Questions and Answers
What is homeostasis?
Homeostasis is a constant, maintenance or static condition in the internal environment.
The interstitial fluid is found in the spaces around ___ and helps bring ___, nutrients & O2 needed by the cells.
cells
What does the cardiovascular system do in relation to homeostasis?
It distributes O2 and nutrients to all parts of the body and carries CO2 and wastes from cells to the lungs and kidneys.
The renal system only excretes CO2 from the body.
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Which type of control in homeostasis works rapidly by sending messages in the form of nerve impulses?
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What component of the homeostatic control system serves as a sensor for changes in the environment?
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What are the two types of feedback control systems mentioned?
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What is the primary function of red blood cells?
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An average 70kg adult man has about ___ L of total body fluids.
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Plasma makes up more than half of blood volume.
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What role does the hypothalamus play in the endocrine system?
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What hormone promotes the retention of water by the kidneys?
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Study Notes
Homeostasis
- Homeostasis maintains a constant internal environment within the body.
- Internal environment (IE) is composed of extracellular fluid, including blood and interstitial fluid.
- Interstitial fluid surrounds cells, delivering ions, nutrients, and oxygen, while allowing waste excretion.
Role of Body Systems in Homeostasis
- Multiple body systems function together to regulate internal environment composition, volume, osmolarity, temperature, pressure, and pH.
- Respiratory System: Exchanges oxygen and carbon dioxide with the external environment.
- Cardiovascular System: Transports oxygen and nutrients and removes carbon dioxide and metabolic wastes.
- Digestive System: Breaks down food, absorbs nutrients, and excretes waste.
- Renal and Liver Systems: Regulate waste excretion and maintain water and mineral balance.
- Nervous and Endocrine Systems: Coordinate and control the activities of all body systems.
Homeostasis Control Mechanisms
- Neural Control: Uses nerve impulses for rapid correction of internal changes.
- Endocrine Control: Employs hormones for slower, prolonged responses.
- Neuroendocrine Control: Combines nerve impulses and hormonal responses.
- Enzymatic Control: Regulates internal chemical reactions.
- Humoral Control: Adjusts hormone levels in response to changes in the extracellular fluid.
Feedback Mechanisms
- Homeostatic systems monitor and evaluate internal conditions through a feedback loop.
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Components of Feedback Mechanism:
- Stimulus: Any change in the environment.
- Receptor: Senses the change and sends signals for compensation.
- Control Center: Evaluates input and generates output to adjust deviations from set points.
- Effector: Executes the response to restore balance.
Types of Feedback Systems
- Negative Feedback: Response counteracts the stimulus, promoting stability.
- Positive Feedback: Response enhances the stimulus, leading to greater change.
Baroreceptor Feedback Mechanism
- In response to increased blood pressure, baroreceptors activate compensatory mechanisms that decrease pressure through cardiovascular adjustments.
Body Fluid Composition and Distribution
- Total body fluids account for about 60% of body weight; approximately 40 to 42 liters in an average adult male.
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Fluid Compartments:
- Intracellular Fluid (ICF): 25L, found inside cells.
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Extracellular Fluid (ECF): 15L, composed of:
- Intravascular (plasma) 3L
- Extravascular (interstitial and transcellular fluids) 12L
Physiological Variations in Body Fluids
- Total body water decreases with age and varies between genders and body composition.
- Infants have higher total body fluid percentages compared to adults, contributing to quicker dehydration rates.
Body Fluid Functions
- Serve as media for chemical reactions, gas exchange, diffusion, filtration, temperature regulation, and protection.
Blood Composition
- Blood consists of cells (erythrocytes, leukocytes, platelets) suspended in plasma.
- Average adult blood volume ranges from 4 to 6 liters, with plasma comprising 52% to 62% of total volume.
Blood Characteristics
- Arterial blood is bright red due to high oxygen content; venous blood is darker due to lower oxygen levels.
- Blood pH ranges from 7.35 to 7.45.
Plasma Functions
- Plasma, about 91% water, transports nutrients, wastes, hormones, and gases.
Hematocrit and Erythrocytes
- Hematocrit measures the volume percentage of red blood cells; normal values are 42.5% for women and 47.5% for men.
- Anemia results from low erythrocyte counts or abnormal hemoglobin.
Endocrine and Nervous System Interaction
- The endocrine system is slower but produces longer-lasting effects compared to the rapid and short-lived signals of the nervous system.
- The hypothalamus integrates both systems, secreting regulatory hormones that affect the pituitary gland.
Pituitary Gland Hormones
- Anterior pituitary secretes 7 hormones including Growth Hormone, Prolactin, and Gonadotropins.
- Posterior pituitary releases Oxytocin and Antidiuretic Hormone (ADH), regulating uterine contractions and water retention respectively.
Abnormal Hormone Secretion
- Disorders like dwarfism and gigantism are linked to growth hormone irregularities.
- Acromegaly is characterized by the enlargement of soft tissues due to excess growth hormone in adults.
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Description
Test your knowledge on homeostasis and the internal environment. This quiz covers key concepts such as the roles of organ systems, interstitial fluid, and the importance of maintaining a stable internal environment for cellular function. See how well you understand these essential biological principles.
