Test 3: Lecture 54 Flashcards
1
Q
___ a molecule secreted by ductless glands into the circulatory system to regulate physiology and behavior of organs throughout the body
A
hormone
2
Q
hormones are produced by ___ glands
A
endocrine
3
Q
hormones offer a critical means of ___ between tissues and organ systems in response to internal and external stimuli
A
communication
4
Q
Hormones do not initiate reactions but rather they affect the ___of pre-existing metabolic functions in a positive or negative fashion
A
rate
5
Q
Some hormones have specific effects on a single cell type, others a more __ effect
A
general
6
Q
Hormones are effective at ___ concentrations
A
minute (very small amount)
7
Q
Hormones have a very ___ half-life in circulation
A
short
(ranging from minutes to hours)
8
Q
endocrine glands produce and secrete hormones ___ into the circulatory system
A
directly
9
Q
endocrine glands ___ have ducts
A
do not
10
Q
key functions of hormones
A
reproduction
growth and dev
homeostasis
energy production, utilization and storage
11
Q
two main classes of hormones
A
amion acid derived
lipid derived (steroids)
12
Q
amino acid derived hormones are :
A
- Whole proteins
- Peptides (fragments of proteins)
- Amines (derivatives of the amino acid tryptophan)
13
Q
Lipid derived hormones are derived from ___
A
cholesterol
14
Q
how do hormone achieve an effect on target cells?
A
receptors
15
Q
each type of hormone has a specific ___ to which it can bind
A
receptor
16
Q
two types of hormone receptors
A
plasma membrane bound
intracellular
17
Q
plasma membrane bound hormone receptors usually bind to ___
A
peptide hormones
18
Q
plasma membrane bound hormone receptors work by ___
A
Binding to cell membrane activates intracellular signal transduction programs that lead to gene expression responses in the nucleus.
19
Q
intracellular hormone receptors usually bind to what type of hormone?
A
steroid (lipid derived)
20
Q
how do intracellular hormone receptors work?
A
Binding to cell membrane activates intracellular signal transduction programs that lead to gene expression responses in the nucleus.
21
Q
two types of control of hormone production
A
external and internal stimuli
22
Q
___ is the main way of regulation of hormone production
A
feedback loops
23
Q
negative feedback loops
A
end product/ intermediates stop reaction
24
Q
positive feedback loops
A
intermediate/ end products induce production
25
pancreas secretion of insulin and glucagon peptides is an examples of ___ hormone
amino acid derived
26
levels of blood sugar regulate secretion of hormones from the \_\_\_
pancreas
27
pancreas secretes ___ when glucose levels are high
insulin
28
insulin binds to insulin receptors on fat and muscle and ___ glucose uptake
promotes
29
three types of cells in the pancreas
islets of langerhans
alpha
beta
delta
30
alpha cells:
secrete glucagon
facilitate the breakdown of glycogen to glucose. This elevated the blood sugar
(islet of langerhans in pancreas)
31
\_\_\_ secrete the hormone insulin, which is essential for the maintenance of normal blood sugar levels. Inadequate levels result in diabetes mellitus
Beta cells
32
beta cells secrete the hormone \_\_\_, which is essential for the maintenance of normal blood sugar levels. Inadequate levels result in \_\_\_
insulin
diabetes mellitus
33
\_\_\_ suppress the release of glucagon and insulin in the pancreas
delta cells
34
delta cells suppress the release of ___ and \_\_\_.
glucagon
insulin
35
\_\_\_ secrete glucagon in the pancreas
alpha cells
36
Human insulin consists of 51aa in two chains connected by 2 ___ bridges
disulfide
37
insulin is a single gene product cleaved into 2 chains during ___ modification.
post-translational
38
insulin is degraded by \_\_\_
glutathione-insulin transhydrogenase (insulinase)
39
insulinase does what?
degrades insulin by cleaving the disulfide links
half life of insulin 5-10 minutes
glutathione-insulin transhydrogenase (insulinase)
40
insulin is synthesized as ___ in the pancreatic beta cells.
preproinsulin
41
preproinsulin is cleaved to ___ in the ER
proinsulin
42
proinsulin is converted into active insulin by ___ in the \_\_\_
cellular endopeptidases in the golgi apparatus
43
The endopeptidases cleave ___ at 2 positions, releasing a fragment called the C-peptide, and leaving 2 peptide chains, the B- and A- chains, linked by 2 \_\_\_bonds.
proinsulin
disulfide
44
what is the quaternary structure of insulin
* Insulin monomers can be in R-state or T-state conformations. (monomer are two strands an alpha and a beta chain)
* Insulin monomers form dimers (T state and R state combine- 4 in total)
* Insulin dimers for hexamers around a Zn2+ (zinc) ion ( 3 dimers bind together)
45
Insulin dimers for hexamers around a ___ ion
zinc
46
the insulin dimer is stabilized by ___ bonds
hydrogen
47
Insulin binding to target cell insulin receptors initiates signal transduction cascades that lead to ___ localizing to plasma membrane
glucose transporters (GLUT 4)
glut 4 lives in vesicles of cell, will get triggered to move to cell membrane and will bring glucose into cell
48
\_\_\_ facilitate influx of glucose into the cell
Glucose transporters (GLUT 4)
49
eat high sugar food will trigger :
beta cells in pancreas to release insulin: cells will use glucose and liver will store glucose as glycogen= normal levels of blood glucose 90 mg/100 ml
50
if you don't eat, blood glucose will fall which leads to \_\_\_
alpha cells in pancreas will release glucagon.
this triggers liver to breakdown glycogen into glucose and blood glucose will increase back to normal levels
51
Type 1 diabetes
insulin dependent
insulin not made: can be treated by giving insulin
52
Type 2 diabetes
non insulin dependent
insulin not recognized by cells, can't bring sugar into the body
53
what is the “master” gland that regulated all other endocrine glands and also releases \_\_\_
pituitary
growth hormone
54
Growth hormone is a \_\_\_hormone
protein
55
growth hormone is secreted by the \_\_\_
pituitary gland
56
Pituitary release is controlled by the \_\_\_
hypothalamus
57
direct effects of growth hormones
**anti insulin** action
increased lipolysis
increased blood and sugar and other anti-insulin effects
58
example of indirect effects of growth hormones
will effect liver and other tissues to make **insulin- like growth factors (IGFs)**
**which will then cause an indirect effect of**
increased cartilage formation and skeletal growth, increased protein synthesis and cell growth and proliferation
59
\_\_\_ feedback control of growth hormone release
negative
60
negative feedback of GH release
growth hormone stops GHRH (growth hormone releasing hormone)
insulin like growth factor 1 (IGF-1) stops growth hormone and activates GHIH (Growth hormone inhibiting hormone)
61
high levels of growth factor will inhibit
growth hormone releasing hormone
62
high levels of insulin like growth factor 1 (IGF1) will stimulate __ and decrease \_\_
growth hormone inhibiting hormone
secreting of growth hormone
63
neurohormones are \_\_\_
hypothalamus hormones
64
\_\_\_ regulate the release of pituitary hormones
hypothalamus hormones
65
steroid hormones are produced in the \_\_\_
adrenal cortex, testis, ovary and some peripheral tissues (adipose tissue)
66
All steroid hormones share a typical (but not identical) ___ ring structure
carbon-based
67
All steroid hormones are derived from ___ and differ only in the ring structure and side chains attached to it.
cholesterol
68
All steroid hormones are \_\_\_soluble but ___ insoluble
lipid
water
69
steroid hormones bind to ___ receptors
intracellular (they are lipid soluble= can freely move through the lipid bilayer)
70
•While \_\_\_hormones are encoded by specific genes, ___ hormones are synthesized from the enzymatic modification of cholesterol.
peptide
steroid
71
•There are far fewer different types of ___ hormones than ___ hormones.
steroid
peptide
72
•The regulation of ___ involves control of the enzymes which modify cholesterol into the steroid hormone of interest.
steroidogenesis
73
•The first enzymatic step in the production of ANY steroid hormone begins with enzymatic modification of \_\_\_
cholesterol
74
cholesterol can be made within the cells from \_\_\_
acetyl CoA
(*de novo synthesis*).
75
A key rate-limiting enzyme for production of cholesterol in the cell from acetyl CoA is \_\_\_
HMG-CoA reductase.
76
There is negative feedback regulation of ___ activity by cholesterol, so that high intracellular cholesterol inhibits de novo synthesis.
HMG-CoA reductase
77
•Cholesterol is also **_taken up by the cell_** in the form of \_\_\_
low density lipoprotein (LDL).
78
•LDL is a complex composed of cholesterol, ___ , \_\_\_, and proteins
phospholipids, triglycerides
(proteins and phospholipids make LDL soluble in blood).
79
•LDL is taken into cells via LDL receptors, and broken down into ___ and then \_\_\_
esterified cholesterol,
free cholesterol
80
two ways cell get cholesterol
from outside cell (LDL)
make it in cell from acetyl CoA
81
All steroid hormones derive from the \_\_\_within the cell.
free cholesterol
82
•A series of enzymatic steps in the ___ convert cholesterol into all of the other steroid hormones and intermediates.
mitochondria and ER
83
what is the rate limiting step of steroid synthesis
The rate-limiting step in this process is the transport of free cholesterol from the cytoplasm into mitochondria**.**
84
the process of transport of free cholesterol from the cytoplasm into mitochondria is carried out by \_\_\_
Steroidogenic Acute Regulatory Protein (StAR)
85
1st step of cholesterol breakdown into other hormones is \_\_\_
CYP11A into **pregnenolone**
86
•Steroid hormones are not water soluble so have to be carried in the blood complexed to specific binding \_\_\_.
globulin proteins
87
•Corticosteroid binding globulin (CBG) carries \_\_\_
cortisol
steroid hormones have to be carried through blood because they are hydrophobic
88
•Sex steroid binding globulin (SHBG) carries ___ and \_\_\_
testosterone and estradiol
steroid hormones have to be carried through blood because they are hydrophobic
89
**Glucocorticoids**
cortisol is the major representative in most mammals – produced by **adrenal cortex**
**class of steroid hormone**
90
**Mineralocorticoids**
; aldosterone being most prominent – produced by adrenal cortex
class of steroid hormone
91
**Androgens**
such as testosterone – produced by testis
class of steroid hormone
92
**Estrogens**
, including estradiol and estrone – produced by ovary
type of steroid hormone
93
**Progestogens** (also known a progestins)
such as progesterone – produced by ovary and adrenal cortex
class of steroid hormone
94
Steroid hormones are classified chemically by number of \_\_\_.
carbons
95
what are the most common number of carbons for steroid hormones?
C18 (ovarian)
C19 (testicular)
C21 (adrenal cortical)
