Endocrine System Flashcards
What are the major differences between the endocrine and nervous system?
the endocrine system;
- transmits ligands
- exhibits longer reaction times
- has longer lasting effects
What are the types of circulating hormones?
- steroids
- biogenic amines
- proteins
What are local hormones?
signaling molecules that don’t circulate in blood
what are Eicosanoids?
a type of local hormone formed from fatty acids within phospholipid bilayer of membrane
What are the effects of eicosanoids?
- autocrine stimulation: effects on the same cell where messenger was formed
- paracrine stimulation:
effects on neighboring cells
What are the advantages of lipid soluble hormones using carrier molecules?
- do not dissolve readily in blood
- carriers are water soluble proteins made by liver
- carriers protect hormones from early destruction
True or false, only lipid soluble hormones use carrier molecules
false, some water soluble hormones use carrier proteins to prolong their life
What two factors determine the concentration of a hormone?
how fast it is synthesized and eliminated
How does hormone elimination occur?
occurs in multiple ways:
- enzymatic degradation in liver cells
- removal from blood via kidney excretion or target cell uptake
What is a hormone’s half life?
time necessary to reduce a hormone’s concentration to half of its original level
How does the half life of water soluble hormones compare to that of steroid hormones?
- water soluble hormones generally have a short half life
- steroid hormones generally have a long half life
What allows for lipid soluble hormones to diffuse across target cell membrane
they are small, nonpolar, and lipophillic
what happens once a lipid soluble hormone enters its target cell
- binds to receptor and forms hormone-receptor complex
- complex binds to a hormone response element of DNA
Why can’t water soluble hormones diffuse through membrane?
they are polar
where are water soluble hormone receptors
on cell membrane
Describe the signal transduction pathway of a water soluble hormone
- hormone is first messenger and binds to receptor
- binding actives a G protein
- G protein activation causes activation of a membrane enzyme
- activated enzyme catalyzes the formation of a second messenger
What are the actions of water soluble hormones?
- enzymes can be activated or inhibited
- growth can be stimulated
- cellular secretions can be released
- membrane permeability can be changed
- muscles can be contracted or relaxed
what are the advantages of a signal transduction pathway?
- signal is amplified at each enzymatic step
- there are many places to regulate pathway activities
What determines the target cells response to a particular hormone?
- number of hormone receptors
- interactions among other hormone actions
What structure is the pituitary gland attached to and how so?
connected to hypothalamus by infundibulum
How do the size and tissue of each part of the pituitary compare?
- posterior pituitary is smaller, neural part
- anterior pituitary is large, glandular part
What are the components of the posterior pituitary?
composed of pars nervosa(lobe) and infundibulum
What are the three sections of the anterior pituitary?
- pars distalis: large anterior rounded portion
- pars tuberalis: thin wrapping around infundibulum
- pars intermedia: scant region between other two
the posterior pituitary is the storage and release site for which hormones?
oxytocin and antidiuretic hormone (both are made in hypothalamus)
What is the relationship between the hypothalamus and the anterior pituitary?
the hypothalamus stimulates anterior pituitary to release its hormones by secreting regulatory hormones