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Questions and Answers
What is the main difference in fluid composition between intracellular fluid (ICF) and extracellular fluid (ECF)?
What is the main difference in fluid composition between intracellular fluid (ICF) and extracellular fluid (ECF)?
How does the percentage of body water in children compare to that in adults?
How does the percentage of body water in children compare to that in adults?
Which of the following is NOT a function of body water?
Which of the following is NOT a function of body water?
What percentage of total body weight does water constitute in adult men?
What percentage of total body weight does water constitute in adult men?
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At which end of the capillaries does filtration primarily occur?
At which end of the capillaries does filtration primarily occur?
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Which of the following ions is found in high concentration in extracellular fluid?
Which of the following ions is found in high concentration in extracellular fluid?
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What happens to the body's water content with an increase in body fat?
What happens to the body's water content with an increase in body fat?
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Which type of fluid primarily serves as digestive juices in the body?
Which type of fluid primarily serves as digestive juices in the body?
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What is the basic unit of structure and function in the body?
What is the basic unit of structure and function in the body?
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What type of cells contain a true nucleus and membrane-bound organelles?
What type of cells contain a true nucleus and membrane-bound organelles?
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What percentage of total body fluids does the intracellular fluid (ICF) constitute?
What percentage of total body fluids does the intracellular fluid (ICF) constitute?
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Which of the following is NOT a component of extracellular fluid (ECF)?
Which of the following is NOT a component of extracellular fluid (ECF)?
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What is the total approximate volume of body fluids in an adult weighing 70 kg?
What is the total approximate volume of body fluids in an adult weighing 70 kg?
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Which organelle is primarily involved in energy production within a eukaryotic cell?
Which organelle is primarily involved in energy production within a eukaryotic cell?
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Which of the following correctly describes the composition of plasma?
Which of the following correctly describes the composition of plasma?
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What allows the selective communication between intracellular and extracellular compartments?
What allows the selective communication between intracellular and extracellular compartments?
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What is the primary source of water input in the body?
What is the primary source of water input in the body?
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What hormone primarily regulates urine volume for water loss?
What hormone primarily regulates urine volume for water loss?
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Which mechanism is primarily involved in maintaining water balance when the body experiences hypovolemia?
Which mechanism is primarily involved in maintaining water balance when the body experiences hypovolemia?
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What is the average range of water loss per day in the body?
What is the average range of water loss per day in the body?
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What type of feedback mechanism maintains homeostasis by inhibiting the stimulus?
What type of feedback mechanism maintains homeostasis by inhibiting the stimulus?
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Which of the following is NOT a factor that stimulates the thirst center in the anterior hypothalamus?
Which of the following is NOT a factor that stimulates the thirst center in the anterior hypothalamus?
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What is the role of homeostasis in the body?
What is the role of homeostasis in the body?
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Which route contributes to insensible water loss?
Which route contributes to insensible water loss?
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Study Notes
Human Body Organization
- Human body is composed of coordinated systems like the digestive system
- Systems consist of organs, which are comprised of tissues with complementary functions
- Tissues consist of numerous cells
- Cells are the fundamental units of body structure and function
- Human cells, as well as multi-cellular animals and plants, are eukaryotic containing a nucleus surrounded by a membrane and other membrane-bound structures
- These membrane-bound structures are called organelles, such as mitochondria and ribosomes, and perform specialized functions
- Prokaryotic cells, for example bacteria, lack these membranous structures
- The eukaryotic cell is enclosed by a plasma membrane, which controls communication between the inside and outside of the cell and facilitates cellular movement
- Organelles are essential for cell survival by carrying out specific functions, such as protein synthesis by ribosomes and energy production by mitochondria
Body Fluids
- Body fluids are aqueous solutions containing various organic molecules (like carbohydrates, lipids, proteins, and nucleic acids) and inorganic molecules and ions
- They constitute about 65% of total body weight, or about 40-42 liters in a 70kg adult
- Body fluids are classified into two main compartments:
- Intracellular Fluid (ICF): The fluid inside the cell, making up two-thirds of total body fluids (about 25-28 liters)
- Extracellular Fluid (ECF): The fluid outside the cell, constituting one-third of total body fluids (about 14-15 liters), separated from ICF by the cell membrane
Extracellular Fluid (ECF)
- ECF is termed the internal environment providing nutrients and other essential substances for cellular function
- It includes:
- Plasma: Found inside blood vessels (3-3.5 liters)
- Interstitial Fluid: Located in spaces between cells and lymphatic vessels (10-12 liters)
- Transcellular Fluid: Present in body cavities (1 liter), including digestive juices and cerebrospinal fluid
- Plasma and interstitial fluid are separated by capillary walls
Composition of Body Fluids
- ECF has high concentrations of sodium, chloride, and bicarbonate ions, whereas ICF contains large amounts of potassium, magnesium, and phosphate ions
- These differences are crucial for sustaining cellular life
Water Balance
- Total body water represents about 60% of body weight in adult men and 50% in women due to higher fat content in women
- Fat percentage negatively affects water percentage
- Children have a higher water content (70%) than adults, making them more vulnerable to dehydration
- Water content decreases in old age
Functions of Body Water
- Crucial for all chemical reactions within the body
- Acts as a powerful solvent dissolving various substances for body access and transportation of nutrients, gasses, and waste
- Important for regulating body temperature due to its high latent heat of evaporation, requiring 0.58°C to evaporate per gram of water
- Moistens tissues like the mouth, eyes, and nose, and lubricates joints
- Facilitates osmotic equilibrium between body compartments due to its ease of passage through cell membranes
- Contributes to digestive secretions and enzyme activity
- Involved in absorption at the venous end of capillaries, gastrointestinal tract (GIT), and kidneys
- Facilitates filtration at the arterial end of capillaries and glomeruli
- Participates in excretion through the GIT, kidneys, and skin
- Mediates exchange at capillary membranes, alveolar membranes, and cell membranes
- Serves as a refractive medium in the eye
Water Balance: Input & Output
- Body water is stabilized by adjusting water intake and loss
- Water input comes from:
- Exogenous Water: Ingested through water or liquids (about 2200 ml/day)
- Endogenous Water: Synthesized during metabolism (about 200 ml/day)
- Water output occurs through:
- Insensible Water Loss: From lungs as water vapor and skin through insensible perspiration (about 700 ml)
- Sweating: Typically 100 ml, but increases during exercise
- Feces: Approximately 100 ml, increasing with diarrhea
- Urine: About 1500 ml
Control of Water Balance
- Water intake is regulated by thirst sensation stimulated by:
- Increased plasma osmolarity (hypertonicity)
- Decreased blood volume (hypovolemia)
- Angiotensin II
- Water loss is primarily controlled by adjusting urine volume, regulated by antidiuretic hormone (ADH), secreted by the posterior pituitary gland
- ADH secretion is also stimulated by hypertonicity and hypovolemia
Homeostasis
- Refers to mechanisms maintaining a stable internal environment
- Crucial for normal cellular function, including:
- Body water
- Ions
- Body temperature
- Blood glucose
- pH
- Arterial blood pressure
- Deviations beyond a narrow range greatly affect cell function
- All body systems work to maintain homeostasis, including:
-
Nervous system (rapid)
-
Endocrine system (slow)
-
Feedback mechanisms regulate the system
-
Negative feedback mechanisms maintain system stability by inhibiting the stimulus. For example:
- Thermoregulation: When body temperature increases, the body responds by sweating and vasodilation, which cools the body down. When body temperature decreases, the body responds by shivering and vasoconstriction, which warms the body up.
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Description
Explore the intricate organization of the human body, including its systems and the role of cells and tissues. This quiz covers essential topics such as the difference between eukaryotic and prokaryotic cells, and the functions of various organelles. Test your knowledge on how these components work together to maintain body function.
