Bihar Board - Class 11 biology - Chapter 7: Structural organisation in animals Handwritten Notes

The structural organization in animals refers to the arrangement of cells, tissues, organs, and systems that work together to perform specific functions essential for the survival and reproduction of the organism. This chapter explores the hierarchy of organization in animals, from simple cellular structures to complex organ systems, and how they contribute to the overall functioning of the body.

Key Points

1. Levels of Structural Organization
   The structural organization in animals is classified into several hierarchical levels:

   • Cellular Level: The basic unit of life. Cells perform various functions essential for the survival of the organism.
   • Tissue Level: Groups of similar cells working together to perform a specific function.
   • Organ Level: Different types of tissues working together to form organs that perform specific tasks.
   • Organ System Level: Groups of organs working together to perform a broader function in the organism.
   • Organismal Level: The entire animal, where all systems function together to maintain life.

2. Animal Tissues
   Tissues are groups of similar cells that perform a specific function. There are four basic types of tissues in animals:

   • Epithelial Tissue: Covers body surfaces and lines internal cavities. It acts as a protective barrier and is involved in absorption, secretion, and filtration.
     • Examples: Skin epithelium, lining of the digestive tract.
   • Connective Tissue: Provides support, connects other tissues, and stores nutrients. It is composed of cells embedded in an extracellular matrix.
     • Examples: Blood, bone, cartilage, adipose tissue.
   • Muscle Tissue: Responsible for movement in the body. There are three types of muscle tissue:
     • Skeletal Muscle: Voluntary muscles that move bones.
     • Cardiac Muscle: Involuntary muscle found in the heart.
     • Smooth Muscle: Involuntary muscle found in the walls of organs like the stomach and blood vessels.
   • Nervous Tissue: Composed of neurons and glial cells, it is responsible for transmitting electrical signals throughout the body.
     • Examples: Brain, spinal cord, nerves.

3. Organ Systems in Animals
   In multicellular animals, different organs work together to perform specific functions. Some key organ systems include:

   • Digestive System: Involved in the breakdown of food and absorption of nutrients. It includes the mouth, stomach, intestines, liver, and pancreas.
   • Respiratory System: Facilitates the exchange of gases (oxygen and carbon dioxide) between the body and the environment. Key organs include the lungs and trachea.
   • Circulatory System: Transports oxygen, nutrients, and waste products throughout the body via the heart, blood, and blood vessels.
   • Nervous System: Controls and coordinates body activities by transmitting electrical signals. It includes the brain, spinal cord, and peripheral nerves.
   • Excretory System: Removes waste products from the body. It includes the kidneys, ureters, bladder, and urethra.
   • Reproductive System: Responsible for reproduction and the continuation of the species.
   • Musculoskeletal System: Provides support, movement, and protection. It includes bones, muscles, and joints.

4. Types of Symmetry in Animals
   Animals exhibit different types of symmetry based on their body plan:

   • Radial Symmetry: The body can be divided into similar halves by multiple planes. Common in organisms like jellyfish and starfish.
   • Bilateral Symmetry: The body can be divided into two equal halves along one plane. This symmetry is common in humans and most animals.
   • Asymmetry: No symmetry, as seen in some sponges.

5. Body Cavities in Animals
   A body cavity is a fluid-filled space that houses and protects internal organs. There are three types of body cavities in animals:

   • Acoelomates: Animals without a body cavity (e.g., flatworms).
   • Pseudocoelomates: Animals with a body cavity that is not fully lined by mesoderm (e.g., roundworms).
   • Coelomates: Animals with a true body cavity lined by mesoderm (e.g., humans, earthworms).

6. Integumentary System
   The integumentary system includes the skin and its appendages (hair, nails, sweat glands). It serves as a protective barrier against mechanical injury, pathogens, and water loss.

7. Homeostasis in Animals
   Animals maintain a stable internal environment through homeostasis, regulating processes like body temperature, pH, and electrolyte balance. Systems like the nervous system, endocrine system, and excretory system play key roles in maintaining homeostasis.

Conclusion

The structural organization in animals is a complex and hierarchical system that allows animals to perform necessary life functions efficiently. From the cellular to the organismal level, tissues, organs, and organ systems work together to ensure the survival, reproduction, and overall health of the animal. A deep understanding of animal anatomy and physiology is crucial for fields like medicine, zoology, and environmental science.

हिंदी के सभी अध्याय के महत्वपूर्ण प्रशन उत्तर के लिए अभी Download करें Vidyakul App - Free Download Click Here