Chapter 1 - An Introduction to the Human Body Flashcards
What are the 11 systems of the human body?
Systems consist of related organs that have a common function. The 11 systems of the human organism are: the integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive systems.
What is the difference between anatomy and physiology?
Anatomy (ana- = up; -tomy = process of cutting) is the science of body structures and the relationships among them.
Whereas anatomy deals with structures of the body, physiology (physio- = nature; -logy = study of) is the science of body functions - how the body parts work.
Structure vs Function
Describe the body’s six levels of structural organization.
Chemical level – This very basic level includes atoms, the smallest units of matter that participate in chemical reactions, and molecules, two or more atoms joined together.
Cellular level - Molecules combine to form cells, the basic structural and functional units of an organism that are composed of chemicals. Cells are the smallest living units in he human body.
Tissue level – Tissues are groups of cells and the materials surrounding them that work together to perform a particular function, similar to the way words are put together to form sentences. There are just four basic types of tissues in your body: epithelial tissue, connective tissue, muscular tissue, and nervous tissue.
Organ level – Organs are structures that are composed of two or more different types of tissues; they have specific functions and usually have recognizable shapes.
System level - A system consists of related organs with a common function.
Organismic level - All the parts of the human body functioning together constitute the total organism.
What are the 6 most important life processes of the human body?
Metabolism is the sum of all chemical processes that occur in the body. One phase of metabolism is catabolism, the breakdown of complex chemical substances into simpler components. The other phase of metabolism is anabolism, the building up of complex chemical substances from smaller, simpler components.
Responsiveness is the body’s ability to detect and respond to changes.
Movement includes motion of the whole body, individual organs, single cells, and even tiny structures inside cells.
Growth is an increase in body size that results from an increase in the size of existing cells, an increase in the number of cells, or both.
Differentiation is the development of a cell from an unspecialized to a specialized state. Such precursor cells, which can divide and give rise to cells that undergo differentiation,
are known as stem cells.
Reproduction refers either to (1) the formation of new cells for tissue growth, repair, or replacement, or (2) the production of a new individual.
Explain the importance of homeostasis and describe the relationship of homeostatic imbalances to disorders.
Homeostasis in the human body is continually being disturbed. Fortunately, the body has many regulating systems that can usually bring the internal environment back into balance. Most often, the nervous system and the endocrine system, working together or independently, provide the needed corrective measures.
Define homeostasis.
Homeostasis is the maintenance of relatively stable conditions in the body’s internal environment.
Differentiate between ICF and ECF.
An important aspect of homeostasis is maintaining the volume and composition of body fluids, dilute, watery solutions containing dissolved chemicals that are found inside cells as well as surrounding them. The fluid within cells is intracellular fluid, abbreviated ICF. The fluid outside body cells is extracellular fluid (ECF).
The ECF that fills the narrow spaces between cells of tissues is known as interstitial fluid. ECF within blood vessels is termed blood plasma, within lymphatic vessels it is called lymph, in and around the brain and spinal cord it is known as cerebrospinal fluid, in joints it is referred to as synovial fluid, and the ECF of the eyes is called aqueous humor and vitreous body.
Because ECF, in particular interstitial fluid, surrounds the cells of the body, it serves as the body’s internal environment. By contrast, the external environment of the body is the space that surrounds the entire body.
Describe the components of a feedback system.
The body can regulate its internal environment through many feedback systems. A feedback system, or feedback loop, is a cycle of events in which the status of a body condition is monitored, evaluated, changed, remonitored, reevaluated, and so on. Each monitored variable, such as body temperature, blood pressure, or blood glucose level, is termed a controlled condition (controlled variable). Any disruption that changes a controlled condition is called a stimulus. A feedback system includes three basic components: a receptor, a control center, and an effector.
A receptor is a body structure that monitors changes in a controlled condition and sends input to a control center. This pathway is called an afferent pathway since the information flows toward the control center. Typically, the input is in the form of nerve impulses or chemical signals. For example, certain nerve endings in the skin sense temperature and can detect changes, such as a dramatic drop in temperature.
A control center in the body, for example, the brain, sets the narrow range or set point within which a controlled condition should be maintained, evaluates the input it receives from receptors, and generates output commands when they are needed. Output from the control center typically occurs as nerve impulses, or hormones, or other chemical signals. This pathway is called an efferent pathway since the information flows away from the control center.
An effector is a body structure that receives output from the control center and produces a response or effect that changes the controlled condition. Nearly every organ or tissue in the body can behave as an effector. When your body temperature drops sharply, your brain (control center) sends nerve impulses (output) to your skeletal muscles (effectors). The result is shivering, which generates heat and raises your body temperature.
Contrast the operation of negative and positive feedback systems.
A negative feedback system reverses a change in a controlled condition, for example the regulation of blood pressure by the slowing of the heartbeat and the dilation of blood vessels.
A positive feedback system tends to strengthen or reinforce a change in one of the body’s controlled conditions, for example the increase of contractions during childbirth.
Because a positive feedback system continually reinforces a change in a controlled condition, some event outside the system must shut it off. If the action of a positive feedback system is not stopped, it can “run away” and may even produce life-threatening conditions in the body. The action of a negative feedback system, by contrast, slows and then stops as the controlled condition returns to its normal state. Usually, positive feedback systems reinforce conditions that do not happen very often, and negative feedback systems regulate conditions in the body that remain fairly stable over long periods.
Differentiate between a disorder and a disease.
A disorder is a general term for any abnormality of structure or function.
A disease is an illness with a definite set of signs and symptoms.
Describe the anatomical position.
Descriptions of any region or part of the human body assume that it is in a standard position of reference called the anatomical position. In the anatomical position, the subject stands erect facing the observer, with the head level and the eyes facing directly forward. The lower limbs are parallel and the feet are flat on the floor and directed forward, and the upper limbs are at the sides with the palms turned forward. Two terms describe a reclining body. If the body is lying facedown, it is in the prone position. If the body is lying faceup, it is in the supine position.
Relate the anatomical names and their corresponding common names for various regions of the human body.
The human body is divided into several major regions that can be identified externally. The head consists of the skull and face. The neck supports the head and attaches it to the trunk. The trunk consists of the chest, abdomen, and pelvis. Each upper limb attaches to the trunk and consists of the shoulder, armpit, arm (portion of the limb from the shoulder to the elbow), forearm (portion of the limb from the elbow to the wrist), wrist, and hand. Each lower limb also attaches to the trunk and consists of the buttock, thigh (portion of the limb from the buttock to the knee), leg (portion of the limb from the knee to the ankle), ankle, and foot. The groin is the area on the front surface of the body marked by a crease on each side, where the trunk attaches to the thighs.
Define the anatomical planes and anatomical sections used to describe the human body.
Planes are imaginary flat surfaces that pass through the body parts. A sagittal plane is a vertical plane that divides the body or an organ into right and left sides. When such a plane passes through the midline of the body or an organ and divides it into equal right and left sides, it is called a midsagittal plane or a median plane. The midline is an imaginary vertical line that divides the body into equal left and right sides. If the sagittal plane does not pass through the midline but instead divides the body or an organ into unequal right and left sides, it is called a parasagittal plane. A frontal or coronal plane divides the body or an organ into anterior (front) and posterior (back) portions. A transverse plane divides the body or an organ into superior (upper) and inferior (lower) portions. Other names for a transverse plane are a cross-sectional or horizontal plane. Sagittal, frontal, and transverse planes are all at right angles to one another. An oblique plane by contrast, passes through the body or an organ at an oblique angle (any angle other than a 90-degree angle).
When you study a body region, you often view it in section. A section is a cut of the body or one of its organs made along one of the planes just described, for example a midsagittal section, a frontal section, or a transverse section.
Outline the major body cavities and the organs they contain.
Body cavities are spaces that enclose internal organs.
The cranial bones form a hollow space of the head called the cranial cavity, which contains the brain. The bones of the vertebral column (backbone) form the vertebral (spinal) canal, which contains the spinal cord. The cranial cavity and vertebral canal are continuous with one another. Three layers of protective tissue, the meninges, and a shock-absorbing fluid surround the brain and spinal cord.
The thoracic cavity or chest cavity is formed by the ribs, the muscles of the chest, the sternum (breastbone), and the thoracic portion of the vertebral column. Within the thoracic cavity are the pericardial cavity, a fluid-filled space that surrounds the heart, and two fluid-filled spaces called pleural cavities, one around each lung. The central part of the thoracic cavity is an anatomical region called the mediastinum, containing all thoracic organs except the lungs themselves. Among the structures in the mediastinum are the heart, esophagus, trachea, thymus, and several large blood vessels that enter and exit the heart. The diaphragm is a dome-shaped muscle that separates the thoracic cavity from the abdominopelvic cavity.
The abdominopelvic cavity extends from the diaphragm to the groin and is encircled by the abdominal muscular wall and the bones and muscles of the pelvis. As the name suggests, the abdominopelvic cavity is divided into two portions, even though no wall separates them. The superior portion, the abdominal cavity, contains the stomach, spleen, liver, gallbladder, small intestine, and most of the large intestine. The inferior portion, the pelvic cavity, contains the urinary bladder, portions of the large intestine, and internal organs of the reproductive system. Organs inside the thoracic and abdominopelvic cavities are called viscera.
Serous Membrane
A membrane is a thin, pliable tissue that covers, lines, partitions, or connects structures. One example is a slippery, double-layered membrane associated with body cavities that does not open directly to the exterior called a serous membrane. It covers the viscera within the thoracic and abdominal cavities and also lines the walls of the thorax and abdomen. The parts of a serous membrane are (1) the parietal layer, a thin epithelium that lines the walls of the cavities, and (2) the visceral layer a thin epithelium that covers and adheres to the viscera within the cavities.
The serous membrane of the pleural cavities is called the pleura.
The serous membrane of the pericardial cavity is the pericardium.
The peritoneum is the serous membrane of the abdominal cavity. Most abdominal organs are surrounded by the peritoneum. Some are not surrounded by the peritoneum; instead, they are posterior to it. Such organs are said to be retroperitoneal.
Name the 9 abdominopelvic regions and the 4 quadrants used to describe the location of organs.
To describe the location of the many abdominal and pelvic organs more easily, anatomists and clinicians use two methods of dividing the abdominopelvic cavity into smaller areas. In the first method, two horizontal and two vertical lines, aligned like a tic-tac-toe grid, partition this cavity into nine abdominopelvic regions. The names of the nine abdominopelvic regions are right hypochondriac, epigastric, left hypochondriac, right lumbar, umbilical, left lumbar, right inguinal (iliac), hypogastric (pubic), and left inguinal (iliac).
The second method is simpler and divides the abdominopelvic cavity into quadrants. The names of the abdominopelvic quadrants are right upper quadrant (RUQ), left upper quadrant (LUQ), right lower quadrant (RLQ), and left lower quadrant (LLQ).
Define each directional term used to describe the human body.
Superior / Inferior
Anterior / Posterior
Medial / Lateral (toward the midline / farther from the midline)
Ipsilateral / Contralateral (on the same / opposite side of the body as another structure)
Proximal / Distal (nearer to / farther from the attachment of a limb to the trunk; nearer to / farther from the origination of a structure)
Superficial / Deep (toward / away from the surface of the body)
Intermediate (between two structures)
