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What is the term for the study of how organisms function and how function is controlled and maintained in order to keep us alive and healthy?
What is the term for the study of how organisms function and how function is controlled and maintained in order to keep us alive and healthy?
What is the term for a measure of a bodily condition or bodily function?
What is the term for a measure of a bodily condition or bodily function?
What is the normal 'basal' or 'at rest' value for a physiological variable?
What is the normal 'basal' or 'at rest' value for a physiological variable?
What is the primary mechanism for maintaining physiological variables within a predictable range?
What is the primary mechanism for maintaining physiological variables within a predictable range?
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What is the consequence of a physiological variable straying too far out of its normal range for too long?
What is the consequence of a physiological variable straying too far out of its normal range for too long?
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What is the dynamic maintenance of physiological variables within a predictable range?
What is the dynamic maintenance of physiological variables within a predictable range?
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What is the primary focus of the field of physiology?
What is the primary focus of the field of physiology?
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What is the term for the condition of normal function in a living system?
What is the term for the condition of normal function in a living system?
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What is the term for the study of functions and mechanisms in a specific class of organisms?
What is the term for the study of functions and mechanisms in a specific class of organisms?
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What is the term for the study of functions and mechanisms in individual organs?
What is the term for the study of functions and mechanisms in individual organs?
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What is the term for the scientific study of the functions and mechanisms in a living system?
What is the term for the scientific study of the functions and mechanisms in a living system?
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What is the Greek term for 'nature, origin' that is used in the definition of physiology?
What is the Greek term for 'nature, origin' that is used in the definition of physiology?
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Which of the following physiological variables has a set-point that is lower during sleep?
Which of the following physiological variables has a set-point that is lower during sleep?
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What is the primary reason for the increased blood pressure in response to excessive salt in the diet?
What is the primary reason for the increased blood pressure in response to excessive salt in the diet?
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Which of the following is an example of a paracrine negative feedback loop?
Which of the following is an example of a paracrine negative feedback loop?
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What is the primary function of the integrating centre in a negative feedback loop?
What is the primary function of the integrating centre in a negative feedback loop?
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Which of the following neuronal integrating centres is responsible for controlling body temperature?
Which of the following neuronal integrating centres is responsible for controlling body temperature?
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What is the result of the sympathetic and parasympathetic nervous systems having opposing actions on bodily functions?
What is the result of the sympathetic and parasympathetic nervous systems having opposing actions on bodily functions?
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What is the term for the ranking of physiological variables in terms of importance to immediate survival?
What is the term for the ranking of physiological variables in terms of importance to immediate survival?
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What is the primary function of the efferent pathway in a negative feedback loop?
What is the primary function of the efferent pathway in a negative feedback loop?
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Which of the following is an example of an endocrine negative feedback loop?
Which of the following is an example of an endocrine negative feedback loop?
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What is the result of a physiological variable drifting away from its set-point?
What is the result of a physiological variable drifting away from its set-point?
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What is the primary function of the hypothalamus in the context of temperature control?
What is the primary function of the hypothalamus in the context of temperature control?
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What is the direction of the nerve signals from the hypothalamus to the effectors in the context of temperature control?
What is the direction of the nerve signals from the hypothalamus to the effectors in the context of temperature control?
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Which of the following is an example of a negative feedback mechanism in the context of temperature control?
Which of the following is an example of a negative feedback mechanism in the context of temperature control?
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Which of the following organs is NOT an endocrine organ?
Which of the following organs is NOT an endocrine organ?
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What is the role of the integrating centre in the context of temperature control?
What is the role of the integrating centre in the context of temperature control?
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What is the primary function of the sensors in the context of temperature control?
What is the primary function of the sensors in the context of temperature control?
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Which of the following is an example of an endocrine gland?
Which of the following is an example of an endocrine gland?
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What is the role of the hypothalamus in the context of endocrine and paracrine feedback control?
What is the role of the hypothalamus in the context of endocrine and paracrine feedback control?
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What is the primary function of pancreatic b-cells in response to increased blood glucose concentration?
What is the primary function of pancreatic b-cells in response to increased blood glucose concentration?
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Which type of hormone receptor is typically associated with a rapid, often transient response?
Which type of hormone receptor is typically associated with a rapid, often transient response?
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What is the primary characteristic of paracrine homeostatic control?
What is the primary characteristic of paracrine homeostatic control?
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What is the effect of increased metabolic demand during exercise on arterioles in skeletal muscle?
What is the effect of increased metabolic demand during exercise on arterioles in skeletal muscle?
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What is the primary function of feed-forward control mechanisms?
What is the primary function of feed-forward control mechanisms?
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Which type of feedback loop is characteristic of parturition (contraction of the uterus to expel the fetus)?
Which type of feedback loop is characteristic of parturition (contraction of the uterus to expel the fetus)?
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What is the result of a physiological variable straying too far out of its normal range for too long?
What is the result of a physiological variable straying too far out of its normal range for too long?
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What is the role of the endothelium in paracrine homeostatic control of skeletal muscle blood flow?
What is the role of the endothelium in paracrine homeostatic control of skeletal muscle blood flow?
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What is the effect of increased estrogen and progesterone levels during pregnancy on the uterus?
What is the effect of increased estrogen and progesterone levels during pregnancy on the uterus?
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What is the primary mechanism of action of glycoprotein hormones and catecholamines?
What is the primary mechanism of action of glycoprotein hormones and catecholamines?
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Study Notes
Homeostasis and Physiological Control
- Homeostasis is the dynamic maintenance of physiological variables within a predictable range to maintain health and well-being.
- Physiological variables are measures of bodily conditions or functions, such as core temperature, blood glucose concentration, and blood pressure.
- Set-point is the normal or basal value for a physiological variable, which can be temporarily overridden or adjusted to suit changing circumstances.
Importance of Homeostasis
- Homeostasis is necessary for short-term immediate survival and medium-long term health and well-being.
- If a physiological variable strays too far from its normal range for too long, it can lead to illness, disease, or death.
Negative Feedback Mechanisms
- Negative feedback is the most common mechanism for maintaining physiological variables.
- It involves a sensor that detects changes in the variable, an integrating center that compares the variable to its set-point, and an effector that produces a response to bring the variable back to its set-point.
- Key features of negative feedback loops include:
- Sensors detect changes in the variable
- Integrating centers compare the variable to its set-point
- Effectors produce responses to bring the variable back to its set-point
- Afferent pathways carry signals from sensors to integrating centers
- Efferent pathways carry signals from integrating centers to effectors
Types of Negative Feedback
- Neuronal feedback control: involves the nervous system, including the sympathetic and parasympathetic nervous systems.
- Endocrine feedback control: involves hormones and the endocrine system.
- Paracrine feedback control: involves local, diffusible substances that act on nearby cells.
Examples of Negative Feedback
- Blood glucose concentration: rises after a meal, then is brought back towards its set-point through homeostatic control.
- Blood pressure: is maintained at a set-point through negative feedback mechanisms.
- Body temperature: is maintained at a set-point through negative feedback mechanisms, including shivering and sweating.
Hierarchy of Importance of Physiological Variables
- Physiological variables are inter-dependent, and some are more important to immediate survival than others.
- For example, osmolality (salt/water balance) is more important to immediate survival than blood pressure.
Feed-Forward and Positive Feedback
- Feed-forward control mechanisms: anticipate a change and bring about a response before the change can be detected by negative feedback sensors.
- Positive feedback control mechanisms: amplify a change in a variable, rather than normalizing it. Examples include anticipation of physical exertion and parturition (contraction of the uterus to expel the fetus).
Physiological Control Systems
- The autonomic nervous system plays a role in physiological control, including the sympathetic and parasympathetic nervous systems.
- The endocrine system plays a role in physiological control, including hormones and endocrine glands.
- Paracrine homeostatic signaling plays a role in physiological control, including local, diffusible substances that act on nearby cells.
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Description
Learn about the principles of physiological homeostasis, negative feedback, and the roles of the autonomic nervous system and endocrine systems in physiological control.
