[Chapter 1] The Human Body: An Orientation Flashcards
[1.1] Form (anatomy) determines function (physiology)
Define Anatomy and Physiology
Anatomy is the study of the structure of body parts and their relationships to one another.
Physiology is the study of the function of the body parts; how they work and carry out their life-sustaining activities.
[1.1] Form (anatomy) determines function (physiology)
The Subdivisions of Anatomy: Gross (Macroscopic)
Gross (macroscopic) anatomy is the study of large body structures visible to the naked eye.
Examples: the heart, lungs, and kidneys.
- Regional anatomy examines all the structures (muscles, bones, blood vessels, nerves, etc.) in a particular region of the body, such as the abdomen or leg, at the same time
- Systemic anatomy examines the body structure system-by-system. For example, when studying the cardiovascular system, you would examine the heart and the blood vessels of the entire body.
- Surface anatomy is the study of internal structures as they relate to the overlying skin surface. Example: you use this when you identify the bulging muscles beneath a bodybuilder’s skin.
[1.1] Form (anatomy) determines function (physiology)
The Subdivisions of Anatomy: Microscopic
Microscopic anatomy deals with structures too small to be seen with the naked eye.
- Cytology considers the cells of the body
- Histology is the study of tissues
[1.1] Form (anatomy) determines function (physiology)
The Subdivisions of Anatomy: Developmental
Developmental anatomy traces strucutral changes that occur throughout the life span.
- Embryology concerns developmental changes that occur before birth
[1.1] Form (anatomy) determines function (physiology)
The Subdivisions of Anatomy: Other
Pathological anatomy studies structural changes caused by disease
Radiographic anatomy studies internal structures as visualized by X-ray images or specialized scanning procedures.
[1.1] Form (anatomy) determines function (physiology)
Some Terminology
Palpation is feeling organs with your hands.
Auscultation is listening to organ sounds with a stethescope.
[1.1] Form (anatomy) determines function (physiology)
The Subdivisions of Physiology
Renal physiology concerns kidney function and urine production
Neurophysiology explains the workings of the nervous system
Cardiovascular physiology examins the operation of the heart and blood vessels
[1.1] Form (anatomy) determines function (physiology)
The Principle of Complementarity
While anatomy provides us with a static image of the body’s architecture, physiology reveals the body’s dynamic and animated workings
Although it is possible to study anatomy and physiology individually, they really are inseperable because function always reflects structure
That is, what a structure can do depends on its specific form.
This key concept is called the principle of complementarity of structure and function
[1.2] The body’s organization ranges from atoms to the entire organism
The Levels of Structural Organization That Make Up The Body: The Chemical and Cellular Levels
Chemical Level → Cellular Level → Tissue Level → Organ Level → Organ System Level → Organismal Level
Chemical Level: at this level, atoms combine to form molecules such as water and proteins. Molecules, in turn, associate in specific ways to form organelles, basic components of the microscopic cells. Cells are the smallest units of living things
Cellular Level: all cells have some common functions, but individual cells vary widely in size and shape, reflecting their unique functions in the body
[1.2] The body’s organization ranges from atoms to the entire organism
The Levels of Structural Organization That Make Up The Body/The Tissue Level/ The Four Types of Tissues
Tissue Level: tissues are groups of similar cells that have a common function. The four basic tissue types in the human body are the:
- Epithelium: covers the body surface and lines its cavities
- Muscle: provides movement
- Connective tissue: provides support and protects organs
- Nervous tissue: provides communication through electrical impulses
[1.2] The body’s organization ranges from atoms to the entire organism
The Levels of Structural Organization That Make Up The Body/The Organ Definition
An organ is a discrete structure composed of at least two tissue types (four is more common) that performs a specific function for the body
Examples of organs: liver, brain, blood vessels, stomach
You can think of each organ of the body as a specialized functional center responsible for a necessary activity that no other organ can perform
[1.2] The body’s organization ranges from atoms to the entire organism
The Levels of Structural Organization That Make Up The Body/The Organ Level
At the organ level, extremely complex functions become possible.
For example, the stomach: Its lining is an epithelium that produces digestive juices. The bulk of its wall is muscle, which churns and mixes stomach contents (food). Its connective tissue reinforces the soft muscular walls. Its nerve fibers increase digestive activity by stimulating the muscle to contract more vigorously and the glands to secrete more digestive juices.
[1.2] The body’s organization ranges from atoms to the entire organism
The Levels of Structural Organization That Make Up The Body/The Organ System Level
Organ system level: organs that work together to accomplish a common purpose make up an organ system
For example, the heart and blood vessels of the cardiovascular system circulate blood continuously to carry oxygen and nutrients to all body cells.
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body
Remember: S L I M E R R U N D C
- Skeletal
- Lymphatic
- Integumentary
- Muscular
- Endocrine
- Respiratory
- Reproductive
- Urinary
- Nervous
- Digestive
- Cardiovascular
[1.2] The body’s organization ranges from atoms to the entire organism
The Levels of Structural Organization That Make Up The Body/The Organismal Level
The highest level of organization is the organism, the living human being
The organismal level represents the sum total of all structural levels working together to keep us alive.
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Integumentary
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Skeletal
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Muscular
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Nervous
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Endocrine
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Cardiovascular
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Lymphatic/Immunity
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Respiratory
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Digestive
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Urinary
[1.2] The body’s organization ranges from atoms to the entire organism
The 11 Organ Systems of the Body: Reproductive
[1.2] The body’s organization ranges from atoms to the entire organism
Example of Interrelationships Among Body Organ Systems
[1.3] What are the requirements of life?
Necessary Life Functions: Maintaining Boundaries
Every living organism must maintain its boundaries so that its internal environment (its inside) remains distinct from the external environment (its outside).
- In single-celled organisms: the external boundary is a limiting membrane that encloses its contents and lets in needed substances while restricting entry of potentially damaging or unnecessary substances
- Similarly, all body cells are surrounded by a selectively permeable membrane
- Additionally, the body as a whole is enclosed and protected by the integumentary system, or skin. This system protects our internal organs from drying out (a fatal change), bacteria, and the damaging effects of heat, sunlght, and an unbelievable number of chemicals in the external environment
[1.4] Homeostasis is maintianed by negative feedback
Homeostatic Control: Variable
Regardless of the factor or event being regulated - the variable - all homeostatic control mechanisms are processes involvong at least three components that work together
[1.4] Homeostasis is maintianed by negative feedback
Homeostatic Control: Receptor
The first component, the receptor, is some type of sensor that monitors the environment and responds to changes, called stimuli, by sending information (input) to the second component, the control center
Input flows from the receptor to the control center along the afferent pathway
[1.4] Homeostasis is maintianed by negative feedback
Homeostatic Control: Control Center
The control center determines the set point, which is the level or range at which a variable is to be maintained
It also analyzes the input it receives and determines the appropriate response
Information (output) then flows from the control center to the third component, the effector, along the efferent pathway
[1.4] Homeostasis is maintianed by negative feedback
Homeostatic Control: Effector
The effector provides the means for the control center’s respsonse (output) to the stimulus
The results of the response then feed back to influence the effect of the stimulus, either reducing it so that the whole control process is shut off, or enhancing it so that the whole process continues at an even faster rate
[1.4] Homeostasis is maintianed by negative feedback
Negative Feedback Mechanisms
Most homeostatic control mechanisms are negative feedback mechanisms.
In these systems, the output shuts off the original effect of the stimulus or reduces its intensity
These mechanisms casue the variable to change in a direction opposite to that of the initial change, returning it to its “ideal” value
The endocrine system is equally important in maintaining homeostasis. A good example of a hormonal negative feedback mechanism is the control of blood sugar (glucose) by insulin. As blood sugar rises, receptors in the body sense this change, and the pancreas (the control center) secretes insulin into the blood. This change in turn prompts body cells to absorb more glucose, removing it from the bloodstream. As blood sugar falls, the stimulus for insulin release ends
Other negative feedback mechanisms regulate heart rate, blood pressure, the rate and depth of breathing, and blood levels of oxygen, carbon dioxide, and minerals
[1.4] Homeostasis is maintianed by negative feedback
Positive Feedback Mechanisms
In positive feedback mechanisms, the result or response enhances the original stimulus so that the response is accelerated
This feedback mechanism is “positive” because the change that results proceeds in the same direction as the initial change, causing the variable to deviate further and further from its original value or range
In contrast to negative feedback controls, which maintain some physiological function or keep blood chemicals within narrow ranges, positive feedback mechanisms usually control infrequent events that do not require continuous adjustments. Typically, they set off a series of events that may be self-perpetuating and that, once initiated, have an amplifying or waterfalle effect. Because of these characteristics, positive feedback mechanisms are often referred to as cascades
Two familiar examples are the enhancement of labor contractions during birth and blood clotting
[1.5] Anatomical terms describe body directions, regions, and planes
Anatomical Position
The anatomical reference point is a standard body position called the anatomical position. This position resembles “standing at attention,” except that the palms face forward and the thumbs point away from the body
It is important to understand the anatomical position because most of the directional terms in this book refer to the body as if it were in this position, regardless of its actual position
The terms “right” and “left” refer to those sides of the person or the cadaver being viewed- not those of the observer
[1.5] Anatomical terms describe body directions, regions, and planes
Directional Terms
Directional terms allow us to explain where one body structure is in relation to another
Using anatomical terms saves words and is less ambiguous
[1.5] Anatomical terms describe body directions, regions, and planes
Regional Terms
The two fundamental divisions of our body are its axial and appendicular parts
- the axial part, which makes up the main axis of our body, includes the head, neck, and trunk
- the appendicular part consists of the appendages, or limbs, which are attached to the body’s axis
Regional terms are used to designate specific areas within these major body divisions and are indicated in Figure 1.7
[1.5] Anatomical terms describe body directions, regions, and planes
Body Planes and Sections
For anatomical studies, the body is often cut, or sectioned, along a flat surface called a plane
The most frequently used body planes are:
- sagittal
- frontal
- transverse
A section is named for the plane along which it is cut; thus, a cut along a sagittal plane produces a saggital section
[1.5] Anatomical terms describe body directions, regions, and planes
Body Planes and Sections: Saggital
A sagittal plane is a vertical plane that divides the body into right and left parts
- A sagittal plane that lies exactly in the midline is the median plane, or midsagittal plane
- All other sagittal planes, offset from the midline, are parasagittal planes
[1.5] Anatomical terms describe body directions, regions, and planes
Body Planes and Sections: Frontal
Frontal planes (also called coronal planes), like sagittal planes, lie vertically. Frontal planes, however, divide the body into anterior and posterior parts
[1.5] Anatomical terms describe body directions, regions, and planes
Body Planes and Sections: Transverse
A transverse, or horizontal, plane runs horizontally from right to left, dividing the body into superior and inferior parts
Of course, many different transverse planes exist, at every possible level from head to foot
A transverse section is also called a cross section
[1.6] Many internal organs lie in membrane-lined body cavities
Overview
Anatomy and physiology textbooks typically describe two sets of internal body cavities called the dorsal and ventral body cavities
These cavities are closed to the outside and provide different degrees of protection to the organs within them
Because these two cavities differ in their mode of embryonic development and their lining membranes, the dorsal body cavity is not recognized as such in many anatomical references. However, the idea of two sets of internal body cavities is a useful learning concept and we use it here
[1.6] Many internal organs lie in membrane-lined body cavities
Dorsal Body Cavity
The dorsal body cavity, which protects the fragile nervous system organs, has two subdivisions:
- The cranial cavity, in the skull, encases the brain
- The vertebral, or spinal, cavity, which runs within the bony vertebral column, encloses the delicate spinal cord.
The spinal cord is essentially a continuation of the brain, and the cranial and spinal cavities are continuous with one another
Both the brain and the spinal cord are covered by membranes called meninges
[1.6] Many internal organs lie in membrane-lined body cavities
Ventral Body Cavity
The more anterior and larger of the closed body cavities is the ventral body cavity. Like the dorsal cavity, it has two major subdivisions:
- The thoracic cavity
- The abdominal cavity
The ventral body cavity houses internal organs collectively called the viscera, or visceral organs
[1.6] Many internal organs lie in membrane-lined body cavities
Ventral Body Cavity: Abdominopelvic Cavity
The thoracic cavity is separated from the more inferior abdominopelvic cavity by the diaphragm, a dome-shaped muscle important in breathing
The abdominopelvic cavity, as the name suggests, has two parts. However, these regions are not physically separated by a muscular or membrane wall.
- Its superior portion, the abdominal cavity, contains the stomach, intestines, spleen, liver, and other organs
- The inferior part, the pelvic cavity, lies in the bony pelvis and contains the urinary bladder, some reproductive organs, and the rectum
The abdominal and pelvic cavities are not aligned with each other. Instead, the bowl-shaped pelvis tips away from the perpendicular as shown in Figure 1.9a.
[1.6] Many internal organs lie in membrane-lined body cavities
Ventral Body Cavity: Membranes
The walls of the ventral body cavity and the outer surfaces of the organs it contains are covered by a thin, double-layered membrane, the serosa, or serous membrane. The part of the membrane lining the cavity waslls is called the parietal serosa. It folds in on itself to form the visceral serosa, covering the organs in the cavity. In the body, the serious membranes are separated not by air but by a thin layer of lubricating fluid, called serous fluid, which is secreted by both membranes. Although there is a potential space between the two membranes, the barely present, slitlike cavity is filled with serous fluid
Serous fluid allows organs to move without friction and is especially important for mobile organs such as the pumping heart and the churning stomach
The serous membranes are named for the specific cavity and organs with which they are associated. For example, as shown in Figure 1.10b, the parietal pericardium lines the pericardial cavity and folds back as the visceral pericardium, which covers the heart. Likewise, the parietal pleurae line the walls of the thoracic cavity, and the visceral pleurae cover the lungs. The perietal peritoneum is associated with the walls of the abdominopelvic cavity, while the visceral peritoneum covers most of the organs within that cavity.
[1.6] Many internal organs lie in membrane-lined body cavities
Ventral Body Cavity: Abdominopelvic Regions and Quadrants - Looking at Quadrants
A simple scheme to locate the abdominopelvic cavity organs in which a tranverse and a median plane pass through the umbilicus at right angles and results in four quadrants which are named according to their positions:
- The right upper quadrant (RUQ)
- The left upper quadrant (LUQ)
- The right lower quadrant (RLQ)
- The left lower quadrant (LLQ)
[1.6] Many internal organs lie in membrane-lined body cavities
Ventral Body Cavity: Abdominopelvic Regions and Quadrants - Looking at Regions
Another division method, used primarily by anatomists, uses two transverse and two parasagittal planes. These planes, positioned like a tic-tac-toe grid on the abdomen, divide the cavity into nine regions
- The umbilical region is the centermost region deep to and surrounding the umbilicus (navel)
- The epigastric region is located superior to the umbilical region
- The hypogastric (pubic) region is located inferior to the umbilical region
- The right and left iliac, or inguinal, regions are located lateral to the hypogastric region
- The right and left lumbar regions lie lateral to the umbilical region
- The right and left hypochondriac regions lie lateral to the epigastric region and deep to the ribs
[1.6] Many internal organs lie in membrane-lined body cavities
Other Body Cavities: Overview
In addition to the large closed body cavities, there are several smaller body cavities. Most of these are in the head and most open to the body exterior
Figure 1.7 provides the terms that will help you locate all but the last two cavities mentioned here
[1.6] Many internal organs lie in membrane-lined body cavities
Other Body Cavities: Oral and Digestive Cavities
The oral cavity, commonly called the mouth, contains the teeth and tongue. This cavity is part of and continuous with the cavity of the digestive organs, which opens to the body exterior at the anus
[1.6] Many internal organs lie in membrane-lined body cavities
Other Body Cavities: Nasal Cavity
Located within and posterior to the nose, the nasal cavity is part of the respiratory system passageways
[1.6] Many internal organs lie in membrane-lined body cavities
Other Body Cavities: Orbital Cavities
The orbital cavities (orbits) in the skull house the eyes and present them in an anterior position
