Physiology Chapter 1: Human Body Organization

Oxygen, which reacts with carbohydrate, fat, and protein to release energy required for cell function.

Extracellular fluid, which provides the ions and nutrients needed by the cells to maintain cell life.

Extracellular fluid contains large amounts of sodium, chloride, and bicarbonate ions, whereas intracellular fluid contains large amounts of potassium, magnesium, and phosphate ions.

<p>Homeostasis is the maintenance of nearly constant conditions in the internal environment, and it is essential for the proper functioning of all organs and tissues.</p> Signup and view all the answers

<p>It transports extracellular fluid through all parts of the body in two stages: movement of blood through the body in blood vessels, and movement of fluid between blood capillaries and intercellular spaces.</p> Signup and view all the answers

<p>The remaining cells of that type usually generate new cells until the supply is replenished.</p> Signup and view all the answers

<p>These concentrations are essential for cells to live, grow, and perform their special functions.</p> Signup and view all the answers

<p>one minute</p> Signup and view all the answers

<p>The kidneys maintain constant ion concentrations in the extracellular fluid.</p> Signup and view all the answers

<p>plasma protein molecules</p> Signup and view all the answers

<p>less than 50 micrometers</p> Signup and view all the answers

<p>It provides nutrients to the extracellular fluid, which are then used by cells to maintain cell function.</p> Signup and view all the answers

<p>oxygen diffusion into the blood</p> Signup and view all the answers

<p>It refers to the internal environment of the body, or the extracellular fluid that surrounds all cells.</p> Signup and view all the answers

<p>changing the chemical compositions of absorbed substances into more usable forms</p> Signup and view all the answers

<p>providing motility for obtaining food and protection against adverse surroundings</p> Signup and view all the answers

<p>to maintain homeostasis</p> Signup and view all the answers

<p>diffusion</p> Signup and view all the answers

<p>liver</p> Signup and view all the answers

<p>permeability</p> Signup and view all the answers

<p>Carbon dioxide is released from the blood into the lung alveoli and carried to the atmosphere.</p> Signup and view all the answers

<p>To remove excess substances from the plasma, including end products of cellular metabolism, ions, and water.</p> Signup and view all the answers

<p>The liver secretes waste products into the bile, which are then eliminated in the feces.</p> Signup and view all the answers

<p>The sensory input portion, the central nervous system (or integrative portion), and the motor output portion.</p> Signup and view all the answers

<p>The autonomic system is a part of the nervous system that operates at a subconscious level and controls many functions of internal organs.</p> Signup and view all the answers

<p>Hormones help regulate cellular function and are transported in the extracellular fluid to all parts of the body.</p> Signup and view all the answers

<p>The eight major endocrine glands produce hormones that regulate various bodily functions.</p> Signup and view all the answers

<p>The nervous system regulates muscular and secretory activities, while the hormonal system regulates metabolic functions.</p> Signup and view all the answers

<p>The immune system consists of white blood cells, tissue cells, and organs that protect the body from pathogens such as bacteria, viruses, parasites, and fungi.</p> Signup and view all the answers

<p>The gastrointestinal tract eliminates undigested material and waste products of metabolism in the feces.</p> Signup and view all the answers

<p>To explain the physical and chemical factors responsible for the origin, development, and progression of life.</p> Signup and view all the answers

<p>Human physiology focuses on the specific characteristics and mechanisms that make the human body a living being.</p> Signup and view all the answers

<p>Red blood cells transport oxygen from the lungs to the tissues.</p> Signup and view all the answers

<p>The human body is organized into organs, which are aggregates of different cells held together by intercellular structures.</p> Signup and view all the answers

<p>Approximately 100 trillion cells.</p> Signup and view all the answers

<p>Different types of cells are specially adapted to perform one or a few specific functions.</p> Signup and view all the answers

<p>Because it operates through complex control systems that respond automatically to stimuli such as hunger and cold.</p> Signup and view all the answers

<p>Despite their differences in function, all cells have certain basic characteristics in common.</p> Signup and view all the answers

<p>The consequence of a vicious cycle in the heart is further weakening of the heart, diminished pumping, decrease in coronary blood flow, and eventual death.</p> Signup and view all the answers

<p>Positive feedback contributes to the formation of blood clots by activating clotting factors, which in turn activate more clotting factors, leading to the formation of a clot that plugs the hole in the vessel.</p> Signup and view all the answers

<p>This process is essential for the progression of labor and the delivery of the baby.</p> Signup and view all the answers

<p>Positive feedback generates nerve signals by causing slight leakage of sodium ions through sodium channels in the nerve membrane, leading to a change in membrane potential, which in turn causes more opening of channels, and so forth, eventually creating the nerve action potential.</p> Signup and view all the answers

<p>Positive feedback amplifies a response, while negative feedback reduces or reverses a response. In the body, positive feedback is often part of an overall negative feedback process, such as in blood clotting, where the positive feedback clotting process is a negative feedback process for maintenance of normal blood volume.</p> Signup and view all the answers

<p>The dashed curve in Figure 1-3 represents the recovery of heart pumping caused by negative feedback after 1 liter of blood is removed from the circulation.</p> Signup and view all the answers

<p>The body uses positive feedback to its advantage in blood clotting, childbirth, and generation of nerve signals.</p> Signup and view all the answers

<p>The formation of unwanted clots is a result of positive feedback getting out of hand, leading to the formation of clots that can cause heart attacks.</p> Signup and view all the answers

<p>The body's ability to overcome positive feedback through negative feedback control mechanisms helps to maintain homeostasis and prevent the development of vicious cycles that can lead to disease and death.</p> Signup and view all the answers

<p>Understanding the concept of positive feedback is essential for understanding how the body maintains homeostasis and how physiological processes are regulated.</p> Signup and view all the answers

<p>The body regulates oxygen levels primarily through the chemical affinity of hemoglobin for oxygen, acting as an oxygen buffer. Carbon dioxide regulation, however, involves a feedback mechanism where increased CO2 levels stimulate the respiratory center, leading to increased breathing and CO2 expulsion.</p> Signup and view all the answers

<p>The integumentary system acts as a barrier protecting internal tissues from the external environment, regulating temperature through sweating and vasoconstriction, excreting waste products, and providing sensory input for external stimuli.</p> Signup and view all the answers

<p>Reproduction ensures the continuation of life and the replacement of individuals, ultimately contributing to the long-term stability and survival of the species, which is essential for maintaining homeostasis on a larger scale.</p> Signup and view all the answers

<p>The liver regulates glucose levels by storing excess glucose as glycogen and releasing it when needed. The pancreas produces insulin and glucagon, hormones that regulate blood sugar levels, ensuring a stable glucose concentration in the extracellular fluid.</p> Signup and view all the answers

<p>The immune system distinguishes self from non-self, identifying and eliminating foreign invaders. It also destroys pathogens through phagocytosis or the production of antibodies and sensitized lymphocytes, preventing infection and disease.</p> Signup and view all the answers

<p>Genetic control systems regulate the production of proteins essential for cellular functions, maintaining internal cellular balance. They also influence the release of signaling molecules that affect neighboring cells and the overall extracellular environment.</p> Signup and view all the answers

<p>The nervous system, specifically the respiratory center, detects elevated carbon dioxide levels in the blood. This triggers increased breathing rate and depth, expelling excess carbon dioxide and restoring homeostasis.</p> Signup and view all the answers

<p>Hemoglobin's strong affinity for oxygen prevents it from releasing oxygen into the tissues when oxygen levels are already high. However, if tissue oxygen levels drop, hemoglobin readily releases oxygen, ensuring adequate supply and maintaining stable tissue oxygen concentrations.</p> Signup and view all the answers

<p>These ions are crucial for various physiological processes, including nerve impulse transmission, muscle contraction, and maintaining osmotic balance. Stable concentrations ensure proper functioning of these processes and overall homeostasis.</p> Signup and view all the answers

<p>The cardiovascular system, nervous system, and endocrine system all contribute to regulating blood pressure. The heart pumps blood, nerves adjust vessel diameter, and hormones influence fluid volume and vascular tone, working in concert to maintain stable blood pressure.</p> Signup and view all the answers

<p>Baroreceptors detect stretch in arterial walls and send impulses to the brain to regulate blood pressure through vasodilation or vasoconstriction.</p> Signup and view all the answers

<p>The vasomotor center is inhibited, leading to decreased heart pumping and dilation of peripheral blood vessels.</p> Signup and view all the answers

<p>Baroreceptors relax, allowing increased activity of the vasomotor center, which causes vasoconstriction and increased heart pumping.</p> Signup and view all the answers

<p>Narrow normal ranges are critical because deviations can lead to severe physiological disruptions or death.</p> Signup and view all the answers

<p>Low potassium levels hinder nerve signal transmission, potentially leading to paralysis.</p> Signup and view all the answers

<p>Increased carbon dioxide concentration stimulates pulmonary ventilation, which reduces carbon dioxide levels back to normal.</p> Signup and view all the answers

<p>Low calcium concentration can cause excessive muscle contractions due to spontaneous nerve impulses.</p> Signup and view all the answers

<p>A significant drop in glucose concentration can lead to mental irritability and convulsions.</p> Signup and view all the answers

<p>Most control systems operate via negative feedback to maintain homeostasis.</p> Signup and view all the answers

<p>Control systems, like those activated by baroreceptors, adjust physiological responses to stabilize internal conditions.</p> Signup and view all the answers

<p>When carbon dioxide concentration falls too low, negative feedback mechanisms are triggered to increase the concentration. This is achieved by processes like reducing ventilation rate or increasing carbon dioxide production, ultimately bringing the concentration back to a normal range. The outcome of this feedback is maintaining a stable carbon dioxide level, crucial for maintaining blood pH and overall homeostasis.</p> Signup and view all the answers

<p>Baroreceptors are specialized sensory receptors that detect changes in arterial pressure. When pressure rises, baroreceptors send signals to the brain, triggering mechanisms to lower the pressure (e.g., slowing heart rate, dilating blood vessels). Conversely, a drop in pressure stimulates responses to increase it. If the baroreceptor system is dysfunctional, the body is unable to effectively regulate arterial pressure, leading to potentially dangerous fluctuations.</p> Signup and view all the answers

<p>Gain in a control system refers to its effectiveness in maintaining stability. In the baroreceptor system, gain is calculated by dividing the 'correction' (amount of pressure change prevented by the system) by the 'error' (remaining pressure change). A higher gain indicates a more effective system. For instance, a gain of -2 means that the baroreceptor system reduces a pressure change by two-thirds. This shows that a higher gain leads to a more stable and controlled system.</p> Signup and view all the answers

<p>Negative feedback is the dominant mechanism because it promotes stability and maintains homeostasis. Positive feedback, on the other hand, amplifies an initial change, leading to further deviation from the set point. This can be detrimental, as seen in cases like heart failure. A decrease in blood volume leads to a decrease in cardiac output, further reducing blood flow to the heart, creating a vicious cycle that can lead to heart failure and even death.</p> Signup and view all the answers

<p>The gain of the baroreceptor system is typically around -2, while the gain of the system regulating internal body temperature is significantly higher, around -33. This indicates that the temperature control system is much more effective than the baroreceptor system in maintaining homeostasis. This difference in gain can be attributed to the critical nature of body temperature regulation for cell survival compared to blood pressure.</p> Signup and view all the answers

<p>When a factor deviates from its normal range, a control system initiates negative feedback to bring it back towards the 'set point'. The set point is the desired or ideal value for that factor. For instance, if blood glucose levels rise, negative feedback mechanisms are triggered to lower them back to the set point, which is typically around 85 mg/dl. This constant adjustment around the set point maintains homeostasis.</p> Signup and view all the answers

<p>Positive feedback amplifies an initial change, leading to further deviation from the set point. This can create a vicious cycle where the initial change exacerbates itself, ultimately leading to harmful consequences. An example is the positive feedback loop in blood clotting. When platelets aggregate at a wound site, they release chemicals that attract more platelets, creating a cascading effect that ultimately stops bleeding. However, this positive feedback loop can become detrimental if it spreads uncontrollably, leading to a blood clot that can obstruct blood flow and cause tissue damage.</p> Signup and view all the answers

<p>'Error' refers to the deviation from the set point that remains after a control system has acted. A larger error indicates a less effective system. Gain is calculated by dividing the 'correction' (amount of change prevented) by the 'error'. A higher gain means a larger correction relative to the error, indicating a more effective system. Therefore, reducing the error by increasing the correction or improving the gain is crucial for a more effective control system.</p> Signup and view all the answers

<p>Maintaining a stable extracellular fluid environment is crucial for cell function and survival. Cells rely on the extracellular fluid for nutrient supply, waste removal, and maintaining proper osmotic balance. Significant deviations from the normal range of key constituents can disrupt cellular processes, leading to impaired function or even cell death. This can have cascading effects on organ systems and overall body function.</p> Signup and view all the answers

<p>The body employs various mechanisms to maintain homeostasis of key constituents. Oxygen levels are regulated by the respiratory system (lungs), while carbon dioxide levels are controlled by the respiratory system and the kidneys. Sodium ion levels are primarily regulated by the kidneys, while glucose levels are controlled by the pancreas (insulin and glucagon). These organs work together to ensure that the concentration of these constituents remains within a narrow range, maintaining overall homeostasis.</p> Signup and view all the answers

<p>Adaptive control is a mechanism where the brain uses feed-forward signals to adjust muscle contractions based on sensory feedback from movements.</p> Signup and view all the answers

<p>Feed-forward control is a strategy used by the brain to initiate muscle contractions based on predictions from prior movements rather than reactive feedback.</p> Signup and view all the answers

<p>Adaptive control is essentially delayed negative feedback, as it involves correcting movements based on previous feedback for future actions.</p> Signup and view all the answers

<p>The interconnectedness of control mechanisms allows for coordinated responses and adjustments across various systems, maintaining overall homeostasis.</p> Signup and view all the answers

<p>Homeostasis is vital because it maintains a stable internal environment, enabling cells to function optimally and survive.</p> Signup and view all the answers

<p>When functional systems fail to maintain homeostasis, it can lead to cell dysfunction, sickness, or even death.</p> Signup and view all the answers

<p>Automaticity refers to the body's ability to maintain homeostasis through the continuous interplay of various functional structures and cells.</p> Signup and view all the answers

<p>Adaptive control is distinguished by its ability to modify future actions based on past feedback, while simpler feedback systems react to immediate errors without such adjustments.</p> Signup and view all the answers

<p>Sensory nerve signals provide the brain with information on the accuracy of movements, allowing for necessary corrections in future actions.</p> Signup and view all the answers

<p>The 'social order' analogy illustrates how approximately 100 trillion cells work together in organized systems to contribute to overall health and homeostasis.</p> Signup and view all the answers