Ch 45 pt 2 Flashcards
What are 2 ways one hormone can have a different effect on target cells?
1) Different receptors for the hormone
2) Different Signal transduction pathways
Ex. Epinephrine has multiple effects that form the fight or flight response
What makes up Endocrine glands?
Endocrine cells grouped in ductless organs
Ex. Thyroid, parathyroid, testes, ovaries
What is the composition of Exocrine Glands?
Have ducts to carry secreted substances onto body surfaces or into body cavities
endocrine pathway
1) Released from an endocrine cell
2) Travel through the bloodstream
3) Interact with specific receptors within a target cell
4) Causes a physiological response
What stimulates secretin to get secreted?
Release of acidic content from stomach into duodenum stimulates endocrine cells
What does secretin cause
Target cells in pancreas to raise the pH in the duodenum (bicarbonate)
Simple neuroendocrine pathway
1) Stimulus is received by a sensory neuron
2) stimulates a neurosecretory cell
3) Neurosecretory cell secretes a neurohormone
4) neurohormone enters the bloodstream and travels to target cells
Example of neuroendocrine pathway with oxytocin and milk secretion
1) Suckling of infant stimulates signals in the nervous system that reach the hypothalamus
2) Nerve Impulse from hypothalamus triggers release of oxytocin from the posterior pituitary
3) Causes mammary glands to secrete milk
Negative feedback
Inhibits a response by reducing the initial stimulus
Positive feedback
Reinforces a stimulus to produce an even greater response
Metamorphosis Process
1) Endocrine Pathway that controls the molting of larva originates in the larval brain, where neurosecretory cell produce PTTH
2) PTTH in the prothoracic gland releases ecdysteroid
3) Bursts of ecdysteroid trigger each successive molt as well as metamorphosis
4) Metamorphosis is not triggered until the level of another hormone, JH (Juvenile hormone), drops
What controls endocrine signaling in vertebrates?
Hypothalamus
What is the hypothalamus’s role?
Receives information from nerves throughout the body and initiates appropriate neuroendocrine signals
Where is the pituitary gland located?
Base of hypothalamus composed of posterior pituitary and anterior pituitary
What is the function of the Posterior pituitary?
Stores and secretes hormones that are made in the hypothalamus
