BIO 132 – Anatomy and Physiology II
1.1. Definition of Homeostasis and the Internal Environment:
a. Homeostasis involves the tendency to maintain the relative __________ of certain physiological variables even in the face of significant environmental change.
b. Examples of physiological variables include __________, __________, and __________.
c. Even though our bodies are surrounded by the external environment, our cells are surrounded by __________ fluid, which constitutes the __________.
d. The key to maintaining homeostasis is the presence of __________.
1.2. Negative Feedback:
a. A typical negative feedback control system involves the following components: __________, __________, and __________.
b. Consider the example of the negative feedback control of arterial blood pressure. Following hemorrhage, the fall in blood pressure is sensed by __________ which send this information to the controller located in the __________. In this example, the two effectors are the __________ and __________ which act to __________ and __________, both of which lead to a(n) __________ in blood pressure.
c. When a physiological variable is altered, the controller compares the value of the variable with the ________; and the difference between the two is known as the __________.
1.3. Positive Feedback:
a. In a positive feedback loop, the effectors cause changes in the controlled variable that tend to _________ the initial change unlike negative feedback systems where the change tends to _________ the initial change.
b. Consider the example of positive feedback mechanisms in the upstroke of the action potential. As Na+ permeability increases, the membrane potential becomes __________.
c. Positive feedback loops are generally found in processes which are __________.
1.4. Cellular Communication:
a. The structure that allows the direct passage of small molecular weight substances from one cell to the next is called a __________.
b. Of the two major communication systems in the body, the one which involves the propagation of action potentials is the __________ system. This system involves the release of molecules called __________ which must diffuse across a space called the __________. These molecules interact with special __________ located on the postsynaptic cell.
c. Neurotransmitter receptors can be found on ________, ________, _________, _________, and _________.
d. The nervous system operates on a time frame of __________.
e. The endocrine system involves the release of signal molecules called __________ into the __________.
f. Cells which have receptors that recognize a given hormone are called __________ for that hormone.
g. Compared to the nervous system the endocrine system operates on a time frame which is ________, taking anywhere from seconds to _________.
h. The example in which a neurotransmitter is released into the blood stream would constitute part of the ___________ system.
i. On the local level, a molecule that interacts with a receptor on itself or a member of the same cell type is called a(n) __________ agent, whereas when the target cell is a different cell type, this molecule is a(n) __________ agent.
1.5. Endocrine Glands:
a. Unlike _______ glands which secrete into blood, exocrine glands secrete into _______ which end up draining to a __________.
b. Of the total number of endocrine glands of the body, some examples of glands whose sole function is hormone production include ________, __________, ___________, _________, and _________.
c. Other organs or tissues secrete hormones in addition to some other main function. Some examples include ________, ________, ________, and _________.
d. The branch of medicine which handles disorders of the endocrine system is called __________, typically involving situations in which endocrine glands secrete inappropriately large amounts of hormone called _________ or too little hormone called __________.
1.6. Control of Hormone Release:
a. In general regulation of hormone release comes in three forms involving __________, __________, or _________.
b. One example of humerol stimuli has to do with the regulation of PTH. Here the humerol factor is __________.
c. _________ release from the adrenal medulla is controlled by sympathetic nerve stimulation.
d. The anterior pituitary gland is an example of where _________ regulate the secretion of anterior pituitary hormones.
e. An example in which hormone A stimulates the secretion of hormone B which in turn inhibits the release of hormone A is called __________.
1.7. Chemical Classes of Hormones:
a. Based on their solubility, hormones can be subdivided into ________ and _________.
b. Of the hormones that are able to diffuse across cell membranes, most are ________ molecules although _________ hormones can also pass cell membranes, presumably due to their _________ and iodines.
c. Of the water soluble hormones, the _________ are all synthesized from amino acids: catecholamines from the amino acid _________, histamine from _________ and serotonin and melatonin from ___________.
d. ________ are all derived from arachidonic acid, and _________ and _________ are examples of this class.
e. Based on their chemistry, hormones can be classified as ________, ___________, and ___________.
f. Lipid soluble hormones typically circulate bound to some __________, although the biologically active pool is the _________ fraction.
g. The concentration of a hormone within blood at any given time depends on the balance between the rate of ________ and the rate of _________. The time period in which the hormone concentration is reduced in half due to some inactivation mechanism is called the ____________.
1.8. Mechanisms of Hormone Action:
a. All hormones interact with a protein called a __________.
b. Receptors for steroid hormones are found within the __________ of a target cell. Upon receptor binding, the hormone-receptor complex binds to ________, altering the rate of production of certain _________.
c. cAMP mediated hormone processes involve a receptor found on the ________ of a cell. The enzyme that is responsible for production of cAMP from _________ is called _____________. Once formed, cAMP activates an enzyme called ________ which in turn carries out the chemical process of __________ of other cellular proteins. The cAMP is finally inactivated through the enzymatic action of a _____________.
d. Following receptor activation, the enzyme ________ cleaves PIP2 to form _________ and _________. DAG activates _________ whereas IP3 liberates Ca2+ from _________ which in turn can activate a regulatory molecule known as __________.
1.9. The Hypothalamus and Pituitary:
a. The pituitary gland can be subdivided into two divisions called the __________ and ___________, derived from different embryonic sources which are the __________ and __________, respectively.
b. Within the adenohypophysis, there are three portions called the __________, _________, and _________.
c. Within the neurohypophysis, there are also three portions called the _________, __________, and _________.
d. The two hormones released from the posterior pituitary are _________ and _________; both of which are synthesized by ___________ located in the __________ and the _________.
e. The axons that project from the hypothalamus into the posterior pituitary constitute the __________. Once in the pars nervosa, they are surrounded by cells called _________.
f. The pars nervosa is supplied by the __________ artery.
g. The hypophyeal-portal system consists of pituitary portal vessels which run between the ________ and __________. These vessels contain hormones released from the hypothalamus that can be classified as _________ or __________. These vessels all originate from the __________ artery.
h. Many of the anterior pituitary hormones are called ________ hormones because they affect other endocrine organs. These hormones are ________, ________, _______, and ________.
i. The pituitary gland sits in a bony depression called the __________.
j. Another name for the pituitary gland is the ___________.