Anatomy and Physiology Vocabulary

(Na-K) System

Systems of the Human Organism

• Nervous system
• Endocrine system
• Respiratory system
• Cardiovascular and lymphatic systems
• Skeletal and muscular systems
• Urinary system
• Digestive system
• Reproductive system
• Integumentary system

Introduction to Homeostasis

• The human body is a complex system where structures work together to maintain homeostasis.
• Homeostasis: A balance in the body's internal environment.
• Renzo, a dancer, demonstrates the importance of homeostasis through his ability to balance and the adjustments his body makes to maintain that balance.
• Experience of oversleeping, rushing to class, and missing breakfast, then feeling better after eating an energy bar, illustrates homeostasis.
• Homeostasis is the maintenance of a relatively constant internal environment despite external fluctuations.
• Renzo's blood sugar disorder exemplifies a disruption in homeostasis.
• Understanding human anatomy and physiology is crucial for understanding disease and for health professionals to perform their duties.
• Knowledge of anatomy and physiology empowers individuals to evaluate treatments, review literature, and discuss the human body with professionals and nonprofessionals.

1. 1 Anatomy and Physiology

• Anatomy: The scientific discipline that investigates the body's structures, such as the shape and size of bones; involves dissecting or cutting apart the body for study.
• Anatomy examines the relationship between a body part's structure and its function.
• Structure and function relationships are a key concept in anatomy and physiology.
• Understanding this relationship makes anatomy easier to appreciate.
• Levels of anatomical study:
  • Developmental anatomy: Studies structural changes from conception to adulthood.
  • Embryology: A subspecialty of developmental anatomy focusing on changes from conception to the end of the eighth week of development.
  • Cytology: Examines the structural features of cells.
  • Histology: Examines tissues, which are composed of cells and surrounding materials.
  • Gross anatomy: Study of structures that can be examined without a microscope; approached systemically or regionally.
    • Systemic anatomy: Studies the body system by system (e.g., cardiovascular, nervous, respiratory).
    • Regional anatomy: Studies the body area by area (e.g., head, abdomen, arm), examining all systems simultaneously.
  • Surface anatomy: Visualizing internal structures by looking at the exterior of the body. For example, the sternum and ribs can be seen and palpated on the chest.
  • Anatomical imaging: Uses technologies like X-rays, ultrasound, and MRI to create pictures of internal structures.
• Anatomical imaging allows medical personnel to look inside the body without exploratory surgery.
• Two humans are not structurally identical.
• Anatomical anomalies: Physical characteristics that differ from the normal pattern, varying in severity from harmless to life-threatening.
• Kidney blood vessel variation: Normally one blood vessel per kidney, but some individuals have two; either way, the kidney receives adequate blood.
• "Blue baby" syndrome: Blood vessels from an infant's heart are not attached correctly, leading to ineffective oxygen supply to tissues.
• Physiology: The scientific investigation of the processes or functions of living things.
  • Goals:
    • Examining the body's responses to stimuli.
    • Examining the body's maintenance of stable internal conditions within a narrow range of values in a constantly changing environment.
• Levels of physiological study:
  • Cell physiology: Examines processes occurring in cells, such as energy production from food.
  • Systemic physiology: Considers the functions of organ systems, such as cardiovascular physiology (heart and blood vessels) and neurophysiology (nervous system).
  • Exercise physiology: Focuses on changes in function and structure caused by exercise.
• Chemicals move along gradients, which is integral to studying physiology.
• Pathology: The medical science dealing with all aspects of disease, with emphasis on the cause, development, and structural/functional changes.

1. 2 Biomedical Research

• Much of what we know about our own physiology is based on physiological studies of other organisms.
• Humans share many characteristics with other organisms.
• Studying single-celled bacteria has allowed scientists to utilize bacteria to synthesize certain human medicines such as insulin.
• Some biomedical research cannot be accomplished using single-celled organisms or isolated cells.
• Sometimes other mammals must be studied, as evidenced by the great progress in open-heart surgery and kidney transplantation made possible by perfecting surgical techniques on other mammals before attempting them on humans.
• Strict laws govern the use of animals in biomedical research; these laws are designed to ensure minimal suffering on the part of the animal and to discourage unnecessary experimentation.
• Although much can be learned from studying other organisms, the ultimate answers to questions about humans can be obtained only from humans because other organisms differ from humans in significant ways.
• A failure to appreciate the differences between humans and other animals led to many misconceptions by early scientists.
• Claudius Galen described a large number of anatomical structures supposedly present in humans but observed only in other animals.
• Galen described the liver as having five lobes. This is true for rats, but not for humans, who have four-lobed livers.
• The errors introduced by Galen persisted for more than 1300 years until Andreas Vesalius, who is considered the first modern anatomist, carefully examined human cadavers and began to correct the textbooks.
• Some current knowledge in molecular biology and physiology has not been confirmed in humans.

1. 3 Structural and Functional Organization of the Human Body

• The body can be studied at six levels of organization: chemical, cell, tissue, organ, organ system, and whole organism.
• As you move through levels, you will notice that each builds on the previous level.
• Disruption of this organized state can result in loss of functions or even death.

Levels of Organization:

1. Chemical Level:
   • Involves how atoms (e.g., hydrogen, carbon) interact and combine to form molecules.
   • A molecule's structure determines its function.
   • Example: Collagen molecules are strong, ropelike protein fibers that give skin structural strength and flexibility.
   • With aging, the structure of collagen changes, and the skin becomes fragile and more easily torn.
2. Cell Level:
   • Cells are the basic structural and functional units of all living organisms.
   • Combinations of molecules form cells.
   • Organelles: Structures inside cells that carry out particular functions (e.g., digestion, movement).
   • Example: The nucleus contains the cell's hereditary information, and mitochondria manufacture ATP (adenosine triphosphate), a molecule cells use for energy.
3. Tissue Level:
   • A tissue is composed of a group of similar cells and the materials surrounding them.
   • The characteristics of the cells and surrounding materials determine the functions of the tissue.
   • The body is made up of four basic tissue types: epithelial, connective, muscle, and nervous.
4. Organ Level:
   • An organ is composed of two or more tissue types that perform one or more common functions.
   • Examples: Urinary bladder, heart, stomach, lung.
5. Organ System Level:
   • An organ system is a group of organs that together perform a common function or set of functions and are therefore viewed as a unit.
   • Example: The urinary system consists of the kidneys, ureters, urinary bladder, and urethra.
   • 11 major organ systems:
     • Integumentary
     • Skeletal
     • Muscular
     • Nervous
     • Endocrine
     • Cardiovascular
     • Lymphatic
     • Respiratory
     • Digestive
     • Urinary
     • Reproductive
6. Organism Level:
   • An organism is any living thing considered as a whole—whether composed of one cell (e.g., a bacterium) or trillions of cells (e.g., a human).
   • The human organism is the combination of all the organ systems.
   • These form a network of systems that are all mutually dependent on one another.

Microbes in Your Body

• Almost as many microbial cells as human cells in your body.
• For every cell in your body, there is at least one microbial cell.
• 40 trillion microbial cells, accounting for between 2 and 6 pounds of your body weight.
• Microbe: Any life form that can only be seen with a microscope (e.g., bacteria, fungi, and protozoa).
• All living organisms fit into one of three domains of living organisms: (1) Bacteria, (2) Archaea, and (3) Eukarya.
• Bacterial cells' genetic material is not separated from the rest of the cell by a barrier.
• Bacterial cells have far fewer separate structures made of membrane for carrying out the cell's metabolic processes than eukaryotic cells.
• Archaea cells are constructed similarly to bacteria; however, they share certain structures, called ribosomes, with eukaryotic cells.
• The term prokaryotic is used to describe bacterial and archaea cells.
• Eukaryotic cells, which include human cells, have the most structural complexity with many smaller structures, called organelles, made with membrane. These smaller structures conduct the metabolic processes of the cell.
• Human Microbiome Project:
  • NIH initiated to examine how microbes affect our health.
  • Five significant regions of the human body were examined: the airway, skin, mouth, gastrointestinal tract, and vagina.
  • Identified over 5000 species and sequenced over 20 million unique microbial genes.
• Human health is dependent upon the health of our microbiota, especially the "good" bacteria.
• The human microbiome is intimately involved in the development and maintenance of the immune system.
• Mounting evidence for a correlation between a host's microbiota, digestion, and metabolism.
• Researches have suggested that microbial genes are more responsible for our survival than human genes.
• Even a few consistent pathogens are present without causing disease, suggesting that their presence may be good for us.
• The human microbiome varies across life span, ethnicity, nationality, culture, and geographic location.
  Autoimmune and inflammatory diseases (Crohn disease, asthma, multiple sclerosis), which have become more prevalent, and a "characteristic microbiome community."
• Any significant change in the profile of the microbiome of the human gut may increase a person's susceptibility to autoimmune diseases and may be associated with exposure to antibiotics, particularly in infancy.
• Microbial transplantations have shown that the protective and other functions of bacteria can be transferred from one person to the next.

1. 4 Characteristics of Life

• Humans are organisms, sharing characteristics with other organisms.
• The most important common feature of all organisms is life.
  • Six essential characteristics of life:

1. Organization

• Specific interrelationships among the parts of an organism and how those parts interact to perform specific functions.
• There are six levels of organization in the body.

2. Metabolism

• The ability to use energy and to perform other vital functions.
• Refers to all of the chemical reactions taking place in the cells and internal environment of an organism.
  * Specialized proteins that break down food molecules

3. Responsiveness

• An organism's ability to sense changes in its external or internal environment and adjust to those changes.
• Cell-to-cell communication.
• The nervous and endocrine systems regulate responses to changes in the environment through cell-to-cell communication.
• Responses can include actions such as moving toward food or water and moving away from danger or poor environmental conditions.
• for example, if the external environment causes the body temperature to rise, sweat glands produce sweat, which can lower body temperature down to the normal range.

4. Growth

• An increase in the size or number of cells, which produces an overall enlargement of all or part of an organism.
• A muscle enlarged by exercise is composed of larger muscle cells than those of an untrained muscle, and the skin of an adult has more cells than the skin of an infant.
• increase in cell number and the deposition of mineralized materials around the cells

5. Development

• Includes the changes an organism undergoes through time, beginning with fertilization and ending at death.
• The greatest developmental changes occur before birth, but many changes continue after birth, and some go on throughout life.
• Involves differentiation ( changes in a cell's structure and function from an immature, generalized state to a mature, specialized state, such as skin, bone, muscle, or nerve cells) and morphogenesis (the change in shape of tissues, organs, and the entire organism).

6. Reproduction

• The formation of new cells or new organisms.
• Reproduction of cells allows for growth and development.
• Allows all living organisms to pass on their genes to their offspring.

1. 5 Homeostasis

• Homeostasis is the existence and maintenance of a relatively constant environment within the body.
• Changes in internal body conditions are called variables.
• To achieve and maintain homeostasis, the body must actively regulate responses to changes in variables.Variables include such conditions as body temperature, volume, chemical content and pH of body fluids, as well as many other variables.
• These variables must be maintained within a narrow range.
• narrow range is referred to as a normal range.
• Homeostatic mechanisms normally maintain body conditions near an ideal normal value or set point.
• These mechanisms are not able to maintain body conditions precisely at the set point. Rather, body conditions increase and decrease slightly around the set point.

Feedback Loops

• A feedback loop allows for a process to be regulated by the outcome.
• In biological systems, there are two types of feedback loops: (1) negative feedback and (2) positive feedback.
• A common misconception is that negative feedback is the decrease of a body parameter, while positive feedback is the increase of a body parameter.
• Feedback loops have three components:
  • (1) a receptor, which monitors the value of a variable by detecting stimuli
  • (2) a control center, such as a part of the brain, which determines the set point for the variable and receives input from the receptor about the variable
  • (3) an effector, which generates the response that adjusts the value of a changed variable
• A changed variable is a stimulus because it initiates a homeostatic mechanism.

Negative Feedback

• Negative-feedback mechanisms are more commonly involved in maintenance of homeostasis than are positive-feedback mechanisms.
• In the context of homeostasis mechanisms, negative means "to decrease."
• Negative feedback is when any deviation from the set point is made smaller or is resisted.
• In other words, the response by the effector is stopped once the variable returns to its set point.
• One of the most familiar examples of a negative-feedback mechanism is maintenance of body temperature.

Positive Feedback

• Positive-feedback mechanisms occur when a response to the original stimulus results in the deviation from the set point becoming even greater.
• Positive means "to increase."
• Feedback continues until the original stimulus (the fetus in the uterus) is removed.
• A physiological example of positive feedback occurs during blood loss. A chemical responsible for blood clot formation, called thrombin, stimulates production of even more thrombin.

There are two basic principles about homeostatic mechanisms to remember:

• many disease states result from the failure of negative-feedback mechanisms to maintain homeostasis
• Some positive-feedback mechanisms can be detrimental instead of helpful.
• Detrimental positive-feedback mechanism is inadequate delivery of blood to cardiac (heart) muscle (blood pressure decreases to the point that the delivery of blood to cardiac muscle is inadequate. As a result, cardiac muscle does not function normally. The heart pumps less blood, which causes the blood pressure to drop even further-a deviation further from the set point. The additional decrease in blood pressure further reduces blood delivery to cardiac muscle, and the heart pumps even less blood, which again decreases the blood pressure. The process self-propagates until the blood pressure is too low to sustain the cardiac muscle, the heart stops beating, and death results).
  *During exercise the normal range for blood pressure increases above the resting range

1. 6 Terminology and the Body Plan

• Knowing the derivation, or etymology, of these words can make learning them easy and fun.
• Most anatomical terms are derived from Latin or Greek.
• Foramen is a Latin word for "hole," and magnum means "large."
• The foramen magnum is therefore a large hole in the skull through which the spinal cord attaches to the brain.
• Suffixes can be added to words to expand their meaning.
• -itis (suffix) means an inflammation, appendicitis is an inflammation of the appendix.

Terminology

• Learn new words, so that word use is clear and correct when speaking to colleagues or writing reports.
• Body Positions

Anatomical Position

• Anatomical position refers to a person standing erect with the face directed forward, the upper limbs hanging to the sides, and the palms of the hands facing forward

• A person is supine when lying face upward and prone when lying face downward.

• Directional Terms

  • Directional terms describe parts of the body relative to each other.
    Relative terms:

• Superior/inferior, the head is above the feet.

• anterior/posterior, navel is anterior to the spine.

• Medial/lateral, the nose is medial to the eye.

• Proximal/distal, the elbow is proximal to the wrist.

• Superficial/deep, the skin is superficial to muscle.
  Body Parts and Regions

• Health professionals use a number of terms when referring to different parts or regions of the body.

• The central region of the body consists of the head, neck, and trunk.

• The trunk can be further divided into three regions: (1) the thorax, (2) the abdomen, and (3) the pelvis.

• The upper limb is divided into (1) the arm, (2) the forearm, (3) the wrist, and (4) the hand.

• The lower limb is divided into (1) the thigh, (2) the leg, (3) the ankle, and (4) the foot.
  Central abdominal region subdivisions:

• Quadrants: right-upper, left-upper, right-lower, and left-lower

• Regions: epigastric, right and left hypochondriac, umbilical, right and left lumbar, hypogastric, and right and left iliac

Planes

• Useful to describe the body as having imaginary flat surfaces, called planes, passing through it.

• A plane divides, or sections, the body, making it possible to "look inside" and observe the body's structures.

• 1. A sagittal plane separates the body or a structure into right and left halves.

• 2. A median plane is a sagittal plane that passes through the midline of the body, dividing it into equal right and left halves.

• 3. A transverse (horizontal) plane runs parallel to the ground, dividing the body into superior and inferior portions.

• 4. A frontal (coronal) plane divides the body into front (anterior) and back (posterior) halves

Organs

• Are often sectioned to reveal their internal structure.
  • Longitudinal: a cut through the length of the organ.
  • Transverse: a cut at a right angle to the length of an organ (cross section).
  • Oblique: a cut made across the length of an organ at other than a right angle.

Body Cavities

• The body contains two types of internal cavities: (1) the dorsal body cavity and (2) the ventral body cavity.
• These cavities, which are closed to the outside, contain our internal organs, providing protection for them.

Dorsal Body Cavity

• Encloses the organs of the nervous system, the brain and spinal cord.
• Two subdivisions of the dorsal body cavity:
  • (1) the cranial cavity, which houses the brain
  • (2) the vertebral canal, which houses the spinal cord.
• Both the brain and spinal cord are covered by membranes called meninges

Ventral Body Cavity

• Houses the vast majority of our internal organs, collectively referred to as the viscera
• Two major subdivisions:
  • (1) the thoracic cavity
  • (2) the abdominopelvic cavity.

The Thoracic Cavity

• Houses primarily the heart and lungs, among other organs.
• Subdivided into sections:
  • (1) two lateral pleural cavities, each of which encloses a lung and is surrounded by the ribs
  • (2) a medial mediastinum, which houses the heart and its major blood vessels, in addition to the thymus, the trachea, and the esophagus.

The Abdominopelvic Cavity

• Enclosed by abdominal muscles

• Superior abdominal cavity and (2) the more inferior pelvic cavity.

• organs of the abdominopelvic cavity are housed within the peritoneal cavity.

• The abdominal cavity contains the majority of the digestive organs, such as the stomach, the intestines, and the liver, in addition to the spleen.

• The pelvic cavity contains the urinary bladder, urethra, rectum of the large intestine, and reproductive organs

Serous Membranes of the Ventral Body Cavity

• The walls of the body cavities and the surface of internal organs are in contact with membranes called serous membranes.
• These membranes are double layered.
• The layer that lines the walls of the cavities is called the parietal serous membrane.
• The layer covering the internal organs (the viscera) is the visceral serous membrane
• In the body, there is no air between the visceral and parietal serous membranes as there is in the balloon; rather, the two membranes are separated by a thin film of serous fluid produced by the membranes.
• As organs move around in the cavities, the combination of serous fluid and smooth serous membranes reduces friction.

Thoracic Cavity Membranes

• The serous membranes are named for the specific cavity and organs they are in contact with

1. Pericardial Cavity:
   • The parietal serous membrane is called the parietal pericardium and the visceral serous membrane is called the visceral pericardium.
   • The space between the two pericardial membranes is called the pericardial cavity and is filled with pericardial fluid
2. Pleural Cavities:
   • Each of the two pleural cavities houses a lung. The parietal serous membrane lining the pleural cavities is called the parietal pleura, while the visceral serous membrane covering the lungs is called the visceral pleura
   • The space between the two pleural membranes is called the pleural cavity and is filled with pleural fluid.
3. Peritoneal Cavity:
   • houses many internal organs, such as the liver, the digestive organs, and the reproductive organs.
   • The parietal serous membrane in the peritoneal cavity is called the parietal peritoneum. The visceral serous membrane is called the visceral peritoneum.
   • The space between the two serous membranes is the specific location of the peritoneal cavity and is filled with peritoneal fluid. In addition to covering organs, a double-folded sheet of visceral peritoneum attaches the digestive organs at certain points to the posterior abdominopelvic cavity wall. These regions of double-folded visceral peritoneum form the mesentery. The mesentery also provides a pathway for nerves and blood vessels to reach the digestive organs. The most notable mesenteric structure is an enormous pouch containing adipose tissue that is suspended from the inferior border of the stomach.

Retroperitoneal

• Some abdominal organs are tightly adhered to the posterior body wall and are covered by peritoneum only on their peritoneal cavity side.
• These organs have a retroperitoneal location and include the kidneys, ureters, adrenal glands, a large portion of the pancreas, parts of the large intestine, and the urinary bladder.

Clinical terminologies based on Serous membrane inflammation:

• Pericarditis: Inflammation of the pericardium.
• Pleurisy: Inflammation of the pleura.
• Peritonitis: Inflammation of the peritoneum.