Questions and Answers
What is homeostasis?
What are homeostatic mechanisms?
Regulatory processes that cells depend on to keep the environment dominated by water (ECF), precisely regulated regardless of external influences.
What are 5 examples of regulatory mechanisms?
Temperature, glucose and nutrients, pH balance, gases (O2 and CO2 levels), fluid volume and ion concentrations.
What is the role of temperature in homeostasis?
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How is blood glucose regulated in the body?
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How do the lungs contribute to pH balance?
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What is the kidney's role in homeostasis?
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What is hypokalemia?
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What is hyperkalemia?
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Define hypocalcemia.
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What causes hypercalcemia?
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What is tetany?
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How is homeostatic mechanism control achieved?
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What mediates lung gas exchange?
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What does the kidney regulate?
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How is temperature regulated in the body?
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What happens during heat loss?
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What causes dehydration?
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What is the mechanism behind thirst?
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How is decreased blood volume corrected?
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What causes a gain of water in the body?
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What does 2,3 DPG do?
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What can shift the hemoglobin dissociation curve to the right?
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What shifts the oxygen dissociation curve to the left?
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What is the normal pH of the body?
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What is acidosis?
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What is alkalosis?
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What is the bicarbonate/carbonic acid buffer system?
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What do the lungs control?
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What do the kidneys control?
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What disturbances in pH are related to HCO3-?
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What describes the bicarbonate/carbonic acid buffer system?
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What is respiratory acidosis?
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What is hypercapnia?
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What is metabolic acidosis?
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Study Notes
Homeostasis
- Represents the desired steady state or equilibrium within the body.
Homeostatic Mechanisms
- Regulatory processes essential for cell function.
- Maintains the extracellular fluid (ECF) environment, precisely regulating chemical and physical elements, regardless of external changes.
Examples of Regulatory Mechanisms
- Temperature: Regulated through the hypothalamus, utilizing muscle activity and blood vessel adjustments.
- Blood Glucose: Managed by the endocrine system via insulin, glucagon, and gluconeogenesis.
- pH Balance: Controlled by lungs and kidneys; lungs expel CO2, while kidneys excrete H+ to maintain acid-base balance.
- Gases: Regulation of oxygen (O2) and carbon dioxide (CO2) levels in the blood.
- Fluid Volume/Ion Concentrations: Primarily managed by the kidneys.
Temperature Regulation
- Involves hypothalamus and muscular actions like shivering for heat production and vasodilation/sweating for heat loss.
Blood Glucose Control
- Insulin lowers blood glucose while glucagon raises it through gluconeogenesis.
pH Regulation
- Lungs expel excess CO2; kidneys excrete hydrogen ions (H+).
Electrolyte and Water Regulation
- Kidneys play a crucial role by removing waste products, conserving water, and regulating electrolytes.
Hypokalemia
- Characterized by low potassium levels, potentially causing paralysis due to impaired nerve impulse transmission.
Hyperkalemia
- Elevated potassium in the blood can severely depress heart muscle function.
Hypocalcemia
- Low calcium levels can lead to symptoms like anorexia, nervousness, seizures, and paralysis (milk fever).
Hypercalcemia
- High calcium concentrations reduce the excitability of neuromuscular tissues.
Tetany
- Condition of involuntary muscle contraction, similar to seizures.
Control of Homeostatic Mechanisms
- Governed primarily by negative feedback loops.
Lung Gas Exchange
- Driven by partial pressure gradients of O2 and CO2.
Kidney Functions
- Regulate pH, water content, and electrolyte balance.
Heat Loss Mechanisms
- Increased external temperature causes blood vessels to dilate, promoting heat loss through radiation and enhanced sweat gland activity for evaporative cooling.
Dehydration
- Can occur from excessive loss of water through sweating, vomiting, or diarrhea.
Thirst Mechanism
- Loss of water leads to increased osmotic pressure, activating osmoreceptors in the brain and stimulating thirst via the hypothalamus.
Correction of Decreased Blood Volume/Osmotic Pressure
- Addressed through drinking and reduced urine volume, regulated by antidiuretic hormone (ADH) affecting kidney water absorption.
Water Gain
- Achieved through drinking or IV fluids, leading to a decrease in ECF osmotic pressure and dilution of urine as ADH secretion halts.
2,3 DPG
- Byproduct of red blood cell anaerobic glycolysis that binds to hemoglobin to enhance oxygen release to tissues.
Shifts in Hemoglobin Dissociation Curve
- Right Shift: Caused by 2,3 DPG, CO2, and H+, allowing more O2 delivery to tissues.
- Left Shift: Caused by decreased PCO2 and lower 2,3 DPG and H+, resulting in less O2 availability to tissues.
Normal Body pH
- Maintained at approximately 7.4.
Acid-Base Disorders
- Acidosis: Increased H+ concentration, indicating a more acidic environment.
- Alkalosis: Decreased H+ concentration or increased pH, indicating alkalinity.
Buffer Systems
- Bicarbonate/carbonic acid buffer system functions alongside protein and phosphate buffering.
Respiratory Control
- Lungs manage CO2 levels, affecting overall pH balance.
Renal Control
- Kidneys regulate H+ and bicarbonate (HCO3-) levels, influencing acid-base status.
Disturbances in pH and HCO3-
- May lead to respiratory acidosis or alkalosis depending on the underlying conditions.
Respiratory Acidosis
- Results from hypercapnia due to hypoventilation, leading to decreased pH; compensatory hyperventilation helps normalize CO2 levels.
Hypercapnia
- Defined as excessive CO2 in the bloodstream.
Metabolic Acidosis
- Results from kidney accumulation of lactic acid or ketone bodies, impacting acid-base balance.
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Explore the key concepts of homeostasis and its regulatory mechanisms through this flashcard quiz. Understand how cells maintain internal stability against external changes. Ideal for students studying biology or related fields.
