Module 1: Introduction to Anatomy and Physiology Study Guide

Course Overview and Administration

The course SCIE18420, Human Anatomy and Physiology for Nurses 1, at Sheridan College provides a foundational introduction to the biological structures and functions of the human body. This course is conducted through three hours of in-class lectures per week and serves as a mandatory pre-requisite for Term 2 of the Practical Nursing (PN) program. To pass the course, students must achieve a minimum grade of $60\%$. The required primary textbook for this course is Patton, K. T. (2019), Anatomy and Physiology (10th ed.), published by Elsevier in Maryland Heights, MO. Additional references include Marieb and Hoehn (2016), Human Anatomy & Physiology (10th ed.).

The evaluation structure for the course consists of several components designed to assess understanding throughout the semester. These include two quizzes worth $5\%$ each (totaling $10\%$), weekly Evolve Modules accounting for $8\%$, and a specific nursing assignment worth $10\%$. Additionally, there is a Self-Study Microbiology Quiz worth $2\%$. Major examinations include a Midterm Examination weighted at $25\%$, a "Bell Ringer" practical-style exam weighted at $15\%$, and a comprehensive Final Examination worth $30\%$.

Fundamental Definitions and Perspectives

Anatomy and physiology represent the dual study of the human organism, which is described as one of the most complex combinations of systems known to man. Anatomy is formally defined as the study of the structure of an organism and the relationship of its specific parts. This field is subdivided into gross anatomy, which deals with structures visible to the naked eye, and microscopic anatomy. Microscopic anatomy includes cytology, the study of cells, and histology, the study of tissues.

Physiology is defined as the study of the functions of living organisms and their respective body parts. This discipline is subdivided based on several criteria. It can be categorized by the organism involved, such as human or plant physiology. It can also be organized by the level of organization, such as molecular or cellular physiology. Finally, it is organized by systemic function, including neurophysiology, respiratory physiology, or cardiovascular physiology.

Characteristics of Human Life

The human organism exhibits ten essential characteristics that define its living state. Responsiveness is the ability of the organism to sense, monitor, and respond to changes in both its external and internal environments. Conductivity refers to the capacity of living cells to transmit a wave of electrical disturbance from one point to another within the body. Growth is characterized by an organized increase in the size and number of cells, leading to an increase in the size of the individual or a specific organ. Respiration involves the exchange of respiratory gases, specifically oxygen and carbon dioxide, between the organism and its environment.

Digestion is the process by which complex food products are broken down into simpler substances that can be absorbed and utilized by individual body cells. Absorption refers to the movement of molecules, the products of digestion or respiratory gases, through a membrane and into body fluids for transport. Secretion is the production and release of important substances, such as hormones or digestive juices, for diverse body functions. Excretion involves the removal of waste products from the body. Circulation is the movement of body fluids containing diverse substances from one area to another in a continuous, circular route through hollow vessels. Finally, reproduction is the formation of new individual offspring.

Structural Levels of Organization

Organization is considered the most important characteristic of body structure. The human body is constructed as a single unit composed of smaller, hierarchically arranged units. At the base is the chemical level, consisting of atoms and molecules. These form organelles, which are "tiny organs" that live inside cells and perform specific functions. The cell is the smallest structural unit and represents an organization of various chemicals. Tissues are organizations of similar cells that perform a common function. Organs are organizations of different kinds of tissues arranged so that they can perform a complex function together. Finally, systems are organizations of many different kinds of organs arranged so that they can perform complex functions for the body as a whole.

Anatomical Positioning and Terminology

The anatomical position is the standardized reference position used to give meaning to directional terms. In this position, the body is standing erect with the feet slightly apart and arms at the sides with the palms turned forward. Directional terms include superior (toward the head or above) and inferior (toward the feet or below). Anterior or ventral refers to the front of the body, while posterior or dorsal refers to the back. Medial indicates a position toward the midline of a structure, and lateral indicates a position away from the midline or toward the side. Proximal means toward or nearest the trunk or the point of origin of a structure, whereas distal means away from or farthest from the trunk or point of origin. Superficial refers to a position nearer the body surface, while deep refers to a position farther away from the surface.

Specific terms are also used to describe regions related to organs. A lumen is the hollow area within many organs. Central refers to being near the center, while peripheral means around the boundary. Medullary refers to an inner region or core of an organ, and cortical refers to the outer region or layer. Basal refers to the base or widest part of an organ, while apical refers to the narrow tip.

Body Planes and Cavities

Body planes are used to section the body or its parts. Sagittal planes are lengthwise planes running from front to back and top to bottom, dividing the body into right and left portions. Transverse planes are crosswise planes that divide the body or any of its parts into upper and lower sections. Coronal planes are lengthwise planes running from side to side and top to bottom, dividing the body into anterior and posterior portions.

The body contains two major sets of cavities: dorsal and ventral. The dorsal cavity includes the cranial cavity (containing the brain) and the spinal cavity (containing the spinal cord). The ventral cavity is divided into the thoracic cavity and the abdominopelvic cavity. The thoracic cavity contains the mediastinum (the mid-portion containing the heart and trachea) and the pleural cavities (containing the lungs). The abdominopelvic cavity consists of the abdominal cavity (stomach, intestines, liver, gallbladder, pancreas, and spleen) and the pelvic cavity (reproductive organs, urinary bladder, and lowest part of the intestine). The abdominopelvic region is further organized into four quadrants (RUQ, LUQ, RLQ, LLQ) or nine specific regions: right hypochondriac, epigastric, left hypochondriac, right lumbar (flank), umbilical, left lumbar (flank), right iliac (inguinal), hypogastric (pubic), and left iliac (inguinal).

Specific Body Regions and the Life Cycle

The body is broadly divided into two major regions: the axial region, which includes the head, neck, and torso, and the appendicular region, which includes the upper and lower extremities. Throughout the life span, the structure and function of the body undergo significant changes. Developmental processes occur during the early years, while aging processes occur during the later years. Infancy and old age are periods when the body functions least well, whereas young adulthood is the period of greatest homeostatic efficiency. Homeostatic mechanisms may be less efficient in infancy and can lose efficiency in advanced old age.

Homeostasis and Control Mechanisms

Homeostasis is defined as the relatively constant internal states maintained by the body despite changes in the environment. It involves staying within a specific setpoint value; disturbances to this balance can lead to disease or death. The body maintains this balance through the internal environment, where cells are bathed in interstitial fluid and blood (cells and plasma). The heart, digestive system, respiratory system, and urinary system work together to transport nutrients, water, and salts while removing $\text{CO}_2$ and nitrogenous wastes.

Communication for homeostatic control is achieved primarily by the nervous and endocrine systems. All control mechanisms involve three components: a sensor or receptor mechanism that detects changes, an integrating or control center (often the hypothalamus) that processes information, and an effector mechanism that carries out a response. Negative feedback is the most common control system; it is inhibitory, meaning it produces an action opposite to the change that activated the system to stabilize variables (e.g., temperature regulation through shivering when the temp drops to $36\,^{\circ}\text{C}$). Positive feedback is stimulatory and reinforces the change occurring, often leading to a destabilizing effect to bring a specific function to swift completion (e.g., labor contractions during birth). Control occurs at three levels: intracellular, intrinsic (autoregulation), and extrinsic.

Analysis of the Eleven Organ Systems

The body is integrated through eleven main organ systems. The Integumentary system provides protection, regulates temperature, and synthesizes chemicals. The Skeletal system provides a framework, protects organs, allows movement, stores minerals, and forms blood cells. The Muscular system (skeletal, smooth, and cardiac muscle) is primarily responsible for movement and stability. The Nervous system (brain, spinal cord, nerves) handles communication, integration, control, and sensory stimuli recognition. The Endocrine system utilizes hormone molecules secreted into the blood to regulate cells throughout the body.

The Cardiovascular system transports substances, regulates temperature, and provides immunity. The Lymphatic and Immune systems transport lymph and protect the body via phagocytosis and chemical reactions. The Respiratory system exchanges $\text{CO}_2$ for oxygen in the alveoli, filters air, and regulates acid-base balance. The Digestive system performs mechanical and chemical breakdown of food, absorbs nutrients, and eliminates feces; the appendix assists by holding bacteria. The Urinary system cleans the blood of waste (excreted as urine) and maintains electrolyte, water, and acid-base balance. Finally, the Reproductive systems (male and female) ensure gene survival through sex cell production, fertilization, and the development and nourishment of offspring.

Questions & Discussion

Pre-Lecture Questions

1. What are Anatomy and physiology? Anatomy is the study of structure; physiology is the study of function.
2. How does the body keep the internal environment in balance? Through homeostatic control mechanisms involving sensors, integrators, and effectors.
3. What name is given to all chemical reactions in the body cells? Metabolism (implied by context of life characteristics).
4. What process allows you to adjust to either extreme heat or cold? Homeostasis, specifically through negative feedback loops like shivering or sweating.
5. When we begin to get dehydrated, we usually get thirsty, which causes us to drink fluids. Is thirst part of a negative or positive feedback control system? Negative feedback, as it seeks to reverse the state of dehydration.

Quick Check: Anatomical Directions

1. The fingers are distal to the wrist.
2. The knee is inferior (or distal) to the pelvis.
3. The lungs are deep to the ribs.
4. The ears are lateral (and posterior) to the nose.

Review Questions

1. The correct sequence of levels forming the structural hierarchy is: C. Chemical, cellular, tissue, organ, organ system, organismal.
2. The structural and functional unit of life is: A. A cell.
3. Two organ systems that bear major responsibility for ensuring homeostasis: A. Nervous system and D. Endocrine system.
4. Terms that apply to the backside of the body in the anatomical position include: C. Posterior; dorsal.