BIOLOGY - ZOOLOGY.pptx Class 11 Organ and organ systems in animals

Biology ppt

1. BIOLOGY - ZOOLOGY LESSON 4 Organ and Organ Systems in Animals

2. Cockroach - Periplaneta americana

3. MORPHOLOGY

4. Morphology The body of the cockroach is divided into: Head Thorax Abdomen

5. Head: It bears a pair of compound eyes and two long antennae arising from their head. The mouth is present on the anterior part which bears a pair of mandibles, a pair of maxillae and labium. A median flexible lobe acts as the tongue. Thorax: The thorax is divided into three parts- Prothorax, Mesothorax, and Metathorax. The head and thorax are connected by prothorax, which is a short extension known as the neck. The mesothorax gives rise to the first pair of wings, while the second pair of wings arise from the metathorax. The thorax region also bears a pair of legs. It also consists of forewings called tegmina. Abdomen: The abdomen of a cockroach is divided into 10 segments. The 7th sternum, along with the 8th and 9th sterna bears a broad genital pouch. The 10th segment contains a pair of the joint filamentous structure called anal cerci.

6. Anatomy: Digestive System: It has a long and coiled alimentary canal divided into three parts- foregut, midgut, and hindgut. Foregut or Stomadaeum - It comprises the buccal chamber, pharynx, esophagus, crop, and gizzard. Midgut or Mesenteron- It is short compared to the foregut and lined with glandular endoderm. Eight blind globular hepatic caeca are present between the gizzard and midgut, which secretes digestive enzymes. Hindgut or Proctodaeum - It consists of the ileum, colon, and rectum.

7. Nervous System: The nervous system of a cockroach is divided into- central nervous system, peripheral nervous system, and sympathetic nervous system. The central nervous system consists of the brain. The peripheral nervous system consists of nerves. The sympathetic nervous system consists of a frontal ganglion. Respiratory System: The respiration in cockroaches occurs through the trachea present on the lateral side of the body. It opens through 10 pairs of small holes called spiracles. The trachea is sub-divided into tracheoles that carry oxygen from outside to different parts of the body.

8. Excretory System: The metabolic waste is excreted by ciliated and glandular Malpighian tubules. The waste is excreted in the form of uric acid. Circulatory System: The cockroach has an open circulatory system. The blood flows through the body cavity. The circulatory system consists of a heart, anterior aorta, and a system of ill-defined blood spaces known as sinuses.

9. Sensory Organs: Thigmoreceptors : They perceive sense for touch and are present on the body, legs, antennae and maxillary palps. Olfactory Receptors: They are present on antennae and palps and sense various smells. Gustatory Receptors: They are present on the maxilla and labial palps and can perceive a sense of taste. Thermoreceptors: These are present on the pads between the first four tarsals and can sense changes in temperature. Auditory Receptors: They are present on the anal cerci and responsible for hearing.

10. Reproductive System: The male reproductive system consists of a pair of testes present in the 4th and 6th segments of the abdomen laterally. The sperms are stored in the seminal vesicles. The female reproductive system consists of two ovaries in the 2nd and 6th segment of the abdomen. Oviducts of each ovary connect to form a single median oviduct. Sperms transfer through spermatophores. The fertilized eggs are present in a case like structure called oothecae . This was the entire structure of a cockroach.

11. The Common Indian Green Frog - Rana hexadactyla

12. Morphology of Frogs: Though larvae have tails, adult frogs are tailless. An adult frog has a stout body which is differentiated into head and trunk. Other external features are a pair of nostrils, protruding eyes, a membranous tympanum (ear), slippery/warty moist skin and webbed limbs. Frogs generally have a slippery moist and highly permeable skin through which they absorb water and respire. Thus, the moist skin acts as a respiratory organ in frogs. Also, the skin is glandular in nature, which produces mucus and toxic substances to warn them of their predators. The color of the skin can vary from brown and green to vivid colors as per secretions. The locomotion of frogs takes place with the help of their forelimbs and hind limbs. Frogs are unisexual i.e., they show sexual dimorphism. A male frog is distinguished from a female frog by the presence of vocal sacs and a copulatory pad on the forelimbs. A female frog lacks these body features. Below is an easy and well-labeled diagram of a frog (Rana tigrina ) for your better understanding.

13. Anatomy: The body plan of frogs consists of well-developed structures which help them in their physiological activities. The body cavity accommodates all the organ systems such as digestive, respiratory, circulatory, excretory, nervous and reproductive systems, whose functions are almost similar to human body systems. Digestive system: The alimentary canal together with the accessory organs makes up the digestive system of the frog. Since frogs are carnivorous they have short intestine. The alimentary canal begins at the mouth (buccal or oral cavity), passes through the pharynx, oesophagus or food pipe, stomach, small intestines, large intestines, rectum and finally ending at the cloaca. The food particles get digested gradually as they travel through various compartments of the alimentary canal.

14. Respiratory system: The amphibian has two modes of respiration – cutaneous respiration and pulmonary respiration. In an aquatic ecosystem, the skin is the respiratory organs where the diffusion of dissolved oxygen takes place. This is called cutaneous respiration. While on land, they use both skin and lungs for respiration. During pulmonary respiration, air entering through nostrils passes to the lungs via the buccal cavity. But during summer and winter sleep, they use only skin for respiration. Circulatory system: Frogs have a well-developed muscular heart with three chambers- two atria and one ventricle. Blood and lymph help in the transportation of food, air and other substances throughout the body via the network of blood vessels. The blood is composed of plasma and blood cells (RBC, WBC, and platelets).

15. Excretory system: The frog is a ureotelic animal whose major excretory product is urea. They have a distinguishable excretory system composed of a pair of kidneys, ureters, cloaca and urinary bladder. The kidneys have the structural unit called nephron which filters the blood and excretes out the waste. Coordination system: The nervous system and the endocrine system together perform the control and coordination in frogs. The endocrine system is composed of the endocrine glands such as pituitary, thyroid, parathyroid, thymus, pineal body, pancreatic islets, adrenals, and gonads. The secretions of these glands called hormones are responsible for metamorphism and other regulatory functions. The nervous system is divided into CNS and PNS. The brain is distinguished as forebrain, midbrain, and hindbrain which control different parts of the body. The brain is enclosed in the cranium and the vertebral column protects the spinal cord.

16. Reproductive system: Both male and female frogs have their own reproductive system where gametes for reproduction are produced. Male frog has testes which produce sperms and eject it through the cloaca. In a female frog, a pair of ovaries produce ovum and pass it to oviduct which opens into the cloaca. The cloaca is a common pathway for excretion and reproduction. At a time, 2500 to 3000 eggs are laid which are fertilized externally.

17. What is Metamorphism? Metamorphosis is a biological process by which animals, including insects, amphibians and few aquatic animals undergo extreme and rapid physical changes sometime after the birth. The result of metamorphosis changes the entire body of an organism. These changes include maturation of enzymes, blood cells, the remodelling of the nervous systems, digestive systems.

18. Metamorphism and Hormones: Viviparous animals give birth to young ones while oviparous animals lay eggs, which eventually grow and become adults. The majority of animal’s offspring look similar to their adults by birth. However, there are few organisms which appear to be different from their adults. In their lifecycle, they undergo many changes. The life cycle of frogs and insects involve sequential stages of change. An adult silk moth starts its life from an egg. Eventually, it becomes a silkworm and later becomes a cocoon. At the last stage, a moth develops from the cocoon. If we consider the life cycle of a frog, there are three stages. Eggs of a frog develop into a larva (tadpole) and later become an adult frog. These drastic changes in appearance and stages are not as long as human growth. The changes in the stages from a larva to an adult are known as metamorphism.

19. Metamorphism is a hormonal effect. Metamorphism in frogs is controlled by the hormones called thyroxine, and it is produced by the gland called the thyroid. For the production of thyroxine, the thyroid gland needs iodine. Frogs need to live in water bodies where sufficient iodine is present for thyroxine production. Hence, deficiency of iodine can retard the growth of a larva to become an adult frog. Metamorphism in insects is also a result of hormonal activity in them.