Introduction to Human Physiology

Human physiology is the branch of biology that studies the normal functioning of the human body and its organ systems. It explains how different organs and systems work together to maintain internal balance and sustain life. For NEET aspirants, human physiology is one of the most important and high-weightage units in Class 11 Biology. A strong command over this chapter helps students answer both conceptual and application-based questions in NEET.

Direct Links to Download 2025-26 Biology Notes (PDF)

► Click “Download Now” next to your subject to access the free PDF.

♦ The Living World ⇒ Download Now

♦ Structural Organisation in Animals ⇒ Download Now

♦ Cell - The Unit of Life ⇒ Download Now

♦ Plant Physiology ⇒ Download Now

♦ Human Physiology ⇒ Download Now

♦ Reproduction in Organisms ⇒ Download Now

♦ Evolution ⇒ Download Now

♦ Microbes in Human Welfare ⇒ Download Now

♦ Biotechnology and its Applications ⇒ Download Now

♦ Ecology ⇒ Download Now

Digestion and Absorption

Digestion is the process of breaking down complex food substances into simpler forms that can be absorbed and utilized by the body. The human digestive system consists of the alimentary canal and associated glands.

Major organs involved in digestion include the mouth, esophagus, stomach, small intestine, large intestine, liver, and pancreas. Enzymes like amylase, pepsin, trypsin, and lipase play a key role in chemical digestion.

Absorption of digested food mainly occurs in the small intestine through finger-like projections called villi, which increase surface area for absorption.

Breathing and Respiration

Breathing is the physical process of inhalation and exhalation, while respiration is a biochemical process that releases energy from food.

The human respiratory system includes the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and lungs. Gas exchange occurs in the alveoli.

Types of respiration:

• External respiration – exchange of gases between lungs and blood

• Internal respiration – exchange of gases between blood and tissues

Hemoglobin plays a crucial role in oxygen transport. Understanding respiratory volumes and capacities is important for NEET.

Body Fluids and Circulation

Circulation involves the transport of oxygen, nutrients, hormones, and waste materials throughout the body. Humans have a closed circulatory system.

Components of circulatory system:

• Heart

• Blood

• Blood vessels

The heart is a four-chambered organ consisting of two atria and two ventricles. Blood circulation occurs through double circulation, ensuring efficient oxygen supply.

Blood consists of plasma, red blood cells, white blood cells, and platelets. Blood groups and coagulation are frequently tested topics in NEET.

Excretory Products and Their Elimination

Excretion is the removal of metabolic waste products from the body. The human excretory system consists of kidneys, ureters, urinary bladder, and urethra.

The functional unit of the kidney is the nephron. Urine formation occurs in three steps:

1. Glomerular filtration

2. Tubular reabsorption

3. Tubular secretion

Regulation of kidney function is controlled by hormones like ADH and aldosterone. Disorders such as kidney failure and dialysis are important exam topics.

Locomotion and Movement

Locomotion refers to the movement of the body from one place to another. It involves coordination between bones, muscles, and joints.

The human skeletal system consists of 206 bones. Muscles are of three types:

• Skeletal muscles

• Smooth muscles

• Cardiac muscles

Sliding filament theory explains muscle contraction, which is a commonly asked NEET concept.

Neural Control and Coordination

The nervous system controls and coordinates body activities through electrical impulses. It is divided into:

• Central nervous system (CNS)

• Peripheral nervous system (PNS)

• Autonomic nervous system (ANS)

Neurons are the structural and functional units of the nervous system. Reflex action, synapse, and nerve impulse transmission are key topics for NEET.

Chemical Coordination and Integration

Chemical coordination in humans is carried out by the endocrine system through hormones. Hormones are secreted directly into the bloodstream and act on target organs.

Major endocrine glands include:

• Pituitary

• Thyroid

• Parathyroid

• Adrenal

• Pancreas

• Gonads

Hormonal disorders like diabetes mellitus, goiter, and dwarfism are important NEET topics.

Importance of Human Physiology for NEET

Human physiology carries maximum weightage in NEET Biology because:

• Most questions are NCERT-based

• Concepts are directly applicable

• Diagrams and flowcharts are frequently asked

Proper revision of this unit can significantly boost NEET scores.

Quick Summary Table

Conclusion

Human Physiology explains the complex yet well-coordinated functioning of the human body. Mastering this unit is essential for NEET aspirants aiming for high scores in Biology. With clear concepts, regular practice, and structured notes, students can confidently tackle questions from this section. StudentBro.in provides reliable, exam-oriented NEET Biology notes to support effective preparation.