Frog Protection and Support PDF

SUPPORT AND PROTECTION EQUIPMENT AND M AT E R I A S M ATE R IAL S YOU PROVIDE Gloves scissors and cutting instrument Safety Pin field frog Dissecting Pan BAC KG ROU ND The body of an animal has a definite form and is composed of variou...

SUPPORT AND PROTECTION EQUIPMENT AND M AT E R I A S M ATE R IAL S YOU PROVIDE Gloves scissors and cutting instrument Safety Pin field frog Dissecting Pan BAC KG ROU ND The body of an animal has a definite form and is composed of various structural parts. These enable the animal to carry out the activities necessary for life, the physiological processes within the body and the external relation with its environment. The frog is a convenient representative animal for an introductory subject because of its cheap and abundant supply, size, frog’s life cycle can be easily observed and it shows resemblance in form and structures to higher vertebrates and man. The details of its structures are readily demonstrated as well as its life habits are easily observed. Ge neral B iolog y : Support and Protection Classification of a field frog Phylum: Chordata Subphylum: Vertebrata Class: Amphibia Order: Anura Family: Ranidae Genus: Rana Species: vittigera Field frog: Rana vittigera Bullfrog: Rana catesbeina A. Frog Morphology The body of a frog is divided into two major parts – the axial region composed of the head and trunk and the appendicular region composed of the appendages of the limbs. The following are the important parts of the morphology of the frog. Snout is a triangular protruding region of the head. Mouth is a large anterior opening of the head of the frog with teeth and tongue. The two eyes are found on the sides of the head. The eyes have upper eyelid, lower eyelid and the third eyelid called nictitating membrane. The nostrils or external nares are two small opening near the tip of the snout. The tympanic membrane is a small round arc of thickened membrane behind each eye. The brow spot is lightly colored spot at the median dorsal part of the head in front of the eyes. The humps is a marked elevation on the mid-dorsal surface of the trunk near the posterior end. The anus is a small opening at the dorsal end of the trunk which serve for the exit of reproductive cells, excretory products, and undigested food matter. There are two forelimbs on the anterior end of the trunk consisting of upper arm, forearm, wrist, manus or hand with four digits or finger. The two hindlimbs on the posterior end of the trunk consist of thigh, shank or middle portion, ankles, with webbed toes, a sixth toe, the prehallux is felt on the inner side of the foot near the most proximal toe, the hallux. Objective To be familiarized with the external parts and skeleton of the frog Activities Anesthetize the frog by pithing. Pin the frog in the dissecting pan and pith the brain and spinbal cord. Locate the different structures of the morphology of the frog. Questions to answer: 1. Classify the frog 2. Why is the skin of the frog always moist? 3. How are you going to determine the sex of the frog by examining its external features alone? 4. Differentiate a toad from a frog? B. Skeletal System of the Frog The skeleton is an essential part of the body machine of every vertebrae animal. It has at least three important functions – serves a framework or support for the softer parts of the bod, provide a firm surface for the attachment of the muscle used in movements and locomotion, and protects soft parts. It also supplies calcium to the blood cells.  Based on the location in the body, the endoskeleton of the vertebrates is divided into axial and appendicular skeleton. The axial skeleton supports the head and the trunk. It is made up of the skull, the visceral skeleton, the vertebral column, ribs (absent in frogs) and the sternum. The appendicular skeleton is made up of pectoral and pelvic girdles and the bones of the forelimbs and the hindlimbs. Skull (Dorsal Side)  The premaxillae are the most anterior pair of teeth bearing bones which form the tip of the upper jaw. The maxillae are pair of teeth bearing bones posterior to the premaxillae. They form the largest and middle segment of the upper jaw. The quadratojugals are a pair of slender bones forming most of the roof of the skull and united at the median line by the sagittal suture. The fronto-parietal is a pair of slender bones forming most of the skull and untied at the median line by the sagittal suture. The spenethmoid is a small squarish bone anterior to the fronto-parietals. The nasala are a pair of triangular bones anterior to the spenethmoid covering the nasal capsules. The prootics are a pair of ring-like projection on each side of the skull posterior to the fronto-parietals forming the auditory capsule enclosing the inner ear. The anterior wall has perforation for the passage of the passage of the cranial nerves. The aquamosals are a pair of T-shaped bones lateral to the prootic, whose longer ends extend outward and backward to the lower jaw. The occipitals are short bones surrounding a large opening, the foramen magnum at the posterior boundary of the skull. The occipital condyles are round prominence on each exoccipital bones. Skull (Ventral Side) The parashenoid is a dagger-shaped bone that forms the floor of the skull. The spenethmoid is a bone at the anterior end of the parasphemoid as seen in the dorsal side. The vomerine are two flat wing-shaped and teeth-bearing bones just porterior to the premaxillae. The palatine is a pair of slender, rod-like bone extending laterally from the anterior end of thr spenethmoid to the maxillae. The pterygoid are pair of three rayed bones joined to the prootics. Squamosals and maxillae. The Lower Jaw Lower jaw may be divided into the left and right halve. Each half contains the following lobes seen from the dorsal side. The meto-meckelian is the anterior bone that unites the right and left halves of the jaw. The dentary is the middle bone. The Angulo-splenial is the porterior bone. The Hyoid Cartilage The hyoid cartilage is a thin, flat hyaline cartilage embedded beneath the tongue. The body is a large central portion of the hyoid. The alary processes are pair of expanded plates at the anterior end of the body. The anterior cornua are the anterior pair of horns extending to the prootics. The thyroid processes is a pair of ossified extension of the body which help support the larynx. The posterior cornua are a pair of shorter horns lateral to the hyoids process. The Vertebral Column The vertebral column consists of ten bones, the vertebrae. The atlas is the first vertebra. It is the most anterior bone of the vertebral column without transverse process. It articulates with the occipital condyles of the skull The typical vertebras are the second to the eight vertebrae The parts of the typical vertebra are as follows: o The centrum is a ventral spoon-like base or body, which is concave anteriorly and convex posteriorly. o The neural arch is a pair of dorso-lateral projections on the centrum and is fused mid-dorsally. The small openings between adjacent neural arches through which spinal nerves connect with the spinal cord are called intervertebral foramina. o The neural canal is the cavity enclosed by the neural arch. o The neural spine is caudally directed projection on the mid-dorsal part of the neural arch. o The transverse processes are a pair of elongated processes which extend at the right angles of the centrum o The prezygapophysis is a pair of articulating processes at the anterior end of the neural arch. o The postzygapophysis is a pair of articulating processes at the posterior end of the neural arch. The sacral vertebra is the ninth vertebra with two long transverse processes extending backward and articulating with the pelvic girdle. The urostyle is the tenth terminal vertebra and is slender with dorsal keel articulating anteriorly with the sacral Vertebra. The Sternum The sternum is the breast bone and is divided by the pectoral girdle into anterior and posterior portions. The omosternum is a tapered bone attached anteriorly to the epicoracoid. The episternum is a flat, slightly circular cartilage at the anterior part of omosternum. The mesosternum is a bony rod. It is the posterior counterpart of the omosternum correspondingly connected to the epicoracoid. The Pectoral Girdle The pectoral girdle together with the sternum forms an arch of bones and cartilage around the anterior portion of the trunk. It is divided into right and left half. The suprascapula is a distal, flat, expanded cartilage forming the dorsal portion of the girdle. The scapula is a smaller piece of bone articulating with the suprascapula. The clavicle or collar bone is a slender bone anteromedial to scapula. The coracoid is bone flared at the median end, posteromedial to the scapula. The opening that separates the clavicle and the coracoid is the fenestra. The posterior cup-shaped cavity between the coracoid and scapula which receives the head of the humerus is the glenoid fossa.  The epicoracoid is a cartilage at the proximal end of the clavicle and the coracoid and joins the halves of the pectoral girdle ventrally. The Pelvic Girdle The pelvic girdle is a V-shaped bone, which articulates with the sacral vertebra and supports the posterior limbs. It has a left and right half and each half consists of the following bones: - The ilium is an anterior, slender bone articulating with transverse process of the sacral vertebra. - The ischium is a short posterior bone of the dorsal side of the girdle. - The pubis is a triangular cartilage on the ventral side of the girdle. - The cup-like depression formed by the union of the three pairs of bone and which receives the head of the femur is called acetabulum. The areas of union to each pair of these boxes are known as iliac, ischium and pubic symphysis. The Anterior Limb The different bones of the forelimbs or anterior limbs are the following: The humerus is the bone of the upper arm. Head fits glenoid fossa of the pectoral girdle. The radio-ulna is the bone of the forearm. The carpals are the bone of the wrist consisting of two rows of the six small bones. The metacarpals are bones of the palm consisting of four slender bones and a rudiment of the thumb. The phalanges are the bones of the fingers consisting of small pieces of bones arranged linearly. The Posterior Limb The following are the bones of the posterior limbs or hindlimbs. The femur is the bone of the thigh and the largest bone in the body. Its head fits into the acetabulum of the pelvic girdle, The tibio-fibula is the bone of the shank posterior to the femur. The tarsals are the bones of the ankle consisting of two rows of bones posterior to the tibio-fibula. The outer calcaneum and the inner astragalus with an oval space between them compromise the proximal row. The small bones comprise the distal row. The metatarsals are five long cylindrical bones of the sole articulating with the posterior limb to the tarsals. The phalanges are bones of the foot consisting of small pieces that are arranged linearly posterior to the Metatarsal. The calcar is a rudimentary bone that supports the prehallux. Objectives To familiarize with the different bones of the frog. Be able to locate the different parts of the bones. Activity Label the illustration of the different bones. Questions to Answer 1. What are the functions of the skeleton? 2. Differentiate endoskeleton from exoskeleton. Give examples. 3. Differentiate typical from atypical vertebra.