd LABORATORY 5 – THE INTERNAL ANATOMY OF THE FROG (PART 1) The internal organs are collectively called viscera. They are lodged within the BODY CAVITY or coelom. 1. Transverse Septum is a connective...

________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd LABORATORY 5 – THE INTERNAL ANATOMY OF THE FROG (PART 1) The internal organs are collectively called viscera. They are lodged within the BODY CAVITY or coelom. 1. Transverse Septum is a connective tissue in the adult frog that divides the coelom into two cavities, namely: a. Pericardial Cavity is a smaller and more anterior compartment that contains the heart b. Pleuro-peritoneal Cavity is a much larger and more posterior compartment that contains the lungs, stomach, liver and the rest of the visceral organs 2. Parietal Peritoneum is a thin, transparent membrane or connective tissue that lines the inner side of the muscular body wall. 3. Mesentery is a double-walled connective tissue extension of the parietal peritoneum that suspends organs from the dorsal body wall. ex. mesogaster of the stomach 4. Visceral Peritoneum is a mesentery or extension of the parietal peritoneum that encloses the visceral organs. 1 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd 5. Omentum is a double-walled connective tissue extension of the parietal peritoneum that connects an organ to another organ. ex. gastro-duodenal omentum Laboratory Activity 5.1 The Buccal Cavity of the Frog The cavity found immediately posterior to the mouth is called the BUCCAL CAVITY. The roof and floor of the mouth are bounded by the upper and lower jaws, which are bordered by lip folds, the upper and lower lip folds, respectively. ROOF OF THE BUCCAL CAVITY 1. Median Subrostral Fossa is a prominent depression on the anterior tip of the roof of the mouth 2. Pulvinar Rostrale are pair of low elevations immediately lateral to the median subrostral fossa 3. Lateral Subrostral Fossae are pair of depressions on each side of the pulvinar rostrale which receives the slight elevations formed from the floor of the mouth after the dipping of the prelingual fossae 4. Sulcus Marginalis is a pair of deep grooves on the inner margins of the upper jaw which receives the ridge-like edges of the lower jaw when the mouth is closed 2 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd 5. Maxillary Teeth are small conical teeth in a row along the edge of the upper jaw, but outer to the sulcus marginalis. These are used to grasp or hold the prey 6. Vomerine Teeth are two small clusters of teeth, borne on the two obliquely placed vomer bones 7. Internal or Posterior Nares or Choanae are pair of slit-like openings that lead into the buccal cavity. If needle is pass into it, it exits into the outside through the external nares. 8. Eyeball Prominences are two large, rounded bulges on the posterior half of the mouth. In the live frog, the eyes could be pulled down into the buccal cavity when swallowing food. FLOOR OF THE BUCCAL CAVITY 1. Tuberculum Prelinguale is a prominent median elevation on the anterior tip of the lower jaw that fits into the median subrostral fossa when the mouth is closed. 2. Prelingual Fossae are pair of tiny depressions lateral to the tuberculum prelinguale. The pulvinar rostrale fits into these depressions when the mouth is closed. 3. Tongue is a prominent, forked muscular structure that occupies the greater area of the floor of the mouth. Observe that its attachment is posteriorly. 3 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd This facilitates its function of catching the prey by it being thrown out into the air. BACK OF THE BUCCAL CAVITY 1. Openings of the Eustachian Tube are pair of slit- like openings on the postero-lateral side of the eyeballs but medial to the angles of the jaw. The Eustachian tube leads to the cavity of the middle ear, thus serving as a passageway of air to equalize internal and external pressures on the tympanic membrane. 2. Opening of the Esophagus is a wide transverse slit posterior to the laryngeal prominence. It connects the most posterior portion of the buccal cavity called pharynx, to the stomach. 3. Laryngeal Prominence is a small, hardened, oval- shaped elevation lodges between the two lateral forks of the tongue and median portion of the floor of the mouth. 4. Glottis is a short, vertical, slit-like opening at the center of the laryngeal prominence. It serves as a passageway of air into the lungs or out into the buccal cavity. 5. Openings of the Vocal Sacs are pair of slit-like openings on the floor of the mouth, located on the postero-medial sides of the lower jaw, but lateral to the posterior portion of the tongue. The vocal sacs are found only in males. These are outpockets of the 4 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd pharyngeal wall and serve as resonators or amplifiers of sound. Laboratory Activity 5.2 The Digestive System of the Frog The DIGESTIVE SYSTEM functions primarily to convert ingested food from to a soluble nutrient that could be carried by the blood and later on absorbed and assimilated by the cell of the body. Digestion involves; 1. ingestion of food 2. passage of food through the digestive tract 3. release of hormones and enzymes that aid in the process of digestion 4. egestion of undigested food materials DIVISIONS OF THE DIGESTIVE SYSTEM A. Digestive Tube is a long that starts from the mouth and ends with the anus. It serves for passage, digestion of food and absorption of nutrients. It is also for egestion of undigested food materials and other waste products of digestion. Mouth is the most anterior opening of the head which is for ingestion of food. Buccal Cavity is the anterior to the mouth. 5 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd Pharynx is the most posterior part of the buccal cavity. Esophagus is a short passageway that connects the pharynx to the stomach. Stomach is the most expanded, large, bag-shaped portion of the digestive tube and is suspended from the dorsal body wall by a mesogaster. It curves more on the outer side than on the inner side. The curves are termed lesser and greater curvatures. The internal folds of the stomach wall called rugae which are very prominent. Pylorus is a slightly constricted part on the posterior end of the stomach and serves as the junction between the stomach and the small intestine. It is guarded by an internal valve called the pyloric valve which regulates the passage of the partly-digested food from the stomach into the small intestine. Small Intestine is the longest portion of the digestive tube where final digestion and absorption takes place. It is suspended from the dorsal body wall by mesenterium or mesentery proper. 6 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd The small intestine has internal folds called villi that increase the absorbing surface of the digestive tube. It has goblet cell secreting mucin protecting its lining. It is divided into; a. Duodenum is the most anterior, wider but shorter division of the small intestine. b. Jejuno-ileum is the more posterior, narrower but longer coiled division of the small intestine. The duodenum is connected with the stomach by means of omentum, the gastro-duodenal omentum and with the liver by means of hepato-duodenal omentum. These two omenta jointly form the gastro-hepato-duodenal omentum or lesser omentum. Large Intestine is a short-dilated tube at the terminal end of the jejuno-ileum that serves as temporary storage of the waste products of digestion. It is divided into 2 segments. The first segment is the rectum that is continuous from the jejuno-ileum and held by mesorectum. The second segment is the cloaca. It is the posterior end of the rectum and located within the pelvic girdle. Cloaca serves as a common passageway of feces, urine and reproductive cells which are then finally eliminated through the anus or vent. 7 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd It is suspended by a mesorectum where a rounded, reddish gland, the spleen is also suspended. Anus or Vent is the terminal opening of the digestive tube. B. Digestive Gland are glands that produce secretions which aid in the conversion of food to nutrient. Liver is ventrally located, conspicuous reddish-brown gland on the anterior portion of the pleuro-peritoneal cavity. It is the largest gland that partly covers the stomach. The liver is divided into three lobes; a. a right anterior lobe b. a left anterior and left posterior lobules c. a median lobe which is best seen by deflecting the right lobe Gall bladder is a greenish sac situated on the ventral wall of the median lobe of the liver. It serves as a temporary storage of bile, a digestive juice secreted by the liver. Bile reaches the gall bladder by way of two fused ducts, the hepatic ducts coming from the left and right lobes of the liver. 8 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd Cystic duct is a tiny duct connected to the neck of the gall bladder and functions to conduct bile out of the gall bladder. Pancreas is an elongated, irregularly-shaped gland that is best seen by deflecting the duodenum anteriorly. It lies between the duodenum and the stomach long the gastro-hepato-duodenal omentum. It secretes enzyme-containing pancreatic juice by way of the tiny pancreatic ducts. The union of the hepatic, cystic and pancreatic ducts forms the common bile duct which empty bile and pancreatic juice into the duodenum of the small intestine. Gastric and Intestinal Glands are found in the mucosa of the innermost lining of the stomach and the small intestine. 9 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd Laboratory Activity 5.3 The Respiratory System of the Frog The RESPIRATORY SYSTEM functions primarily for the breathing-in of oxygen and the breathing-out carbon dioxide. Oxygen is needed to convert glucose to release energy needed for metabolic activities of the body. During the process, carbon dioxide is produced which is a toxic metabolic waste needed to be eliminated. The major process in the respiratory system is respiration that is a combination of two processes. The process of taking-in oxygen is called inspiration and the process of giving-off carbon dioxide is called expiration. Respiration between the organism and the environment is consists of two phases; 1. EXTERNAL RESPIRATION is the exchange of gases between the blood and the external environment which takes place in the respiratory organ. 2. INTERNAL RESPIRATION is the exchange of gases between the blood and the cells of the body. Vertebrates have varied main respiratory organs. Gills for aquatic animals and lungs for terrestrial ones. Some insects have booklungs while others have tracheal system. 10 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd The Respiratory System of the frog is consisting of the following; External Nares are the outer respiratory openings. Internal Nares are inner respiratory openings in the roof of the buccal cavity. Olfactory Canal is a short passageway between the external nares and the internal nares buccal cavity. Laryngeal Prominence is a circular cartilaginous respiratory structure with glottis. a. Arytenoid Cartilages are pair of valve-like cartilages that guard the glottis and at the same time form the dorsal roof of the larynx. a. Cricoid Cartilage is the ring-like cartilage that surrounds and supports the arythenoid. Glottis is a slit-like respiratory opening at center of the laryngeal prominence. Larynx or Voice Box connects glottis to lungs. It is located infront of the heart and below the pharyngeal cavity. It is supported by the hyoid cartilage which is a flat body covered by muscles at the floor of the buccal cavity. It is partly surrounded by cricoid cartilage. 11 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd Vocal cords are the very thin, membrane-like folds attached to arytenoid. These are sound-producing apparatus which are situated in the area of the larynx. Lungs is a pair of thin-walled sacs which may be shriveled or distended depending upon the amount of air inside. It is covered by the pleura which is continuous with the parietal peritoneum. The lungs’ functional units are alveoli which are numerous minute compartments which increase the surface area for the exchange of gases without necessarily increasing the size of the lungs. In the walls of the alveoli are capillaries. 12 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd LABORATORY 6 – THE INTERNAL ANATOMY OF THE FROG (PART 2) The UROGENITAL SYSTEM is a combination of two systems consisting of the urinary and the reproductive systems. These systems are morphologically and functionally associated with one another so they can be combined to form the urogenital system. For example, in the male frog, the duct for passage of urine is also utilized for the passage of the spermatozoa. Laboratory Activity 6.1 The Urinary System of the Frog The URINARY SYSTEM is composed of a pair of kidneys and their urinary ducts. The main organ of excretion is the kidney. It functions for the elimination of excess water and by-products of metabolism such as nitrogenous wastes and salts. Kidneys are pair of reddish, elongated, flattened organs that are lined ventrally by the parietal peritoneum. The kidneys are retroperitoneal organs because they are lodged in a space called the cisterna magma or subvertebral lymph sinus, situated outside the peritoneal cavity. 1 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd Adrenal Glands are pair of yellowish, irregularly-shaped glands on the ventral surface of the kidney. Mesonephric Ducts are pair of slender, straight, white tubes on the postero-lateral edge of the kidney, but medial to a dark blood vessel called renal portal vein. Each course posteriorly and conducts waste products from the kidney into the cloaca. Urinary Bladder is a bi-lobed outgrowth on the ventral surface of the cloaca that serves as temporary storage of urine. Contraction of the walls of the urinary bladder spurts the urine into the cloaca and out through the anus. Cloaca is the posterior portion of the large intestine which is used for passageway of urine from the urinary bladder. Anus or Vent is the terminal opening at the posterior end of the cloaca through which urine pass out. Nephron is the functional unit of the kidney which is composed of Malphigian body and uriniferous tubule. Malpighian Body or Renal Corpuscle consists of glomerlus and Bowman’s capsule. 2 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd Within the kidney, the following structures are seen; Uriniferous Tubules are numerous intricately coiled and tubular structures. Glomerulus or Rete Mirabile are numerous darkly stained network of blood capillaries on the ventral portion of the kidney. Bowman’s Capsule is a thin double walled cup-shaped structure enclosing the glomerulus. One end is connected to a uriniferous tubule while the other end is open. Through the open end, blood vessels connect with the capillaries of the glomerulus. The REPRODUCTIVE SYSTEM is made of gonads, the ovaries and testes which produce the reproductive cells and their ducts which serve as passageway for the reproductive secretions. It is also concern with the production of reproductive cells and secretion of sex hormones. Frogs are dioecious, the male species is different from the female species. 3 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd Laboratory Activity 6.2 The Male Reproductive System of the Frog Testes are pair of elongated, yellowish structures on the ventral surface of the kidney. Its mesentery is the mesorchium which is best seen by stretching the testes from the kidney. Vasa Efferentia are the minute, slender tubules lying on the mesorchium. They serve as ducts which conduct sperms from the testes to the kidney. Seminal Receptacle is the expanded posterior end of the mesonephric duct where spermatozoa are temporarily stored. Vestigial Oviduct is a slender, white coiled tube, running lateral to the mesonephric duct which is joins just after the mesonephric duct emerges from the posterior end of the kidney. It is well developed in some males but not functional to them. 4 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd Laboratory Activity 6.3 The Female Reproductive System of the Frog Ovaries are pair of lobulated, saccular organs on the ventral wall of the kidney and are suspended from the dorsal body wall by the mesovarium. The ovary becomes very much enlarged when the small, globular, dark-colored eggs are produced. A young ovary appears as a white and very much folded structure. Mullerian Ducts or Oviducts are highly convoluted, white long tubes on each side of the ovary and lying close to the abdominal wall where it is suspended by a mesentery called mesotubarium. It has three parts; 1. Ostium – the most anterior, funnel-shapes mouth of the oviduct that lies near the bases of the esophagus and lungs. It serves as the entrance of eggs which are released from the ovary into the coelomic cavity upon rupture of the thin portion of the mesovarium. 2. Oviduct Proper 5 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd 3. Uterine Enlargement – posterior enlarged thin but highly distensible sac connected to the cloaca Corpora Adiposa or Fat Bodies are yellowish, finger-like structures on the anterior level of the kidney and attached to the ovary. It stores reserve food especially during the breeding season. 6 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd LABORATORY 7 – THE INTERNAL ANATOMY OF THE FROG (PART 3) The CIRCULATORY SYSTEM consists of two interrelated systems, the Cardiovascular System and Lymphatic System. The CIRCULATORY SYSTEM performs the following functions; 1. transport of respiratory gases (oxygen and carbon dioxide), nutrients, waste products, hormones and minerals within the body 2. defense against foreign organisms 3. maintenance of body temperature in warm-blooded or homeothermic animals Laboratory Activity 7.1 The Organs of Cardiovascular System of the Frog The CARDIOVASCULAR SYSTEM is composed of; A. The HEART is the muscular organ that pumps blood to all parts of the body through the blood vessels. 1 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd In frog, the following are the EXTERNAL STRUCTURES of the heart. Three Chambers 2 atria 1 ventricle - two anterior (R & L) - one cone-shaped - thin-walled - muscular or thick-walled - darkly colored - lightly colored Conus arteriosus or Bulbous cordis is a large tube situated on the ventral side of the right atrium. Sinus venosus is a triangular, darkly-colored structure on the dorsal surface of the heart where the two precaval veins and postcaval vein empty. The following are the INTERNAL STRUCTURES of the frog’s heart. Right and Left atria are two thin-walled chambers of the heart separated by a connective tissue partition called the inter-auricular septum. Ventricle is the thick-walled, cone-shaped, posterior part of the heart Papillary muscles are the finger-like muscular partitions that project into the cavity of the ventricle and they also 2 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd serve as the points of origin of the chordae tendinae. Chorda tendineae are small, thread-like fibers preventing turning of the valves during ventricular contraction. Muscular pockets are the fissure-like chambers separated by muscular partitions. They prevent complete mixture of oxygenated and unoxygenated blood while flowing into the ventricle during atrial contraction. B. The circulating BLOOD which consists of fluid plasma and the cellular components. The cellular components are the platelet or thrombocyte, RBC or erythrocyte and WBC or leucocyte. CLUSTER OF THROMBOCYTES ERYTHROCYTES LYMPHOCYTE MONOCYTE 3 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd NEUTROPHIL EOSINOPHIL BASOPHIL C. The system of BLOOD VESSELS serves as passageway of blood. There are three kinds of blood vessels. CAPILLARIES are the smallest blood vessels and have the thinnest walls consisting of only one layer of epithelial cells. These blood vessels are usually found within the organs. ARTERY - thick-walled - lighter in color - deeply set - supply blood from the heart to different organs of the body 4 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd - carry oxygenated blood, except for pulmonary artery which carries unoxygenated blood - blood flow is in spurts or is pulsating VEIN - thin-walled, thus blood could be seen through - darkly-colored - superficially set - collect or drain blood from an organ to the heart - carry unoxygenated blood, except for the pulmonary vein which carries oxygenated blood - blood flow is smooth and continuous - with valves which prevent the back-flow of blood When blood never leaves blood vessel, the kind of Circulatory System is said to be Closed Circulatory System. Vertebrates have this kind of circulatory system. If blood leaks out from the blood vessel, this is an abnormal condition is called hemorrhage. CIRCULATION is the movement of blood in the blood vessel to deliver substances and to collect metabolic wastes to and from different parts of the body. There are two primary divisions of the blood circulation. 1. CARDIO-PULMONARY CIRCULATION is the movement of blood from heart to lung and back to the heart. Its main purpose is to deliver carbon 5 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd dioxide to the lung for expiration and to gather oxygen from the lung. 2. SYSTEMIC CIRCULATION is the movement of the blood from the heart to the different organs of the body and back to the heart. Its main purpose is to deliver oxygen to different organs of the body and to collect carbon dioxide. Systemic Circulation is of two divisions; a. VENOUS SYSTEM consists of veins with their contained unoxygenated blood flowing towards the heart. b. ARTERIAL SYSTEM consists of arteries with their contained oxygenated blood flowing away from the heart. Laboratory Activity 7.2 The Venous System of Frog’s Circulation The anterior of frog’s heart has dark triangular area, the sinus venosus. Sinus venosus receives unoxygenated blood from right and left precaval veins or superior vena cava and one postcaval vein or inferior vena cava. The precava is joined by three veins before it enters the sinus venosus. 6 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd I. Systemic Veins are the blood vessels that carry unoxygenated blood directly to the heart. BRANCHES OF THE PRECAVA 1. External Jugular Vein is the most anterior branch of the precaval. It is formed by the union of Lingual Vein and Mandibular / Maxillary Vein. 2. Innominate Vein is the middle branch of the precava that is joined by Internal Jugular Vein and Subscapular Vein. 3. Subclavian Vein is the most posterior branch of precava that aches posteriorly and at the level of the forelimb. It is formed by the union of Brachial Vein and Musculo-cutaneous Vein. Musculo-cutaneous Vein courses posteriorly along the lateral abdominal wall where it is formed by the union of Muscular Vein and Cutaneous Vein. BRANCHES OF THE POSTCAVA From the sinus venosus, the dark blood vessel shortly posterior to it is the postcava. Hepatic Veins Spermatic or Ovarian Vein Renal Veins Lumbar Veins Adiposal vein 7 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd II. Portal Veins are blood vessels that penetrate the capillaries of an organ before going into the ordinary circulation. HEPATIC PORTAL VEIN is a large blood vessel embedded in the pancreas before entering the liver. It is formed by the union of Gastric Vein, Pancreatic Vein, Splenic Vein, Intestinal Veins. Shortly before entering the liver, the hepatic portal vein breaks into capillaries that receive blood from the large anterior Abdominal Vein. Unoxygenated blood of the liver is drained into the hepatic veins, the postcava, sinus venosus and into the right atrium of the heart. RENAL PORTAL VEIN is a large, dark blood vessel that is best viewed on the lateral margin of each kidney, lateral to the mesonephric duct. The renal portal vein, near the posterior region of the kidney is joined by Dorso-lumbar Vein, Femoral Vein and Sciatic Vein. In female frog, the Oviducal Vein coming from the oviduct joins the renal portal vein directly or indirectly through Femoral Vein. 8 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd Pelvic Vein is a medial branch of Sciatic Vein that received the short Vesicular Vein that drains blood from the urinary bladder. Anterior Abdominal Vein is formed by the union of two pelvic veins. It is coursing underneath the linea alba. Before anterior abdominal vein joins the hepatic portal vein anteriorly, it receives smaller veins draining blood from the ventral abdominal wall. III. PULMONARY VEIN is the dark blood vessel that carry oxygenated blood from the lungs to the heart. Laboratory Activity 7.3 The Arterial System of Frog’s Circulation The frog’s heart has swollen, bulb-like conus arteriosus on the postero-ventral wall. It narrows anteriorly into tube-like structure called the truncus arteriosus that divides anteriorly into two trunks – the left and the right. It immediately divides into three trunks after the bifurcation; 1. an anterior Common Carotid Artery 2. a median Systemic Arch or Arch of Aorta 3. a posterior branch, the Pulmocutaneous Artery 9 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd BRANCHES OF THE COMMON CAROTID ARTERY 1. External Carotid or Lingual Artery 2. Internal Carotid Artery – Palatine Artery, Cerebral Artery and Ophthalmic Artery BRANCHES OF THE SYSTEMIC ARCH 1. Laryngeal Artery 2. Esophageal Artery 3. Occipito-vertebral Artery – Occipital Artery, Vertebral Artery 4. Systemic Artery – Subclavian Artery and Brachial Artery 5. Left Systemic Artery and Right Systemic Artery The Dorsal Aorta is formed by the union of the left and right systemic arteries. Branches of the Dorsal Aorta 1. Coeliaco-mesenteric Artery a. Coeliac Artery – R and L Gastric Arteries, Hepatic Artery b. Mesenteric Artery – Duodenal Artery, Intestinal Arteries, Splenic Artery, Hemorrhoidal Artery 2. Renal Arteries 3. Gonadal Artery – Spermatic Artery and Ovarian Artery 4. Adiposal Artery 10 ________________________________________________________GENERAL ZOOLOGY * 2024/mt-vd 5. Lumbar Arteries – Mesenteric Artery and Oviducal Arteries Branches of the Common Iliac Artery 1. Epigastric Artery 2. Recto-vesico Artery 3. Femoral Artery 4. Sciatic Artery BRANCHES OF THE PULMOCUTANEOUS ARTERY 1. Cutaneous Artery 2. Pulmonary Artery 11