Exam 2 Flashcards
What is hormone-receptor interaction?
Hormones interact with specific receptors on target cells, leading to a biological response. This interaction is crucial for the hormone’s effects and is often compared to a lock and key mechanism.
What factors influence hormone concentration in the blood?
Factors include the rate of hormone secretion, rate of metabolism or excretion, quantity of transport proteins, and changes in plasma volume.
How do steroid hormones function?
Steroid hormones enter cells, bind to intracellular receptors, and directly influence gene expression by interacting with DNA, leading to protein synthesis.
What is the second messenger hypothesis?
Non-steroid hormones bind to surface receptors, activating a second messenger inside the cell (e.g., cAMP), which then triggers the cellular response.
What is an amplifying cascade?
Hormone binding triggers a chain of events inside the cell, where each step amplifies the initial signal, leading to a large cellular response from a small hormonal stimulus.
What is the G-protein/adenylate cyclase/cAMP system?
This system involves hormone binding to a receptor, activating G-proteins, which then activate adenylate cyclase. Adenylate cyclase converts ATP to cAMP, which acts as a second messenger to activate protein kinase A.
What is the calcium and calmodulin second messenger system?
This system allows calcium ions to bind to calmodulin, which activates various intracellular processes, particularly during muscle contraction.
What are hypothalamus-releasing factors?
These factors control hormone secretion from the anterior pituitary gland by releasing hormones into the bloodstream, which then act on the pituitary.
How does the hypothalamus control the posterior pituitary?
The hypothalamus directly controls the secretion of hormones (like oxytocin and vasopressin) from the posterior pituitary via nerve signals.
What are the sites, stimuli, and actions of key hormones?
Epinephrine & norepinephrine increase heart rate and blood glucose; glucagon increases glucose release from the liver; insulin promotes glucose uptake; cortisol mobilizes energy stores; aldosterone regulates blood pressure; thyroxine controls metabolic rate; growth hormone promotes growth; estrogen & testosterone regulate reproductive function.
What is the role of testosterone and growth hormone in muscle growth?
Both promote muscle growth; however, excessive use of anabolic steroids (testosterone) can have severe side effects, including heart issues and hormonal imbalances.
How do catecholamines affect glycogen mobilization?
Plasma catecholamines (epinephrine, norepinephrine) activate the cAMP system to mobilize glycogen, while intracellular calcium-calmodulin influences glycogenolysis during muscle contraction.
What are the mechanisms of blood glucose homeostasis?
They include mobilization of liver glycogen, mobilization of free fatty acids from adipose tissue, gluconeogenesis in the liver, and blocking glucose entry into cells.
What changes occur in hormones during exercise?
Insulin decreases while glucagon, cortisol, growth hormone, epinephrine, and norepinephrine increase, helping maintain blood glucose levels.
What are fast-acting vs. slow-acting hormones?
Fast-acting hormones (e.g., epinephrine, norepinephrine, insulin, glucagon) rapidly adjust glucose levels, while slow-acting hormones (e.g., cortisol, growth hormone) help sustain energy balance over longer periods.
How do hormone levels affect free fatty acid mobilization?
Decreased insulin and increased catecholamines enhance the mobilization of free fatty acids from adipose tissue for energy.
What is the organization of the nervous system?
The nervous system is divided into the central nervous system (CNS: brain and spinal cord) and peripheral nervous system (PNS: sensory and motor neurons).
What is the structure and function of a nerve?
A nerve is composed of bundles of neurons that transmit signals, consisting of a cell body, dendrites (which receive signals), and an axon (which sends signals).
What is the withdrawal reflex pathway?
It involves sensory neurons detecting pain, sending signals to the spinal cord, where interneurons activate motor neurons to withdraw the body part from danger.
What are depolarization, action potential, and repolarization?
Depolarization is when the cell membrane becomes less negative; action potential is a rapid electrical signal that travels along the axon; repolarization is the return to resting state after the action potential.
What are position receptors?
Proprioceptors (like muscle spindles and Golgi tendon organs) detect body position and movement, helping to control movement and maintain balance.
What is the role of the vestibular apparatus?
Located in the inner ear, it helps maintain balance and equilibrium by detecting changes in head position and motion.
What brain centers are involved in voluntary movement?
The motor cortex, basal ganglia, and cerebellum coordinate and initiate movement.
What is the autonomic nervous system?
It controls involuntary bodily functions (e.g., heart rate, digestion) and is divided into the sympathetic (fight-or-flight) and parasympathetic (rest-and-digest) systems.
