Unit 3.2 The Endocrine System Flashcards
(112 cards)
1
Q
What is homeostasis?
A
The maintenance of dynamic equilibrium in the body.
2
Q
For cells to function normally, what do they need?
A
They need stable conditions which fluctuate within very narrow ranges.
3
Q
A number of different body systems work together (integrate) to maintain a dynamic equilibrium, which system plays an important part in maintaining homeostasis?
A
The endocrine system.
4
Q
The nervous system is able to provide fast and effective control over a whole range of body function, Sometimes there is a need to provide a sustained long term control over a whole range of body functions, what is this the role of?
A
Hormones.
5
Q
What do hormones act as?
A
Chemical messengers.
6
Q
Where are hormones produced and released?
A
They are produced in specific glands and released directly into the blood stream to control a wide range of metabolic functions.
7
Q
Which two systems act together to coordinate and regulate the functions of all of the body?
A
The nervous and endocrine systems.
8
Q
What is the difference between the nervous system and the endocrine system?
A
The nervous system acts on specific muscles and glands while the endocrine system helps to regulate virtually every type of body cell.
9
Q
The nervous system is the body’s fast acting electrical coordination system. Impulses travel around the nervous system in milliseconds but their effect is short lived.
The second control system in the body is chemical, the endocrine system.
What are the chemical messengers called?
A
In the endocrine system chemical messengers called hormones are produced.
10
Q
Where and hormones produced and how do they travel?
A
Hormones are produced in one part of the body (end endocrine glands) and transferred to another, possibly distance site by the bloodstream.
11
Q
Although the endocrine system is a much slower process than a nervous response, how are the effects different?
A
The effects of hormones can last a very long time.
12
Q
What are the mediator molecules that are released in one part of the body but regulate the effect of cells in other parts of the body?
A
Hormones.
13
Q
How long does it take for hormones to take effect?
A
They may take effect in seconds, over hours, days, months or even years.
14
Q
What do hormones (chemical messages) control?
A
Our metabolic rate, the regulation of blood sugar, and the amount of salt and water in body fluids.
15
Q
In what period of life are the effects of hormones on the body seen most dramatically?
A
During puberty - where dramatic changes occur in the physical appearance of boys and girls as they are transformed into men and women by the sex hormones released by the endocrine system.
16
Q
What are the endocrine organs, where are they found? how much do they weigh combined?
A
The endocrine organs are small and scattered around the body. The combined weight is around 0.1kg.
17
Q
What two type of molecules are hormones nearly all either?
A
Hormones are nearly all either amino acid based molecules (proteins) or steroids.
18
Q
What are examples of steroid hormones?
A
Sex hormones made by the gonads and the hormones made in the adrenal cortex. most others are proteins or protein like molecules.
19
Q
Most hormones circulate around the entire body - how do they do this?
A
Hormones pass form the secretory cells that make them directly into the bloodstream, where they affect target cells.
20
Q
What happens to the hormones in time?
A
They are inactivated by the liver and excreted by the kidneys.m
21
Q
What occurs if someone suffers from liver or kidney failure?
A
Excessive levels of hormones may build up in the blood.
22
Q
What are local hormones?
A
Local hormones acts on nearby cells or on the same cell that produced them, without first entering the blood streams. Paracrines act on neighbouring cells and autocrines act on the same cell that secreted them.
23
Q
What is interleukin-2 an example of?
A
A hormone that behaves as both a paracrine and autocrine hormone. Interleukin-2 regulates white blood cells
24
Q
What is hormone production dependent on and usually controlled by?
A
Hormone production is dependent on the needs of the body and it usually controlled by a feedback system.
25
What is the level of hormone produced often linked to the level of?
Another chemical or metabolite in the body
26
What is the most common feedback system for hormone production?
A negative feedback control which allows the body to control the levels of many different substances very tightly.
27
What happens when the endocrine gland senses the levels of a metabolite increase?
More hormone is produced which reduces the metabolite levels.
28
Reducing the metabolite level in turn causes what?
A fall in the level of hormone production results in the metabolite level rising again.
29
What is an example of a negative feedback control system?
The control of insulin and glucagon secretion by the pancreas.
30
What are the main endocrine glands?
The pituitary, thyroid, parathyroid, adrenal and the hypothalamus and pancreas.
31
As hormones are secreted directly into the blood stream, the endocrine glands do not possess what?
Ducts - for this reason the endocrine glands are also called ductless glands.
32
What are known as exocrine glands?
Glands that produce non-hormonal secretions like enzymes usually do possess a duct.
33
What 3 ways can endocrine glands be stimulated?
- Hormonal = endocrine glands can be stimulated by other hormones.
- Humoral = stimulation by changes in the levels of certain ions and nutrients in the blood.
- Neural = In some cases nerve fibres stimulate hormone release, for example adrenaline.
34
Where is the pituitary gland found?
The pituitary gland is a small gland found just below they hypothalamus
35
What is a major link between the nervous system and the endocrine system?
The hypothalamus.
36
The pituitary has 2 lobes, what are these called?
The anterior and posterior lobes - these control much of the activity of the cells of the body.
37
Where is the growth hormone produced, what is its action?
Produced by the anterior lobe of the pituitary gland, also known as somatotrophic hormone because it stimulates the somatic cells. It stimulates growth, especially of bones and muscles.
38
Where is the Thyroid stimulating hormone (TSH) produced, what is its action?
Produced by the anterior lobe of the pituitary gland, This stimulates the thyroid gland to secrete the hormone thyroxine (T4)
39
Where is the Adrenocorticotrophic hormone (ACTH) produced, what is its action?
Produced by the anterior lobe of the pituitary gland, ACTH stimulates the adrenal cortex to produce glucocorticoid hormones.
40
Where is the Follicle stimulating hormone (FSH) produce, what is its action?
Produced by the anterior lobe of the pituitary gland, it controls the maturation of the ovarian follicles and oestrogen production in females and the production of sperm in males.
41
Where is the Luteinising hormone (LH) also known as interstitial cell stimulating hormone (ICSH) produced, what is its action?
Produced by the anterior lobe of the pituitary gland. In women, LH stimulates the ovaries and leads to the formation of corpus luteum which produces the hormone progesterone.
In men ICSH causes the interstitial cells between seminiferous tubules to secret androgens (male hormones)
42
Where is prolactin hormone produced, what is its action?
Produced by the anterior lobe of the pituitary gland, it controls the production of milk from the mammary glands.
43
Some hormones are stored in the posterior pituitary until they are needed, where are these made?
In the hypothalamus.
44
What are the hormones released from the posterior lobe of the pituitary gland released in response to?
Nervous impulses from the hypothalamus.
45
Where is the Antidiuretic hormone (ADH) also known as vasopressin produced, what is its action?
Antidiuretic hormone (ADH) is released from the posterior lobe of the Pituitary gland. It is important in controlling the water balance of the body. It affects the amount of water reabsorbed into the blood by the kidney tubules.
46
Where is Oxytocin produced and what is its action?
Oxytocin is released from the posterior lobe of the Pituitary gland. It stimulates the contraction of the smooth muscle in the uterus during the process of giving birth.
47
The thyroid gland is the only endocrine gland that does what?
Stores large supplies of its secretory products.
48
How many days supply of the two hormones it makes does the thyroid contain? What are these hormones?
About 100 days. It makes thyroxine and calcitonin.
49
What do thyroid hormones act in and stimulate?
Thyroid hormones act in the regulation of metabolism - they stimulate protein synthesis and increase cellular respiration so more glucose and fatty acids are used up for ATP production.
50
They increase the breakdown of fats (lipolysis) and increase cholesterol excretion - what does this do?
Reduced blood cholesterol levels.
51
How does calcitonin decrease the level of calcium in the blood?
By inhibiting the action of osteoclasts. this causes calcium to be deposited in the bones.
52
How are thyroxine levels controlled in the body?
- The thyroid gland produces thyroxine that feeds back to the hypothalamus and pituitary gland, suppressing the production of releasing factor TSH.
- The hypothalamus produces a releasing factor that affects the anterior pituitary.
- The anterior pituitary produced thyroid stimulating hormone that is then released into the blood.
53
Where do you find the parathyroid gland?
4 pea sized glands very close to the thyroid gland.
54
What hormone does the parathyroid gland produce - what does this control?
They produce a hormone called parathormone (PTH). this is essential in controlling the balance of calcium, magnesium and phosphate ions in the body by increasing the number and activity of osteoclasts.
55
What happens to neurones if blood calcium levels fall too low?
Neurones become extremely irritable and overactive. - they deliver impulses to muscles at such a rapid rate the muscles go into uncontrollable spasms (tetanic contractions as occur in tetanus) which can be fatal.
56
PTH is the most important regulator of calcium in the blood. What is the response to blood calcium levels below a certain point?
When blood calcium levels drop below a certain level, the parathyroid glands release PTH which stimulates bone destruction cells (osteoclasts) to break down bone matrix, releasing calcium into the blood.
57
Where are the adrenal glands found? What are the parts of this gland?
Just above the kidneys. They have an adrenal medulla and an outer adrenal cortex.
58
What is the adrenal medulla a modified part of?
The autonomic nervous system.
59
Which hormone and neurotransmitter does the adrenal medulla produce and secrete?
The hormone adrenaline and the neurotransmitter noradrenaline, both of which have an important role in the nervous system.
60
What response does the release of adrenaline cause? What does this cause in the body?
The fight or flight response - This causes the heart to speed up and increases blood flow to the heart and the big skeletal muscles of the limbs while decreasing blood flow to the digestive system.
61
Which hormone is the adrenal cortex stimulated by?
ACTH (adrenocorticotrophic hormone) from the pituitary gland.
62
What three classes of hormones, known as the corticosteriods does the adrenal cortex produce?
Mineralocorticoids, glucocortcoids and sex hormones.
63
What do the mineralocorticoids regulate?
These hormones regulate the balance of mineral ions (electrolytes) in the body. For example, aldosterone causes sodium ions and water to be reabsorbed in the renal tubules.
64
What hormones do glucocorticoids include and what do these do?
These include cortisone and cortisol - they support normal cell metabolism and help the body cope with long term stress by adjusting blood glucose levels.
65
What do the sex hormones help in?
Although oestrogen and testosterone are produced mainly in the ovaries and testes respectively, small amounts of both are produced in the adrenal cortex. These help in the development and functioning of the sex organs and the secondary sex characteristics. The effects are most important in females than in males after puberty when the testes are the main source of testosterone in men.
66
The pancreas has 2 very different functions in the body. What does the exocrine pancreas produce?
The exocrine pancreas forms the main part of the organ. The cells of the exocrine pancreas produce digestive enzymes which are secreted into the first part of the small intestine to help digest your food.
67
Which hormones does the endocrine pancreas produce? Why are these important?
Insulin and glucagon - which between them control the level of blood glucose. This is very important as the cells of the body need a constant supply of glucose for cellular respiration, to produce the ATP energy needed for all the reactions of life.
68
What is the normal level of glucose in the blood?
80 - 100mg glucose/100ml of blood.
69
What is the cluster of cells called in the pancreas that produce the hormones?
Islets of Langerhans.
70
How many Islets of Langerhans are there throughout the pancreas and which cells make insulin and glucagon?
In an adult there are around 1 million of these islets scattered throughout the pancreas. In the islets insulin is made by the beta cells and glucagon by the alpha cells.
71
What is the basic function of insulin and glucagon?
Insulin helps to lower the blood glucose level when it becomes too high and glucagon increases the blood glucose level when it falls below normal.
72
What does low blood glucose levels (hypoglycaemia) stimulate?
The secretion of glucagon from alpha cells.
73
What does glucagon act on and how does it cause glucose levels to rise?
Glucagon acts on liver cells (hepatocytes) to accelerate the conversion of glycogen into glucose and promotes the formation of glucose from lactic acid and amino acids. This means liver cells release glucose into the blood more rapidly and glucose levels increase.
74
What happens if blood glucose levels continue to rise?
High blood glucose levels (hyperglycemia) inhibit the release of glucagon - this is negative feedback.
75
What does hyperglycemia stimulate the secretion of?
Insulin by the beta cells.
76
How does insulin cause the blood glucose levels to fall?
Insulin acts on various cells in the body to speed up the diffusion of glucose into cells, especially skeletal muscle fibres.
It speeds up the conversion of glucose to glycogen. For storage in liver and muscles.
It increases the uptake of amino acids by cells, increases protein synthesis and speeds up the synthesis of fatty acids, for storage.
It slows the conversion of glycogen to glucose and slows the formation of glucose from lactic acid and amino acids.
Glucose is removed to supply cellular respiration.
77
What happens if the blood glucose drops below normal?
Low blood glucose (hypoglycemia) inhibits the release of insulin (negative feedback) and stimulates the release of glucagon.
78
What do most problems associated with endocrine glands result from?
Over (hyper) or under (hypo) active secretion of hormones.
79
Disease arising from hyper-or hyposecretion of hormones from the pituitary gland:
What dose Hyper secretion of growth hormone cause?
GH stimulates skeletal and soft tissue growth - overproduction of GH leads to gigantism in children or acromegaly in adults. In acromegaly the hands and feel and features of the face continue to grow - it is nearly always due to a pituitary tumour.
80
Disease arising from hyper-or hyposecretion of hormones from the pituitary gland: What does Hyposecretion of growth hormone cause?
Under production of GH in children can lead to one form of dwarfism.
81
Disease arising from hyper-or hyposecretion of hormones from the pituitary gland: What does hyposecretion of antidiuretic hormone (ADH) cause?
A reduction in ADh from the posterior pituitary leads to large quantities of very dilute urine and excessive thirst, this is a very rare condition known as diabetes insipidus.
82
What is any enlargement of the thyroid gland known as?
Goitre
83
What sex is Goitre more common in?
It is more common in women than in men.
84
What percentage of the population have goitre?
Up to 9% of the population have it, which is often regarded as a cosmetic defect.
85
What can a large goitre cause?
It can cause difficulty breathing and may be removed surgically.
86
When can goitre occur?
Goitre can occur in both a hyper and a hypo-secreting thyroid - it can also occur when there is a lack of iodine in the diet. There is not enough iodine to produce thyroxine and the thyroid gland grows and becomes hyperactive in attempt to make more hormone. it can be prevented or treated by supplementing iodine levels in the diet, for example by iodised salt.
87
Diseases arising from hyper- or hypo-secretion of hormones from the thyroid gland: What is hyperthyroidism?
This is a common disease affecting 2-5% of all females at some time - 5 more times more common in women than in men. The most common cause is Graves disease which is a multi system auto immune disorder - common symptoms include bulging eyeballs (exophthalmos), heavy perspiration and weight loss.
88
Diseases arising from hyper- or hypo-secretion of hormones from the thyroid gland: What is hypothyroidism?
Under activity of the thyroid is usually caused by disease f the thyroid itself. It is about 14 times more common in women than in men. It produces many symptoms such as lethargy, fatigue, weight gain, physical and mental slowness and may have other symptoms including dry thin hair, bradycardia (slow heart beat), dry skin and sluggish reflexes.
89
What is hyperparathyroidism?
Hyperactivity of any of the 4 parathyroid glands causes excessive secretion of parathormone (PTH) Because PTH is responsible for calcium balance, excess hormone can lead to osteoporosis and bone fracture due to a loss of calcium from the bones.
90
What is Hypoparathyroidism?
This results in low blood calcium or hypocalcaemia, which leads to increased excitability of central nervous system. In addition low blood calcium can cause muscle spasms or tetany (involuntary contraction of muscle)
91
Disease arising from hyper and hyposecretion of hormones form the adrenal glands - what is hypersecretion?
Hypersecretion from the adrenal glands is called Cushing's syndrome - patients tend to be obese with a characteristic moon face - children may stop growing.
92
Disease arising from hyper and hyposecretion of hormones form the adrenal glands - What is hyposecretion?
A relatively rare but life threatening condition usually known as Addisons disease. Patients show general weakness, low blood pressure, anorexia (loss of appetite), dehydration, muscle wasting, depression, GI disorders and increased skin pigmentation.
93
What is it called if the pancreas produces little or no insulin?
Diabetes Mellitus.
94
If the pancreas cannot produce insulin what is the condition known as?
Insulin Dependent diabetes mellitus (IDDM) or Type 1 diabetes.
95
If the pancreas loses its ability to produce sufficient insulin over time or the body cells stop responding to the insulin that is produced, then what is the condition referred to as? What is this often linked with?
Non-insulin dependent diabetes mellitus (NIDDM) or type 2 diabetes. This is often linked with increasing age and also with obesity and lack of exercise.
96
What does the lack or loss of insulin lead to?
Excessive glucose in the blood, known as hyperglyceamia.
97
What happens to the excess glucose in the blood?
It is eventually lost from the body in the urine (glycosuria) taking water with it. Initially this elads to extreme thirst, weight loss, dehydration, drowsiness and loss of energy as proteins and fats are consumed as fuel. Eventually it can lead to coma and death.
98
Posterior pituitary hormones and antagonists:
| What are the medicines available to treat diabetes indipidus?
Largely drugs which mimic and take the place of ADH (vasopressin) known as analogues.
99
What is often used to replace natural thyroxine in people with an under active thyroid gland?
Levothyroxine.
100
An overactive thyroid gland may be treated using medicines that stop what?
Medicines that stop the thyroid gland producing thyroxine.
101
What can be used to relieve the symptoms until the treatment begins to work for an over active thyroid?
Beta blockers
102
What can be used to destroy part of the thyroid gland, shrinking it and reducing the amount of hormone it can produce?
Radioiodine - in some circumstances the thyroid gland may be removed completely by surgery.
103
How can Cushing's syndrome be treated?
Cushing's syndrome is often the result of a tumour on the adrenal glands or pituitary gland. Surgery or radiotherapy are commonly used to reduce or remove the tumour.
104
How is Addisons disease treated?
With replacement hormones.
105
What is needed to treat people with Type 1 diabetes and some people with Type 2?
Insulin, it replaced the insulin their body cannot make.
106
In many cases, what can reduce or even eliminate the symptoms of Type 2 diabetes?
Losing weight, meal planning and increases exercise levels.
107
What percent of people with Type 2 diabetes also take oral medication to help treat or control their hypoglyceamia?
About 60-70%
108
How does metformin work?
It inhibits the breakdown of glycogen to form glucose in the liver.
109
How do sulphonylureas, gliptins and GLP-1 antagonists work?
They all increase insulin production and release from the beta cells in the pancreas.
110
How do Giltazone (thiazolidinediones) work?
They make body cells more sensitive to the insulin that is produced by the pancreas.
111
What does Acarbose do?
It slows the rate at which complex carbs are broken down to glucose in the digestive system - this in turn slows the absorption of glucose into the bloodstream and this reduces the blood glucose peak which follows a meal - it isn't commonly used as it can have uncomfortable side effects.
112
What can type 2 diabetes patients who are unable to manage their weight with diet, exercise and medicine potentially undergo?
Gastric bypass or laparoscopic gastric banding to help drive weight loss.
