Ch. 1 (flashcards)
Anatomy and Physiology: Core Concepts
Anatomy describes the structures of the body: what they are made of, where they are located, and their associated structures. This includes studying internal and external structures and their physical relationships.
Physiology studies the functions of anatomical structures: how individual organs and entire organ systems work, both independently and cooperatively, to maintain life.
Human anatomy focuses on:
Gross (macroscopic) anatomy: Examines large, visible structures without a microscope. Examples include surface anatomy (exterior features), regional anatomy (body areas like the head or leg), and systemic anatomy (organ systems).
Microscopic anatomy: Deals with structures too small to be seen without magnification.
Cytology: The study of internal structure of individual cells.
Histology: The study of tissues (groups of specialized cells and their products).
Human physiology focuses on:
Cell physiology: Study of the functions of living cells, including events at chemical and molecular levels.
Organ physiology: Study of the function of specific organs (e.g., cardiac physiology).
Systemic physiology: Study of the functions of an entire organ system (e.g., cardiovascular physiology).
Pathological physiology: Study of the effects of diseases on organ or system functions.
A patient presents with signs (objective, measurable indicators like fever or rash) and symptoms (subjective experiences reported by the patient like pain or nausea); physicians use the scientific method to reach a diagnosis by forming a hypothesis about the cause of illness and testing with clinical data.
Levels of Organization
Chemical level: The simplest level; atoms are the smallest stable units of matter (e.g., carbon, hydrogen, oxygen); molecules are groups of atoms held together by chemical bonds (e.g., water H2OH2O, glucose C6H12O6C6H12O6).
Cellular level: Cells are the smallest living units in the body. They are formed by molecules interacting to create organelles, which are then organized into sophisticated structures.
Tissue level: Tissues are groups of similar cells that work together to perform a specific function (e.g., muscle tissue, epithelial tissue, connective tissue, nervous tissue).
Organ level: Organs are functional units composed of two or more different types of tissues working together to perform complex functions (e.g., heart, stomach, brain).
Organ system level: An organ system is a group of interacting organs that coordinate to perform major functions of the body; humans have 1111 organ systems that work interdependently.
Organism level: The highest level of organization; an individual life form, representing all body systems working together to maintain life and health.
Organ Systems (overview)
Integumentary system — Major organs: skin, hair, sweat glands, nails; Functions: protects against environmental hazards (physical, chemical, pathogen), regulates body temperature through sweating and blood flow, provides sensory information (touch, pressure, temperature, pain), synthesizes vitamin D3D3.
Skeletal system — Major organs: bones, cartilages, ligaments, bone marrow; Functions: provides support and protection for soft tissues and organs, stores calcium and other minerals, forms blood cells (hematopoiesis) within the bone marrow, allows for movement through muscle attachment.
Muscular system — Major organs: skeletal muscles and tendons (which attach muscles to bone); Functions: enables movement of the body and its parts, provides protection and support for internal tissues, generates heat to maintain body temperature (thermoregulation).
Nervous system — Major organs: brain, spinal cord, peripheral nerves, sense organs (e.g., eyes, ears); Functions: directs immediate responses to stimuli, coordinates activities of other organ systems, processes and interprets sensory information, controls voluntary and involuntary actions.
Endocrine system — Major organs: pituitary gland, thyroid gland, pancreas, adrenal glands, gonads (testes/ovaries), pineal gland, and other endocrine tissues; Functions: directs long-term changes in other organ systems, regulates metabolism, growth, development, and reproduction through hormones.
Cardiovascular system — Major organs: heart (pumps blood), blood (transport medium), blood vessels (arteries, veins, capillaries); Functions: distributes blood cells, water, nutrients, oxygen, carbon dioxide, and waste products; helps regulate body temperature, pH, and defends against disease.
Lymphatic system — Major organs: spleen, thymus, lymph vessels, lymph nodes, tonsils, lymphatic tissue; Functions: defends against infection and disease, returns excess interstitial fluid and leaked plasma proteins to the bloodstream (maintains fluid balance).
Respiratory system — Major organs: nasal cavities, sinuses, larynx, trachea, bronchi, lungs (containing alveoli); Functions: delivers air to alveoli (sites of gas exchange), exchanges oxygen and carbon dioxide between air and blood, produces sounds for communication (phonation).
Digestive system — Major organs: teeth, tongue, pharynx, esophagus, stomach, small and large intestines, liver, gallbladder, pancreas; Functions: processes and digests food, absorbs water and nutrients (vitamins, minerals, organic molecules), stores energy reserves.
Urinary system — Major organs: kidneys, ureters, urinary bladder, urethra; Functions: excretes waste products (urea, toxins), maintains water and electrolyte balance, regulates blood pH, stores urine prior to voluntary elimination.
Male Reproductive system — Major organs: testes, epididymides, ductus deferens, seminal glands, prostate, urethra, penis, scrotum; Functions: produces male sex cells (sperm) and hormones (e.g., testosterone), delivers semen to the female reproductive tract, supports sexual intercourse.
Female Reproductive system — Major organs: ovaries, uterine tubes, uterus, vagina, external genitalia (labia, clitoris), mammary glands; Functions: produces female sex cells (oocytes) and hormones (e.g., estrogen, progesterone), supports embryonic and fetal development, provides nourishment to a newborn (milk), enables sexual intercourse and reproduction.
Body Cavities and Serous Membranes
The Ventral body cavity (coelom) is a large, anterior cavity divided by the diaphragm into two main subdivisions: the superior thoracic cavity and the inferior abdominopelvic cavity. These cavities contain internal organs collectively called viscera.
Serous membranes (serosa) are thin, double-layered membranes that line the walls of the ventral body cavities and cover the surfaces of the organs within them. They reduce friction between organs and cavity walls.
They consist of two layers:
Parietal layer: Lines the internal surface of the body wall or cavity.
Visceral layer: Covers the external surface of the organs within the cavity.
A thin layer of serous fluid between these layers lubricates and prevents friction.
Thoracic cavity subdivisions:
Right and left pleural cavities: Each surrounds one lung. The pleura is the serous membrane lining these cavities.
Mediastinum: The central tissue mass between the pleural cavities. It contains the trachea, esophagus, thymus, and major blood vessels (aorta, vena cava).
Pericardial cavity: Enclosed within the mediastinum, it surrounds the heart. The pericardium is the serous membrane lining this cavity.
Abdominopelvic cavity: Extends from the diaphragm to the pelvis.
Peritoneal cavity: A potential space within the abdominopelvic cavity, lined by the peritoneum (serous membrane).
Parietal peritoneum: Lines the inner surface of the abdominal wall.
Visceral peritoneum: Covers many of the digestive and other organs within the abdominal cavity.
Abdominal cavity: The superior portion, containing most of the digestive organs (stomach, liver, spleen, small and most of the large intestines).
Retroperitoneal space: Area posterior to the peritoneum, housing organs such as the kidneys, ureters, pancreas, and parts of the digestive tract (e.g., duodenum, ascending and descending colon).
Pelvic cavity: The inferior portion, largely enclosed by the pelvic bones, containing reproductive organs, the rectum, and the urinary bladder.
Directional Terms and Anatomical Planes
Anatomical position: The universally accepted reference position for describing the body: stand erect, feet slightly apart, face forward, arms at sides with palms turned forward, and thumbs pointing away from the body.
Supine: Lying face up, on the back.
Prone: Lying face down, on the stomach.
Directional terms: Used to locate and describe relative positions of structures in the body:
Superior (cranial): Toward the head or upper part of a structure; above. (e.g., The nose is superior to the mouth.)
Inferior (caudal): Away from the head or toward the lower part of a structure; below. (e.g., The navel is inferior to the breastbone.)
Anterior (ventral): Toward or at the front of the body; in front of. (e.g., The sternum is anterior to the spine.)
Posterior (dorsal): Toward or at the back of the body; behind. (e.g., The heart is posterior to the sternum.)
Medial: Toward or at the midline of the body; on the inner side of. (e.g., The heart is medial to the arms.)
Lateral: Away from the midline of the body; on the outer side of. (e.g., The arms are lateral to the chest.)
Proximal: Closer to the origin of the body part or the point of attachment of a limb to the body trunk. (e.g., The elbow is proximal to the wrist.)
Distal: Farther from the origin of a body part or the point of attachment of a limb to the body trunk. (e.g., The fingers are distal to the elbow.)
Superficial (external): Toward or at the body surface. (e.g., The skin is superficial to the skeletal muscles.)
Deep (internal): Away from the body surface; more internal. (e.g., The lungs are deep to the skin.)
Abdominopelvic quadrants: For clinical examination, the anterior abdominopelvic surface is divided into four quadrants by a transverse plane and a midsagittal plane intersecting at the umbilicus:
Right Upper Quadrant (RUQ): Contains liver (right lobe), gallbladder, pylorus of stomach, duodenum, head of pancreas, right adrenal gland, right kidney, superior part of large intestine.
Right Lower Quadrant (RLQ): Contains cecum, appendix, most of small intestine, right ureter, right ovary/spermatic cord.
Left Upper Quadrant (LUQ): Contains liver (left lobe), spleen, most of stomach, jejunum and proximal ileum, body and tail of pancreas, left adrenal gland, left kidney, superior part of large intestine.
Left Lower Quadrant (LLQ): Contains sigmoid colon, descending colon, most of small intestine, left ureter, left ovary/spermatic cord.
Abdominopelvic regions (named): A more precise division using two transverse and two sagittal planes, creating nine regions for specific anatomical localization.
Top row: Right hypochondriac, Epigastric, Left hypochondriac.
Middle row: Right lumbar, Umbilical, Left lumbar.
Bottom row: Right inguinal (iliac), Hypogastric (pubic), Left inguinal (iliac).
Sectional Planes and Sectional Anatomy
A section is a slice through a 3D object or body part; used to visualize internal organization and relationships of structures that are otherwise obscured. Essential for medical imaging.
Planes: Imaginary flat surfaces used to divide the body or an organ for observation:
Frontal (coronal) plane: Divides the body into anterior (front) and posterior (back) portions; results in a frontal or coronal section. (e.g., viewing the front vs. back half of the brain).
Sagittal plane: Divides the body into left and right portions.
Midsagittal plane (median plane): Passes directly through the midline, dividing the body into equal left and right halves.
Parasagittal plane: Divides the body into unequal left and right portions.
Transverse (horizontal) plane: Divides the body into superior (upper) and inferior (lower) portions; results in a cross-section. (e.g., viewing a slice through the abdomen).
Anatomical Landmarks and Terminology
Surface anatomy: The study of general form (morphology) and superficial anatomical markings. Key landmarks are used to locate deeper structures on or near the body surface, crucial for physical examination and diagnosis.
Examples of common regional terms (for quick recall and communication):
Cephalic: Head; Facial: Face; Ocular: Eye; Nasal: Nose; Buccal: Cheek; Mental: Chin.
Cervical: Neck; Thoracic: Chest; Abdominal: Abdomen; Umbilical: Navel.
Manual: Hand; Carpal: Wrist; Palmar: Palm; Plantar: Sole of foot.
Major regional terms help accurately orient positioning of structures throughout the body, providing a common language for healthcare professionals.
Homeostasis and Regulation
Homeostasis: The fundamental principle that all body systems work together to maintain a stable internal environment (internal constancy), even when external conditions change. Physiological variables such as temperature, fluid balance, and blood glucose are kept within narrow, normal ranges.
Regulation types:
Autoregulation (intrinsic regulation): Occurs when a cell, tissue, organ, or organ system automatically adjusts its activities in response to an environmental change, without involving the nervous or endocrine system. (e.g., local blood vessel dilation in response to low oxygen).
Extrinsic regulation: Responses that are controlled by the nervous system and/or the endocrine system. These systems can issue commands to many cells or organs simultaneously (e.g., body-wide temperature control by the brain).
A homeostatic regulatory loop typically consists of three components:
Receptor (sensor): Detects a stimulus (a change in the internal or external environment) and transmits information to the control center. (e.g., thermoreceptors in skin detect cold).
Control center (integration center): Receives and processes the information from the receptor, then compares it to a set point (desired value) and issues commands to an effector. (e.g., the hypothalamus in the brain).
Effector: A cell, organ, or system that carries out the instructions from the control center to oppose or enhance the stimulus. (e.g., sweat glands, muscles, blood vessels).
Negative feedback: The primary mechanism for homeostatic regulation. The effector's response negates or opposes the original stimulus, bringing the variable back toward its set point or normal range. This reduces the intensity of the original stimulus.
Example: Body temperature control. If body temperature rises, receptors detect it, the control center activates effectors (sweat glands, blood vessel dilation) to cool the body, which reduces the original rise in temperature.
Example: Blood glucose regulation. When blood glucose rises, the pancreas releases insulin to lower it. When blood glucose falls, the pancreas releases glucagon to raise it.
Positive feedback: A less common regulatory mechanism where the initial stimulus produces a response that amplifies the original stimulus, pushing the variable further away from the set point. This process typically moves the body rapidly toward a completion of an event.
Example: Blood clotting (platelets release chemicals that attract more platelets, accelerating clot formation until the bleeding stops).
Example: Childbirth (uterine contractions stimulate the release of oxytocin, which in turn increases the strength and frequency of contractions until the baby is born).
Dynamic equilibrium: Homeostasis involves a state of dynamic equilibrium, where physiological parameters fluctuate within a narrow range around a set point. There is continuous adjustment and adaptation to maintain balance. Failure of homeostatic regulation can lead to disease or pathological conditions.
Quick Reference Numeric/Terminology Details
Number of organ systems in the human body: 1111.
Normal human body temperature range: 36.7∘C36.7∘C to 37.2∘C37.2∘C (or 98.1∘F98.1∘F to 99.0∘F99.0∘F).
Room temperature example often used in regulation diagrams: 22∘C22∘C (or 71.6∘F71.6∘F).
Key imaging modalities in sectional anatomy for diagnostic purposes: MRI (Magnetic Resonance Imaging), PET (Positron Emission Tomography), CT (Computed Tomography).