Chapter 2.docx

chapter 2: introduction to the human body **Human Anatomy** It is the scientific (meaning factual) study of the body's structures The ***where*** of the body's components. **Two Subbranches of Anatomy** 1. **Microscopic Anatomy** Some of the structures in anatomy are very small and...

chapter 2: introduction to the human body **Human Anatomy** It is the scientific (meaning factual) study of the body's structures The ***where*** of the body's components. **Two Subbranches of Anatomy** 1. **Microscopic Anatomy** Some of the structures in anatomy are very small and can only be observed and analyzed with the assistance of a microscope. It can only be done on cells and tissues removed from the body (which is not optimal for brain tissue). 2. **Gross Anatomy** It is also known as **macroscopic** **anatomy**. It talks about when larger structures can readily be seen, manipulated, measured, and weighed. **Two General Approaches to Study Body Structures** 1. **Regional** The body is subdivided into regions. It is the study of the interrelationships of all the structures in a specific body region. Relatedness of body structures. Its goal is to build a three-dimensional understanding of the placement and relationships among structures. 2. **Systemic** In accordance with the organ systems. It is the study of the structures that make up a discrete body system (a group of structures that work together to perform a unique body function). **Physiology** It is the scientific study of the chemistry and physics of the structures of the human body and the ways in which they work together to support the functions of life. The ***how*** of the body's components. Organs work hand in hand. **The Themes of Anatomy and Physiology** - Structure and function - Evolution and human variation - Flow - Homeostasis **Structure and Function** **Form** is closely related to function in all living things. An example is protein structure because it is intimately tied to protein function. Changes in structure may alter the function. Another example is **bipedalism** (humans are the only adult mammals that walk predominantly on two feet. **Evolution** It is a change in gene expression that occurs from generation to generation. What is or is not advantageous has to do with the immediate environment. An example is melanin because it allows the body to withstand UV rays. Physiological variation is more diverse and widespread because it affects the **recognition** **and** **treatment** **of** **diseases**. **Flow** Substances flow according to gradients. **Three Types of Gradients** 1. **Concentration Gradients** 2. **Electrical Gradients** 3. **Pressure Gradients** \* In all examples of flow, there are also factors that oppose, or resist, flow. \* We can summarize the rate of flow as being determined by the size of the gradient divided by resistance; or \* Flow is proportional to the size of the gradient and inversely proportional to resistance. **Homeostasis** It is the state of dynamic stability of the body's internal conditions. Examples of must-remain constant parameters in our body include **oxygen levels, pH, nutrient availability, and temperature**. - **Setpoint** \* Not all physiological variables are homeostatically regulated, such as heart rate. - **Negative feedback** - **Positive feedback** **Structural Organization of the Human Body** **Element** These are unique pure substances that composes all matter in the universe. Examples include hydrogen, oxygen, carbon, nitrogen, calcium, and iron. **Atom** These are the smallest units of any pure substance (element). These are made up of subatomic particles such as protons, electrons, and neutrons. **Molecule** These are two or more atoms combined. Examples include water molecules, proteins, and sugars found in living things. These are the chemical building blocks of all body structures. **Cell** It is the smallest independently functioning unit of a living organism. All living structures of human anatomy contain cells, and almost all functions of human physiology are performed in cells or are initiated by cells. They perform all functions of life. **Organelles** A human cell functions as its own tiny world encased in a protective membrane that encloses a variety of tiny functioning units. **Tissue** They are a group of many cells that work together to perform a specific function. **Organ** It is a structure of the human body that is composed of two or more tissue types; each organ performs one or more specific physiological functions. **Organ system** It is a group of organs that work together to perform major functions or meet physiological needs of the body. Assigning organs to organ systems can be imprecise because organs that "belong" to one system can also have functions integral to another system; therefore, most organs contribute to more than one system. **Organism** It is the highest level of organization. It is a living being that has a cellular structure and that can independently perform all physiologic functions necessary for life. **Anatomical Terminology** Its purpose is not to confuse, but rather increase precision and reduce medical errors. We eliminate ambiguity. They are derived from ancient Greek and Latin words. **Anatomical Position** To eliminate confusion, we use this standard position when describing the relative position of one structure to another. The body standing upright, with the feet shoulder width apart and parallel, and toes forward. The upper limbs are held out to each side, and the palms of the hands face forward with thumbs out to the sides. The terms right and left refer to the patient's or cadaver's right and left. \* The body's position can be described as: 1. **Prone** 2. **Supine** \* These terms are sometimes used in describing the position of the body during specific **physical examinations or surgical positions**. **Regional Terms** \* Written in the latter part. **Directional Terms** These are essential for describing the relative locations of different body structures. 1. **Anterior (Ventral)** 2. **Posterior (Dorsal)** 3. **Superior (Cranial)** 4. **Inferior (Caudal)** 5. **Lateral** 6. **Medial** 7. **Superficial** 8. **Deep** 9. **Proximal** 10. **Distal** \* The terms proximal and distal are only used to describe two structures on the same limb. You would not use these terms to describe structures on the trunk or axis of the body. **Sections and Planes** Used to visualize internal anatomy. **Section** It is a slice of a three-dimensional structure that has been cut. **Plane** It is an imaginary slice through the body used in imaging. **Anatomy of 2D Sections and Planes** It illustrates some of the challenges around visualization of section. **The Three Planes in Anatomy and Medicine** 1. **Sagittal Plane** 2. **Frontal Plane** 3. **Transverse Plane** **Organization and Compartmentalization** Compartments are typically divided by sheets called **membranes**; however, that term has multiple meanings, so be extra careful with each context. **The Two Largest Body Compartments** These include the **Posterior Cavity** and the **Anterior Cavity**, both of which contain and protect delicate internal organs. **Subdivisions of the Posterior and Anterior Cavities** **Posterior Cavity (Dorsal Cavity)** 1. **Cranial Cavity** 2. **Spinal Cavity (Vertebral Cavity)** \* Both of them are continuous, uninterrupted structures. **Anterior Cavity (Ventral Cavity)** 1. **Thoracic Cavity** - **Two Pleural Cavities** - **Mediastinum** 2. **Abdominopelvic Cavity (Peritoneal Cavity)** - **Abdominal Cavity** - **Pelvic Cavity** **Abdominal Regions and Quadrants** 1.4F: Abdominopelvic Regions - Medicine LibreTexts **Membranes of the Anterior Body Cavity** **Serous Membrane** It is also referred to as a **serosa**. It is one of the thin membranes that cover the walls and organs in the thoracic and abdominopelvic cavities. They form fluid-filled sacs, or cavities, that are meant to cushion and reduce friction on internal organs when they move; such as when the lungs inflate or the heart beats. **Parietal Layers** They line the walls of the body cavity. ***Pariet*** refers to a cavity wall. **Visceral Layer** It covers the organs (the **viscera**). \* Between the parietal and visceral layers is a thin, fluid-filled serous space, or cavity. \* They both secrete thin, slippery fluid that fills the cavity and lubricates the membranes. **Three Serous Cavities with Their Associated Membranes** 1. **Pleura** 2. **Pericardium** 3. **Peritoneum** **From the Laboratory Manual** **Body Parts and Regions** These are the parts and different regions identified externally in the human body. \* These parts are distributed into two major regions: 1. **Axial Region** 2. **Appendicular Region** **Body Parts Under Each Smaller Region** **Head (Cephalic)** Includes the skull and the face. --------------------- --------------------------------------------------------------------------------------------------------------------------- **Skull** Bony part of the head that encloses and protects the brain. **Face** Anterior (front) portion of the head where the eyes, nose, mouth, forehead, cheeks, and chin are found. **Neck (Cervical)** Supports he head and attaches it to the trunk; found between the head and the trunk. **Trunk** Body part that consists of the chest, abdomen, pelvis, and back. **Chest** Body part found between the neck and abdomen anteriorly. **Abdomen** Body part found between the chest and pelvis anteriorly. **Back** Posterior portion of the trunk that is between the neck and the buttocks. **Upper Limbs** These are attached to the trunk by the shoulder girdle, comprised of the clavicle anteriorly and the scapula posteriorly. **Shoulder** Part of the body where the upper limb is attached to the shoulder girdle. **Upper Arm** Part of the upper limb from the shoulder to the elbow. **Forearm** Part of the upper limb from the elbow to the wrist. **Wrist** Part of the upper limb, which connects the hand to the forearm. **Hand** Part of the upper limb, which includes palm and fingers. **Lower Limbs** These are attached to the trunk by the pelvic girdle consisting of the ilium, ischium, and pubic bones. **Buttocks** Posterior rounded area in the pelvis where the thigh is attached. **Thigh** Part of the lower limb that is attached to the pelvis. **Leg** Part of the lower limb from the knee to the ankle. **Ankle** Portion of the lower limb that attaches foot to the leg. **Foot** Part of the lower limb, which is composed of the sole and toes. **Anatomical Terms** **Axial** Central part of the body, which includes the head and the trunk. ---------------------- ------------------------------------------------------------------ **Cephalic** Head **Cranial** Portion of the skull surrounding the brain **Facial** Face **Orbital** Eye **Frontal** Forehead **Otic** Ear **Nasal** Nose **Buccal** Cheek **Oral** Mouth **Mental** Chin **Occipital** Back of the head **Cervical** Neck **Thoracic** Chest **Sternal** Breast bone **Mammary** Breast **Abdominal** Anterior body trunk inferior to the ribs **Umbilical** Navel **Coxal** Hip **Pelvic** Pelvis **Pubic** Genital area **Dorsal** Back **Scapular** Shoulder **Vertebral** Area of spine **Lumbar** Area of back between ribs and hips **Appendicular** Extremities or limbs **Acromial** Highest point of the shoulder **Axillary** Armpit **Brachial** Upper arm **Antecubital** Anterior surface of elbow **Olecranal** Elbow **Antebrachial** Forearm **Volar** Antero-medial aspect of the forearm **Carpal** Wrist **Palmar** Palm **Digital** Digits or fingers (upper limb); toes (lower limb) **Inguinal** Groin **Gluteal** Buttocks **Femoral** Thigh **Patellar** Anterior surface of the knee **Popliteal** Posterior surface of the knee **Crural** Anterior surface of the leg **Sural** Posterior surface of the leg **Fibular/Peroneal** Lateral side of the leg **Tarsal** Ankle **Pedal** Foot **Plantar** Sole of foot **Calcaneal** Heel **Directional Terms** **Superior** Above; refers to the upper part of a structure or the body ------------------------ -------------------------------------------------------------------------------------------- **Inferior** Below; refers to the lower part of a structure or the body **Anterior (Ventral)** In front of; front of the body **Posterior (Dorsal)** Behind; refers to the backside of the body **Medial** On the inner side of; near the midline of the body **Lateral** On the outer side of; farther from the midline of the body **Intermediate** Between a more medial and a more lateral structure **Ipsilateral** On the same side of the body as another structure **Contralateral** On the opposite side of the body from another structure **Proximal** Close to the point of attachment of a limb to the trunk; away from the point of origin **Distal** Farther from the point of attachment of a limb to the trunk; away from the point of origin **Superficial** Near the surface of the body **Deep** Away from the surface of the body; more internal **Anatomical Planes and Sections** **Sagittal Plane** It is a vertical plane that divides an organ or the body into right and left halves Body Sections Produced: **Sagittal Section** - **Mid-Sagittal Plane or Median Plane** - **Parasagittal Plane** **Frontal or Coronal Plane** It divides an organ or the body into anterior (front) and posterior (back) portions. Body Sections Produced: **Frontal or Coronal Section** **Transverse or Cross-sectional or Horizontal Plane** It divides an organ or the body into superior (upper) and inferior (lower) portions. Body Sections Produced: **Transverse or Cross or Horizontal Sections** **Oblique Plane** It is a plane that passes through an organ or the body at an angle or the body at an angle between the transverse plane and either sagittal or frontal plane. Body Sections Produced: **Oblique Section**