Human Biology Essentials
Essential facts about the human body and its systems.
How many bones are in the adult human body?
206
What is the role of red blood cells?
Transport oxygen from the lungs to body tissues and return carbon dioxide to the lungs via haemoglobin.
What are the four chambers of the heart?
Right atrium, right ventricle, left atrium, left ventricle. Right side pumps blood to lungs; left side pumps oxygenated blood to the body.
What is the function of the liver?
Detoxification, protein synthesis, bile production for digestion, glycogen storage, and metabolism of fats, carbohydrates, and proteins.
What is DNA?
Deoxyribonucleic acid โ a double helix molecule made of nucleotide bases (A, T, G, C) that encodes genetic instructions for the development and function of all living organisms.
What is the largest organ of the body?
The skin โ it covers ~1.7โ2 mยฒ, regulates temperature, prevents infection, and contains sensory receptors.
What is the difference between arteries and veins?
Arteries carry oxygenated blood away from the heart (except pulmonary artery). Veins carry deoxygenated blood toward the heart (except pulmonary vein). Arteries have thicker, muscular walls.
What is the function of the pancreas?
Exocrine: produces digestive enzymes (lipase, amylase, proteases). Endocrine: secretes insulin and glucagon to regulate blood sugar.
How many pairs of chromosomes do humans have?
23 pairs (46 total): 22 pairs of autosomes and 1 pair of sex chromosomes (XX = female, XY = male).
What is the central nervous system?
The brain and spinal cord. It processes sensory information and coordinates responses. The peripheral nervous system connects the CNS to the rest of the body.
What is ATP?
Adenosine triphosphate โ the primary energy currency of the cell, produced mainly in mitochondria via cellular respiration.
What is the blood-brain barrier?
A selective semi-permeable membrane formed by tight junctions between endothelial cells in brain capillaries, protecting the brain from pathogens and toxins while allowing nutrients and gases to pass.