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Questions and Answers
What is a necessary characteristic of ligands that bind to nuclear/intracellular receptors?
What is a necessary characteristic of ligands that bind to nuclear/intracellular receptors?
Which type of receptor is the largest group in humans?
Which type of receptor is the largest group in humans?
What is the role of agonists in receptor signalling?
What is the role of agonists in receptor signalling?
Which of the following is NOT a type of G-Protein Coupled Receptor (GPCR)?
Which of the following is NOT a type of G-Protein Coupled Receptor (GPCR)?
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What is the function of ion channels in biological signalling?
What is the function of ion channels in biological signalling?
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What type of neurotransmitters are involved in G-Protein Coupled Receptor (GPCR) signalling?
What type of neurotransmitters are involved in G-Protein Coupled Receptor (GPCR) signalling?
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What is the primary function of the control centre in a homeostatic system?
What is the primary function of the control centre in a homeostatic system?
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What type of hormone is involved in local control of blood flow?
What type of hormone is involved in local control of blood flow?
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What is the consequence of a failure of homeostasis?
What is the consequence of a failure of homeostasis?
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What is the function of the sensor in a homeostatic system?
What is the function of the sensor in a homeostatic system?
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What is the type of signalling molecule involved in the transmission of action potentials?
What is the type of signalling molecule involved in the transmission of action potentials?
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What is the level of homeostasis that involves the control of [Ca2+]?
What is the level of homeostasis that involves the control of [Ca2+]?
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Which of the following endogenous signaling molecules is NOT a local hormone?
Which of the following endogenous signaling molecules is NOT a local hormone?
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Which of the following types of signaling molecules is characterized by being small and charged, and having receptors in the plasma membrane?
Which of the following types of signaling molecules is characterized by being small and charged, and having receptors in the plasma membrane?
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Which of the following drugs can be used to mimic the action of a hormone?
Which of the following drugs can be used to mimic the action of a hormone?
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Which of the following receptors is NOT a type of receptor involved in biological signaling?
Which of the following receptors is NOT a type of receptor involved in biological signaling?
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Which of the following is a target for drugs that involves a specific shape?
Which of the following is a target for drugs that involves a specific shape?
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Which of the following neurotransmitters is an exception to the classification of neurotransmitters?
Which of the following neurotransmitters is an exception to the classification of neurotransmitters?
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Which of the following types of receptors is characterized by being activated due to phosphorylation?
Which of the following types of receptors is characterized by being activated due to phosphorylation?
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Which of the following is a characteristic of ion channels (ligand gated) receptors?
Which of the following is a characteristic of ion channels (ligand gated) receptors?
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What is the primary response to infection in terms of thermoregulation?
What is the primary response to infection in terms of thermoregulation?
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What is the effect of antipyretic drugs on the body's thermoregulation?
What is the effect of antipyretic drugs on the body's thermoregulation?
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What is the definition of a partial agonist ligand?
What is the definition of a partial agonist ligand?
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What is the result of a core temperature above 38°C?
What is the result of a core temperature above 38°C?
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What is the effect of prostaglandin E2 on the body's thermoregulation?
What is the effect of prostaglandin E2 on the body's thermoregulation?
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What is the definition of a ligand?
What is the definition of a ligand?
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What is the result of a core temperature below 36.7°C?
What is the result of a core temperature below 36.7°C?
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What is the definition of positive feedback?
What is the definition of positive feedback?
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Study Notes
Homeostasis
- Maintenance of a constant internal environment, but not a steady state, rather a dynamic equilibrium
- 3 levels of homeostasis: intracellular, organ, and whole body
- Characteristics of control systems: communication, control centre, receptor, and effector
Communication
- Nervous system: action potential
- Endocrine system: hormones
- Paracrine system: local hormones
- Autocrine system: many agents
Control Centre
- Determines set point, input, and response
Receptor
- Receives information from sensory receptors
Effector
- Responds to signals from the control centre
Failure of Homeostasis
- Can lead to disease
Thermoregulation
- Normal core temperature: 37.2°C
- If core temperature is above 37.2°C: sweating, vasodilation
- If core temperature is below 36.7°C: shivering, vasoconstriction
Positive Feedback
- Stimulus produces a response that increases its effect
- System goes out of control, leading to a catastrophic change
Biological Rhythms
- Pyrexia (fever): normal response to infection, core temperature raised to a higher set point
Hyperthermia
- Core temperature above 38°C
- Malignant hyperthermia: rare reaction to some anaesthetic agents
- Artificially induced hyperthermia: used in the treatment of some cancers
Hypothermia
- Core temperature below 36.7°C
- Decreased ADH production, leading to increased osmolality
Biological Signalling Molecules
Ligand and Receptor
- Ligand: small molecule that binds specifically to a receptor site
- Receptor: a molecule that binds a ligand and produces a response
Agonist, Antagonist, and Partial Agonist
- Agonist: binds to a receptor and activates it
- Antagonist: binds to a receptor, but does not activate it
- Partial agonist: binds to a receptor, but does not produce a maximum response
Endogenous Biological Signalling
- Includes endocrine hormones, paracrine hormones, autocrine agents, and neurotransmitters
Exogenous Biological Signalling
- Includes drugs, some of which mimic hormones
Types of Signalling Molecules
- Hydrophilic: amines, peptides, and proteins
- Lipophilic: steroids
Neurotransmitters
- Classified into amino acids, monoamines, peptides, and exception: acetylcholine
Targets for Drugs
- Receptors
- Ion channels
- Transporters
- Enzymes
Types of Receptors
- Kinase linked receptors (K)
- Ion channels (ligand gated) (I)
- Nuclear/intracellular receptors (N)
- G-protein coupled receptors (G)
Tyrosine Kinase Receptors
- Activated due to phosphorylation
Ion Channels (Ligand Gated)
- Open ion channels for duration of binding, allowing selective flow of ion current down its electrochemical gradient
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Description
Quiz on homeostasis, its definition, and the 3 levels of homeostasis, including intracellular, organ, and whole body control. Learn about biological signalling molecules and their role in maintaining a constant internal environment.
