Human Anatomy Basics

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### Parts of the Brain The brain is the command center of the nervous system. - **Cerebrum:** - Largest part of the brain. - Responsible for thought, voluntary movement, language, reasoning, and perception. - Divided into four lobes: - **Frontal Lobe:** Planning, decision-making, personality, voluntary movement. - **Parietal Lobe:** Sensory information processing (touch, temperature, pain), spatial awareness. - **Temporal Lobe:** Hearing, memory, emotion, language comprehension. - **Occipital Lobe:** Vision and visual processing. - **Cerebellum:** - Located at the back of the brain, below the cerebrum. - Coordinates voluntary movements, balance, posture, and motor learning. - **Brainstem:** - Connects the cerebrum and cerebellum to the spinal cord. - Controls vital involuntary functions like breathing, heart rate, blood pressure, and sleep. - Composed of: - **Midbrain:** Vision, hearing, motor control, sleep/wake cycles. - **Pons:** Relays signals from the cerebrum to the cerebellum, involved in sleep, respiration, swallowing, bladder control. - **Medulla Oblongata:** Controls heart rate, breathing, blood pressure, digestion, vomiting. - **Diencephalon:** - Located deep within the brain, above the brainstem. - Includes: - **Thalamus:** Relays sensory and motor signals to the cerebral cortex, regulates consciousness, sleep, and alertness. - **Hypothalamus:** Controls body temperature, hunger, thirst, fatigue, sleep, and circadian cycles. It also links the nervous system to the endocrine system via the pituitary gland. - **Pituitary Gland:** - A small gland located at the base of the brain, attached to the hypothalamus. - Often called the "master gland" because it produces hormones that control many other endocrine glands and body functions, including growth, metabolism, and reproduction. ### Parts of the Heart The heart is a muscular organ that pumps blood throughout the body. - **Atria (Left & Right):** - **Right Atrium:** Receives deoxygenated blood from the body via the superior and inferior vena cava. - **Left Atrium:** Receives oxygenated blood from the lungs via the pulmonary veins. - **Ventricles (Left & Right):** - **Right Ventricle:** Pumps deoxygenated blood to the lungs via the pulmonary artery. - **Left Ventricle:** Pumps oxygenated blood to the rest of the body via the aorta. It has the thickest muscular wall due to the high pressure required. - **Valves:** Prevent backflow of blood. - **Tricuspid Valve:** Between right atrium and right ventricle. - **Mitral (Bicuspid) Valve:** Between left atrium and left ventricle. - **Pulmonary Valve:** Between right ventricle and pulmonary artery. - **Aortic Valve:** Between left ventricle and aorta. - **Septum:** - A muscular wall that divides the heart into right and left sides, preventing the mixing of oxygenated and deoxygenated blood. - **Major Blood Vessels:** - **Aorta:** Main artery carrying oxygenated blood from the left ventricle to the body. - **Pulmonary Artery:** Carries deoxygenated blood from the right ventricle to the lungs. - **Pulmonary Veins:** Carry oxygenated blood from the lungs to the left atrium. - **Vena Cava (Superior & Inferior):** Carry deoxygenated blood from the body to the right atrium. ### Major Body Organs and Their Functions A brief overview of other key organs. - **Lungs:** - **Function:** Facilitate gas exchange (oxygen into blood, carbon dioxide out of blood) through respiration. - **Liver:** - **Function:** Detoxifies chemicals, metabolizes drugs, produces bile for digestion, stores glycogen, synthesizes proteins (e.g., clotting factors). - **Kidneys:** - **Function:** Filter waste products from the blood, regulate blood pressure, maintain electrolyte balance, produce urine. - **Stomach:** - **Function:** Digests food by secreting acids and enzymes, mixing food with digestive juices to form chyme. - **Small Intestine:** - **Function:** Primary site for absorption of nutrients from digested food into the bloodstream. - **Large Intestine (Colon):** - **Function:** Absorbs water and electrolytes, forms and stores feces, houses beneficial gut bacteria. - **Pancreas:** - **Function:** Produces digestive enzymes (exocrine function) and hormones like insulin and glucagon (endocrine function) to regulate blood sugar. - **Gallbladder:** - **Function:** Stores and concentrates bile produced by the liver, releasing it into the small intestine to aid fat digestion. - **Skin:** - **Function:** Largest organ; acts as a protective barrier, regulates body temperature, senses touch/pressure/pain, produces Vitamin D. - **Spleen:** - **Function:** Filters blood, removes old red blood cells, stores blood, and plays a role in the immune system.