Lecture 75 Flashcards
1
Q
Hormone definition:
A
Chemical substance that has been secreted by a gland (or a group of glands) or a tissue into body fluid
Has physiological control effect on other cells of the body
2
Q
hormones have a __ control effect on other cells of the body
A
Physiological control effect
3
Q
Endocrine definition:
A
secrete hormones directly in the blood stream
4
Q
exocrine definition
A
Exocrine goes into ducts, but ducts tend to go out of the body
5
Q
hormonal effects can occur during various time scales: two hormones that last seconds to minutes:
A
norepinephrine
epinephrine
6
Q
synonym for epinephrine and norepinephrine:
A
adrenaline and noradrenaline
7
Q
hormonal effects can occur during various time scales: two hormones that last hours to several days:
A
cortisol
insulin
8
Q
Hormonal effects can occur during various time scales: two hormones that last several weeks to months:
A
(1) thyroxine
(2) Growth hormone
9
Q
true/false: the nervous system can interact with hormonal system:
A
true
10
Q
The nervous system can interact with hormonal system: Sympathetic nervous system can
A
stimulate adrenal glands
11
Q
The nervous system can interact with hormonal system: Central nervous system can:
A
control the pituitary gland
12
Q
true/false: all hormones are controlled by nervous system
A
false: some but not all
13
Q
The endocrine (hormonal) system controls:
A
different metabolic function of body
14
Q
The endocrine (hormonal) system controls different metabolic functions of body, namely 4:
A
(1) Chemical reaction rate of cells
(2) Transport of substances through cell membrane
(3) Growth of body
(4) Secretion of other hormones
15
Q
There are approximately __ types of endocrine glands and tissues
A
9
16
Q
There are approximately nine types of endocrine glands and tissues:
A
- pituitary
- adrenal
- thyroid
- parathyroid
- islets of Langerhans
- ovaries
- testes
- placenta
- duodenum
17
Q
There is one pituitary gland which has two halves. One half is the __ pituitary, which is pointed to the front of the body
A
anterior
18
Q
the pituitary gland is primarily controlled by:
A
other hormones
19
Q
the anterior pituitary gland secretes six hormones:
A
o growth hormone
o adrenocorticotropin
o thyroid-stimulating hormone
o follicle-stimulating hormone
o luteinizing hormone,
o prolactin
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20
Q
the posteriror pituitary is primarlily under:
A
neuronal control
21
Q
the posterior pituary is pointed to:
A
the back of the body
22
Q
the posterior pituitary secretes two hormones:
A
(1) Antidiuretic hormone (ADH)
(2) Oxytocin
23
Q
There are two adrenal glands, one on each
A
kidney
24
Q
Each adrenal gland has __ parts
A
two
25
The adrenal cortex is the __ of the adrenal gland
outer part
26
the adrenal cortex is under:
hormonal control
27
the adrenal cortex secretes two hormones:
o cortisol
o aldosterone
28
the inside part of the adrenal gland
adrenal medulla
29
the adrenal medulla is under:
neural control
30
The adrenal medulla secretes two _ hromones
two "catecholamine" hormones
31
The adrenal medulla secretes two "catecholamine" hormones:
o adrenaline (epinephrine) --> major secretion
o noradrenaline (norepinephrine) --> minor secretion
32
major secretion of the adrenal medulla:
adrenaline (epinephrine)
33
minor secretion of the adrenal medulla:
noradrenaline (norepinephrine)
34
The thyroid gland is located
up in the sternal and mediastinal area of the thorax.
It is situated above the thymus, which sits on top of the heart.
35
The thyroid has various shapes but generally has
two lobes - shaped like a butterfly
36
The thyroid gland secretes three hormones:
o thyroxine (T4)
o triiodothyronine (T3)
o calcitonin
37
There are __ parathyroid glands, which are located within the thyroid gland
4
38
Even though it is within the thyroid gland, the parathyroid gland is considered a separate gland due to its
completely different control and function
39
the parathyroid gland secretes which hormone:
parathyroid hormone
40
the parathyroid gland secretes how many hormones?
1
41
millions of islets of Langerhans are in the
pancreas
42
There are millions of islets of Langerhans in the pancreas. They are not really considered a gland, rather, they are an
endocrine tissue
43
islets of langergans secrete several hormones including:
insulin
glucagon
44
ovaries are considered an:
endocrine gland
45
ovaries produce hormones including:
(1) estrogens
(2) progersterone
46
There are two testes (testicles), portions of them are considered an
endocrine gland
47
the testes produce hormones including:
testosterone
48
There are two testes (testicles), portions of them are considered an
endocrine gland
49
The placenta (during menstruation, conception and gestation) is considered an
endocrine tissue
50
The placenta makes hormones including
o human chorionic gonadotropin
o estrogens
o progesterone
o somatomammotropin
51
the duodenum contains which endocrine gland?
Bruner's gland
52
The duodenum (small intestine) contains Brunner's glands, considered an
endocrine gland
53
the duodenum (Brunner's glands) secretes:
secretin -- coordinates digestion
54
Hormones can be classified as __ or __ according to the range of their effect
local hormone or general hormone
55
Hormones can be classified as local hormone or general hormone according to:
the range of their effect
56
Local hormones primarily have
specific local effects on specific tissues (target tissue)
57
Local hormones : definition is not based on
where they come from, but where they have their effect
58
secretin can be considered a
local hormone
59
secretin can be considered a local hormone because it is released from __, transported in __, cause ___
* Released from duodenal (intestinal) wall, transported in blood to pancreas, cause pancreas secretions for digestion
60
secretin causes:
pancreas secretions for digestion
61
Cholecystokinin can be considered a:
local hormone
62
Cholecytoskinincan be considered a local hormone because it is released in __. transported to __ and cause (2) __
Released in small intestine transported to:
(1) gallbladder --> cause gallbladder contraction
(2) pancreas --> cause secretion of digestive enzyme.
63
Adrenocorticotropin can be considered a
local hormone
64
Adrenocorticotropin can be considered a local hormone because it is released from
anterior pituitary gland
65
Adrenocorticotropin
stimulates
adrenal cortex to secrete adrenocortical hormones
66
general hormones can be effective on __ and cause many different reactions
General hormones can be effective on many parts of the body and cause many different
reactions
67
What are three examples of general hormones?
(1) Epinephrine (E) and Norepinephrine (NE)
(2)Growth hormone (GH)
(3)Thyroid hormone (T3 and T4)
68
Epinephrine (E) and Norepinephrine (NE) secreted by (2):
(1) secreted by adrenal medullae under sympathetic stimulation
(2) secreted by sympathetic nerves
69
Epinephrine (E) and Norepinephrine (NE) cause :
constriction of blood vessels and increase of arterial pressure
70
Epinephrine (E) and Norepinephrine (NE) has effects on
most organs and tissues of the body (a general hormone)
71
Growth hormone (GH) released from
anterior pituitary gland
72
Growth hormone (GH) cause:
growth in all parts of body
73
Thyroid hormone (T3 and T4) released from
thyroid gland
74
thyroid hormone cause:
Increase chemical reaction rate in almost all body cells
75
Hormones can be classified chemically into three types:
steroid, protein, and tyrosine.
76
Steroid-based hormones are built from
cholesterol
77
Steroid hormones are based on
the cholesterol molecule
78
The adrenal cortex will turn the cholesterol into
many other hormones including cortisol and aldosterone
79
the placenta and ovaries can turn cholesterol into
estrogen
80
the testicles can turn cholesterol into
testosterone
81
The steroid hormones tend to cross the plasma membranes of cells and get direct access to the inside of the cell (cytoplasm and nucleus). This happens because cholesterol is
hydrophobic
82
receptors for steroid hormones are usually found
within the cell cytoplasm or nucleus
83
Mechanism of steroid hormone action follows a general pathway (6 steps):
Steroid hormones enter cytoplasm of cell -> bind with receptors in cytoplasm (sometimes nucleus)* -> diffuse or transported into nucleus -> bind to and activate DNA strands -> initiate transcription process of genes to form RNA messenger -> RNA goes into cytoplasm through nuclear pore complex -> promote functions inside the cells.
84
The thyroid gland can turn tyrosine into
thyroxine (T4) and triiodothyronine (T3)
85
tyrosine is an
important amino acid to make proteins, but it can also be turned into several different hormones
86
The adrenal medullae can turn tyrosine into
epinephrine and norepinephrine
87
The thyroid gland adds iodine molecules to tyrosine which makes
T3 and T4 hydrophobic (lipophilic).
88
how does the thyroid gland use tyrosine to make hormones
The thyroid gland adds iodine molecules to tyrosine which makes T3 and T4 hydrophobic (lipophilic).
89
how does the adrenal gland use tyrosine to make hormones
The adrenal gland hydroxylates tyrosine which makes cateholamines hydrophilic (lipophobic)
90
The adrenal gland ___ tyrosine which makes it ____
The adrenal gland hydroxylates tyrosine which makes it hydrophilic (lipophobic)
91
T3 and T4 have their receptors
inside of the cells
92
For thyroid hormones there is a chain of events leading to their action on the body:
Thyroid hormones enter the cell -> bind with receptor in cell nucleus* -> hormone-receptor complex binds with DNA -> activates transcriptions of specific genes and subsequent formation RNA messenger -> mRNA goes into cytoplasm through nuclear pore complex -> new proteins (enzymes) are formed and become the controller to promote metabolic activities in all cells of body*
In some cases the receptors are found within the nucleus not the cytoplasm.
## Footnote
Thyroid hormones enter the cell → bind to nuclear receptors → hormone-receptor complex binds to DNA → activates transcription of specific genes → mRNA is produced and exits the nucleus → translated in the cytoplasm to form new proteins (enzymes) → these proteins regulate metabolic activity throughout the body.
93
For epinephrine (E), norepinephrine (NE), also including acetylcholine (Ach), they must interact with receptors on
the cell surface
94
epinephrine (E), norepinephrine (NE), chain of events leading to the eventual function on the body
E or NE -> bind with receptors on the cell membrane -> cause conformational change of proteins structure of the receptor -> open or close channels for ions (Na or K) (change of membrane permeability) -> change of cell membrane potential -> cause cell excitation or inhibition
95
A protein is
a long chain of amino acids that fold up
96
A peptide is a much shorter version, it is technically less than
20 amino acids long
97
protein or peptide-based hormones (4):
(1) anterior pituitary hormones
(2) posterior pituitary hormones
(3) insulin and glucagon
(4) parathormone
98
protein/ peptide-based hormone: anterior pituitary hormones released from
anterior pituitary
99
protein or peptide based hormones: posterior pituitary hormones released from:
posterior pituitary
100
protein or peptide based hormone: insulin and glucagon released from
islet of Langerhans
101
protein or peptide based hormone: parathormone Released from:
parathyroid gland
102
All of the protein and peptide-based hormones are
hydrophilic
103
All of the protein and peptide-based hormones are hydrophilic, (lipophobic) so they prefer to use receptors on
the surface of cell membrane
104
protein and peptide-based hormones chain of events leading to the eventual function on the body:
Protein or peptide-based hormones bind receptors on membrane (protrudes to exterior of cell) -> structure change in receptor -> receptor becomes activated enzyme "adenyl cyclase" -> activate the formation of "cyclic adenosine monophosphate" (cAMP) -> second messenger activates a cascade of enzymes -> cause powerful effects on cells
## Footnote
Hormone Binding: Protein or peptide-based hormones bind to specific receptors located on the cell membrane (these receptors protrude outward from the cell surface).
Receptor Activation: Hormone binding causes a conformational (structural) change in the receptor.
Enzyme Activation: The activated receptor stimulates the enzyme adenyl cyclase.
cAMP Production: Adenyl cyclase catalyzes the conversion of ATP to cyclic adenosine monophosphate (cAMP).
Signal Amplification: cAMP acts as a second messenger, initiating a signaling cascade that activates multiple downstream enzymes.
Cellular Response: This enzyme cascade leads to significant physiological effects in the target cell.
105
Second messengers are
cell-signalling pathways that communicate between the receptor on the cell surface and the inside of the cell
106
Cyclic adenosine monophosphate (cAMP) as second messenger
Hormones (protein or peptide based) ->bind to receptor on cell membrane-> activated receptor stimulates enzyme "adenyl cyclase" -> adenyl cyclase catalyzes the formation of cAMP -> camp acts as second messenger ainitiating a signalling cascade that cativate a cascade of enzymes -> cause different effects on cells.
107
Ca2+ Calmodulin as second messenger
Hormones -> receptor -> open channels for Ca2+ ions -> Ca2+ diffused into cell and bind with calmodulin -> calmodulin is activated by conformational change -> activated calmodulin can cause multiple effects inside the cell in the same way that cAMP does
## Footnote
Hormones bind to receptors → open Ca²⁺ channels → Ca²⁺ enters the cell and binds to calmodulin → calmodulin undergoes a conformational change → activated calmodulin triggers various cellular responses, similar to the effects of cAMP.
108
Ca2+ Calmodulin as second messenger:Example: smooth muscle contraction
Ca2+ -> diffuse into smooth muscle membrane -> bind with calmodulin -> Ca2+-calmodulin complex activates myosin kinase (enzyme) -> cause the phosphorylation of myosin head of smooth muscle -> formation of cross-bridge for muscle contraction
## Footnote
Ca²⁺ enters the smooth muscle cell through calcium channels in the membrane → binds to calmodulin in the cytoplasm → forms Ca²⁺-calmodulin complex → activates myosin light-chain kinase (MLCK) → MLCK phosphorylates myosin heads → enables cross-bridge formation → leads to smooth muscle contraction.
109
IP3 and diacylglycerol as second messenger
Hormones -> receptor -> activates enzyme phospholipase C attached to the inside projection of the receptor -> cause phospholipids in the cell membrane to split into small substances such as inositol trisphosphate (IP3) and diacylglycerol that serve as "second messenger
## Footnote
Hormones bind to membrane receptors → activates phospholipase C on the inner side of the membrane → phospholipase C cleaves membrane phospholipids into IP₃ and diacylglycerol (DAG)
110
Concentration of hormones is extremely low in the blood. The levels range from
few picograms/mL, and as high as a few micrograms/mL
111
The rate of secretion of hormones is extremely small, it is measured in
microgram/mL/day
112
Hormones are
very small chemicals molecules that defy conventional measuring techniques. There are some fancy ways of measuring them.
113
Hormones can be measured by the method of
radioimmunoassay (RIA)
114
mass spectrometry
o a radio-labelled standard of the hormone is bought from a company.
o The mass spectrometer determines the profile of the standard.
o The sample is run in the mass spectrometer and compared against the standard.
o This method can be very precise and very quantitative. However, it is technically very demanding, expert scientists and expensive infrastructure are required.
115
An important aspect of hormones, is the control of their
secretion rate
116
By controlling the secretion rate, the body can
control how much effect the hormone is having, and it can 'shut off' the hormone secretion if there is too much
117
Most hormones are at a ___ and can
a steady state and can be adjusted down and up as needed.
118
__ most common way hormones are controlled
Negative feedback
119
two kinds of negative feedback:
direct and indirect.
120
Direct negative feedback is when
hormone inhibits its own secretion when it reaches a high enough level.
121
example direct negative feedback
Gland secretes hormone -> hormone accumulates in blood -> hormone gets back to gland -> hormone inhibits its own secretion.
122
Indirect negative feedback is when
the "effect" of the hormone inhibits the hormone secretion.
123
example indirect negative feedback:
Gland secretes hormone -> hormone accumulates in blood -> hormone stimulates a tissue -> the tissue produces some effects, for example, heat is produced ->the effects, in this example heat, will go back to the gland and inhibit the secretion of the hormone.
124
Direct positive feedback
Gland secretes hormone -> hormone accumulates in blood -> the hormone goes back to the gland and promotes the secretion of the hormone.
125
indirect positive feedback
Gland secretes hormone hormone accumulates in blood the hormone stimulates a tissue the gland and produces some effect which then promotes the secretion of the hormone
126
The number of receptors in the target cell varies from
day to day even from seconds to minutes.
127
Receptors can be activated or deactivated by
altering their second messenger cell signalling pathway, or by altering their location in the cell
128
Receptors can be destroyed by
enzymes, then they are just gone.
129
Receptors can be created by
synthesis
130
Chronic over-stimulation of a receptor will lead to a
deactivated or destroyed receptor
