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HUBS 191 > Endocrine System > Flashcards

Endocrine System Flashcards

1
Q

Define homeostasis?

A

The presence of a stable internal environment

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2
Q

The normal range of a given variable is specific to…

A

each individual

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3
Q

Is the population reference range tending to be wider or thinner than an individual’s range?

A

Wider

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4
Q

Can an individual’s normal range move out of the population range?

A

Yes

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5
Q

True or False?

An individual cannot experience symptoms if outside of the population reference range.

A

False

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6
Q

What is the synaptic (or neural) system?

A

involves endocrine gland cells that secrete hormones that are carried in the bloodstream to act on target cells.

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7
Q

Is the synaptic system slow or fast?

A

Slow but produces long responses that are widespread.

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8
Q

What are hormones?

A

chemical messengers that are produced in one location and travel to the target cell via the bloodstream to cause a repsonse.

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9
Q

What can hormones act upon?

A

cells that have specific receptors to the hormone either in the target cell membrane or inside the target cell.

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10
Q

What is the chemical classification of water-soluble hormones?

A

Peptides (75%) and catecholamines

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11
Q

What is the chemical classification of lipid-soluble hormones?

A

Steroids, thyroid hormones

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12
Q

What is the storage for water-soluble hormones?

A

Stored until required

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13
Q

What is the storage for lipid-soluble hormones?

A

Made when required

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14
Q

What is the transport system for water-soluble hormones?

A

Dissolved in the blood

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15
Q

What is the transport system for lipid-soluble hormones?

A

Bound to a carrier protein in the blood.

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16
Q

Where is the receptor location for water-soluble hormones?

A

Cell membrane

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17
Q

Where is the receptor location for lipid-soluble hormones?

A

Intracellular – in cytoplasm or nucleus

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18
Q

What is the response speed for water-soluble hormones?

A

Rapid

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19
Q

What is the response speed for lipid-soluble hormones?

A

Slow

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20
Q

What is the mechanism of action for water-soluble hormones?

A
  1. Hormone binds to a receptor on the target cell membrane, activating an associated G-protein.
  2. The G-protein either activates/inhibits adenylyl cyclase or increases intracellular Ca2+.
  3. A 2nd messenger is produced or reduced.
  4. Downstream proteins/pathways are either activated or deactivated.
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21
Q

What is the mechanism of action for water-soluble hormones?

A

Before acting, lipid-soluble hormones must dissociate from a carrier protein.

  1. Hormone diffuses across the cell membrane and binds to an intracellular receptor.
  2. hormone-receptor complex acts as a transcription factor.
  3. A target gene is activated and transcribed to make mRNA.
  4. mRNA is translated to make a new protein.
  5. This protein mediates a cell-specific response.
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22
Q

What does the amount of hormone in the blood depend on?

A

Hormone secretion and the rate of removal from the blood

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23
Q

What leads to endocrine disorders?

A

if hormone levels are not controlled

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24
Q

What is negative feedback?

A

The maintenance of a function when it exceeds the normal range

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25
Q

What is the pancreas?

A

exocrine gland due to its pancreatic acini cells that secrete digestive enzymes and is also an endocrine gland due to its pancreatic islets

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26
Q

What are pancreatic islets?

A

contains beta cells and alpha cells

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27
Q

What do beta cells secrete?

A

insulin

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28
Q

What do alpha cells secrete?

A

glucagon

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29
Q

What should blood glucose concentration be?

A

between 70 and 110 mg dL-1

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30
Q

What are the 2 metabolic states that individuals move between?

A

Fed state and fasting state

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31
Q

What is the fed state?

A

cellular uptake of nutrients, anabolic metabolism – glycogen, protein and fat synthesis.

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32
Q

What is the fasting state?

A

mobilisation of nutrients, catabolic metabolism – glycogen, protein and fat breakdown.

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33
Q

What is the function of insulin?

A

Increase fuel storage

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34
Q

What is the function of glucagon?

A

Increase fuel release

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35
Q

What is Secreted in response to insulin?

A

Increased blood glucose concentration

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36
Q

What is Secreted in response to glucagon?

A

Decreased blood glucose concentration

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37
Q

What is secreted by insulin?

A

Pancreatic islet beta cells

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38
Q

What is secreted by glucagon?

A

Pancreatic islet alpha cells

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39
Q

What influence does insulin have on the liver?

A

Glucose output stops, increased net glucose uptake

Glycogen and fat synthesis

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40
Q

What influence does glucagon have on the liver?

A

Increased breakdown of glycogen

Increase glucose and ketone synthesis

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41
Q

What effect does insulin have on muscles cells?

A

Increased glucose uptake

Increased amino acid uptake, glycogen and protein synthesis

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42
Q

What effect does insulin have on adipose cells?

A

Increased glucose uptake and fat synthesis

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43
Q

What is the overal effect of insulin?

A

Decreased blood glucose concentration

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44
Q

What is the overall effect of glucagon?

A

Increased blood glucose concentration

Increased blood ketones concentration

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45
Q

What is the pituitary gland?

A

found attached to the hypothalamus, inferior to the brain, and has posterior and anterior lobes

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46
Q

What does the hypothalamus control?

A

pituitary secretion of hormones via neural and hormonal input

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47
Q

What are pituitary hormones?

A

act on target cells or stimulate secretion of further hormones by other glands.

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48
Q

What is the connection to the hypothalamus for the posterior pituitary?

A

Via neurons whose axons extend into the pituitary

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49
Q

What is the connection to the hypothalamus for the anterior pituitary?

A

Via blood vessels

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50
Q

What is the hormone synthesis posterior pituitary?

A

Made in neuron cell bodies in the hypothalamus

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51
Q

What is the hormone synthesis and storage for the posterior pituitary?

A

pituitary

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52
Q

What is the storage for the posterior pituitary?

A

stored in axon terminals in the pituitary

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53
Q

What is the storage for the anterior pituitary?

A

pituitary

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54
Q

What is the action of the hypothalamus on the gland for the posterior pituitary?

A

Neural communication to stimulate hormone release

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55
Q

What is the action of the hypothalamus on the gland for the anterior pituitary?

A

Endocrine communication using releasing hormones to stimulate or inhibit hormone release by binding to cell membrane receptors.

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56
Q

What is the travel of hormones for the posterior pituitary?

A

Blood vessels

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57
Q

What is the travel of hormones for the anterior pituitary?

A

Blood vessels

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58
Q

What is an example of a (peptide) hormone for the posterior pituitary?

A 
Antidiuretic hormone (kidney water reabsorption)
Oxytocin (uterine contraction, release of breast milk)
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59
Q

What is an example of a (peptide) hormone for the anterior pituitary?

A

Prolactin

Growth hormone

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60
Q

What is the anterior pituiatary?

A

releasing hormone stimulates pituitary hormones which stimulate another hormone

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61
Q

What is the growth hormone directly act on?

A

muscle, liver and fat cells

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62
Q

What does growth hormone stimulate?

A

protein synthesis

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63
Q

What does growth hormone inhibit?

A

glucose uptake in muscle cells, glucose synthesis in liver cells and triglyceride breakdown in fat (adipose) cells

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64
Q

What does growth hormone promote?

A

promotes bone, muscle and other tissue growth by causing the release of Somatomedin C (a hormonal growth factor) that promotes cell division

65
Q

When is the growth hormone at its highest conc?

A

During sleep and in a lifetime as a child

66
Q

Where is the growth hormone released from?

A

the anterior pituitary gland in response to growth hormone-releasing hormone (GR-RH)

67
Q

Where is a growth hormone-releasing hormone (GR-RH) released from?

A

GHRH neurons in the hypothalamus.

68
Q

What is growth hormone inhibited by?

A

the release of growth hormone inhibiting hormone (GH-IH or somatostatin - SS)

69
Q

What is the release of growth hormone inhibiting hormone (GH-IH or somatostatin - SS) released by?

A

somatostatin neurons in the hypothalamus.

70
Q

Where is the thyroid gland located?

A

inferior to the larynx and covers the anterior and lateral surfaces of the trachea.

71
Q

What is the thyroid gland composed of?

A

Spherical sacs called follicles, which are surrounded by follicular cells that function to synthesise thyroid hormones. Clear cells are clustered in the gaps between follicles and function to synthesise calcitonin

72
Q

What is the thyroid hormone?

A

a hormone essential for metabolic activity.

73
Q

What hormone is involved in calcium homeostasis?

A

Calcitonin

74
Q

What is thyroglobulin (TGB) made up of?

A

thyroid follicles

75
Q

What does iodine react with when it enters the blood?

76
Q

What does iodine reacting with tyrosine form?

A

thyroid hormone

77
Q

What does the thyroid hormone do when it is needed?

A

detach from TGB and travel bound to a carrier protein to target cells

78
Q

What are the 2 types of thyroid hormones?

A

T3 – the active form, and T4 – the more plentiful form

79
Q

What is the action of T3?

A

First must detach from a carrier protein in the blood

  1. Enters target cell and binds to a T3 receptor (bound to a specific DNA site) in the nucleus.
  2. Specific genes are activated to transcribe mRNA.
  3. mRNA translation occurs in the cytoplasm, synthesising specific proteins (e.g. Na+/K+ pump).
80
Q

What is the response time for T3?

A

45 minutes - days

81
Q

What is the basal metabolic rate?

A

the body’s energy expenditure when the person is under basal conditions

82
Q

What are the basal conditions?

A
  • awake
  • physical and mental rest
  • lying down
  • not moving
  • at a comfortable temperature
  • fasted (12-18 hours)
83
Q

What is thyroid hormone needed for?

A

normal growth, alertness and metabolism

84
Q

What are the effects of thyroid hormone on a person metabolism?

A
  • Increases body heat production.
  • Stimulates fatty acid oxidation in a variety of tissues.
  • Increases proteolysis, mostly from muscle.
  • Stimulates carbohydrate metabolism, enhances insulin-dependent entry of glucose into cells, increases gluconeogenesis and glycogenolysis.
85
Q

What does calcium do in the body?

A

can enter the blood from our diet via absorption by the digestive tract, can be reabsorbed by the kidneys and by osteoclasts in bone

86
Q

How can calcium be lost from the body?

A

faeces, urine, or can be deposited into the bone by osteoblasts

87
Q

What hormones are involved in calcium regulation?

A

PTH, calcitriol and calcitonin

88
Q

where are the parathyroid glands found?

A

posterior aspect of the thyroid gland

89
Q

What do parathyroid glands secrete?

A

parathyroid hormone

90
Q

How is the release of PTH altered?

A

increased when plasma Ca2+ concentration is low and decreased when it is high.

91
Q

What does PTH release lead to?

A

increased bone breakdown and kidney Ca2+ reabsorption, thus leading to increased plasma Ca2+ levels.

92
Q

What does PTH stimulate?

A

conversion of vitamin D to calcitriol, which further stimulates bone breakdown and kidney reabsorption, as well as increasing intestinal Ca2+ reabsorption.

93
Q

What can bone breakdown be stimulated by?

A

calcitonin

94
Q

where are the adrenal glands situated?

A

the superior aspect of each kidney

95
Q

What are the 3 layers that secrete steroid hormones?

A
  1. Outer layer – aldosterone
  2. Middle layer – cortisol
  3. Inner later – androgens
96
Q

What is the adrenal medulla?

A

innermost region of the glands

97
Q

What does the adrenal medulla secrete mostly?

A

adrenaline

98
Q

When is noradrenaline secreted?

A

as part of the sympathetic nervous system response to stress

99
Q

Is adrenaline water-soluble?

A

yes - thus binds to cell membrane receptors and acts via a second messenger to cause a fast cellular response

100
Q

What happens when adrenaline is secreted?

A

acts with noradrenaline to cause the fright, flight or fight response in times of stress.

101
Q

A signal from the hypothalamus causes to sympathetic preganglionic fibre to send as action potential to either

A

Adrenal medulla secretory cells or sympathetic chain ganglion

102
Q

What do Adrenal medulla secretory cells secrete?

A

adrenaline (80%) and noradrenaline (20%) into the bloodstream to act on effector cells.

103
Q

What does sympathetic chain ganglion do?

A

send an AP down sympathetic postganglionic fibres, which synapse onto effector cells and secrete noradrenaline.

104
Q

What does adrenaline act on?

A

skeletal muscle and liver cells to increase the breakdown of glycogen, and on fat cells to increase the breakdown of fat to fatty acids.

105
Q

What does the anterior pituitary secrete?

106
Q

What does ACTH stimulate?

A

the middle layer of the adrenal cortex to secrete cortisol.

107
Q

What is cortisol?

A

steroid hormone

108
Q

When is cortisol produced?

A

as required and is carried through the blood via a carrier protein

109
Q

When is cortisol concentration at its highest?

110
Q

What are the effects of cortisol in response to stress?

A

• Increasing:
o Blood glucose levels
o Fat, protein and carbohydrate metabolism to maintain blood glucose concentration
o Blood pressure
o Heart and blood vessel tone and contraction
• Promoting anti-inflammatory actions
• Activation of the CNS

111
Q

What is cortisol secretion controlled by?

A

negative feedback

112
Q

What is cortisol secretion stimulated by?

A

ACTH secretion

113
Q

What is ACTH secretion stimulated by?

114
Q

What is the result of cortisol?

A

stimulates protein breakdown and decreased glucose uptake in muscle cells, increased fat breakdown and decreased glucose uptake in fat cells, and increased glucose synthesis in liver cells

115
Q

What are the other effects of cortisol?

A

including helping to cope with stress, maintenance of blood pressure and in the long-term it suppresses the immune system

116
Q

What is Hyposecretion

A

too little (or no) hormone secreted

117
Q

What is Hypersecretion

A

too much hormone secreted

118
Q

What is Hyposensitive

A

receptors have little (or no) response

119
Q

What is Hypersensitive

A

receptors respond too much

120
Q

What is Autoimmunity

A

destruction of receptors

121
Q

What is Genetic mutation

A

gain or loss of function caused by mutations

122
Q

What is Tumors

A

excess tissue leads to hypersecretion, can sometimes prevent release

123
Q

What is Addison’s disease?

A

hyposecretion of cortisol and aldosterone

124
Q

What are the effects of Addison’s disease?

A

Lowered cortisol leads to increased ACTH secretion, stimulating melanin synthesis which darkens the pigment of your skin. It also can result in low blood pressure and weakness (due to lack of fuel)

125
Q

What is Addison’s disease caused by?

A

autoimmunity and other factors

126
Q

What is Cushing’s disease?

A

hypersecretion of cortisol

127
Q

What are the effects of Cushing’s disease?

A

. This results in high blood pressure and weakness (due to muscle wasting).

128
Q

What is Cushing’s disease caused by?

A

tumors and other factors

129
Q

How does CRH respond when the hypothalamus senses stress?

A
  1. Anterior pituitary secretes ACTH
  2. Further APs in sympathetic preganglionic fibres
  3. Posterior pituitary secretes ADH
130
Q

What are the effects of ACTH?

A
  • Stimulates the adrenal cortex to synthesise and secrete cortisol
  • Cortisol increases blood glucose and blood pressure
131
Q

What are the effects of adrenaline?

A

• Synapse on the adrenal medulla, stimulating adrenaline secretion
o Increased blood glucose, heart rate and blood pressure

132
Q

What are the effects of ADH?

A
  • Decreased water excretion in kidneys

* Increased blood volume and blood pressure

133
Q

What does the hypothalamus stimulate during stress?

A

adrenal glands, SNS and the posterior pituitary

134
Q

What are the 3 phases of stress response?

A

alarm phase
resistance phase
exhaustion phase

135
Q

What is the alarm phase?

A

general sympathetic system is activated, causing pupil and blood vessel dilation, increased heart rate and force of contraction, and other responses.

136
Q

What is the resistance phase?

A

Many effects on the body

137
Q

What is the exhaustion phase caused by?

A

prolonged stressful stimuli and can lead to heart attacks.

138
Q

What does hyposecretion of GH lead to?

139
Q

What does hypersecretion of GH lead to?

140
Q

What is infantile hypothyroidism caused by?

A

hyposecretion of thyroid hormone

141
Q

What are the effects of infantile hypothyroidism?

A

low metabolic rate, cold intolerance, retarded growth and inhibition of brain development.

142
Q

What is infantile hypothyroidism caused by?

A

by iodine deficiency in the mother’s diet

143
Q

What is a simple goitre?

A

Iodine deficiency disorder

144
Q

What is simple goitre a result of?

A

hyposecretion of thyroid hormone

145
Q

What are the effects of simple goitre

A

When the thyroid hormone store is depleted, the secretion of TRH and TSH increases in attempt to stimulate the thyroid to make more hormone. This excess of TSH leads to thyroid gland growth.

146
Q

What is graves disease?

A

hypersecretion of thyroid hormone

147
Q

What are the effects of graves disease?

A

high metabolic rate, weight loss, heat intolerance, increased heart rate, nervousness, hair loss, exophthalmos (bulging eyes) and thyroid swelling.

148
Q

What is graves disease caused by?

A

autoimmune disorders

149
Q

What is Hyperparathyroidism a result of?

A

hypersecretion of parathyroid hormone, normally as a result of parathyroid tumours

150
Q

What does Hyperparathyroidism cause?

A

bones to become soft, deformed and fragile. This also causes increased levels of calcium and phosphate in the blood and promotes the formation of calcium phosphate kidney stones.

151
Q

When does Hypercalcaemia occur?

A

levels of calcium in the blood are low

152
Q

What are the effects of Hypercalcaemia?

A

increased excitability of the nervous system due to a shift in RMP to -60 mV. This results in muscle tremors, spasms or cramps. When extremely low this can cause paraesthesia in the hands and face, muscle cramps and laryngospasm which can lead to suffocation

153
Q

What is Hypercalcaemia caused by?

A

vitamin D deficiency, diarrhoea, thyroid tumours, underactive parathyroid glands, pregnancy and lactation.

154
Q

What is type 1 diabetes a result of?

A

hyposecretion of insulin caused by the destruction of pancreatic beta cells by the immune system

155
Q

What is type 2 diabetes a result of?

A

hyposensitivity to insulin caused by desensitisation of insulin receptors. This is associated with obesity

156
Q

What can diabetes result in?

A

glucosuria, polyuria, polydipsia, diabetic neuropathy, heart problems, diabetic retinopathy, disrupted blood flow and more

157
Q

What can increase blood glucose concentration?

A

Growth hormone, adrenaline and cortisol, as well as glucagon

158
Q

When might there need to be changed in a set point?

A

change in altitude, due to the need for higher oxygen-carrying capacity in blood cells. Different climates result in BMR changes. Fevers result in temporary changes in body temperature.

HUBS 191 (5 decks)

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