1
Q
What is a hormone?
A
Chemical messengers that cause a change
2
Q
What chemicals can hormones be made of?
A
Proteins/peptides, or derivatives of them (adrenaline, insulin, glucagon), steroids (oestrogen, testosterone)
3
Q
What is the organ that releases hormones called?
A
Endocrine, gland
4
Q
What are the cells/organs that respond to hormones called?
A
Target cells
5
Q
How are hormones transported around the body?
A
In the blood stream
6
Q
Suggest why some cells respond to a hormone whilst others don’t
A
Cells that respond to specific complementary receptor molecule to the hormone, receptor may be on plasma membrane, in cytoplasm, or in the nucleus. Once hormone bound, initiates response
7
Q
What hormone does the thyroid release?
A
Thyroxine
8
Q
What hormone do the ovaries release?
A
Oestrogen, progesterone
9
Q
What hormone does the pancreas release?
A
Insulin, glucagon
10
Q
What hormone does the pineal gland release?
A
Melatonin
11
Q
What hormone does the pituitary gland release?
A
Growth hormone, anti-diuretic hormone, gonadotropins
12
Q
What hormone do the testes release?
A
Testosterone
13
Q
What hormone do the adrenal glands release?
A
Adreneline
14
Q
What hormone does the thymus release?
A
Thymosin
15
Q
What are endocrine glands?
A
Secretions enter intercellular fluid then the blood stream, are ductless, stay in the body (endo)
16
Q
What are exocrine glands?
A
Secrete substances that enter ducts, ultimately exit the body (exo), mucus, saliva, sweat, tears, digestive enzymes
17
Q
What are steroid hromones?
A
Lipid soluble, so pass through phospholipid component of plasma membranes. Will bind to a receptor molecule, forming a hormone receptor complex
This complex acts as a transcription factor, facilitates/inhibits transcription of a particular gene. Receptors may be in nucleus or cytoplasm
Eg. oestrogen
18
Q
Outline the action of steroid hormones
A
- Lipid soluble so passes through bilayer
- Oestrogen (example) binds to complementary receptor in cytoplasm, forming hormone-receptor complex
- Hormone-receptor complex moves in the nucleus and binds to a section of DNA (a gene). Acts as a transcription factor, either initiating or inhibiting transcription of the gene
19
Q
What are non-steroid hormones?
A
Example: adrenaline
A polar molecule derived from amino acid tyrosine
Being hydrophilic, it cannot pass through the plasma membrane, so binds to receptor molecules on the surface of the target cell.
Triggers a chain of reactions within the cell
20
Q
Outline the method of action of adrenaline (non steroid hormone)
A
- Adrenaline binds to complementary receptor in the cell surface membrane
- This activates a G protein, which is associated with the receptor on the innter surface of the membrane
- The G protein activates an enzyme, andenyl cyclase, which converts ATP to cAMP
- cAMP acts as a secondary messenger, and activates an enzyme cascade in the cell, which results in the hydrolysis of glycogen to glucose
21
Q
How can adrenaline (non steroid hormones) have a cascade effect on the cell?
A
One adrenaline molecule can cause the formation of many cAMP molecules, which in turn catalyse the production of many active enzymes, so one hormone molecule results in many active enzymes within a cell
22
Q
Outline features of the hormonal system
A
- Transmission is relatively slow
- Carried in the blood
- Communication by chemicals called hormones
- Carried to all parts of body, only target cells/organs respond
- Widespread response
- Usually a slow response
- Often a longer lasting response
- Effects often permanent and irreversible
23
Q
Outline features of the nervous system
A
- Transmission is very rapid
- Transmission by nerve impulses
- Communication by “ “
- Travel to specific parts
- Response localised
- ” rapid
- ” short lived
- Effects temporary, reversible
24
Q
What two hormones control blood glucose levels?
A
Insulin and glucagon
25
What is the negative feedback loop for blood glucose control?
Insulin from pancreas, no glucagon secreted ----> blood glucose decrease -----> glucagon from pancreas, no insulin secreted -----> blood glucose increase -----> repeat
26
What are features of the islets of Langerhans?
Excellent blood supply
Made up of two main cell types: alpha and beta
Able to detect glucose concentration in blood as it passes through the capillaries, and then respond to changes in glucose by switching on or off secretion of insulin and glucagon
27
When is insulin secreted?
When blood sugar levels are high
28
When is glucagon secreted?
When blood sugar levels are low
29
Why are normal blood glucose levels maintained as close to 90mg 100cm^-3 blood as possible?
Provide glucose for respiration, very serious in brain as cells can only respire glucose, unable to store glycogen
High glucose concentrations would make water potential of the blood become lower, so cells in the body would lose water by osmosis
30
What factors increase blood glucose concentration?
Digestion
Liver hydrolyses stored glycogen into glucose, then releases it
Liver converts lipids and fats into glucose and releases it
31
What factors decrease blood glucose concentration?
Lack of food intake (carbohydrates)
Respiration by cells
Conversion into glycogen by liver and muscle cells
32
What is negative feedback?
The mechanism that detects and reverses a change, bringing the system back to the optimum
33
Outline the method of control when blood glucose goes above optimium
- Blood glucose rises, which could be the result of ingestion of food, or release of glucose from the liver,
- Detected by alpha and beta cells of the islets of Langerhans, where the cells then stop secreting glucagon, and beta cells secrete insulin
- Effector causes liver cells to stop breaking glycogen down due to drop in glucagon, most body cells increase uptake and use of glucose due to rise in insulin
- Blood glucose is stabilised
34
Outline the method of control when blood glucose goes below optimium
- Blood glucose falls, which could be the result of a high rate of cellular uptake and use of glucose or failure to ingest carbohydrate foods
- Detected by alpha and bata cells in islets of Langerhans, alpha cells secrete glucagon and beta cells stop secreting insulin
- Effector causes liver cells to break down glycogen into glucose due to rise in glucagon, most body cells decrease uptake and use of glucose due to fall in insulin
- Blood glucose is stabilised
35
How do beta cells control insulin secretion?
FINISH!!
36
How does the liver respond when blood glucose levels are above optimum?
1. More glucose enters the cell so blood
glucose concentration falls.
2. More glucose is converted to glycogen for
storage. Glycogenesis.
3. More glucose is converted to fats.
4. More glucose is used in respiration by
increasing the rate of respiration.
37
How does the liver respond when blood glucose levels are below optimum?
1. Hydrolysing glycogen to glucose (glycogenolysis) and releasing glucose into the blood stream
2. Removing glucose transporter proteins from their membranes so less glucose is absorbed.
3. Using more fatty acids in respiration.
4. Amino acids and fats are converted into additional glucose by gluconeogenesis.
38
What is glycogenolysis?
Glycogen stored in the liver and muscle cells is broken down into glucose, which is released into the bloodstream, increasing blood glucose concentration
39
What is gluconeogenesis?
The production of glucose from non-carbohydrate sources.
For example, the liver is able to make glucose from glycerol (lipids) and amino acids. This glucose is released into the bloodstream and causes an increase in blood glucose concentration
40
Why does blood glucose level fall faster and greater in a non-diabetic person than a diabetic?
Insulin stimulates liver to convert glucose into glycogen, more respiration occurring
41
What causes the blood glucose level to eventually fall in a diabetic person?
Used in respiration, lost from the body in urine
42
What are the symptoms of diabetes?
High blood glucose concentration
Glucose present in urine
Excessive thirst
Excessive need to urinate
Weight loss
Constant hunger
Tiredness
43
Why is tiredness a symptom of diabetes?
No glucose uptake and conversion to glycogen by the liver
No stored glycogen to be hydrolysed into glucose to be released back into the blood when blood glucose levels fall, so cells lack glucose for respiration and fatigue occurs
44
What is diabetes mellitus?
A condition in which blood glucose concentrations cannot be controlled effectively
45
What is hyperglycaemia?
A state in which the blood glucose concentration is too high (hyper = above, glyc = glucose, aemia = blood)
Permanently high blood glucose concentrations can lead to significant organ failure
46
What is hypoglycaemia?
A state in which the blood glucose concentration is too low, leads to tiredness and irritability. In severe cases, it can cause impairment of brain function, confusion, seizures and death
47
What is type 1 diabetes?
The body stops producing insulin.
Beta cells are unable to synthesise insulin.
Starts in childhood
48
What is type 2 diabetes?
The body is unable to use insulin to control blood glucose levels.
Either not enough insulin is produced or the receptor molecules on the liver cells do not respond on the insulin
People over 40 years old were most at risk, although it is now occurring more in children.
90% of all diabetics are this type.
49
What can cause type 1 diabetes?
Beta cells destroyed by the persons own immune system in an autoimmune disease.
Beta cells may be destroyed as a result of a viral infection.
50
What can cause type 2 diabetes?
Obesity
Lack of regular exercise
Having a diet high in sugar, especially refined sugars.
Being of Asian or Afro-Caribbean origin
Family history.
51
What are treatments for type 1 diabetes?
- Insulin injections.
- Monitor blood glucose and inject/ eat a biscuit when necessary.
- Insulin pump therapy
- Islet of Langerhans cell transplantation.
- Pancreatic transplant.
- Use of stem cells to grow into new islets of Langerhans/beta cells. To avoid rejection issues, research is progressing on using stem cells from embryos which were produced via somatic cell nuclear transfer [SCNT]. Or from adult stem cells found in the patient’s body.
- Take medication which reduces the amount of glucose that the liver releases.
52
What are treatments for type 2 diabetes?
Change lifestyle, monitor diet and match carbohydrate intake with use.
Take drugs to slow down the absorption of glucose in the intestine.
May have to inject insulin if levels produced are not high enough.
Lose weight, exercise more
53
What are possible cures for diabetes?
Pancreas transplant
Beta cell transplant
Stem cells
Stem cells from somatic cell nuclear transfer
54
What are the advantages/disadvantages of a pancreas transplant?
Limited donors, will require a lifetimes of immunosuppressant drugs, risks in major surgery
High success rate
55
What are the advantages/disadvantages of a beta cell transplant?
Will require a lifetime of immunosuppresant drugs
Not highly successful
56
What are the advantages/disadvantages of stem cells?
Stem cell lines can supply unending source of stem cells for treatment
Rejection problems may still occur
Moral objections to ending embryos life
57
What are the advantages/disadvantages of stem cells from somatic cell nuclear transfer?
Embryos created using patients nucleus so no rejection issues
In both stem cell cures, investigating how to switch on and off the required genes to allow stem cells to differentiate into beta cells
58
What are the advantages to insulin from genetically modified bacteria compared to insulin from pigs or cows?
Exact copy of human insulin, thus
- Less likely to trigger immune system and cause allergic reaction
- More rapid response
Can be mass produced to meet high demand
Can be produced to a reliable standard
Mass production allows it to be cheaper than animal insulin
Lower risk of infection from pig prions
No objections from religious groups or vegitarians
59
Draw the diagram to show how the fight or flight response is coordinated
Sensory input ----> receptor ----> coordination: brain (particularly hypothalamus: stimulates pituitary gland to release hormone ACTH which is transported in blood and acts on adrenal cortex)
This then leads to...
- Impulses being sent down sympathetic motor neurones ----> adrenal medulla ----> noradrenaline OR adrenaline
- Impulses being sent down sympathetic motor neurones ----> glands and smooth muscles ----> activated
- Pituitary gland secretes ACTH to activate ---> adrenal cortex ----> approx. 30 hormones released into blood
60
What is the advantage of dilating pupils for the fight or flight response?
Take in as much light as possible for better vision
61
What is the advantage of increased heart rate and blood pressure for the fight or flight response?
Pump more oxygenated blood around the body
62
What is the advantage of increasing blood glucose levels for the fight or flight response?
Increase respiration to provide energy for muscle contraction
63
What is the advantage of increasing metabolic rate for the fight or flight response?
Heightened levels of activity require increased metabolic rate to mobilise all of the nutrients required
64
What is the advantage of making hairs stand up via erector pili muscles for the fight or flight response?
Make animal look bigger and fiercer, frighten off attacker
65
What is the advantage of increasing ventilation rate and depth for the fight or flight response?
Increased removal of CO2 and supply of oxygen
66
What is the advantage of releasing endorphins in the brain for the fight or flight response?
Acts as natural painkiller, wounds inflicted on mammal do not affect activity
67
What is the advantage of increasing sweat production for the fight or flight response?
Increased metabolism generates heat, needs to be removed
68
What is the advantage of arterioles taking blood to digestive system and skin constricting and those that go to liver and muscles dilating for the fight or flight response?
Diverts blood flow away from skin and digestive system towards muscles, ATP production
69
What do the Glucocorticoid hormones (eg cortisol) do?
Raises blood glucose levels in times of stress
Regulates blood pressure and cardiovascular function in response to stress
70
What do the Mineralocortoid hormones (eg aldosterone) do?
Helps to control concentration of sodium and potassium in the blood, maintaining blood pressure
71
What do the androgen hormones do?
Small amounts of male and female sex hormones released
Especially important in women after menopause
72
What does adrenaline do?
Increases heart rate
Stimulates conversion of glycogen to glucose
Relaxes smooth muscle in the bronchioles
Increases stroke volume of heart
Causes general vasoconstriction to raise blood pressure
Dilates pupils
Increases mental awareness
Inhibits action of gut
Causes body hairs to stand erect
73
What does noradrenaline do?
Works with adrenaline in times of stress
Increases heart rate, widening pupils, widening air passages, narrow blood vessels in non-essential organs
74
What increases heart rate
Before and during exercise
When nervous, excited, frightened or stressed
75
What does myogenic mean?
Muscle is able to contract and relax of own accord
76
What is the typical resting heartbeat?
60-80bpm
77
What can the nervous and hormonal system alter?
Frequency and force of contraction, stroke volume
78
What does the cardiovascular centre in the medulla oblongata receive input from?
Stretch receptors in the muscles
Chemoreceptors in aorta, cartoid artery and medulla oblongata, detect CO2 levels in blood by pH changes
Baroreceptors (pressure receptors) in aorta and cartoid arteries which detect blood pressure changes
79
What does the input to the cardiovascular centre cause?
Initiates impulses via autonomic nervous system to the sympathetic nerve to increase frequency of contraction, or parasympathetic to decrease
80
What is glycogenolysis?
Biochemical break-down of glycogen to glucose
81
What is glucokinase?
An enzyme that catalyses the phosphorylation of glucose.
Biology
flashcards
Decks in class (27)
# Cards
-
Biodiversity63
-
Biological Molecules45
-
Biological Molecules Definitions39
-
Biotechnology and Cloning69
-
Cell Division and Cellular Organisation45
-
Cell Structure33
-
Cellular Control51
-
Classification and Evolution44
-
Communicable Diseases63
-
Ecosystems49
-
Enzymes33
-
Exchange Surfaces19
-
Homeostasis and Excretion58
-
Hormones81
-
Inheritence57
-
Manipulating Genomes52
-
Muscles30
-
Nerves87
-
Nucleotides and Nucleic Acids19
-
Photosynthesis60
-
Plasma Membranes27
-
Plant Responses40
-
Populations and Sustainability44
-
Respiration77
-
Statistical Testing11
-
Transport in Animals55
-
Transport in Plants66
