Chapter 1: Introduction to Anatomy & Physiology PDF

Chapter 1: An Introduction to Anatomy & Physiology Dr. Kimberly Wallace Associate Professor of Biology Del Mar College Overview of Chapter 1 Purpose of Chapter 1: To introduce the structure and function of the human body. To explain how the body’s systems are organized...

Chapter 1: An Introduction to Anatomy & Physiology Dr. Kimberly Wallace Associate Professor of Biology Del Mar College Overview of Chapter 1 Purpose of Chapter 1: To introduce the structure and function of the human body. To explain how the body’s systems are organized and how they work together. Main Topics: Levels of structural organization The human body systems Characteristics of living organisms Requirements for life Homeostasis and its importance Anatomical terminology Body cavities and organ protection Imaging techniques Anatomy & Physiology Anatomy is the study of the body’s structures Where is it? What does it look like? What is it called? Physiology is the study of the body’s functions What does it do? Why does it do it? How does it do it? STRUCTURE DICTATES FUNCTION Approaches to studying Anatomy Gross anatomy, or macroscopic anatomy, examines large, visible structures Surface anatomy: studies exterior features and markings Regional anatomy: examines body areas Sectional anatomy: examines cross sections Systemic anatomy: focuses on individual organ systems *** our approach Clinical anatomy: medical specialties Developmental anatomy: from conception to adulthood, including embryology Figure 1.2 Gross and Microscopic Anatomy (a) Gross anatomy considers large structures such as the brain. (b) Microscopic anatomy can deal with the same structures, though at a different scale. This is a micrograph of nerve cells from the brain. LM × 1600. (credit a: “WriterHound”/Wikimedia Commons; credit b: Micrograph provided by the Regents of University of Michigan Medical School © 2012) Approaches to studying Anatomy Cont’d Microscopic anatomy: examines cells and molecules using a microscope Cytology: study of cells Histology: study of tissues Approaches to studying Physiology Cell physiology: functions of organelles and cells Organ physiology: functions of specific organs Systemic physiology: functions of organ systems Pathological physiology: effects of diseases on organs or systems Characteristics/Functions of Living Organisms All living organisms share specific characteristics: 1. Organization: Life is organized at various levels (chemical, cellular, tissue, organ, organ system, organism). 2. Metabolism: The chemical reactions within cells that generate energy and allow growth and repair. Includes catabolism (breaking down molecules) and anabolism (building molecules). 3. Responsiveness to Stimuli: The ability to respond to changes in the internal and external environment (e.g., reflex actions, sensory responses). 4. Movement: Includes movement within the body (e.g., blood flow, food movement through digestive system) and movement of the organism as a whole. Characteristics of Living Organisms (Cont’d) 5. Growth and Development: Organisms grow (increase in size) and develop (change in structure and function over time). 6. Reproduction: The ability to produce offspring, ensuring the continuation of the species. 7. Homeostasis: The maintenance of a stable internal environment despite external changes.  1. ORGANIZATION The body is organized hierarchically from simple to complex: 1. Chemical Level: Atoms and molecules (e.g., water, proteins, DNA). 2. Cellular Level: Cells are the basic units of life. Different types of cells perform specific functions (e.g., muscle cells, nerve cells). 3. Tissue Level: Tissues are groups of similar cells working together to perform a specific function (e.g., muscle tissue, epithelial tissue). 4. Organ Level: Organs are made of different types of tissues working together to perform specific functions. 5. Organ System Level: Organ systems are groups of organs that work together to accomplish a common goal 6. Organismal Level: The entire human body functions as a whole. Figure 1.3 Levels of Structural Organization of the Human Body The organization of the body often is discussed in terms of six distinct levels of increasing complexity, from the smallest chemical building blocks to a unique human organism. Organ Systems There are 11 organ systems. You should become familiar with the names, major organs, and general functions of each system. A memory device for learning their names is RUN MRS LIDEC. This will give you the first letter of the name of each organ system as follows: R= Respiratory M= Muscular L= Lymphatic U= Urinary R= Reproductive I= Integumentary N= Nervous S= Skeletal D= Digestive E= Endocrine C= Cardiovascular Some textbooks include a 12th system called the Immune System, but we will Figure 1.4 Organ Systems of the Human Body Organs that work together are grouped into organ systems. Figure 1.5 Organ Systems of the Human Body (continued) Organs that work together are grouped into organ systems. 2. METABOLISM Metabolism is all of the chemical reactions taking place in your body. Some of these are breaking down molecules while others are building them. Anabolism is the process whereby smaller, simpler molecules are combined into larger, more complex substances. Your body can assemble, by utilizing energy, the complex chemicals it needs by combining small molecules derived from the foods you eat Catabolism is the process by which larger more complex substances are broken down into smaller simpler molecules. Catabolism releases energy. The complex molecules found in foods are broken down so the body can use their parts to assemble the structures and substances needed for life. in this class Figure 1.6 Metabolism Anabolic reactions are building reactions, and they consume energy. Catabolic reactions break materials down and release energy. Metabolism includes both anabolic and catabolic reactions. 3. RESPONSIVENESS Responsiveness is the ability of an organism to adjust to changes in its internal and external environments. An example of responsiveness to external stimuli could include moving toward sources of food and water and away from perceived dangers. Changes in an organism’s internal environment, such as increased body temperature, can cause the responses of sweating and the dilation of blood vessels in the skin in order to decrease body temperature. 4. MOVEMENT Human movement includes not only actions at the joints of the body, but also the motion of individual organs and even individual cells. As you read these words, red and white blood cells are moving throughout your body, muscle cells are contracting and relaxing to maintain your posture and to focus your vision, and glands are secreting chemicals to regulate body functions. Your body is coordinating the action of entire muscle groups to enable you to move air into and out of your lungs, to push blood throughout your body, and to propel the food you have eaten through your digestive tract. Consciously, of course, you contract your skeletal muscles to move the bones of your skeleton to get from one place to another and to carry out all of the activities of your daily life. Figure 1.7 Marathon Runners Runners demonstrate two characteristics of living humans—responsiveness and movement. Anatomic structures and physiological processes allow runners to coordinate the action of muscle groups and sweat in response to rising internal body temperature. (credit: Phil Roeder/flickr) 5. GROWTH & DEVELOPMENT Growth is the increase in body size. Humans, like all multicellular organisms, grow by increasing the number of existing cells, increasing the amount of non- cellular material around cells (such as mineral deposits in bone), and, within very narrow limits, increasing the size of existing cells. 6. REPRODUCTION Reproduction is the formation of a new organism from parent organisms. In humans, reproduction is carried out by the male and female reproductive systems. Because death will come to all complex organisms, without reproduction, the line of organisms would end. Requirements for Human Life Oxygen Atmospheric air is only about 20 percent oxygen, but that oxygen is a key component of the chemical reactions that keep the body alive, including the reactions that produce ATP. Nutrients A nutrient is a substance in foods and beverages that is essential to human survival. The three basic classes of nutrients are water, the energy-yielding and body-building nutrients (macromolecules), and the micronutrients (vitamins and minerals). Narrow Range of Temperature The chemical reactions upon which the body depends can only take place within a narrow range of body temperature, from just below to just above 37°C (98.6°F). When body temperature rises well above or drops well below normal, certain proteins (enzymes) that facilitate chemical reactions lose their normal structure and their ability to function and the chemical reactions of metabolism cannot proceed. Narrow Range of Atmospheric Pressure Figure 1.8 Extreme Heat Humans acclimate to some degree to repeated exposure to high temperatures. (credit: McKay Savage/flickr) Figure 1.9 Harsh Conditions Climbers on Mount Everest must accommodate extreme cold, low oxygen levels, and low barometric pressure in an environment hostile to human life. (credit: Melanie Ko/flickr) 7. HOMEOSTASIS Homeo= same Stasis= state or condition Homeostasis is the process of maintaining a relatively constant set of conditions such as blood pressure, temperature, oxygen levels, blood glucose, blood pH, etc, despite changes in the external environment. Why is it important?: It is essential for the survival of cells and the overall functioning of the organism. All body systems work together to maintain a stable internal environment. Systems respond to external and internal changes to keep variables within normal ranges. 7. HOMEOSTASIS Cont’d Homeostasis is controlled by homeostatic regulatory mechanisms. The job of a homeostatic regulatory mechanism is to limit fluctuations of internal conditions to keep them close to a set point, or desired value that occurs within a normal range. A homeostatic regulatory mechanism consists of a 1. R​ eceptor (Sensor) Receives the stimulus 2. ​Control center Processes the signal and sends instructions 3. ​Effector Carries out instructions 7. HOMEOSTASIS Cont’d When a body condition changes and begins to move away from the set point, the body uses one of two mechanisms to restore homeostasis: negative feedback and positive feedback. Negative feedback The response of the effector negates the stimulus (reverses trend) Body is brought back into homeostasis Normal range is maintained This is the most common form of homeostatic regulation. Positive feedback Initial stimulus produces a response that amplifies the original change in conditions Body is moved away from homeostasis (reinforces trend) Normal range is not maintained A positive feedback loop completes a dangerous process quickly to reestablish homeostasis. This form of homeostatic regulation is used less often. Figure 1.10 Negative Feedback System In a negative feedback system, a stimulus—a deviation from a set point—is resisted through a physiological process that returns the body to homeostasis. (a) A negative feedback system has five basic parts. (b) Body temperature is regulated by negative feedback. Figure 1.11 Positive Feedback Loop Normal childbirth is driven by a positive feedback loop. A positive feedback loop results in a change in the body’s status, rather than a return to homeostasis.  Anatomical Position, Medical Terminology and Directional Terminology Anatomical Position is a common reference point for all anatomists and medical practitioners. Combined with medical terminology and directional erminology, these allow us to describe areas of the body with precision and specificity. Anatomical position is standing facing forward with legs about hip’s width apart and palms facing forward. Although many of our patients will not present hemselves this position, all directional terms will assume the patient’s osition is the anatomical position. Anatomical position: hands at sides, palms forward Supine: lying down, face up Prone: lying down, face down  Directional Terminology vs Regional Terminology Directional Terms are always comparisons between two body areas. They exist in pairs which have opposite meanings. Superior/inferior, anterior/posterior, medial/lateral, superficial/deep, proximal/distal Example: The nose is inferior to the forehead. The forehead is superior to the nose. Regional terms are stand-alone descriptions of a particular body area. Example: The patient complained of pain in the lumbar region. *** Be sure to use your Lab Guide to know which regional terms you Figure 1.13 Directional Terms Applied to the Human Body Paired directional terms are shown as applied to the human body.  Frontal (forehea d) Regions Crania l Cephalic (skull) (head) Facial (face) Cervical (neck) Thoracic (thorax, Axillary chest) (armpit ) Brachial (arm) Abdomina Antecubita l l (abdomen (front of ) elbow) a Anterior 31 view  Antebrachial Pelvic (forearm) (pelvis) Regions Carpal (wrist) Palmar (palm) Manual (hand) Inguinal (groin) Pubic Patellar (pubis) (kneecap) Femoral Crural (thigh) (leg) Tarsal (ankle) Pedal (foot) a Anterior view Regions Cephalic (head) Cervical (neck) Dorsal (back) Upper limb b Posterior view  Lumbar Upper Regions (loin) limb Gluteal (buttock) Lower Popliteal limb (back of knee) Sural (calf) Calcaneal (heel of foot) Plantar (sole of foot) b Posterior view  Sectional Planes A section is a slice through a three-dimensional object used to visualize internal organization. The internal view that it reveals is dependent on the direction of the slice. A Sectional plane is a single view along a two-dimensional flat s here are several sectional planes used in anatomy. The sectional ane used should be indicated in any x-ray/image/photo/photomicrogr  Sectional Planes cont’d Frontal (coronal) plane Vertical plane that divides body into anterior and posterior p A cut in this plane is a frontal section (coronal section) Sagittal plane Vertical plane dividing body into left and right portions A cut in this plane is a sagittal section Midsagittal plane lies in the middle Parasagittal plane is offset from the middle Transverse plane divides body into superior and inferior portion A cut in this plane is called a transverse section (cross section) Figure 1.14 Planes of the Body The three planes most commonly used in anatomical and medical imaging are the sagittal, frontal (or coronal), and transverse plane.  Frontal or coronal Sagittal plane plane Plane is oriented parallel to long axis Plane is oriented parallel to long axis A sagittal section separates right and left portions. You A frontal, or examine a sagittal section, coronal, section but you section sagittally. separates anterior In a midsagittal section, the and posterior plane passes through the portions of the midline. It separates the body. Coronal body into equal right and usually refers to left sides. sections passing through the skull. A parasagittal section misses the midline. It separates the body into Directional term: unequal right and left sides. frontally or coronally Midsagittal plane Directional term: sagittally Transverse, or horizontal, plane Plane is oriented perpendicular to long axis Frontal plane A transverse, or cross, Transverse plane section separates (inferior view) superior and inferior portions of the body. Directional term: transversely or horizontally Body Cavities and Serous Membranes Our bodies contain chambers that are nested inside each other…sort of like a Russian nesting doll set. Each chamber is called a cavity. These cavities provide cushioning, stabilize organ positions, provide room for growth and provide protection from friction and infection. The boundaries of each cavity are often formed by structures known as serous membranes. In each cavity, a single Serous membrane folds into two layers that line the cavity and cover the surface of the organs in that cavity. Each serous membrane consists of a parietal and a visceral layer Parietal serosa lines cavity (forms outer wall of cavity) Visceral serosa covers organ(s) Body Cavities and Serous Membranes cont’d You push your fist into the side of an inflated balloon. It is only one balloon, but you Visceral layer form three layers: outer balloon, trapped air, inner Serous fluid balloon (on your hand). This is how the serous membrane Parietal layer works. The outer layer (parietal) forms the wall, the inner layer (visceral) covers the organ, and the middle layer is made of a fluid created by the other two (in place of trapped air). Figure 1.17 Serous Membrane Serous membrane lines the pericardial cavity and reflects back to cover the heart—much the same way that an underinflated balloon would form two layers surrounding a fist.  Body Cavities and Serous Membranes cont’d Major Body Cavities Dorsal Cavity: Cranial Cavity: Houses the brain. Spinal Cavity: Contains the spinal cord. Ventral Cavity: Thoracic Cavity: Contains the heart and lungs. Pleural Cavities exist around each lung (serous membranes: visceral pleura, parietal p Mediastinum (space between pleural cavities) Pericardial Cavity around heart (serous membrane: visceral pericardium, parietal pericardium) Abdominopelvic Cavity: Houses digestive organs, kidneys, bladder, and reproductive or Abdominal Cavity houses digestive organs (serous membrane: visceral peritoneum, pa peritoneum) Pelvic Cavity houses bladder and reproductive organs Figure 1.15 Dorsal and Ventral Body Cavities The ventral cavity includes the thoracic and abdominopelvic cavities and their subdivisions. The dorsal cavity includes the cranial and spinal cavities.  Dividing the Abdomen: Quadrants and Regions The abdominal region contains many of the body’s organs. In order to be even more precise in describing this area, the abdomen can be subdivided two different ways: Quadrants: A vertical line and a horizontal line are drawn through the umbilicus, dividing the abdomen into four sub-areas called quadrants. Regions: two vertical lines (right and left lateral planes) and two horizontal lines (transpyloric plane and transtubercular plane) are drawn which divide the abdomen into nine regions. Each region has its own name. Figure 1.16 Regions and Quadrants of the Peritoneal Cavity There are (a) nine abdominal regions and (b) four abdominal quadrants in the peritoneal cavity. Medical Imaging Techniques Medical imaging is essential for diagnosing and studying the internal structures and functions of the human body. Several techniques are used to visualize organs, tissues, and systems without the need for invasive procedures: X-Ray: Description: Uses radiation to create images of the inside of the body. It is most commonly used for visualizing bones. Applications: Detecting fractures, infections, and some cancers. Pros: cheap and fast. Great for bones/teeth. Cons: Subjects patient to radiation. Not detailed. Only useful on hard tissues. CT Scan (Computed Tomography): Description: Combines X-ray images taken from different angles and uses a computer to create cross-sectional (sliced) images of the body. Applications: Examining organs, soft tissues, and blood vessels in more detail than traditional X-rays. Pros: more detailed and can view soft tissues Cons: Subjects patient to many times more radiation. Figure 1.18 X-Ray of a Hand High energy electromagnetic radiation allows the internal structures of the body, such as bones, to be seen in X-rays like these. (credit: Trace Meek/flickr) Figure 1.19 Medical Imaging Techniques (a) The results of a CT scan of the head are shown as successive transverse sections. (b) An MRI machine generates a magnetic field around a patient. (c) PET scans use radiopharmaceuticals to create images of active blood flow and physiologic activity of the organ or organs being targeted. (d) Ultrasound technology is used to monitor pregnancies because it is the least invasive of imaging techniques and uses no electromagnetic radiation. (credit a: Akira Ohgaki/flickr; credit b: “Digital Cate”/flickr; credit c: “Raziel”/Wikimedia Commons; credit d: “Isis”/Wikimedia Commons) Medical Imaging Techniques Cont’d MRI (Magnetic Resonance Imaging): Description: Uses strong magnetic fields and radio waves to generate detailed images of organs and soft tissues without using ionizing radiation. Applications: Evaluating soft tissues like muscles, brain, and spinal cord. Commonly used for diagnosing neurological disorders, joint injuries, and certain cancers. Pros: No radiation. Precise imaging. Great for finding tumors. Cons: Expensive. Uncomfortable for patient. Room must be shielded. Ultrasound: Description: Uses high-frequency sound waves to create images of organs and tissues inside the body. It is non-invasive and does not use radiation. Applications: Commonly used for monitoring pregnancy, assessing blood flow, and visualizing organs like the liver and heart. Pros: Least invasive. Cons: Image quality dependent on technician ability. Unable to penetrate bone and gas. Medical Imaging Techniques Cont’d PET Scan (Positron Emission Tomography): Description: Uses a radioactive substance to visualize metabolic activity and functional processes in the body. Applications: Detecting cancer, monitoring heart function, and studying brain activity. Pros: Can show live physiologic activity. Low radiation to patient. Cons: Expensive. Endoscopy: Description: A flexible tube with a camera is inserted into the body to visualize the inside of hollow organs (e.g., stomach, intestines). Applications: Diagnosing gastrointestinal issues, performing biopsies, and other internal examinations. Pros: No radiation. Cons: Uncomfortable for patient.