Chapter 45 Flashcards
What are the chemical classes of hormones?
- Polypeptides
- Amines derived from amino acids
- Steroid hormones
Lipid-soluble hormones
Pass through cell membranes
Water-soluble hormones
Cannot pass through cell membrane
Insulin is what type of hormone? Therefore…
Water-soluble, so its receptor is on cell membrane
Steroids are what type of hormone?
Lipid-soluble
What is the pathway of a water-soluble hormone?
- Secretion from cell (exocytosis)
- Free travel through bloodstream
- Bind to cell-surface receptor
What is the pathway of a lipid-soluble hormone?
- Diffuse across membrane
- Travel through bloodstream bound to transport proteins
- Diffuse through membrane of target cell
The hormone epinephrine is a _____-soluble hormone and is secreted by ________
- water-soluble
- adrenal glands
What are the 2 responses to epinephrine?
- Inhibition of glycogen synthesis
- Promotion of glycogen breakdown
What is the typical response to a lipid-soluble hormone
Change in gene expression
How can the same hormone have different effects on target cells?
Target cells have
- Different receptors
- Different pathway
- Different proteins for carrying out response
What are animal hormones?
Chemical signals secreted into circulatory system that communicate regulatory messages within body
Endocrine system vs nervous system
- Endocrine: secretes hormones that communicate longer-acting and slower responses (reproduction, development, growth)
- Nervous: secretes high-speed hormones along specialized cells called neurons to regulate other cells
Function of hormones
Mediate responses to environmental stimuli and regulate growth, development, reproduction (endocrine)
Function of local regulators
Chemical signals that travel short distances by diffusion and regulate blood pressure, help nervous system function, and reproduction (endocrine)
Types of local regulators?
- Paracrine signals act on cells nearby
- Autocrine signals act on own cell
Function of neurons
Contact target cells at synapses (nervous)
What happens as synapses?
Neurons secrete neurotransmitters that diffuse a short distance to bind to receptors on target cell
Function of neurohormones
Originating from neurons in the brain, these hormones diffuse through bloodstream to target cells (nervous)
Function of pheromones
Released from body through exocrine glands and used to communicate with other individuals
Paracrine vs autocrine
Both local regulators secreted by endocrine system
- Paracrine acts on nearby cells
- Autocrine acts on own cell
How does nitric oxide help erectile disfunction?
-NO is neurotransmitter/local regulator from nervous system
Activates enzyme that relaxes nearby muscle cells, increasing blood flow in tissues
How do prostaglandins contribute to menstrual cramps?
-Local regulators
Stimulate muscle cells of uterine walls to trigger muscle contractions
Function of endocrine signals
Secreted into extracellular fluids and travel via bloodstream (endocrine)
Endocrine vs exocrine glands
- Endocrine glands are ductless and secrete hormones into surrounding fluid
- Exocrine glands have ducts and carry substances to outside the body (pheromones use this)
What happens in a negative feedback loop of a pathway?
Inhibits response by reducing initial stimulus
The pancreas has what two cells used for homeostasis of blood glucose level? What does each cell release?
- Beta cells release insulin
- Alpha cells release glucagon
What situation would cause insulin to be released?
If blood glucose level rises
What situation would cause glucagon to be released?
If blood glucose level falls
How does insulin reduce blood glucose levels?
- Promoting uptake of glucose into glycogen
- Slowing glycogen breakdown in liver
- Promoting fat storage
How does glucagon raise blood glucose levels?
- Stimulating conversion of glycogen to glucose in liver
- Stimulating breakdown of fat/protein into glucose
Difference between type I and type II diabetes
- Type I: immune system destroys pancreatic beta cells (which secrete insulin)
- Type II: insulin deficiency or reduced response of target cells due to change in insulin receptors
