Introduction to Anatomy and Physiology

• Physiology is the study of how living organisms function
• It explores the mechanical, physical, and biochemical functions of living organisms
• It integrates functions at various levels, from molecular to systemic
• Anatomy is the study of the structure of living organisms
• It includes the identification and description of the structures of living things
• Anatomy ranges from macroscopic (gross) to microscopic levels

Organizational Levels in Organisms

• Chemical level involves atoms and molecules
• Cellular level consists of cells, the basic structural and functional units of an organism
• Tissue level is composed of groups of similar cells performing specific functions
• Organ level involves two or more tissue types working together to perform specific functions
• System level consists of related organs with a common function
• Organismal level represents the entire living individual

Homeostasis

• Refers to the maintenance of a stable internal environment
• It is essential for the survival and function of cells
• Homeostatic control systems involve receptors, control centers, and effectors
• Receptors detect changes in the internal environment
• Control centers process information and coordinate a response
• Effectors carry out the response to restore homeostasis
• Negative feedback mechanisms reverse the original stimulus to maintain homeostasis
• Positive feedback mechanisms amplify the original stimulus, leading to a rapid change

Cell Structure and Function

• Cells are the basic structural and functional units of life
• Major components include the plasma membrane, cytoplasm, and nucleus
• The plasma membrane is a selective barrier that regulates the passage of substances into and out of the cell
• Cytoplasm contains organelles suspended in cytosol
• The nucleus houses the cell's genetic material (DNA)
• Organelles perform specific functions within the cell
• Mitochondria produce ATP through cellular respiration
• Ribosomes synthesize proteins
• The endoplasmic reticulum (ER) is involved in protein and lipid synthesis
• The Golgi apparatus processes and packages proteins
• Lysosomes contain enzymes for intracellular digestion
• Cytoskeleton provides structural support and facilitates cell movement
• Cell membrane transport mechanisms include passive and active transport
• Passive transport does not require energy like diffusion and osmosis
• Active transport requires energy like pumps and vesicular transport
• Endocytosis brings substances into the cell
• Exocytosis releases substances from the cell

Tissues

• Tissues are groups of similar cells performing specific functions
• Four primary tissue types: epithelial, connective, muscle, and nervous
• Epithelial tissue covers surfaces, lines body cavities, and forms glands
• Connective tissue supports, connects, and separates different types of tissues and organs in the body
• Muscle tissue is responsible for movement
• Nervous tissue transmits electrical signals

The Skeletal System

• Provides support, protection, movement, mineral storage, and blood cell formation
• Bones are dynamic living tissues
• Bone composition includes organic (collagen and cells) and inorganic (mineral salts) components
• Bone cells include osteoblasts (bone-forming), osteocytes (mature bone cells), and osteoclasts (bone-resorbing)
• Bone types include compact and spongy bone
• Compact bone is dense and provides strength
• Spongy bone is porous and contains bone marrow
• Bone development involves ossification (bone formation) and remodeling (bone resorption and formation)
• The axial skeleton includes the skull, vertebral column, and rib cage
• The appendicular skeleton includes the bones of the limbs and girdles
• Joints (articulations) are where bones meet
• Joint types include fibrous, cartilaginous, and synovial
• Synovial joints are freely movable and contain synovial fluid for lubrication

The Muscular System

• Responsible for movement, posture, and heat production
• Muscle types include skeletal, smooth, and cardiac
• Skeletal muscle is voluntary and attached to bones
• Smooth muscle is involuntary and found in the walls of internal organs
• Cardiac muscle is involuntary and found in the heart
• Skeletal muscle structure includes muscle fibers (cells), myofibrils, and sarcomeres
• Muscle contraction involves the interaction of actin and myosin filaments
• ATP provides energy for muscle contraction
• Motor neurons stimulate muscle contraction at the neuromuscular junction
• Muscle fatigue results from depletion of energy reserves or accumulation of metabolic wastes

The Nervous System

• Controls and coordinates body functions through electrical and chemical signals
• Divisions include the central nervous system (CNS) and peripheral nervous system (PNS)
• CNS consists of the brain and spinal cord
• PNS consists of nerves and ganglia outside the CNS
• Neurons are the basic functional units of the nervous system
• Neuron structure includes a cell body, dendrites, and an axon
• Neurons transmit electrical signals called action potentials
• Synapses are junctions between neurons where neurotransmitters are released
• Neurotransmitters transmit signals across the synapse
• The brain is the control center of the nervous system
• Major brain regions include the cerebrum, cerebellum, and brainstem
• The cerebrum is responsible for higher-level functions like thought and memory
• The cerebellum coordinates movement and balance
• The brainstem controls basic life functions like breathing and heart rate
• The spinal cord transmits signals between the brain and the body
• Sensory and motor pathways connect the brain and spinal cord to the body
• The autonomic nervous system regulates involuntary functions
• Divisions of the autonomic nervous system include the sympathetic and parasympathetic nervous systems
• The sympathetic nervous system prepares the body for "fight or flight"
• The parasympathetic nervous system promotes "rest and digest" functions

The Endocrine System

• Regulates body functions through hormones
• Hormones are chemical messengers secreted by endocrine glands
• Major endocrine glands include the pituitary, thyroid, adrenal, pancreas, and gonads
• Hormones travel through the bloodstream to target cells
• Hormones bind to receptors on target cells to elicit a response
• Hormone actions include regulating metabolism, growth, reproduction, and mood
• The hypothalamus controls the pituitary gland
• The pituitary gland secretes hormones that regulate other endocrine glands
• The thyroid gland produces hormones that regulate metabolism
• The adrenal glands produce hormones that regulate stress response and electrolyte balance
• The pancreas produces insulin and glucagon, which regulate blood glucose levels
• The gonads (testes and ovaries) produce sex hormones

The Cardiovascular System

• Transports blood, oxygen, nutrients, and hormones throughout the body
• Components include the heart, blood vessels, and blood
• The heart is a muscular pump that circulates blood
• Blood vessels include arteries, veins, and capillaries
• Arteries carry blood away from the heart
• Veins carry blood back to the heart
• Capillaries are the site of exchange between blood and tissues
• Blood consists of plasma and formed elements (red blood cells, white blood cells, and platelets)
• Red blood cells transport oxygen
• White blood cells defend against infection
• Platelets are involved in blood clotting
• Blood pressure is the force exerted by blood against blood vessel walls
• The cardiac cycle consists of systole (contraction) and diastole (relaxation) of the heart chambers
• The lymphatic system returns fluid to the bloodstream and plays a role in immunity
• Lymph nodes filter lymph and contain immune cells

The Respiratory System

• Involved in gas exchange (oxygen and carbon dioxide)
• Components include the nose, pharynx, larynx, trachea, bronchi, and lungs
• The lungs contain alveoli, where gas exchange occurs
• Ventilation (breathing) involves inspiration (inhaling) and expiration (exhaling)
• Gas exchange occurs by diffusion across the respiratory membrane
• Oxygen is transported in the blood bound to hemoglobin
• Carbon dioxide is transported in the blood as bicarbonate ions

The Digestive System

• Breaks down food into absorbable nutrients
• Components include the mouth, esophagus, stomach, small intestine, large intestine, liver, gallbladder, and pancreas
• Digestion involves mechanical and chemical processes
• Mechanical digestion includes chewing and peristalsis
• Chemical digestion involves enzymes that break down carbohydrates, proteins, and fats
• Absorption of nutrients occurs primarily in the small intestine
• The liver produces bile, which emulsifies fats
• The gallbladder stores and concentrates bile
• The pancreas secretes digestive enzymes and bicarbonate
• The large intestine absorbs water and electrolytes and eliminates waste

The Urinary System

• Filters blood and eliminates waste products in the form of urine
• Components include the kidneys, ureters, urinary bladder, and urethra
• The kidneys filter blood to produce urine
• Nephrons are the functional units of the kidneys
• Urine formation involves filtration, reabsorption, and secretion
• The ureters transport urine from the kidneys to the urinary bladder
• The urinary bladder stores urine
• The urethra eliminates urine from the body

The Reproductive System

• Involved in sexual reproduction
• Male reproductive system includes the testes, epididymis, vas deferens, seminal vesicles, prostate gland, and penis
• The testes produce sperm and testosterone
• Female reproductive system includes the ovaries, fallopian tubes, uterus, vagina, and mammary glands
• The ovaries produce eggs and estrogen and progesterone
• Fertilization occurs in the fallopian tubes
• The uterus supports the development of the fetus during pregnancy

Explore anatomy, the study of structure, and physiology, the study of function in living organisms. Understand organizational levels from chemical to organismal. Learn about homeostasis, the maintenance of a stable internal environment.