What is the main function of the endocrine system? _______________________ ___________ _________________ ____________________ _____________ BI 203 Human Anatomy & Physiology II

Nervous System How did the nervous system regulate other tissues? What was the medium for transmitting the control signal? Intercellular communication via the Nervous system can be likened to using the ______________________… The message goes from point of origin ____________ __________ to target tissue. Pulses (__________) regulate response. Any other system(s) that regulate other tissues? BI 203 Human Anatomy & Physiology II

The Endocrine system on the other hand is more like a ______ _______________… The message is sent everywhere and anybody (tissue) with a _________ can get the message. Concentration (___________) regulates response. Historically these two systems thought to be very independent. Now their interdependence is recognized BI 203 Human Anatomy & Physiology II

One aspect shared between 2 systems is use of intercellular chemical signals Type FunctionExample _______ _______________Prostaglandins _______ _______________histamine _______ _______________Thyroxine _______ _______________Oxytocin _______ _______________Acetylcholine _______ _______________sex pheromone BI 203 Human Anatomy & Physiology II

Where do hormones come from? ______________ The Endocrine system is comprised of what organs (glands)? Actually other organs are also capable of secreting hormones… Example the heart and the placenta BI 203 Human Anatomy & Physiology II

The activity of endocrine glands depends on Feedback mechanisms (see pg ). These ________ one or more ___________ and often consist of 3 components: 1) ___________ What are their function? 2) ___________________ What function? 3) __________ How about their function? How is hormone secretion controlled? BI 203 Human Anatomy & Physiology II

2 main situations… 1) Variable is maintained within “+” & “-” limits thresholds Set point Normal range Where are the receptors working? Where does the receiver respond? Where is the effector(s) active? BI 203 Human Anatomy & Physiology II

2 main situations… 2) The variable moves away from a “normal” value Set point Normal range thresholds Where are the receptors working? Where does the receiver respond? Where is the effector(s) active? BI 203 Human Anatomy & Physiology II

Comparing the status of the variable prior to and after the response... which one would you classify as positive feedback and which one is negative feedback??? Set point BI 203 Human Anatomy & Physiology II

An example from your body… BI 203 Human Anatomy & Physiology II

3 patterns of regulation… 1) _____________ _____________Substance (value of the monitored substance) initiates response and secretion of hormones. Ex. elevated ___________ results in increased ______ levels, which in turn reduce blood glucose levels. How is hormone secretion controlled? BI 203 Human Anatomy & Physiology II

How is hormone secretion controlled? 3 patterns of regulation… 1) Other substance acting on gland 2) __________________ Nervous stimulation results in the release or inhibition of hormones. Ex. ___________ released as a result of ___________ stimulation. BI 203 Human Anatomy & Physiology II

How is hormone secretion controlled? 3 patterns of regulation… 1) Other substance acting on gland 2) Neural control glands 3) ________________ ________________ The secretion of one hormone influences the secretion (+ or -) of another hormone. Ex. ______ causes release of ______ BI 203 Human Anatomy & Physiology II

How are hormones distributed? All hormones by definition travel via ________! They can travel either: 1) ________, in an unbound state 2) ________ with plasma proteins When hormones are bound to their protein (usually specific protein for each hormone) they exist in an _____________ of bound and free hormones. Response ? BI 203 Human Anatomy & Physiology II

Do hormones persist once formed? ____! They are “______________” at various rates depending on the nature of the hormone ( some hormones are removed from circulation within 2 min. of secretion ). Hormones are only active if _______ and are usually only acted upon if ______ Amount of time to remove 1/2 the initial dose is the ________. ________ based hormones have short 1/2 lives ________ (steroids) have long 1/2 lives BI 203 Human Anatomy & Physiology II

Take 5!!! How is the half-life of a hormone affected by a decrease in the concentration of the specific plasma protein to which that hormone binds? Discuss with your neighbor and predict an answer BI 203 Human Anatomy & Physiology II

How are hormones removed from circulation? 4 mechanisms used: 1) _____________ -- enzymatically broken down by liver, kidneys, lungs etc. 2) _____________ -- hormones that can’t be broken by themselves are combined with another compound and then they can be excreted. 3) _____________ -- some hormones can be excreted by the kidneys in urine and by the liver in bile. 4) _____________ -- some hormones are pumped back into cells that can re-use them later. BI 203 Human Anatomy & Physiology II

How do hormones work? Hormones bind to _______ __________ on target tissues. This binding results in ____ _________ of cell activities. Response can be _______ or _________… For example tissue fatigue or down-regulation BI 203 Human Anatomy & Physiology II

Target tissues can modify their response to a hormone by _______ and ______ regulation. Why do tissue responses vary over time? ______________ is the decrease in the number of hormone receptors. Caused by: 1) Decrease in ________ __________ 2) Hormone/receptor binding can lead to ___________ and ____________ Is this pattern effective for Long-term constant levels or short-term changing concentrations? BI 203 Human Anatomy & Physiology II

________ is an increase in hormone receptors Why do tissue responses vary over time? For example, _________________________ (FSH) causes and increase in the number of ___________________ (LH) receptors Is this pattern effective for Long-term constant levels or short-term changing concentrations? BI 203 Human Anatomy & Physiology II

Take 5!!! Estrogen is a hormone secreted by the ovary. It is secreted in > amounts after menstruation and a few days before ovulation. Among its many effects is causing up-regulation of receptors for another hormone secreted by the ovaries, progesterone. Progesterone is secreted after ovulation and a major effect is to cause the uterus to become ready for the embryo to attach. Predict the result if the ovary secretes too little estrogen? Discuss with your neighbor and predict an answer (see Predict #3, pg. 537) BI 203 Human Anatomy & Physiology II

How do hormones and their receptors vary? 2) ______________ _________ (made of cholesterol) ~ Testosterone Would you expect these to be hydrophylic or hydrophobic? BI 203 Human Anatomy & Physiology II Hormones fall into 2 basic categories: 1) ______________ ________________ (amino acid derivatives) ~ T4 ________________ ~ TRH ________________ ~ TSH ________________ ~ GH

How do hormones and their receptors vary? __________ also fall into 2 major categories: 1) ________________ Receptors embedded in the _____________ with a receptor site on the outside and an “effector” component inside. 2) ________________ Receptors are in the ________ or in the nucleus of the cell. Based on solubility properties which type of hormone is most likely paired with which type of receptor? BI 203 Human Anatomy & Physiology II

_______________ _____________ regulate/influence cells via 3 basic mechanisms: Less common with hormones, other chemical signals operate this way... 1)2)3)1)2)3) How do hormones and their receptors vary? BI 203 Human Anatomy & Physiology II

2) When hormone binds with receptor protein, then internal G protein (w/ subunits gamma, beta and alpha) _____________. ά _________ from others GTP replaces GDP (active state) then eventually the GTP is changed back to GDP and all reconnect. How do hormones and their receptors vary? BI 203 Human Anatomy & Physiology II

3) Some receptors have internal portions that function as _______, or they are closely associated with __________. Ex. ________ ________ hormone and receptor cause enzyme portion (GCase) to make cyclic GMP How do hormones and their receptors vary? BI 203 Human Anatomy & Physiology II

The other major class of hormone receptors is ________________________ These receptors are in the __________ or _________ of the host/target cell. Hormones that bind to these receptors must be able to pass through the ______________ (ex. Lipid based steroids). These hormones influence the ________ ____ of cellular products or _________ _________ How do hormones and their receptors vary? BI 203 Human Anatomy & Physiology II

How do hormones and their receptors vary? Ex. ____________ 1) 2) 3) 4) 5) 6) BI 203 Human Anatomy & Physiology II

How can effects? A small number of _________ bind with __________ activating several existing components, all of which activate more components individually, causing a large number of final product. This is the ________________. Is this more likely with proteinaceous or lipid-based hormones? BI 203 Human Anatomy & Physiology II

Hormone Receptor/ion channels Cell Response Receptor/G proteins Activates genes Receptor/intracellular enzymes BI 203 Human Anatomy & Physiology II