CSS Syllabus Paper General Science & Ability (Part-I)

BIOLOGICAL SCIENCE …

HUMAN PHYSIOLOGY

Human physiology is the scientific study of the functions and mechanisms that occur within the human body to maintain its optimal functioning. It encompasses various systems, organs, tissues, and cells, all working together in a highly coordinated manner. Here is a brief account of some key aspects of human physiology:

1.    Circulatory System: The circulatory system, comprising the heart, blood vessels, and blood, is responsible for transporting oxygen, nutrients, hormones, and waste products throughout the body.   The heart pumps oxygenated blood from the lungs to the body's tissues, while deoxygenated blood returns to the heart to be sent to the lungs for oxygenation.

2.    Respiratory System: The respiratory system facilitates the exchange of oxygen and carbon dioxide between the body and the environment. It includes the nose, trachea, bronchi, and lungs.  In the lungs, oxygen is taken up by red blood cells and transported to tissues, while carbon dioxide, a waste product, is removed from the body during exhalation.

3.    Nervous System: The nervous system is responsible for coordinating and controlling bodily functions. It comprises the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves throughout the body).

   It transmits electrical signals called nerve impulses to regulate body activities, including movement, sensation, cognition, and the autonomic functions like heart rate and digestion.

4.  Musculoskeletal System: The musculoskeletal system provides support, stability, and movement to the body. It includes bones, muscles, tendons, and ligaments.   Muscles enable voluntary movements, while bones serve as a framework and protect vital organs. Tendons connect muscles to bones, and ligaments connect bones to other bones, providing stability to joints.

5.    Digestive System: The digestive system processes food, extracts nutrients, and eliminates waste products. It comprises organs such as the mouth, esophagus, stomach, small intestine, large intestine, liver, and pancreas. Digestion starts in the mouth, where food is broken down mechanically and chemically, and continues through the various organs until nutrients are absorbed into the bloodstream.

6.  Endocrine System: The endocrine system regulates body functions through the secretion of hormones. Hormones are chemical messengers that travel through the bloodstream to target organs and tissues, influencing processes such as metabolism, growth, reproduction, and mood. Key glands of the endocrine system include the pituitary gland, thyroid gland, adrenal glands, and pancreas.

7.        Urinary System: The urinary system filters waste products from the blood and helps maintain fluid and electrolyte balance. It comprises the kidneys, ureters, bladder, and urethra. The kidneys filter blood to remove waste products and excess water, producing urine, which is then transported to the bladder for storage and subsequently eliminated through the urethra.

8.    Reproductive System: The reproductive system is responsible for the production of offspring. In males, it includes the testes, which produce sperm, and accessory glands and ducts. In females, it comprises the ovaries, which produce eggs, and structures like the uterus, fallopian tubes, and vagina that facilitate fertilization, implantation, and gestation.

9.  Immune System: The immune system protects the body against pathogens, such as bacteria, viruses, and fungi. It consists of various specialized cells, tissues, and organs, including white blood cells, lymph nodes, the spleen, and the thymus. The immune system recognizes and destroys harmful substances, preventing infections and diseases.

10.                Integumentary System: The integumentary system is composed of the skin, hair, nails, and associated glands. It serves as a protective barrier against external threats, regulates body temperature, and helps in the synthesis of vitamin D. Additionally, the skin contains sensory receptors that detect touch, pressure, pain, and temperature.

11.  Skeletal System: The skeletal system provides support, protection, and structure to the body. It consists of bones, cartilage, ligaments, and tendons. Apart from its mechanical functions, the skeletal system is involved in hematopoiesis (the production of blood cells) and serves as a storage site for minerals, such as calcium and phosphorus.

12.      Lymphatic System: The lymphatic system works closely with the immune system to defend the body against infections and diseases. It includes lymphatic vessels, lymph nodes, the spleen, thymus, and tonsils. The lymphatic system collects and transports lymph (a clear fluid containing immune cells) throughout the body, filtering it and removing foreign substances and cellular waste.

13.   Homeostasis: Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes. Various physiological mechanisms and feedback loops work together to regulate factors such as body temperature, blood pressure, pH levels, and glucose concentration. For instance, sweating helps cool the body during exercise to prevent overheating.

14. Metabolism: Metabolism encompasses all the chemical reactions occurring within the body to maintain life. It involves two main processes: catabolism, which breaks down complex molecules into simpler ones to release energy, and anabolism, which uses energy to build complex molecules. Metabolism is regulated by hormones and influenced by factors such as nutrition, exercise, and genetic factors.

15.     Neurotransmission: Neurotransmission is the process by which nerve cells (neurons) communicate with each other. It involves the release, diffusion, and binding of chemical messengers called neurotransmitters across the synapses. This communication is essential for functions like sensory perception, motor control, memory, and emotions.

It's important to note that human physiology is a vast and continuously evolving field of study. This brief account provides an overview of some major systems and processes in the human body, but there is much more to explore and discover in the fascinating intricacies of human physiology.

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