Module 5: Hormonal Communication Flashcards
1
Q
Effects of peptide hormones:
A
Fast changes in protein activity though sometimes changes to gene expression may occur
2
Q
What is a hormone?
A
A hormone is a chemical messenger that is transported via the bloodstream to act on target cells.
3
Q
Major Endocrine Glands:
A
Pituitary Gland, Pineal gland, Thyroid Gland, Pancreas, Adrenal gland, Ovary, Testis
4
Q
Pineal Gland:
A
Pineal Gland produces melatonin - functions biological clock
5
Q
Pituitary Gland:
A
FSH/ LH, ADH, growth hormone, oxytocin, prolactin - multiple functions.
6
Q
FSH/LH
A
Found in the ovaries and aids menstrual cycle
7
Q
ADH:
A
Kidneys - osmoregulation
8
Q
Growth hormone:
A
many target organs -> growth and division.
9
Q
Oxytocin:
A
Uterus - birth contractions
10
Q
prolactin:
A
breast tissue - milk production
11
Q
Thryroid Gland:
A
Produces thyroxin which controls metabolic rate in the liver.
12
Q
Adrenal Glands:
A
Produces Adrenaline and cortisol which target many organs.
13
Q
Testes:
A
testosterone targets many organs to develop male characteristics.
14
Q
Ovaries:
A
Estrogen/ progesterone - target uterus and control menstrual cycle.
15
Q
What are the 3 types of hormones?
A
Steroid hormones, peptide hormones and amino acid derivatives.
16
Q
Steroid Hormones:
A
Lipophilic so can freely diffuse across the plasma membrane.
Bind to receptors in either cytoplasm or nucleus.
Forms receptor-hormone complex which moves into the nucleus and stimulates/inhibits transcription.
17
Q
Peptide Hormones:
A
Hydrophilic so cannot freely cross the plasma membrane.
Bind to receptors on the cell surface membrane.
Activates a series of intracellular molecules (second messengers) that regulate cell activity through a cascade reaction.
18
Q
Amine Hormones:
A
Derived from amino acid tyrosine.
They don’t all share identical properties.
19
Q
Synthesis of Peptide Hormones:
A
Sythesised as prohormones which must then be activated
20
Q
Synthesis of Steroid Hormones:
A
Synthesised in a series of reactions of from cholesterol.
21
Q
Synthesis of Amino acid derivative Hormones:
A
Synthesised from the amino acid tyrosine.
22
Q
Storage of Peptide hormones:
A
Stored in vessicles.
23
Q
Storage of Steroid hormones:
A
Not stored- released immediately
24
Q
Storage of Amino acid derivatives hormones:
A
Stored before release (storage mechanism vessicles)
25
Solubility of Peptide Hormones:
Tend to be polar and water soluble, travelling freely in the blood.
26
Solubility of steroid hormones in water:
Non-polar and require carrier proteins to travel in the blood.
27
Solubility of amino acid derivative:
Some are polar and others must be protein-bound.
28
Receptors of peptide hormones:
Bind to receptors on cell surface membrane and stimulate the release of second messenger molecules
29
Receptors of steroid hormones:
Bind to intracellular receptors to change gene expression directly.
30
Effects of steroid hormones:
Alterations in gene expression, slower onset with long duration.
31
Effects of Amino Acid derivative hormones:
Adrenaline functions like peptides. Thyroid hormones act similar to steroids.
32
Adrenal Cortex:
Produces hormones vital to life.
Produces steroid based hormones.
Controlled by hormones secreted by pituitary gland.
33
What are the 3 groups of hormones released by the adrenal cortex?
Glucocorticoids, Mineralocorticoids, Androgens
34
Adrenal Medulla:
Produces non-essential hormones (adrenaline and noradrenaline (neurotransmitter))
Produces amine based hormones.
Triggered by sympathetic stimulation.
35
Where is the pancreas located?
Located to the rear of the bottom half of the stomach.
36
What are the two types of function of the pancreas?
Endocrine and Exocrine.
37
What is the exocrine function of the pancreas?:
To secrete a variety of digestive enzymes and alkaline pancreatic juice into the pancreatic duct to the duodenum.
38
What is the endocrine function of the pancreas?:
To secrete glucagon, insulin, somatostatin, and pancreatic polypeptide into the blood via fenestrated capillaries.
39
On a micrograph what is the appearance of islets of Langerhans?
Lightly stained, large spherical clusters.
40
On a micrograph what is the appearance of pancreatic acini?
Darker stained, small berry-like clusters.
41
What is the name of the cells on the inside of a duct at the acini?
centroacinar cells
42
What is the purpose of the many fenestrated capillaries permeating islets of Langerhans?
Quick diffusion of pancreatic hormones into the blood.
43
What separates the islets of Langerhans from the Acini?
A delicate sheath of reticular fibres
44
What kind of staining method is used to differentiate between alpha and beta cells in pancreatic islets?
Differential Staining, because standard techniques is less clear.
45
Beta cells:
Filled with insulin granules.
| Secrete insulin
46
Alpha cells:
Filled with glucagon granules. Secrete glucagon, larger than beta cells and located peripherally in the islet.
47
What are the "White gaps" between cells?
Connective tissue (Don't draw large gaps between cells)
48
What is the most common effect of diabetes?
Hyperglycaemia (blood glucose level above safe range)
49
What are the three ways in which glucose enters the bloodstream?:
Absorption in the gut following carbohydrate digestion.
Hydrolysis of glycogen stores.
Non-carbohydrates (e.g lipids, lactate and amino acid) into glucose.
50
Why does the amount of glucose absorbed into the blood from products of digestion vary substantially?
Some meals are much more carbohydrate-rich.
51
Without meals do blood glucose levels still fluctuate?
Yes, they fluctuate around a set point.
52
Why do blood glucose levels fluctuate?
Blood glucose levels are constantly changing as blood glucose is being absorbed by skeletal muscle tissue and released at the liver and adipose tissue. Furthermore, insulin and glucagon are worked as a part of a negative feedback mechanism.
53
Why does glucose need to be in the blood?
To be transported to cells to provide glucose for cellular respiration to produce ATP.
54
Why is Hyperglycaemia harmful?
The high glucose levels cause the tissue fluid to be hypertonic to the blood, causing water to leave cells into the blood, damaging cells and also reducing chemical reactions.
55
What is the name of the process where glycogen is broken down in the liver to release glucose?
Glycogenolysis.
56
What is the name of the process where glucose is made from non-carbohydrate sources?
gluconeogenesis.
57
Where are glucagon receptors located?
Liver and fat cells.
58
What two responses to glucagon slow down the decrease of blood glucose levels?
Reducing the absorption of glucose into liver cells.
| Decreasing the rate of glucose breakdown (by decreasing the rate of cell respiration)
59
Summary outline of the link between cell signaling and glucagon:
Alpha cells secrete glucagon. Glucagon binds to receptors on the cell surface membrane of liver cells, causing a conformation change. The confirmation change activates a G-protein which activates an enzyme that catalyzes the production of a second messenger. This leads to a cascade of reactions leading to the breakdown of glycogen into glucose.
60
What cells have insulin receptors?:
Most cells.
61
Why, after cells have let in lots of glucose, must the cells use/ dispose of the glucose?:
The cells will become hypertonic to the blood, risking cell lysis. Therefore the cells try to "use up" the glucose to reduce this risk.
62
How does insulin reduce blood glucose levels?:
It increases the absorption of glucose into cells, by increasing cell surface membrane permeability to glucose.
Insulin also activates enzymes within liver and adipose cells that convert glucose into glycogen.
Increases the rate of glucose breakdown (higher respiration rates)
63
What is Glycogenesis?
The conversion of glucose into glycogen.
64
How does insulin increase the uptake of glucose into cells?
Insulin binds to specific receptors on the membranes of target cells. This releases a chemical signal which stimulates the production vesicles lined with glucose transporter proteins. These vesicles fuse with the cell surface membrane, increasing the permeability of the cell to glucose. This increases the rate of facilitated diffusion.
65
Outline the stages of events leading to the secretion of insulin.
Concentration of blood glucose is high -> Glucose molecules enter the Beta-cell by facilitated diffusion -> the cell respires the glucose to produce ATP - > ATP causes the K+ channels to close -> prevent K+ ions from leaving cell -> depolarises membrane -> voltage-gated Ca2+ channels open -> influx of Ca2+ ions causes insulin-containing vesicles to move towards the membrane, where they fuse through exocytosis and release insulin into the capillaries.
66
What is the increased thirst experienced by diabetes sufferers caused by?
Cells don't have enough water due to blood's hypertonicity.
67
What is the increased urination experienced by diabetes sufferers caused by?
The hypertonicity of the water compared to surrounding tissues, increases the water content of the blood -> Excess water in blood leads to less ADH production -> less water is retained in DCT and collecting duct
68
Acute (short term/ fast-acting) complications of Diabetes:
Diabetic ketoacidosis, hyperosmolar hyperglycaemia, or death.
69
Chronic complications of Diabetes:
Cardiovascular disease, stroke, chronic kidney disease, foot ulcers, and damage to eyes.
70
Diabetes Type 1:
Insulin is not produced by Beta cells.
Cannot detect high levels of glucose or release insulin.
Lack of insulin affects glycogen stores, causing fatigue.
Unknown cause - potentially autoimmune?
Treated with insulin injections.
Usually occurs during childhood.
71
Diabetes Type 2:
High glucose + high insulin levels have caused the body to become resistant.
Associated with inactivity, excess weight, consumption of refined carbohydrates.
Treated with medication, insulin injections, or control of diet.
72
On a blood-glucose concentration graph what does a slow decrease tell you?
The person is likely diabetic.
73
How does type 2 diabetes occur?
Prolonged overproduction of insulin leads to desensitisation of insulin receptors and-so (more) glucose is not removed from the bloodstream.
74
Treating Diabetes: Pancreas Transplant
80% successful in removing the symptoms, however donor organs are rare.
Injected Beta Cells have an 8% success rate, immunosuppressant drugs eventually stop cells producing insulin.
75
Advantages of Stem cells for treating diabetes:
Overcomes donor organ problem, reduced cell transplant rejection, insulin injections abundant.
76
Disadvantages of Stem cells for treating diabetes:
destruction of human embryos, injected stem cells could become cancerous tumours, due to limited ability to control them.
77
Adrenocortical system:
Release of longer term stress hormones from the adrenal cortex is coordinated by hormones from the pituitary gland. This occurs when the hypothalamus stimulates the pituitary gland to secrete ACTH.
78
Sympathetic System:
Stimulates adrenal medulla to release stress hormones.
79
Fight or Flight: Step 1
Autonomic nervous system detects a threat.
80
Fight or Flight: Step 2
Hypothalamus communicates with the sympathetic nervous system, and the adrenal cortical system.
81
Fight or Flight: Step 3
The sympathetic nervous system uses nervous impulses to stimulate the adrenal medulla, glands and smooth muscle to respond appropriately.
82
Fight or Flight: Step 4
Hypothalamus communicates with pituitary gland.
83
Fight or Flight: Step 5
Pituitary gland releases ACTH
84
Fight or Flight: Step 6
Stimulates the adrenal cortex to release cortisol and corticosterone.
85
Corticosterone:
Suppresses the immune system and inflammatory responses.
86
Cortisol:
Increases blood pressure, increase blood sugar, suppresses immune system.
87
Adrenaline (Physical properties):
Polar (hydrophilic), amino acid derived hormone.
88
Action of Adrenaline:
Adrenaline binds to complimentary receptors.
This activates the enzyme adenyl cyclase via an anchored g protein.
This catalyses the reaction of ATP into cAMP, which acts as a secondary messenger and activates protein kinases, which phosphorylate other enzymes.
The glycogen then undergoes glycolysis into glucose.
89
Action of adrenaline in cardiac tissue.
Depolarises the cell membrane of SAN cells.
90
Basal Heart Rate:
The heart rate resulting form the myogenic pacemaker cells.
91
Effects of Adrenaline:
Increases heart rate, blood glucose concentration levels.
92
Noradrenaline as a hormone:
Increases heart rate, widens pupils, widening air passages in the lungs and narrowing blood vessels near non-essential organs.
