Chapter 45 Flashcards
What does the endocrine system do?
It releases signaling molecules (hormones) into the bloodstream ; a hormone may affect one or more regions throughout the body
What are hormones?
They are the body’s long distance regulators that reach specific target cells ; they are kind of slow acting, but they have long last effects ; they coordinate responses to stress, dehydration, and low blood sugar
What is the endocrine system well adapted for?
It is well adapted for coordinating gradual changes that affect the entire body (low concentrations of hormones can have long-lasting effects)
What is the nervous system well adapted for?
It is well adapted for directing immediate and rapid responses to the environment, especially in controlling fast locomotion and behavior
What does the hypothalamus help do?
It helps integrate communication of both the nervous and endocrine systems
What are the two criteria for communication between animal cells through secreted signals?
The type of secreting cell ; the route taken by the signal in reaching its target
What are the five different types of intercellular communication?
Endocrine signaling, Paracrine signaling, autocrine signaling, synaptic signaling, and neuroendocrine signaling
What does endocrine signaling do?
It maintains homeostasis, mediates responses to stimuli, regulated growth and development, and triggers changes underlying sexual maturity and reproduction
How does endocrine signaling work?
Hormones secreted into extracellular fluids by endocrine cells reach their target cells via the bloodstream
What are local regulators?
They are molecules that act over short distances, reaching target cells solely by diffusion
What does Paracrine and autocrine signaling do?
They play roles in the processes like blood pressure regulation, nervous system function, and reproduction
Difference between paracrine and autocrine signaling?
In paracrine signaling the target cells lie near the secreting cells, and in autocrine signaling the target cells is also secreting cell
What are PGs and what do they do?
Prostaglandin ; They regulate nearby cells in various ways, depending on the tissue ; They are secreted by the placenta to induce uterine contractions during childbirth ; They also promote fever and inflammation and intensify the sensation of pain (body’s defense)
What do cytokines do?
They are local regulators that enable immune cell communication
What do growth factors do?
They are local regulators that promote cell growth, division, and development
What does NO (nitric oxide) function as?
It functions as both a local regulator and a neurotransmitter
How does synaptic signaling work?
At synapses, secreted molecules called neurotransmitters diffuse short distances and bind to receptors on target cells
How does neuroendocrine signaling work?
Specialized neurosecretory cells secrete neurohormones that diffuse from the nerve endings into the bloodstream
What are pheromones and what can they do?
They are chemicals that are released into the environment ; They serve many functions like marking trails leading to food, defining territories, warning of predators, and attracting potential mates
What are the three classes of hormones?
Polypeptides (water-soluble), steroids (lipid-soluble), and amines (most are water-soluble)
How do water-soluble hormones travel?
They are secreted by exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors
How do lipid-soluble hormones travel?
They diffuse across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells
How does epinephrine work?
It bids to receptors on the plasma membrane of liver cell which triggers the release of messenger molecules that activate enzymes and result in the release of glucose into the bloodstream
What does the hypothalamus do?
It coordinates endocrine signals, and with the help of the pituitary gland links the nervous and endocrine signals
