Module 1: Introduction to Human Body

Lesson 4: Homeostasis

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Mỗi bài học (lesson) bao gồm 4 phần chính: Thuật ngữ, Luyện Đọc, Luyện Nghe, và Bàn Luận.
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Dưới đây là danh sách những thuật ngữ Y khoa của module Introduction to Human Body.
Khái quát được số lượng thuật ngữ sẽ xuất hiện trong bài đọc và nghe sẽ giúp bạn thoải mái tiêu thụ nội dung hơn. Sau khi hoàn thành nội dung đọc và nghe, bạn hãy quay lại đây và luyện tập (practice) để quen dần các thuật ngữ này. Đừng ép bản thân phải nhớ các thuật ngữ này vội vì bạn sẽ gặp và ôn lại danh sách này trong những bài học (lesson) khác của cùng một module.

Medical Terminology: Introduction to Human Body

abdominopelvic cavity
division of the anterior (ventral) cavity that houses the abdominal and pelvic viscera
anabolism
assembly of more complex molecules from simpler molecules
anatomical position
standard reference position used for describing locations and directions on the human body
anatomy
science that studies the form and composition of the body’s structures
anterior
describes the front or direction toward the front of the body; also referred to as ventral
anterior cavity
larger body cavity located anterior to the posterior (dorsal) body cavity; includes the serous membrane-lined pleural cavities for the lungs, pericardial cavity for the heart, and peritoneal cavity for the abdominal and pelvic organs; also referred to as ventral cavity
catabolism
breaking down of more complex molecules into simpler molecules
caudal
describes a position below or lower than another part of the body proper; near or toward the tail (in humans, the coccyx, or lowest part of the spinal column); also referred to as inferior
cell
smallest independently functioning unit of all organisms; in animals, a cell contains cytoplasm, composed of fluid and organelles
computed tomography (CT)
medical imaging technique in which a computer-enhanced cross-sectional X-ray image is obtained
control center
compares values to their normal range; deviations cause the activation of an effector
cranial
describes a position above or higher than another part of the body proper; also referred to as superior
cranial cavity
division of the posterior (dorsal) cavity that houses the brain
deep
describes a position farther from the surface of the body
development
changes an organism goes through during its life
differentiation
process by which unspecialized cells become specialized in structure and function
distal
describes a position farther from the point of attachment or the trunk of the body
dorsal
describes the back or direction toward the back of the body; also referred to as posterior
dorsal cavity
posterior body cavity that houses the brain and spinal cord; also referred to the posterior body cavity
effector
organ that can cause a change in a value
frontal plane
two-dimensional, vertical plane that divides the body or organ into anterior and posterior portions
gross anatomy
study of the larger structures of the body, typically with the unaided eye; also referred to macroscopic anatomy
growth
process of increasing in size
homeostasis
steady state of body systems that living organisms maintain
inferior
describes a position below or lower than another part of the body proper; near or toward the tail (in humans, the coccyx, or lowest part of the spinal column); also referred to as caudal
lateral
describes the side or direction toward the side of the body
magnetic resonance imaging (MRI)
medical imaging technique in which a device generates a magnetic field to obtain detailed sectional images of the internal structures of the body
medial
describes the middle or direction toward the middle of the body
metabolism
sum of all of the body’s chemical reactions
microscopic anatomy
study of very small structures of the body using magnification
negative feedback
homeostatic mechanism that tends to stabilize an upset in the body’s physiological condition by preventing an excessive response to a stimulus, typically as the stimulus is removed
normal range
range of values around the set point that do not cause a reaction by the control center
nutrient
chemical obtained from foods and beverages that is critical to human survival
organ
functionally distinct structure composed of two or more types of tissues
organ system
group of organs that work together to carry out a particular function
organism
living being that has a cellular structure and that can independently perform all physiologic functions necessary for life
pericardium
sac that encloses the heart
peritoneum
serous membrane that lines the abdominopelvic cavity and covers the organs found there
physiology
science that studies the chemistry, biochemistry, and physics of the body’s functions
plane
imaginary two-dimensional surface that passes through the body
pleura
serous membrane that lines the pleural cavity and covers the lungs
positive feedback
mechanism that intensifies a change in the body’s physiological condition in response to a stimulus
positron emission tomography (PET)
medical imaging technique in which radiopharmaceuticals are traced to reveal metabolic and physiological functions in tissues
posterior
describes the back or direction toward the back of the body; also referred to as dorsal
posterior cavity
posterior body cavity that houses the brain and spinal cord; also referred to as dorsal cavity
pressure
force exerted by a substance in contact with another substance
prone
face down
proximal
describes a position nearer to the point of attachment or the trunk of the body
regional anatomy
study of the structures that contribute to specific body regions
renewal
process by which worn-out cells are replaced
reproduction
process by which new organisms are generated
responsiveness
ability of an organisms or a system to adjust to changes in conditions
sagittal plane
two-dimensional, vertical plane that divides the body or organ into right and left sides
section
in anatomy, a single flat surface of a three-dimensional structure that has been cut through
sensor
(also, receptor) reports a monitored physiological value to the control center
serosa
membrane that covers organs and reduces friction; also referred to as serous membrane
serous membrane
membrane that covers organs and reduces friction; also referred to as serosa
set point
ideal value for a physiological parameter; the level or small range within which a physiological parameter such as blood pressure is stable and optimally healthful, that is, within its parameters of homeostasis
spinal cavity
division of the dorsal cavity that houses the spinal cord; also referred to as vertebral cavity
superficial
describes a position nearer to the surface of the body
superior
Phía trên
describes a position above or higher than another part of the body proper; also referred to as cranial
Above something: Ở vị trí phía trên
supine
face up
systemic anatomy
study of the structures that contribute to specific body systems
thoracic cavity
division of the anterior (ventral) cavity that houses the heart, lungs, esophagus, and trachea
tissue
group of similar or closely related cells that act together to perform a specific function
transverse plane
two-dimensional, horizontal plane that divides the body or organ into superior and inferior portions
ultrasonography
application of ultrasonic waves to visualize subcutaneous body structures such as tendons and organs
ventral
describes the front or direction toward the front of the body; also referred to as anterior
ventral cavity
larger body cavity located anterior to the posterior (dorsal) body cavity; includes the serous membrane-lined pleural cavities for the lungs, pericardial cavity for the heart, and peritoneal cavity for the abdominal and pelvic organs; also referred to as anterior body cavity
X-ray
form of high energy electromagnetic radiation with a short wavelength capable of penetrating solids and ionizing gases; used in medicine as a diagnostic aid to visualize body structures such as bones
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Dưới đây là các bài văn nằm ở bên trái. Ở bên phải là các bài luyện tập (practice) để đánh giá khả năng đọc hiểu của bạn. Sẽ khó khăn trong thời gian đầu nếu vốn từ vựng của bạn còn hạn chế, đặc biệt là từ vựng Y khoa. Hãy kiên nhẫn và đọc nhiều nhất có kể, lượng kiến thức tích tụ dần sẽ giúp bạn đọc thoải mái hơn.
Maintaining homeostasis requires that the body continuously monitor its internal conditions. From body temperature to blood pressure to levels of certain nutrients, each physiological condition has a particular set point. A set point is the physiological value around which the normal range fluctuates. A normal range is the restricted set of values that is optimally healthful and stable. For example, the set point for normal human body temperature is approximately 37°C (98.6°F). Physiological parameters, such as body temperature and blood pressure, tend to fluctuate within a normal range a few degrees above and below that point. Control centers in the brain and other parts of the body monitor and react to deviations from homeostasis using negative feedback. Negative feedback is a mechanism that reverses a deviation from the set point. Therefore, negative feedback maintains body parameters within their normal range. The maintenance of homeostasis by negative feedback goes on throughout the body at all times, and an understanding of negative feedback is thus fundamental to an understanding of human physiology.
A negative feedback system has three basic components (Figure 1a). A sensor, also referred to a receptor, is a component of a feedback system that monitors a physiological value. This value is reported to the control center. The control center is the component in a feedback system that compares the value to the normal range. If the value deviates too much from the set point, then the control center activates an effector. An effector is the component in a feedback system that causes a change to reverse the situation and return the value to the normal range.

In order to set the system in motion, a stimulus must drive a physiological parameter beyond its normal range (that is, beyond homeostasis). This stimulus is “heard” by a specific sensor. For example, in the control of blood glucose, specific endocrine cells in the pancreas detect excess glucose (the stimulus) in the bloodstream. These pancreatic beta cells respond to the increased level of blood glucose by releasing the hormone insulin into the bloodstream. The insulin signals skeletal muscle fibers, fat cells (adipocytes), and liver cells to take up the excess glucose, removing it from the bloodstream. As glucose concentration in the bloodstream drops, the decrease in concentration—the actual negative feedback—is detected by pancreatic alpha cells, and insulin release stops. This prevents blood sugar levels from continuing to drop below the normal range.

Humans have a similar temperature regulation feedback system that works by promoting either heat loss or heat gain (Figure 1b). When the brain’s temperature regulation center receives data from the sensors indicating that the body’s temperature exceeds its normal range, it stimulates a cluster of brain cells referred to as the “heat-loss center.” This stimulation has three major effects:

  • Blood vessels in the skin begin to dilate allowing more blood from the body core to flow to the surface of the skin allowing the heat to radiate into the environment.
  • As blood flow to the skin increases, sweat glands are activated to increase their output. As the sweat evaporates from the skin surface into the surrounding air, it takes heat with it.
  • The depth of respiration increases, and a person may breathe through an open mouth instead of through the nasal passageways. This further increases heat loss from the lungs.

In contrast, activation of the brain’s heat-gain center by exposure to cold reduces blood flow to the skin, and blood returning from the limbs is diverted into a network of deep veins. This arrangement traps heat closer to the body core and restricts heat loss. If heat loss is severe, the brain triggers an increase in random signals to skeletal muscles, causing them to contract and producing shivering. The muscle contractions of shivering release heat while using up ATP. The brain triggers the thyroid gland in the endocrine system to release thyroid hormone, which increases metabolic activity and heat production in cells throughout the body. The brain also signals the adrenal glands to release epinephrine (adrenaline), a hormone that causes the breakdown of glycogen into glucose, which can be used as an energy source. The breakdown of glycogen into glucose also results in increased metabolism and heat production.
Positive feedback intensifies a change in the body’s physiological condition rather than reversing it. A deviation from the normal range results in more change, and the system moves farther away from the normal range. Positive feedback in the body is normal only when there is a definite end point. Childbirth and the body’s response to blood loss are two examples of positive feedback loops that are normal but are activated only when needed.

Childbirth at full term is an example of a situation in which the maintenance of the existing body state is not desired. Enormous changes in a person’s body are required to expel the baby at the end of pregnancy. And the events of childbirth, once begun, must progress rapidly to a conclusion or the life of a person giving birth and the baby are at risk. The extreme muscular work of labor and delivery are the result of a positive feedback system (Figure 2).

The first contractions of labor (the stimulus) push the baby toward the cervix (the lowest part of the uterus). The cervix contains stretch-sensitive nerve cells that monitor the degree of stretching (the sensors). These nerve cells send messages to the brain, which in turn causes the pituitary gland at the base of the brain to release the hormone oxytocin into the bloodstream. Oxytocin causes stronger contractions of the smooth muscles in of the uterus (the effectors), pushing the baby further down the birth canal. This causes even greater stretching of the cervix. The cycle of stretching, oxytocin release, and increasingly more forceful contractions stops only when the baby is born. At this point, the stretching of the cervix halts, stopping the release of oxytocin.

A second example of positive feedback centers on reversing extreme damage to the body. Following a penetrating wound, the most immediate threat is excessive blood loss. Less blood circulating means reduced blood pressure and reduced perfusion (penetration of blood) to the brain and other vital organs. If perfusion is severely reduced, vital organs will shut down and the person will die. The body responds to this potential catastrophe by releasing substances in the injured blood vessel wall that begin the process of blood clotting. As each step of clotting occurs, it stimulates the release of more clotting substances. This accelerates the processes of clotting and sealing off the damaged area. Clotting is contained in a local area based on the tightly controlled availability of clotting proteins. This is an adaptive, life-saving cascade of events.

OpenStax. (2022). Anatomy and Physiology 2e. Rice University. Retrieved June 15, 2023. ISBN-13: 978-1-711494-06-7 (Hardcover) ISBN-13: 978-1-711494-05-0 (Paperback) ISBN-13: 978-1-951693-42-8 (Digital). License: Attribution 4.0 International (CC BY 4.0). Access for free at openstax.org.

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.

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.

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Dưới đây là video và các luyện tập (practice) của bài này. Nghe là một kĩ năng khó, đặc biệt là khi chúng ta chưa quen nội dung và chưa có nhạy cảm ngôn ngữ. Nhưng cứ đi thật chậm và đừng bỏ cuộc.
Xem video và cảm nhận nội dung bài. Bạn có thể thả trôi, cảm nhận dòng chảy ngôn ngữ và không nhất thiết phải hiểu toàn bộ bài. Bên dưới là script để bạn khái quát nội dụng và tra từ mới.
Script:
  1. Homeostasis is the activity of cells throughout the body to maintain the physiological state within a narrow range that is compatible with life.
  2. Homeostasis is regulated by negative feedback loops and, much less frequently, by positive feedback loops.
  3. Both have the same components of a stimulus, sensor, control center, and effector.
  4. However, negative feedback loops work to prevent an excessive response to the stimulus, whereas positive feedback loops intensify the response until an end point is reached.
  5. An example of negative feedback is the regulation of body temperature.
  6. When body temperature rises above the set point, sweat is produced, which evaporates, cooling the body and bringing temperature back to normal.
  7. An example of positive feedback is childbirth.
  8. During labor, contractions intensify as the baby moves towards the birth canal.
  9. This further stimulates the release of oxytocin, causing stronger contractions until the baby is delivered.
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