Nervous and Respiratory Systems

Nervous System

• The nervous system coordinates and controls bodily functions via signal transmission.
• It has two main parts: the central nervous system (CNS) – brain and spinal cord – and the peripheral nervous system (PNS) connecting the CNS to the body.
• Neurons are specialized cells transmitting electrochemical signals.
• The brain is the body's control center, managing functions like thought, memory, emotion, and movement.
• The spinal cord acts as a pathway for signals between the brain and body.
• Sensory neurons detect stimuli and send signals to the CNS, while motor neurons transmit signals from the CNS to muscles and glands.

Respiratory System

• The respiratory system facilitates gas exchange, taking oxygen and releasing carbon dioxide.
• Key organs include lungs, trachea, bronchi, and bronchioles.
• Breathing involves inhalation (air into lungs) and exhalation (air out of lungs).
• Gas exchange occurs in alveoli, tiny air sacs in the lungs.
• Oxygen diffuses from alveoli to blood, and carbon dioxide diffuses from blood to alveoli.
• The respiratory system is essential for oxygen supply and carbon dioxide removal from tissues.

Digestive System

• The digestive system processes food, breaking it down into absorbable nutrients.
• Organs include mouth, esophagus, stomach, small intestine, large intestine, and rectum.
• Mechanical digestion physically breaks down food; chemical digestion uses enzymes to break food into smaller molecules.
• Digestive enzymes break down carbohydrates, proteins, and fats.
• Nutrient absorption primarily occurs in the small intestine.
• Undigested materials are eliminated through the rectum and anus.
• The liver, gallbladder, and pancreas support digestion by producing enzymes and bile.

Endocrine System

• The endocrine system is a network of glands secreting hormones into the bloodstream, regulating bodily functions.
• Hormones are chemical messengers regulating metabolism, growth, and development.
• Key glands include pituitary, thyroid, adrenal, and pancreas.
• The pituitary gland (master gland) controls other endocrine glands.
• The thyroid gland controls metabolism.
• The adrenal glands respond to stress and regulate salt/water balance.
• The pancreas regulates blood sugar.
• The endocrine system works with the nervous system to maintain homeostasis.

Circulatory System

• The circulatory system, also known as the cardiovascular system, circulates blood throughout the body.
• It consists of the heart, blood vessels (arteries, veins, capillaries), and blood.
• The heart pumps blood to the lungs for oxygenation and then to the rest of the body.
• Arteries carry oxygen-rich blood away from the heart.
• Veins carry oxygen-poor blood back to the heart.
• Capillaries allow nutrient, oxygen, and waste exchange between blood and tissues.
• Blood contains red blood cells (carrying oxygen), white blood cells (immune system), and platelets (clotting).
• The circulatory system delivers oxygen and nutrients to cells, removing waste products, and maintaining homeostasis.