Endocrine Flashcards
1
Q
Regulated variable definition
A
A variable for which there is a sensor and a system to ensure the variable is kept within a normal range, around a set point
2
Q
Normal range definition
A
Restricted set of values for a regulated variable that permits optimal cell functioning, i.e dynamic about set point
3
Q
Set point
A
The physiological value of any given variable around which its normal range fluctuates. Each person has a unique set point
4
Q
Population reference range
A
The set of values for a regulated variable that are considered normal and/or healthy (wider than any individual’s normal range) 95% of individuals will have a set point within this reference range
5
Q
Purpose of negative feedback and example
A
Keep a regulated variable within its normal range, around its set point
e.g core temperature
6
Q
Feedback control loop: sensors
A
Monitor variable and detect changes
7
Q
Feedback control loop: control centre
A
Compares variable’s changed value to its set point. Sends signals to effector if correction (or amplification) required
8
Q
Feedback control loop: effectors
A
Act to oppose (or amplify) effect of stimulus, thereby correcting (or exacerbating) change and restoring variable to set point if negative
9
Q
Purpose of positive feedback and exmaple
A
Amplification: drives a process to completion
e.g breast milk release
10
Q
What is the endocrine system characterised by
A
Chemicals released into the blood, slower but longer lasting effects than nervous system
11
Q
Hormone definition
A
Chemicals released by endocrine gland cells, travel through blood, bind to receptors on or in target cell, made from amino acids or cholesterol
12
Q
Thyroid gland location
A
Wraps around anterior of trachea
13
Q
Adrenal gland location
A
On top of kidneys
14
Q
Lipid soluble hormones
A
Require carrier proteins to travel in blood, bind to intracellular receptors (e.g thyroid hormone)
15
Q
Water soluble hormones
A
Don’t require carrier proteins, bind to receptors on cell membrane (e.g adrenaline)
16
Q
Cellular response of lipid soluble hormones
A
Stimulate creation of new proteins (stimulates gene transcription), often enzymes to produce a response.
17
Q
Cellular response of water soluble hormones
A
Bind to membrane receptors, activate a 2nd messenger system to produce an amplified response (small amount of hormone = big response)
18
Q
When do hormone effects stop
A
When it unbinds from receptor, used or excess hormone gets broken down and/or recycled, or excreted
19
Q
Lipid soluble hormone types
A
Amines (thyroid hormones), steroids
20
Q
Water soluble hormone types
A
Amines (catecholamines), peptides and proteins
21
Q
What are catecholamines
A
Adrenaline (epinephrine) and norepinephrine (noradrenaline)
22
Q
What type of hormone is cortisol
A
Steroid
23
Q
Are water soluble hormones pre made or made to demand
A
Pre made and stored until needed
24
Q
Are thyroid hormones pre made or made to demand
A
Pre made and stored
25
Are steroids pre made or made to demand
Made as required
26
Do lipid or water soluble hormones have a faster cellular response
Water soluble as lipids stimulate synthesis of proteins which takes time
27
How does the water soluble hormone action mechanism occur
Binds to receptor on membrane, activating attached G protein which activates or inhibits 2nd messengers (e.g cAMP or Ca2+) which affect actions of other proteins
28
Why do water soluble hormones have a faster response
2nd messengers are already pre made
29
2nd messenger examples
cAMP, Ca2+
30
Do water or lipid soluble hormones have longer lasting effects
Lipid: lasts hours to days
Water: lasts milliseconds to minutes
31
Which glands are involved in plasma calcium concentration homesostasis
Thyroid gland, parathyroid glands and kidneys
32
How does the body use calcium
2nd messenger which affect actions of other proteins, interacts with vesicles to facilitate release of neurotransmitter, interacts with myofilaments to facilitate cross bridge formation, stored in bones as hydroxyapatite
33
Where is most calcium stored
In the bones (99%)
34
How does calcium enter the blood plasma
Absorbed into blood from digestive tract, reabsorbed into blood from bone broken down by osteoclasts, reabsorbed back into blood by kidneys
35
How does calcium exit the blood plasma
Osteoblast activity during bone remodeling and growth, filtered out of blood by kidneyslo
36
Parathyroid glands location
Posterior of thyroid hormone (4)
37
What do parathyroid glands secrete
Parathyroid hormone (PTH)
38
What is the most important hormone in calcium homeostasis
Parathyroid hormone
39
What does parathyroid hormone stimulate the kidneys to secrete
Calcitriol
40
What does the thyroid gland secrete in calcium homeostasis
Calcitonin (minor role)
41
What effect does calcitriol have on the digestive system
Calcium absorption by blood increased
42
What type of hormone is parathyroid hormone
Water soluble
43
What effect does PTH have on bones
More calcium resorption (more calcium into plasma)
44
What effect does PTH have on kidneys
More calcium reabsorbtion from pre-urine filtrate (more calcium into plasma), more vitamin D converted to calcitriol (acts on digestive tract, kidneys and bone)
45
What effect does an increase of plasma calcium have on parathyroid glands
Decreased secretion of PTH
46
What effect does a decrease in plasma calcium have on parathyroid glands
Increased secretion of PTH
47
What effect does calcitonin have have on bone
Less calcium resorption by osteoclasts (less calcium into plasma)
48
What effect does calcitonin have on kidneys
Less calcium reabsorption from pre-urine filtrate (less calcium into plasma)
49
How does the body use glucose
All body cells use glucose as the main substrate for making ATP, make other substances essential for functioning (e.g gylcoproteins), stored as glycogen or fat
50
How does glucose enter the blood plasma
Absorbed from digestive tract, released into blood by liver
51
How does glucose exit the blood plasma
Removed from blood by all body cells, stored in liver and skeletal muscle as glycogen, and in adipose as fat
52
Pancreas location
Behind stomach on left side of abdomen
53
Which pancreatic islet cells secrete which hormone
Alpha cells secrete glucagon, beta cells secrete insulin
54
What does glucagon stimulate (glucose gone)
Gluconeogenesis, glycogenolysis, ketone synthesis
55
What does insulin stimulate (in, in)
All body cells increase uptake of glucose, liver and skeletal muscle cells take excess glucose from blood to store as glycogen, adipose store excess as fat
56
What type of hormone is calcitriol
Water soluble
57
What type of hormone is calcitonin
Water soluble
58
What is the goal of PTH
Increase calcium
59
What is the goal of calcitonin
Decrease calcium
60
What is the goal of calcitriol
Increase calcium
61
Which connection has a portal bloodstream
Hypothalamus to anterior pituitary
62
How to identify anterior and posterior pituitary
Anterior has big belly
63
Where do posterior pituitary hormones come from
Made in hypothalamic neuron cell bodies, then travel down axon and are stored in the axon terminals. Released into main bloodstream when action potential depolarises axon terminal
64
Posterior pituitary hormones
Oxytocin and ADH
65
What does oxytocin do
Stimulates milk release during infant feeding, stimulates contraction of uterine walls during childbirth (both positive feedback)
66
What does ADH do
Stimulates kidney to reabsorb water when a person is dehydrated
67
Where do anterior pituitary hormones come from
Anterior pituitary cells (hypothalamic neurons secrete releasing or inhibiting hormones that travel via a blood portal system to anterior pituitary, bind to membrane receptors on anterior pituitary cells causing anterior pituitary hormones release)
68
Anterior pituitary hormones
Growth hormone, thyroid stimulating hormone, adrenocorticotropin hormone
69
What does growth hormone do
Stimulates liver, skeletal muscle and adipose for fuel mobilisation, stimulates liver to release IGF-1 for growth
70
What does TSH do
Stimulates thyroid to release thyroid hormones to increase BMR
71
What does ACTH do
Stimulates adrenal gland (cortex) to release cortisol in a daily pattern and during the stress response
72
What negatively feeds back on releasing and inhibiting hypothalamic hormones
3rd hormone from target endocrine organ
73
Hypothalamic-pituitary-thyroid hormones
Thyrotropin releasing hormone, thyroid stimulating hormone (anterior), thyroid hormones (T3, T4)
[T!! for thyroid]
74
What do the thyroid hormones do
Increase BMR, stimulation of growth in foetus and childhood, increased mental alertness
75
How are thyroid hormones made
Tyrosine (Y) binds to iodine in cells lining thyroid follicles, in thyroglobulin protein (made by thyroid follicles)
76
What hormones do the thyroid gland secrete
Thyroid hormones (T3 and T4), and calcitonin
77
What does calcitonin do
Minor hormone involved in calcium homeostasis
78
What is T3
Thyroid hormone: tyrosine with 3 iodine
79
What is T4
Thyroid hormone: tyrosine with 4 iodine
80
How are thyroid hormones released
T3 and T4 detach from iodised TGB as they're needed
81
How do lipid soluble hormones have an effect
Bind to receptors in nucleus, specific genes activated to transcribe mRNA, specific proteins synthesised leading to effect (45 minutes - days)
82
What is BMR
The energy the body requires for its most basic functions to sustain life
83
How do thyroid hormones increase BMR
Increase thermogenesis (body heat production), oxygen consumption and ATP production and use, fat and protein breakdown. Also have complex interaction with various organs to ensure enough glucose is available for metabolic processes without significantly disturbing plasma glucose homeostasis
84
When are growth hormone concentrations the highest
During sleep (higher in children and highest at puberty)
85
What are the direct effects of growth hormone
Fuel mobilisation:
Muscle: inhibits cellular uptake of glucose, stimulates protein synthesis
Liver: stimulates glucose synthesis
Adipose: increases fat breakdown
86
What are the indirect effects of growth hormone
Growth:
Via insulin-like growth factor 1, secreted by liver, promotes growth of bones, muscle and other tissue
87
Hypothalamic-pituitary-liver hormones
GHRH, GHIH -> GH -> IGF-1
[G!! Need to Grow to Live]
88
Hypothalamic-pituitary-adrenal hormones
CRH -> ACTH -> Cortisol
[C!! adrenal Cortex]
89
What does cortisol do
Mobilises fuel (liver, muscle, adipose, pancreas (glucagon)), maintains normal blood pressure (unsure how), suppresses/reduces inflammation to increase immunity
90
When is cortisol highest during a day
When you first wake up (sleep patterns disturbed = disturbed cortisol secretion)
91
Where is cortisol secreted from
Adrenal cortex
92
Where is aldosterone secreted from
Adrenal cortex
93
Where are catecholamines secreted from
Adrenal medulla
94
What are catecholamines
Adrenaline (epinephrine) and noradrenaline (norepinephrine)
95
What are the three stages of the stress response
Alarm, resistance, exhaustion
96
What physically happens in the alarm phase
Increased breathing rate (more oxygen), heart rate and blood pressure (circulation of oxygen and glucose to brain and skeletal muscle), dry mouth (reduced activation of unnecessary functions), dilated pupils
97
What is the control centre for sympathetic and parasympathetic nervous systems
Hypothalamus
98
What does stress trigger the hypothalamus to do
Activate sympathetic nervous system
99
What hormone do sympathetic nerves trigger the release of in the alarm phase
Adrenaline and noradrenaline from the medulla of the adrenal gland
100
What do catecholamines do in the stress response
Bind to membrane receptors and lead to amplification of cellular responses to help the body deal with stress
101
What's the name for fat breakdown in adipose cells
Lipolysis
102
What happens generally in the resistance phase
Glycogen reserves were depleted in alarm phase so lipid and protein stores need to be mobilised.
103
What is the main hormone of the resistance phase
Cortisol
104
When does the resistance phase occur
When stress lasts longer than a few hours
105
Which hormones contribute to fuel mobilisation in resistance phase
Cortisol, glucagon, adrenaline, growth hormone
106
Which hormones contribute to increased blood pressure in resistance phase
Cortisol, ADH, aldosterone
107
Which hormone contributes to reduced inflammation in resistance phase
Cortisol
108
What type of cells use fats from adipose and amino acids from skeletal muscle in resistance phase
Non neural cells
109
For which cells is glucose primarily mobilised for in resistance pahse
Neural tissue
110
How does ADH lead to increased blood pressure in resistance phase
Vasoconstriction of blood vessels, stimulates kidney to reabsorb more water into plasma
111
How does aldosterone lead to increased blood pressure in resistance phase
Stimulates kidneys to reabsorb more Na+ into plasma, so water follows
112
Why does exhaustion phase occur
The body's compensatory responses are inadequate to sustain health and energy reserves (lipid reserves) are depleted (organs damaged as structural proteins broken down)
113
Diseases linked to prolonged stress
Chronic high blood pressure, stroke, heart disease, autoimmune disease
114
What leads to organ failure in exhaustion phase
Structural proteins of organs broken down, inability to regulate plasma glucose and ion concentrations
115
What can help to relieve the effects of stress
Socialisation and altruistic acts (oxytocin turns stress into resilience), exercise, mindfulness
116
What hormones are lipid soluble
Cortisol, aldosterone, thyroid hormones (T3, T4)
117
What can go wrong with hormone signalling
Hyposecretion, hypersecretion, hyposensitivty
118
What is Addison's disease
Hyposecretion of cortisol and aldosterone
119
What causes Addison's disease
Autoimmune disease that attacks the adrenal cortex
120
What are the symptoms of Addison's disease
Low blood pressure, low blood glucose (fatigue, drowsiness, muscle weakness)
121
What is Cushing's disease
Hypersecretion of cortisol
122
What causes Cushing's disease
Adrenal cortex tumor or taking glucocorticoid medications for long periods
123
What are the symptoms of Cushing's disease
High blood pressure, thinning of arms and legs and weight gain in torso
124
What are the cortisol disorders
Addison's and Cushing's
[Addison is tired and lies on a cushion]
125
What is dwarfism
Hyposecretion of growth hormone
126
What causes dwarfism
Genetic mutation or inheritance
127
What is gigantism
Hypersecretion of growth hormone
128
What causes gigantism
Tumor in pituitary gland in childhood (resulting in too many anterior pituitary cells)
129
What is acromegaly
Hypersecretion of growth hormone
130
What causes acromegaly
Pituitary gland tumor in early adulthood
131
What are the symptoms of acromegaly
Large and irregularly shaped extremities and characteristic facial features (prominent jaw)
132
What are the growth hormone disorders
Dwarfism, gigantism, acromegaly
133
What is infantile hypothyroidism
Hyposecretion of thyroid hormone in infants
134
What causes infantile hypothyroidism
Missing or poorly developed thyroid gland, poorly functioning anterior pituitary, lack of iodine in mother's diet
135
What are the symptoms of infantile hypothyroidism
Low metabolic rate, delayed growth and development, swollen tongue and around eyes
136
What is adult hypothyroidism
Hyposecretion of thyroid hormone in adults
137
What are the causes of adult hypothyroidism
Autoimmune disease, iodine deficiency in diet, surgical removal of thyroid gland
138
What are the symptoms of adult hypothyroidism
Low metabolic rate, tiredness, weight gain
139
What is a simple goitre
Hyposecretion of thyroid hormone
140
What causes a simple goitre
Lack of iodine in diet
141
What are the symptoms of a simple goitre
Enlarged thyroid gland; a goitre
142
What is Graves disease
Hypersecretion of thyroid hormone
143
What causes Graves disease
Autoimmune disease
144
What are the symptoms of Graves disease
High metabolic rate, weight loss, bulging eyes, goitre
145
What are the thyroid hormone disorders
Infantile and adult hypothyroidism, simple goitre, Graves disease
146
What is hyperparathyroidism
Hypersecretion of parathyroid hormone
147
What causes hyperparathyroidism
Parathyroid tumor
148
What are the symptoms of hyperparathyroidism
Bones become soft, deformed and fragile, kidney stones (excess calcium build up)
149
What is hypoparathyroidism
Hyposecretion of parathyroid hormone
150
What causes hypoparathyroidism
Damaged parathyroid glands due to genetic or autoimmune disease
151
What are the symptoms of hypoparathyroidism
Muscle tetany (spasms: calcium dictates muscle contraction), seizures (neurons fire too easily)
152
What are the parathyroid hormone disorders
Hyper and hypoparathyroidism
153
What is type 1 diabetes mellitus
Hyposecretion of insulin
154
What causes type 1 diabetes
Destroyed beta islet cells by a virus or autoimmune disease
155
What are the symptoms of diabetes
Polyuria (excessive urine production), polydipsia (excessive thirst)
156
What is type 2 diabetes
Chronic insulin resistance and hyposecretion of insulin as beta cells get worn out
157
What causes type 2 diabetes
Unhealthy lifestyle (inactivity, poor diet, obesity)
158
What are the insulin disorders
Diabetes type 1 and 2
