AP Biology Review Systems 1. Homeostasis: The Endocrine

The Endocrine System

Local vs Long Distance Signaling Which type is the endocrine system? Which type is the immune system?

Local vs Long Distance Signaling Local regulators – affect only nearby cells Paracrine signaling – cells release chemicals to nearby cells Neurotransmitters released from neurons Hormones – affect distant cells Endocrine signaling – chemicals released into blood and carried throughout body

Local vs Long Distance Signaling Cells can also pass messages directly - Gap junctions - Plasmodesmata - “ID tag” recognition

Signal Transduction Pathway What is happening in each step?

Signal Transduction Pathway The steps involved in passing along a message to cause a cellular effect Signal – something will “land” on the cell surface or go through surface Transduction – passing/converting the message Pathway – the steps along the way

Signal Transduction Pathway These pathways are similar among all types of cells, even among very different organisms (including bacteria, yeast, plants, and animals) What does this tell us about these pathways? They evolved early Why would they have been so important that they evolved so early?

One chemical signal, different effects How does the signal know which cell to “talk” to? Why might there be different effects with different cells?

Specificity of Signals The type of proteins a cell has determine which signals it responds to and how it responds

Cell Signal Receptors What determines whether a signal will bind to a membrane protein or an intracellular protein? Membrane signals – cannot get through Large – polar – ionic Ex: protein hormones Intracellular signals – can get through Hydrophobic – small Ex: lipid hormones (steroids)

Types of Chemical Signals: Hormones Most chemical signals bind to plasma membrane proteins Signals tend to be __?__molecules Rate is __?__ Called a “__?__-messenger system” Transduction Reception- transduction-response/effect Protein – fast second 12

Types of Chemical Signals: Hormones Most chemical signals bind to plasma membrane proteins Signals tend to be protein molecules Rate is faster Called a “second-messenger system” Transduction Reception- transduction-response/effect Protein – fast second 13

Cell Signaling: Protein Hormones Cytoplasm Response Response may regulate activities Ex: epinephrine signals breakdown of glycogen to glucose Notice the signal amplification!

Types of Chemical Signals: Hormones Steroid hormones work differently Why? Rate ends up being ___?___ Effect is production of ____?_____ Slower proteins 15

Types of Chemical Signals: Hormones Steroid hormones work differently Why? – can enter cell easily Rate ends up being slower Effect is production of proteins Slower proteins 16

Cell Signaling: Lipid Hormones Nuclear Response Signal may trigger products to be made Ex: growth factor signals DNA to make certain proteins needed for growth

Negative Feedback What is the stimulus? What is the response?

Negative Feedback Stimulus & Response in opposite directions Ex: calcium levels too high in blood… calcitonin causes uptake of calcium from blood

The stimulus and response go in the SAME direction. Positive Feedback How will stimulus and response relate for this type of feedback? Do you think this is more or less common than negative feedback? Why? The stimulus and response go in the SAME direction. If negative fdbk has stimulus-response in opposite directions, what will positive be?

Positive Feedback Pressure on uterus  oxytocin released causing more pressure… When does the reaction end?

Vertebrate Endocrine System

Endocrine Glands/Organs Pituitary Growth hormone Stimulates growth Oxytocin Childbirth; lactation attachment Tropic hormones Travel to other glands (ex: TSH, ACTH, FSH) ADH (Anti-Diuretic Hormone) Retain water

Endocrine Glands/Organs Thyroid Thyroxine Regulates metabolism Calcitonin Uptake of Ca in blood

Endocrine Glands/Organs Parathyroid PTH Regulates calcium levels (adds Ca to blood)

Endocrine Glands/Organs Adrenal Epinephrine Fight-or-flight response Release of glucose for more ATP

Endocrine Glands/Organs Pancreas (Pancreatic islets) Insulin Removes glucose from blood Glucagon Release glucose from glycogen (add to blood)

Endocrine Glands/Organs Testes Testosterone Stimulated sperm production Maintains male sex characteristics