5.1.4 - Hormonal communication Flashcards
1
Q
What is the purpose of the endocrine system ?
A
To react to changes in the body
2
Q
Why does the endocrine system use hormones ?
A
To send information about changes in the environment around the body to bring about a designated response
3
Q
What is the endocrine system made of ?
A
Endocrine glands
4
Q
What is an endocrine gland ?
A
A gland that is specialised to secrete hormones
5
Q
What do the endocrine glands release ?
A
- Hormones
- Secreted directly into the bloodstream
6
Q
Give some examples of endocrine glands
A
- Adrenal glands
- Pancreas glands
7
Q
What is an advantage of the pituitary gland and the hypothalamus being so close together ?
A
It ensures that the nervous and hormonal responses of the body are closely linked and coordinated
8
Q
What hormones does the pituitary gland produce ?
A
- Growth hormone
- Anti-diuretic hormone
- Gonadotrophins
9
Q
What is the purpose of the growth hormone ?
A
Controls growth of bones and muscles
10
Q
What is the purpose of anti-diuretic hormones ?
A
Controls the absorption of water in kidneys
11
Q
What is the purpose of gonadotrophins ?
A
Control development of ovaries and testes
12
Q
What hormones does the thyroid gland produce ?
A
Thyroxine
13
Q
What is the purpose of thyroxine ?
A
- Controls the rate of metabolism and rate that glucose is used up in respiration
- Promotes growth
14
Q
What hormones does the adrenal gland produce ?
A
Adrenaline
15
Q
What is the purpose of adrenaline ?
A
Increases heart rate, breathing rate and it raises blood sugar level
16
Q
What hormones does the testis produce ?
A
Testosterone
17
Q
What is the purpose of testosterone ?
A
Controls sperm production and secondary sexual characteristics
18
Q
What hormone does the pineal gland produce ?
A
Melatonin
19
Q
What is the function of melatonin ?
A
It affects reproductive development and daily cycles
20
Q
What hormone does the thymus produce ?
A
Thymosin
21
Q
What is the function of thymosin ?
A
Promotes production and maturation of white blood cells
22
Q
What hormones does the pancreas produce ?
A
- Insulin
- Glucagon
23
Q
What is the function of insulin ?
A
Converts excess glucose into glycogen in the liver
Lower blood glucose level
24
Q
What is the function of glucagon ?
A
Converts glycogen back to glucose in the liver
Increase blood glucose levels
25
What hormones does the ovary produce ?
- Oestrogen
- Progesterone
26
What is the function of oestrogen ?
Controls ovulation and secondary sexual characteristics
27
What is the function of progesterone ?
Prepares the uterus lining for receiving an embryo
28
Why are hormones sometimes referred to as chemical messengers ?
They carry information from one part of the body to another
29
What can hormones be ?
- Steroids
- Proteins
- Glycoproteins
- Polypeptides
- Amines
- Tyrosine derivatives
30
Where are hormones secreted ?
Directly into the blood when a gland is stimulated
31
What can cause hormones to be secreted ?
- A change in concentration of a particular substance
- The result of another hormone or a nerve impulse
32
What transports hormones ?
The blood plasma all over the body
33
Once secreted, where do the hormones go ?
- They diffuse out of the blood and bind to specific receptors for that hormone
- These receptors are found on the membranes or in the cytoplasm of cells in the target organs. These are known as Target cells
34
What do hormones trigger once they are bound to their receptors ?
They stimulate the target cells to produce a response
35
What is a result of hormones not being directly released into their target cells ?
A slower and less specific form of communication
36
What is a result of hormones not being broken down as quickly as neurotransmitters ?
Can result in a much longer lasting and widespread effect
37
Type of communication - Hormonal VS Nervous
- Hormones in hormonal system
- Nerve impulses in nervous system
38
Transmission - Hormonal VS Nervous
- By the blood stream and relatively slow in hormonal system
- By the neurones and rapid in nervous system
39
Where they travel - Hormonal VS Nervous
- Hormones travel to all parts of the body, but only target organs respond
- Nerve impulses travel to specific parts of the body
40
Response - Hormonal VS Nervous
- Response is widespread and slow in hormonal
- Response is localised and rapid in nervous
41
How long the effect lasts - Hormonal VS Nervous
- Effect may be permanent for hormonal
- Effect is temporary for nervous
42
Are they reversible - Hormonal VS Nervous
- Irreversible for hormonal
- Reversible for nervous
43
Where are the adrenal glands located ?
- On top of each kidney
- Made up of two distinct parts surrounded by a capsule
44
What are the two parts of the adrenal glands ?
- Adrenal cortex
- Adrenal medulla
45
What is the adrenal cortex ?
- The outer region of the glands
- This produces Cortisol and Aldosterone
46
What is the adrenal medulla ?
- The inner region of the glands
- Produces adrenaline
47
What controls the hormones released from the adrenal cortex ?
The pituitary gland
48
What are the three main types of hormones produced by the adrenal cortex ?
- Glucocorticoids
- Mineralocorticoids
- Androgens
49
What are glucocorticoids ?
- Cortisol
- Corticosterone
50
What is the function of cortisol ?
- Helps regulate metabolism by controlling how the body converts fats, proteins and carbs to energy
- Helps regulate blood pressure and cardiovascular function in response to stress
51
What is the function of corticosterone ?
Works with cortisol to regulate immune response and suppress inflammatory reactions
52
What controls the release of glucocorticoids ?
Hypothalamus
53
What are the mineralocorticoids ?
Aldosterone
54
What is the function of aldosterone ?
Helps control blood pressure by maintaining the balance between salt and water concentrations in the blood and body fluids
55
What controls the release of mineralocorticoids ?
The kidney
56
What are androgens ?
Small amounts of male and female sex hormones
57
What is the impact of androgens like ?
Relatively small impact compared to oestrogen and progesterone
58
When are androgens important ?
Always but especially in women after the meno pause
59
What releases androgens ?
Ovaries and testes
60
When are the hormones of the adrenal medulla released ?
- When the body is stressed
- When the sympathetic nervous system is stimulated
61
What hormones does the adrenal medulla release ?
- Adrenaline
- Noradrenaline
62
What is the function of adrenaline ?
- Increases the heart rate sending blood quickly to the muscles and brain
- It also rapidly raises blood glucose levels by converting glycogen to glucose in the liver
63
What is the function of noradrenaline ?
- Produces effects such as increased heart rate, widening of pupils, widening of air passages in the lungs and the narrowing of blood vessels in non essential organs
This results in higher blood pressure
64
Where is the pancreas found ?
Upper abdomen, behind the stomach
65
What type of organ is the pancreas ?
Glandular organ
66
What is the pancreas’s overall role ?
- Produce and secrete hormones and digestive enzymes
67
What are the two functions of the pancreas ?
- Exocrine gland
- Endocrine gland
68
What is the pancreas’s function as an exocrine gland ?
To produce enzymes and release them via a duct into the duodenum
69
What is the pancreas’s function as an endocrine gland ?
To produce hormones and release them into the blood
70
What type of tissue is most of the pancreas made of ?
Exocrine glandular tissue
71
What is exocrine glandular tissue responsible for ?
Producing digestive enzymes and an alkaline fluid called pancreatic juice
72
Once secreted, where do the enzymes and pancreatic juices end up ?
The duodenum via the pancreatic duct via smaller ducts
73
What is the duodenum ?
The top part of the small intestine
74
What are the three types of digestive enzymes the pancreas produces ?
- Amylases
- Proteases
- Lipases
75
What are the role of amylases ?
- Break down starch into simple sugars
- e.g. pancreatic amylase
76
What are the role of proteases ?
- Break down proteins into amino acids
- e.g. trypsin
77
What are the role of lipases ?
- Break down lipids into fatty acids and glycerol
- e.g. pancreatic lipase
78
What hormones is the pancreas responsible for producing ?
- Insulin
- Glucagon
79
What do glucagon and insulin play a role in ?
Controlling blood glucose concentration
80
Where are the islets of langerhans found ?
They are endocrine tissues found within the exocrine tissue in the pancreas
81
What is the function of the cells in the islets of langerhans ?
They are responsible for producing glucagon and insulin and secreting these hormones directly into the bloodstream
82
Islets of langerhans vs Pancreatic acini - Appearance (staining)
- Islets of langerhans are lightly stained
- Pancreatic acini are darker stained
83
Islets of langerhans vs Pancreatic acini - Shape
- Islets of langerhans are in large spherical clusters
- Pancreatic acini are in small berrylike clusters
84
Islets of langerhans vs Pancreatic acini - Type of tissue
- Islets of langerhans are endocrine
- Pancreatic acini are exocrine
85
Islets of langerhans vs Pancreatic acini - Function
- Islets of langerhans produce and secrete hormones
- Pancreatic acini produce and secrete digestive enzymes
86
What are the two types of cells within the islets of langerhans ?
Alpha and beta cells
87
What is the role of alpha cells ?
Secrete glucagon
88
What is the role of the beta cells ?
Secrete insulin
89
Which type of cell is present more in the islet of langerhans ?
Alpha cells are larger and more numerous
90
What does the body use to produce ATP ?
Glucose
91
What type of a molecule is glucose ?
- Small and soluble
- Carried in the blood plasma
92
What is the concentration of glucose normally like in the blood plasma ?
90mg per cm3 of blood
93
What can cause blood glucose concentration to increase ?
- Diet
- Glycogenolysis
- Gluconeogenesis
94
How can your diet increase the amount of blood glucose in your blood ?
- When you eat carb rich food and sweet foods, the carbs they contain are broken down in the digestive system to release glucose
- The glucose is released into the bloodstream which increases the blood glucose concentration
95
What is glycogenolysis ?
- Glycogen stored in the liver and muscle cells is broken down into glucose
- The glucose is released into the bloodstream which increases the blood glucose concentration
96
What does glycogenolysis actually mean ?
The splitting of glycogen (to produce glucose)
97
What is gluconeogenesis ?
- This is the production of glucose from non carb sources
- The liver can make glucose from glycerol (lipids) and amino acids
- The glucose is released into the bloodstream which increases the blood glucose concentration
98
What does gluconeogenesis actually mean ?
Formation of new glucose
99
What can cause blood glucose concentration to decrease ?
- Respiration
- Glycogenesis
100
How can respiration cause the blood glucose concentration to decrease ?
Some of the glucose in the blood is used by cells to release energy. This is required to carry out normal body functions
101
What is the correlation between physical activity and the demand for glucose ?
The higher the level of physical activity, the higher the demand for glucose and the greater the decrease of blood glucose concentration
102
What is glycogenesis ?
- The production of glycogen
- When blood glucose concentration is too high, excess glucose taken in through the diet is converted into glycogen which is stored in the liver
103
What does lysis mean ?
Splitting
104
What does neo mean ?
- New
105
What does genesis mean ?
Means birth/origin
106
Where is insulin produced ?
By the beta cells in the islets of langerhans
107
What is the role of insulin ?
If the blood glucose concentration is too high, the beta cells detect this and respond by secreting insulin to lower the blood glucose concentration
108
Which cells do not have insulin receptors on the cell surface membrane ?
red blood cells
109
What does insulin cause when it binds to its glycoprotein receptors ?
- Causes a change in the tertiary structure of the glucose transport protein (GTP) channels
- This causes the channels to open allowing more glucose to renter the cells
110
What does insulin also activate ?
Enzymes within some cells to convert glucose into glycogen and fat
111
How does insulin lower the blood glucose concentration ?
- Increasing the rate of absorption of glucose by cells
- Increasing the rate of respiration
- Increasing the rate of glycogenesis
- Increasing the rate of glucose to fat conversion
- Inhibiting the release of glucagon from the alpha cells of the islets of langerhans
112
How does increasing the respiratory rate of cells decrease blood glucose concentration ?
This increases their need for glucose and causes a higher uptake of glucose from the blood
113
How does increasing the rate of glycogenesis decrease blood glucose concentration ?
Insulin stimulates the liver to remove glucose from the blood by turning the glucose into glycogen and storing it in the liver and muscle cells
114
What detects the blood glucose concentration turning back to normal (insulin) ?
The beta cells of the islets of langerhans in the liver
115
What happens when glucose concentration falls below a certain level (insulin)?
The beta cells reduce their secretion of insulin
116
What does negative feedback ensure ?
That in any control system, changes are reversed and returned back to the set level
117
Where is glucagon produced ?
In the alpha cells of the islets of langerhans
118
What is the role of glucagon ?
When blood glucose concentration is too low, the alpha cells detect this and respond by secreting glucagon which increases the blood glucose in the blood
119
Which cells have glucagon receptors ?
- liver cells and fat cells
- Therefore these are the only cells that can respond to glucagon
120
How does glucagon raise blood glucose concentration ?
- Increasing Glycogenolysis
- Increasing Gluconeogenesis
- Reducing the amount of glucose absorbed by the liver cells
121
How does glycogenesis decrease blood glucose ?
Causes the formation of more glycogen
122
How does increasing gluconeogenesis increase blood glucose ?
Increasing the concentration of amino acids and glycerol into glucose in the liver
123
What detects the blood glucose concentration turning back to normal (glucagon) ?
The alpha cells of the islets of langerhans in the liver
124
What happens when glucose concentration falls below a certain level (glucagon)?
The alpha cells reduce their secretion of glucagon
125
Why is the system of maintaining blood glucose concentration said to be self regulating ?
As it is the level of glucose in the blood that determines the quantity of insulin and glucagon that is released
126
What is one of the effects of adrenaline ?
Raise the blood glucose concentration to allow more respiration to occur
127
Control of insulin secretion - Normal levels
Potassium channels in the plasma membrane of the beta cells are open and potassium ions diffuse out of the cell.
The inside of the cell is at a potential of -70mV with respect to the outside of the cell
128
Control of insulin secretion - High blood glucose
- Glucose enters the cell by a glucose transporter
- The glucose is then metabolised inside the mitochondria, resulting in the production of ATP
- The ATP binds to potassium channels and causes them to close. They are known as ATP sensitive potassium channels
- As potassium ions can no longer diffuse out of the cell, the potential difference reduces to around -30 mV and depolarisation occurs
- Depolarisation causes the voltage gated calcium channels to open
- Calcium ions enter the cell and cause secretory vesicles to release the insulin they contain by exocytosis
129
What hormones does the body rely on to keep blood glucose constant ?
- Glucagon
- Insulin
130
What does having diabetes mean ?
It means that you are unable to metabolise carbs properly, in particular glucose
131
What cant your body do if you suffer from diabetes ?
- Your pancreas either does not produce enough insulin
- Your body cannot effectively respond to the insulin produced
132
What is hyperglycaemia ?
- Raised blood sugar
- It is a common effect of uncontrolled diabetes
133
What can hyperglycaemia lead to over time ?
Serious damage of many body systems, especially the nerves and blood vessels
134
What are the common symptoms of diabetes ?
- High blood glucose concentration
- Excessive need to urinate (polyuria)
- Excessive thirst (polydipsia)
- Constant hunger
- Weight loss
- Tiredness
135
What are the two main types of diabetes ?
- Type 1 diabetes
- Type 2 diabetes
136
What cant people with type 1 diabetes do ?
- The beta cells in the islets of langerhans do not produce insulin
137
What is the cause of type 1 diabetes ?
- It is not known at the moment , the disease cannot be cured or prevented
- In many cases it arises as a result of an autoimmune response where the body’s own immune system attacks the beta cells
138
How can you treat type 1 diabetes ?
Insulin injections
139
When does type 1 diabetes arise ?
In childhood, and people develop the symptoms quickly
140
What cant people with type 2 diabetes do ?
- They cannot effectively use insulin and control their blood sugar levels
- This is either because the persons beta cells do not produce enough insulin or the persons body cells do not respond to insulin
141
Why cant diabetics effectively use insulin ?
- The glycoprotein insulin receptors on the cell membrane do not work properly
- The cells lose their responsiveness to insulin, and therefore do not take up enough glucose, leaving it in
142
What can cause type 2 diabetes ?
- Excess body weight
- Physical inactivity
- Habitual and excessive overeating of refined carbs
143
How can you treat type 2 diabetes ?
Exercising
144
When does the risk of type 2 diabetes increase ?
The risk of type 2 diabetes increases with age
145
What is type 1 diabetes said to be ?
- It is said to be insulin dependent
- This is because it has to be controlled with regular injections
146
What do people with type 1 diabetes regularly have to do ?
Regularly have to test their blood glucose concentration, normally by pricking their finger
147
Why do people with type 1 diabetes have to prick their fingers ?
- The drop of blood is analysed by the machine, which tells the person their BG level
- The person can then work out the dose of insulin they need to inject
148
What does the administration of insulin do ?
- Increases the amount of glucose absorbed by cells (increases the rate of respiration)
- Causes glycogenesis to occur, resulting in a reduction of blood glucose concentration
149
What will happen if you inject yourself with too much insulin ?
They may experience hypoglycaemia
150
What will happen if you inject yourself with too little insulin ?
They may experience hyperglycaemia
151
What is hypoglycaemia ?
Very low blood glucose concentrations that can result in unconsciousness
152
What is hyperglycaemia ?
Can result in unconsciousness and death if left untreated
153
What is the first line of control in type 2 diabetes ?
Regulate the persons carb intake through their diet and matching this to their exercise levels
154
What does regulating carbohydrate intake involve ?
- Increasing exercise levels
- Losing weight
155
What do type 2 diabetics do if diet and exercise are not enough ?
- Drugs have to be used
- These can be drugs that stimulate insulin production or slow down the rate at which the body absorbs glucose from the intestine
156
Where was insulin originally obtained from ?
Pancreas of cows and pigs
157
What could insulin from animals cause ?
Allergic reactions because it differed slightly from human insulin
158
When was the structure of human insulin identified ?
In 1955
159
How is insulin now made ?
Made by genetically modified bacteria
160
What advantages are there for insulin from GM bacteria ?
- Less likely to cause allergic reactions
- Insulin can be produced in much higher quantities
- Production costs are much cheaper
- Ethical and religious concerns of using animal insulin are now overcome
161
What is the relationship between transplantable pancreases and their availability ?
The demand for transplantable pancreases heavily outweighs their availability
162
Why are immunosuppressant drugs needed after a transplant ?
To ensure that the body accepts the transplanted pancreas, which can leave a person susceptible to infection
163
How have doctors attempted to cure diabetes ?
By injecting patients with pancreatic beta islet cells
164
How many cell transplants have been successfully performed ?
Fewer than 8% of cell transplants have been successful
165
What do the immunosuppressant drugs do to insulin producing cells ?
- Increase the metabolic demand of insulin producing cells.
- Eventually this exhausts their capacity to produce insulin
166
Why is type 1 diabetes a candidate for stem cell therapy ?
There is evidence that a relatively small number of islet cells can restore insulin production
167
What potential do totipotent stem cells have ?
They have the potential to grow into any type of cells
168
Where would stem cells to treat type 1 diabetes be taken from ?
Embryos
169
How do we obtain the stem cells from the embryo ?
- We have to destroy the early embryo
- This means destroying a potential human life
170
Evaluation for using an embryo for the stem cells (ethical)
- The embryos used as a source for these stem cells would usually be destroyed anyways
- They are spare embryos from infertility treatments or from terminated pregnancies
171
What is another alternative to using embryonic matter ?
Using preserved umbilical stem cells
172
What advantages does the use of stem cells offer ?
- Donor availability would not be an issue
- Stem cells can produce an unlimited source of new beta cells
- Reduced likelihood of rejection as embryonic stem cells are generally not rejected
- People no longer have to inject themselves with insulin
173
How can stem cells be made ?
By somatic cell nuclear transfer (SCNT)
174
What is a major consideration surrounding transporting stem cells into the body ?
They might induce the formation of tumours as a result of unlimited cell growth
