Lecture 76 Flashcards
1
Q
Pituitary Gland also known as:
A
Hypophysis
2
Q
Pituitary Gland lies in:
A
Sella turcica at base of brain
3
Q
Pituitary Gland is connected to the __ by the pituitary stalk
A
hypothalamus
4
Q
Pituitary Gland connected to the hypothalamus by
A
pituitary stalk
5
Q
pituitary stalk is also known as
A
hypophysial stalk
6
Q
The pituitary gland has two parts called lobes:
A
- anterior pituitary (adenohypophysis)
- posterior pituitary (neurohypophysis)
7
Q
anterior pituitary also known as
A
adenohypophysis
8
Q
posterior pituitary also known as:
A
neurohypophysis
9
Q
There are __ hormones secreted by anterior pituitary gland
A
six
10
Q
growth hormone (GH) also known as:
A
somatotropin
11
Q
six hormones secreted by anterior pituitary gland:
A
- growth hormone (GH) (also known as somatotropin)
- adrenocorticotropin (ACTH) (also known as corticotropin)
- thyroid-stimulating hormone (TSH) (also known as thyrotropin)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin (PRL)
12
Q
growth hormone (GH) promotes:
A
growth of entire body by affecting protein formation cell multiplication, differentiation
13
Q
adrenocorticotropin (ACTH) also known as
A
corticotropin
14
Q
adrenocorticotropin controls:
A
secretion of hormones from adrenal cortex that affects metabolism of glucose, protein and fats.
15
Q
adrenocorticotropin controls secretion of hormones from adrenal cortex and affects:
A
metabolism of glucose, protein and fats.
16
Q
thyroid-stimulating hormone (TSH) (also known as
A
thyrotropin
17
Q
thyroid-stimulating hormone (TSH) stimulate:
A
thyroid gland to control secretion rate of thyroxine and triiodothyronine (Which control the rate of intracellular chemical reaction of entire body).
18
Q
thyroid-stimulating hormone stimulate thyroid gland to control secretion rate of thyroxine and triiodothyronine which control:
A
the rate of intracellular chemical reaction of entire body
19
Q
Follicle-stimulating hormone (FSH)
control growth of
A
gonads and hormonal and reproductive activities
20
Q
Luteinizing hormone (LH), function:
A
Control growth of gonads and hormonal and reproductive activities (same function as follicle-stimulating hormone)
21
Q
Prolactin (PRL) promotes
A
mammary gland and milk production
22
Q
The posterior pituitary secretes __ hormones
A
two
23
Q
The posterior pituitary secretes two hormones:
A
- Antidiuretic hormones (ADH) (also known as vasopressin)
- Oxytocin
24
Q
Antidiuretic hormones (ADH) also known as:
A
vasopressin
25
Antidiuretic hormones (ADH) (also known as vasopressin) control:
rate of water excretion into urine --> to help controlling water concentration in body fluids.
26
Oxytocin help for (2):
(1): Delivering milk from glands of breast to the nipples during suckling
(2): Baby delivery at the end of gestation
27
The anterior pituitary is considered to be primarily under:
hormonal control
28
The anterior pituitary is considered to be primarily under hormonal control because:
other hormones called controlling factors determine the secretion from the lobe
29
The posterior pituitary is considered to be under:
neural control
30
The posterior pituitary is considered to be under neural control because:
neurons go directly into the lobe and secrete the hormones.
31
There are __ main cell types in the anterior pituitary gland
five
32
five main cell types in the anterior pituitary gland
*Sally came to get laid
1. Somatotropes
2. Corticotropes
3. Thyrotropes
4. Gonadotropes
5. Lactotropes
33
Somatotropes: What percent of the pituitary cells are of that type
30 - 40% of are this type
34
Somatotropes secrete:
growth hormone (GH)
35
Corticotropes secrete:
adrenocorticotropin (ACTH)
36
Corticotropes: what percent of the pituitary cells are of that type
20%
37
Thyrotropes: What percent of the pituitary cells are of that type
3 - 5% are this type
38
Thyrotropes secrete:
thyroid-stimulating hormones (TSH)
39
Gonadotropes: What percent of the pituitary cells are of that type:
3 - 5% are this type
40
Gonadotropes secrete:
gonadotropic hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
41
Gonadotropic hormones:
(1) luteinizing hormone (LH)
(2) follicle-stimulating hormone (FSH).
42
Lactotropes: What percent of the pituitary cells are of that type:
* 3 - 5% are this type
43
Lactotropes secrete
prolactin (PRL)
44
Secretions from anterior pituitary are controlled by
hormones
45
Secretions from anterior pituitary are controlled by 2 hormones (also known as controlling factors):
(1) hypothalamic releasing hormone
(2) hypothalamic inhibitory hormone
46
Secretions from anterior pituitary are controlled by hormones also generally termed:
controlling factors
47
Secretions from anterior pituitary are controlled by hormones:
(1) hypothalamic releasing hormone and (2) hypothalamic inhibitory hormone, also known as controlling factors. These factors are synthesized in ___
specialized neurons in the hypothalamus
48
(1) hypothalamic releasing hormone and (2) hypothalamic inhibitory hormone, also known as controlling factors. These factors are synthesized in specialized neurons in the hypothalamus and transmitted via __
long portal vein to the anterior lobe
49
hormones secreted by posterior pituitary (2) are synthesized in:
hypothalamus
50
How many hormones are synthesized in the pituitary gland?
6 ** remember the two posterior pituitary hormones are synthesized in hypothalamus
51
Secretions from anterior pituitary are controlled by hormones: There are six of these controlling factor hormones:
Giant Giants can throw great punches
1. Growth hormone releasing hormone (GHRH)
2. Growth hormone inhibitory hormone (GHIH)
3. Corticotropin-releasing hormone (CRH)
4. Thyrotropin-releasing hormone (TRH)
5. Gonadotropin-releasing hormone (GnRH)
6. Prolactin inhibitory hormone (PIH)
52
which pituitary hormone is exclusively controlled by an inhibitory factor?
prolactin
53
Growth hormone releasing hormone (GHRH)
causes
secretion of growth hormone.
54
Growth hormone inhibitory hormone (GHIH) causes
* Causes inhibition of the secretion of growth hormone.
55
Corticotropin-releasing hormone (CRH) causes
secretion of adrenocorticotropin
56
Thyrotropin-releasing hormone (TRH) causes
secretion of thyroid-stimulating hormone
57
Gonadotropin-releasing hormone (GnRH) causes:
secretion of luteinizing and follicle-stimulating hormone
58
Prolactin inhibitory hormone (PIH)
Causes
inhibition of secretion of prolactin secretion.
59
Anterior Pituitary Secretions: In order for these controlling factor hormones to work, there is a cascade of events that leads to secretion of hormones from anterior pituitary
(1) The hypothalamus receives signal from different sensory sources in the nervous system.
(2)The required controlling factor hormone is synthesized in special neurons in the hypothalamus. The endings of these neurons (nerve fibers) connect to median eminence in hypophysial stalk area.
(3) The controlling factor hormone is released from these endings of neurons and absorbed into the hypothalamic-hypophysial (long) portal vessels.
(4) The long portal vessel carries the hormones to the anterior pituitary lobe where it is released onto the trope cells.
(5) The relevant trope cell has a receptor for the controlling factor hormone, and it secretes the actual hormone into the veins.
(6) The hormone now goes into circulation and does its thing.
60
The hypothalamus receives signal from
different sensory sources in the nervous system.
61
In order for these controlling factor hormones to work, there is a cascade of events that leads to
secretion of hormones from anterior pituitary (6 steps):
* The hypothalamus receives signal from different sensory sources in the nervous system.
* The required controlling factor hormone is synthesized in special neurons in the
hypothalamus. The endings of these neurons (nerve fibers) connect to median eminence
in hypophysial stalk area.
* The controlling factor hormone is release from these endings of neurons and absorbed
into the hypothalamic-hypophysial (long) portal vessels.
6
* The long portal vessel carries the hormones to the anterior pituitary lobe where it is
released onto the trope cells.
* The relevant trope cell has a receptor for the controlling factor hormone, and it secretes
the actual hormone into the veins.
* The hormone now goes into circulation and does its thing.
62
Growth hormone also known as
somatotropin
63
Growth hormone is controlled by how many controlling factors (hypothalamic hormones)
2: it is the only anterior pituitary hormone controlled by 2 facots (GHRH /GHIH)
64
Growth hormone : big / small: what kind of base?
small protein-based hormone
65
Growth hormone affects
almost all tissues of body
66
GH promotes __ when baby is growing up, and promotes ___ increase in adulthood.
GH promotes growth when baby grows up, and promotes muscle size increase in adulthood
67
GH can increase (3):
(1) The physical size of cells
(2) The number of cells
(3)the amount of protein inside of a cell
68
In addition to the growth-promoting effects, there are three main effects that growth hormone has on metabolism, it affects protein, fat, and carbohydrates. :
1. Growth hormone promotes protein synthesis
2. Growth hormone enhances fat as a source of energy.
3. Growth hormone decreases the use of glucose for energy
4. Growth hormone decreases the use of protein for energy
69
Metabolic effect of GH (1/3): How does growth hormone promote protein synthesis (3 ways )?
(1) GH can enhance transport of most amino acids through cell membrane to the interior of
cells → increase the concentration of amino acid in cells → increase protein
synthesis.
(2) GH increases the formation of RNA → promotes more protein to be synthesized by
ribosomes in cytoplasm → increases transcription of DNA in nucleus.
(3) GH reduces the breakdown of cell protein.
70
Chemically speaking, fat is a:
triglyceride
71
triglyceride has a
glycerol backbone with three fatty acids attached to it.
72
GH causes triglyceride to break down into
glycerol and three free fatty acids
73
Metabolic effect of GH (2/4): How does GH enhance fat as a source of energy
GH causes triglyceride to break down into glycerol and three free fatty acids -> release of fatty acids from adipose tissue -> increase the concentration of fatty acids in body fluids -> enhances conversion of free fatty acids -> acetylcoenzyme A (acetyl-CoA) used for energy.
74
GH mobilization of fat requires time
hours to occur
75
GH at excessive amounts of may cause what two bad things :
ketosis and fatty liver disease
76
Metabolic effect of GH (3/4): How does growth hormone decrease the use of glucose for energy (2 ways) ?
(1) GH increases fatty acids conversion to energy -> negative feedback effect to block breakdown of glycogen to glucose -> enhances the deposition of glycogen in hepatic or muscle cells -> glycogen accumulates
(2) GH diminishes the uptake of glucose by cells → increases the blood glucose
concentration → hyperglycemia might occur if GH is excessive
77
Metabolic effect of GH (3/4): growth hormone decreases the use of glucose for energy : __ might occur if GH excessive (not chronically though)
hyperglycemia
78
If excessive GH chronically increases blood concentration of glucose and it increases to 50% or more above normal, it is called
pituitary diabetes
79
pituitary diabetes --> similar to ___ in its symptoms.
type II
80
If the pituitary diabetes is chronic due to illness or GH abuse ->
GH over-stimulating islet of Langerhans to secrete extra insulin -> the islets can be damages -> diabetes mellitus may develop (diabetogenic effect).
81
growth hormone effect on metabolism 4/4 :Growth hormone decreases the use of protein for energy by:
promoting the use of fat for energy, the protein is not used to create energy. Now the protein can be used to increase muscle mass
82
Under normal conditions does GH alter the balance of blood glucose
no
83
GH excess would be an abnormal situation typically due to a
Cancerous tumour that over produces GH
84
Regulation of growth hormone secretion rate is affected by at least __ things
four
85
Regulation of growth hormone secretion rate is affected by at least four things:
1. GH secretion is promoted by malnutrition, starvation, anorexia, bulimia
2. GH secretion is promoted by exercise
3. GH secretion is promoted by sleep
4. GH secretion is promoted by trauma.
86
The secretion of growth hormone is controlled by ___ that are secreted from hypothalamus
two factors
87
how is GH secretion promoted by malnutrition, starvation, anorexia, bulimia (2)?
(1) low concentration of fatty acids in the blood causes GH secretion
12
(2) low concentration of glucose causes GH secretion
88
How is GH secretion promoted by exercise?
(1) after about 2 hours of strenuous exercise it causes GH secretion
(2) one reason is due to lactic acid in the blood stimulating GH secretion, happens in
anaerobic exercise.
89
how is GH secretion is promoted by sleep
after about 2 hours of sleep it causes GH secretion
90
how is GH secretion promoted by sleep?
after about 2 hours of sleep it causes GH secretion
91
The secretion of growth hormone is controlled by two factors that are secreted from hypothalamus
1. Growth hormone releasing hormone (GHRH)
2. Growth hormone inhibitory hormone (GHIH) (also known as somatostatin
92
Growth hormone releasing hormone (GHRH): Short-term effect:
Increase Ca2+ ions transport into cell -> fusion of GH secretory vesicles with cell membrane -> release of GH into blood.
Increases Ca²⁺ influx into somatotroph cells in the anterior pituitary.
This triggers fusion of growth hormone (GH) secretory vesicles with the cell membrane.
Leads to exocytosis and release of GH into the bloodstream.
93
Growth hormone releasing hormone (GHRH): Long-term effect:
Increase transcription in nucleus by the genes that cause new GH synthesis.
94
Growth hormone inhibitory hormone also known as :
somatostatin
95
what does growth hormone inhibitory hormone (GHIH) (also known as somatostatin) do:
This one is inhibitory, it will inhibit the Ca2+ and prevent synthesis of GH
96
Abnormalities of Growth Hormone Secretions: If the regulation fails, then at least __ abnormalities of growth hormone secretion can occur.
1. Panhypopituitarism
2. Dwarfism
3. Gigantism
4. Acromegaly
5. Aging caused by decreased secretion of GH
97
Panhypopituitarism: 4 poins:
(1) Decreased secretion of all anterior pituitary hormones.
(2) It can be congenital or occur during life.
(3) The lack of GH results in abnormal growth.
(4) The lack of all other pituitary hormones causes a multitude of other issues.
98
Dwarfism results from:
(1) Specific deficiency of GH alone
(2) it can be due to a special case of panhypopituitary dwarfism during childhood.
99
dwarfism : body does not develop in appropriate proportions?
false - body develops in appropriate proportion but rate of development decreased greatly
100
True/False: Panhypopituitary dwarf pass through puberty
false
101
Dwarfism characterized by: no sufficient __ for ___
* No sufficient gonadotropic hormone for developing sexual function
102
1/3 of dwarfs resulted from deficiency of GH alone can
develop mature sexual function.
103
Pygmy people are born with
A defective GH response
104
Gigantism
* Excessive quantities of GH produced caused by tumour in pituitary gland.
* Body tissue grow rapidly -> a giant as tall as 8 feet (nearly 2.5 meters).
105
Acromegaly
*Acidophilic tumor occurs after adolescence.
*Soft tissue continue to grow, bone grow thickness.
Elevated GH levels
106
Aging caused by decreased secretion of GH disease characteristics (3)
*Decreased secretion of GH --> accelerates aging process.
*Result from decreased protein synthesis in body tissue and increased deposition of fat.
*Picture of child with accelerated aging.
107
The posterior pituitary lobe (also known as the neurohypophysis) is composed of cells called
pituicytes
108
The posterior pituitary gland is a supporting structure for:
nerve fibers and nerve endings
109
The antidiuretic hormones (ADH) (vasopressin) are synthesized in the:
supraoptic nuclei* of hypothalamus
110
The oxytocin is synthesized in:
paraventricular nuclei of hypothalamus
111
Oxytocin and ADH bind with ___ and are transported to their nerve endings in posterior pituitary gland.
neurophysins
112
Oxytocin and ADH bind with neurophysins and are transported to their nerve endings in:
posterior pituitary gland
113
Neurophysins are
chaperone proteins
114
Neurophysins are chaperone proteins, that help
ADH or oxytocin to get from the nuclei of the hypothalamus down to the posterior lobe
115
When nerve impulses from supraoptic and paraventricular nuclei of hypothalamus reach to the nerve endings, the hormones (oxytocin and ADH) is released from the vesicles in the nerve endings by
exocytosis
116
Rare example of a positive feedback system...
oxytocin cause contraction of the pregnant uterus at the end of gestation for helping with birth of the baby
117
Oxytocin has two main functions:
1. Cause contraction of the pregnant uterus at the end of gestation for helping with birth of the baby. Rare example of a positive feedback system...
2. Cause milk to be expressed from the alveoli into the ducts so that baby can obtain it by suckling.
118
oxytocin: describe milk let down reflex:
Suckling stimuli on nipple of the breast elicits signals, ➔ signals are transmitted
through sensory nerves to the brain, ➔ reach to the oxytocin neurons in the
paraventricular nuclei in the hypothalamus, ➔ cause release of oxytocin from
posterior pituitary gland, ➔ oxytocin is carried by blood to breasts, ➔ cause contraction of myoepithelial cells, ➔ milk flow (milk ejection or milk letdown)
119
The main purpose of ADH is to
maintain blood pressure homeostasis
120
The main purpose of ADH is to maintain blood pressure homeostasis by:
secreting (or not secreting) ADH
121
Osmosis is
the movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration
122
solvent:
a liquid that things get dissolved in (e.g. water)
123
selectively permeable:
only allows solvent or small molecules through
124
solute:
a thing that dissolves in a liquid (e.g. NaCl)
125
dissolve:
when a solid is "absorbed" by a liquid
126
The change of concentration of ADH from small amount to large amount in the body fluid is rapid/ fast in order to balance blood osmolarity.
rapid (only a few minutes)
127
ADH secretion regulated through two main ways:
1. osmosis
2. cardiovascular function.
128
Osmosis regulates ADH (1/2 ways)
The secretion of ADH is regulated by osmosis through osmoreceptors in the hypothalamus.
Osmoreceptors are specialized neurons in the hypothalamus that expand when the blood is dilute, and they contract when the blood is concentrated.
When osmotic pressure of blood changes the osmoreceptor cells change their size, which affects ADH secretions.
129
Osmosis regulates ADH:cascade of effects occurring in the hypothalamus when extracellular body fluid is too concentrated:
When the extracellular body fluid becomes highly concentrated, water in the osmoreceptor diffuses out of the cell membrane by osmosis -> decrease the size of osmoreceptor ->initiates the nerve impulses in the hypothalamus --> impulses are transmitted to the posterior pituitary -> cause secretion of ADH, water retention in kidney.
130
Antidiuretic hormone (ADH) secretion:When the extracellular body fluid becomes highly concentrated:
water in the osmoreceptor
diffuses out of the cell membrane by osmosis ➔ decrease the size of osmoreceptor
➔ initiates the nerve impulses in the hypothalamus ➔ impulses are transmitted to the
posterior pituitary ➔ cause secretion of ADH, water retention in kidney.
130
When the extracellular fluid becomes too dilute
water diffuses into the osmoreceptor
➔ increase the cell size of the osmoreceptor ➔ decrease the signal for ADH
secretion, water excretion at kidney.
131
Secretion of ADH is also controlled by the cardiovascular reflexes (method 2/2) in response to
the decrease in blood volume or blood pressure. When blood volume is decreased 15 - 25%, the secretion rate increase to as high as 50 times normal. This is called a pressor response, its why ADH has another name, vasopressin.
132
In the atria of the heart, there are special cells called baroreceptors that can:
relax or stretch according to blood pressure.
133
In the atria of the heart, there are special cells called:
baroreceptors
134
when blood pressure is high baroreceptors ___
stretch
135
When the blood pressure low baroreceptor __
relax
136
When the blood pressure low baroreceptors relax ->
increase the secretion of ADH -> cause constriction of blood vessels around body, and water retention in kidney. -> blood pressure rises
137
when the blood pressure is high, baroreceptors stretch -->
decrease the secretion of ADH -> dilation of blood vessels around body, and water excretion by kidney -> blood pressure falls
138
The luminal membrane
thus separates
'blood' from urine
139
A cascade of events leads to changes in urine:
When ADH is released into blood and is transported to kidney, it binds with the receptors on luminal membranes cause formation of cAMP cause phosphorylation of chemicals in the special vesicles vesicles insert into apical cell membrane increase the permeability of collecting tubules and ducts to water water is reabsorbed from the collecting tubules and duct by osmosis water is conserved in the body producing very concentrated urine.
140
ADH is also called
vasopressin,
141
How does ADH cause constriction or dilation of the blood vessels?
High concentration of ADH causes constriction of arterioles throughout the body to increase the arterial pressure. ADH thus has effects on arterial resistance. Does so by acting on smooth muscle cells around the vessels.
142
'pressor' response
When the blood volume or blood pressure decreases, secretion of ADH then constriction (tightening) of blood vessels
143
When blood pressure goes above the normal value, then the pressor response process works in reverse:
If blood pressure is high ADH is no longer secreted, water is excreted by the kidney into urine, and the arterioles relax, which lowers blood pressure.
144
Homeostasis will eventually bring blood pressure to the optimal point, as determined by continuous monitoring by
(1) The baroreceptors in the heart
(2) The osmoreceptors of the hypothalamus
