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A2 Biology > Hormonal Communication > Flashcards

Hormonal Communication Flashcards

1
Q

What are the types of hormone?

A

Protein and peptide hormones

Steroid hormones

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2
Q

Example of protein hormones?

A

Adrenaline, insulin, glucagon

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3
Q

Example of steroid hormones?

A

Oestrogen and testosterone

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4
Q

Which hormone can enter the cell?

A

Steroid hormones

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5
Q

Why can’t protein hormones enter the cell?

A

Proteins are not soluble in the phospholipid membrane

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6
Q

What is the endocrine system?

A

A communication system using hormones as signalling molecules

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7
Q

Where are hormones released from?

A

Endocrine glands

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8
Q

Describe endocrine glands?

A

Ductless
Consist of group of cells that manufacture and release the hormone directly into the blood in capillaries running through the gland

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9
Q

Examples of endocrine glands?

A 
Pituitary gland 
Thyroid gland 
Thymus 
Adrenal gland
Pancreas
Ovaries and testes
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10
Q

Example of exocrine gland?

A

Saliva gland

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11
Q

How are hormones transported?

A

Via the bloodstream

All over the body

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12
Q

What are target cells?

A

The cells that revive the endocrine signal

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13
Q

What are non-steroid hormones also know as?

A

First messengers

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14
Q

What do the first messengers do?

A

Signalling molecules outside the cell
Bind to the cell surface membrane
Initiate the release of the second messenger within the cell

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15
Q

What is usually activated when the non-steroid hormone binds to the cell?

A

The G protein

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16
Q

What does the G- protein do?

A

Activate an effector molecule- usually adenyl cyclase

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17
Q

What is the role of the effector molecule?

A

Usually an enzyme

Converts an inactive molecule into the active second messenger

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18
Q

What is the role of adenyl cyclase?

A

Converts ATP to cyclic AMP (cAMP)

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19
Q

What may the second messenger do?

A

Act directly on another protein such as an ion channel

Or it may initiate a cascade of enzyme- controlled reactions that alter the activity of the cell

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20
Q

Where are the adrenal glands found?

A

Anterior to the kidneys

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21
Q

What is the structure of the adrenal glands?

A

Each gland is divided into the outer adrenal cortex and the inner adrenal medulla

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22
Q

What are the layers in the adrenal cortex?

A

Zona glomerulosa
Zone fasciculata
Zonal reticularis

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23
Q

What is the zona glomerulosa?

A

Outermost layer

Secretes mineralocorticoids such as aldosterone

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24
Q

What is the zona fasciculata?

A

Middle layer

Secretes glucocorticois such as cortisol

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25
What is the zona reticularis?
Innermost layer | Secretes precursor molecules- used to make sex hormones
26
What does the adrenal medulla secrete?
Adrenaline and noradrenaline
27
What is the very outer layer of the adrenal gland?
Capsule
28
What type of hormones are those released from the adrenal glands?
Steroid hormones
29
Summary of the action of steroid hormones from the adrenal cortex?
Hormone passes through the cell membrane and binds with a specific receptor in the cytoplasm.
30
What happens in the cell once the steroid hormone has bind to the receptor?
The receptor- steroid hormone complex enters the nucleus and binds to a receptor on the chromosome. This stimulates the production of mRNA for protein synthesis.
31
What is the role of mineralocorticoids (aldosterone) ?
Helps to control blood sodium and potassium concentrations. There also help to maintain blood pressure.
32
How does aldosterone carry out its function?
It acts on the cells of the distal convoluted tubule and collecting ducts.
33
Role of glucocorticoids (cortisol) ?
Helps to control the metabolism of carbohydrates, fats and proteins in the liver.
34
When is cortisol released?
As a response to stress or a result of low blood glucose concentration.
35
How does cortisol carry out its function?
By stimulating the production of glucose from stored compounds in the liver
36
Where else can cortisol be real eased from?
The zona reticularis, only if the correct enzymes are present
37
Where are the precursor androgens taken up? What is their function?
Ovaries and testes and converted to sex hormones. | Regulate the production of gametes.
38
Describe adrenaline?
Polar molecule From the amino acid tyrosine Cannot enter cells through the plasma membrane
39
What is the effect of adrenaline not entering the cell?
As many cells have adrenaline receptors the effects of adrenaline are wide spread
40
What is the main role of adrenaline?
To prepare the body for activity
41
What are the effects of adrenaline?
``` Increases heart rate and stroke volume Dilates pupils Relaxes smooth muscle in bronchioles Increases mental awareness Inhibits gut action Causes hairs to stand erect Converts glycogen to glucose ```
42
What is unusual about the pancreas?
It has both endocrine and exocrine functions.
43
What are the two secretions from the pancreas?
Pancreatic juices containing digestive enzymes | Hormones secretes from Islet of langerhans
44
What is an acinus?
A group of exocrine cells in the pancreas surrounded by tubules
45
What do the tubules from the acini form?
Intralobular ducts that combine to make up the pancreatic duct
46
Role of pancreatic duct?
Transports pancreatic juices containing enzymes to the small intestine
47
What enzymes are in the pancreatic juices?
Amylase Trypsinogen Lipase
48
What does the pancreatic juices also contain?
Sodium hydrogencarbonate- neutralises
49
What does the islet of Langerhans contain?
Alpha and beta cells | - endocrine function
50
What do the alpha cells secrete?
Glucagon
51
What do the beta cells secrete?
Insulin
52
What does the beta membrane contain?
Potassium and calcium ion channels
53
When is insulin released?
When blood glucose concentration is too high
54
Are the potassium ion channels on a beta cell normally open or closed?
Potassium channels are normally open to allow potassium ions to flow out
55
How is insulin released? Part 1
When glucose concentration increases glucose enters the beta cell. This glucose metabolised to ATP. ATP closes the P ion channels.
56
How is insulin released? Part 2
The accumulation of protein ions alters the potential difference across the beta membrane which causes Ca channels to open. Ca+ causes the vesicles of insulin the fuse with the membrane releasing the insulin by exocytosis
57
What is the normal blood glucose concentration?
Between 4-6
58
What is a person said to be if their blood glucose concentration drops below 4 mmol dm-3?
Hypoglycaemic
59
What is hypoglycaemia?
An inadequate delivery of glucose to the body tissues and brain
60
Symptoms of hypoglycaemia?
Mild- tiredness and irritability | Severe- impairment of brain function, confusion, seizures, unconsciousness and death
61
What is hyperglycaemia?
If blood glucose concentration is allowed to rise too high
62
When is glucagon released?
If blood concentration is too low
63
How many amino acids does insulin contain?
51
64
What enzyme is activated when when insulin binds to an insulin receptor?
Tyrosine kinase
65
What effects does insulin have on the cell?
Vesicles containing glucose transporter proteins fuse with membrane- more glucose enters cell Glucose in the cell is converted to glycogen More glucose is converted to fats and used in respiration
66
Where is a low blood glucose concentration detected?
Alpha cells in islet of langerhans
67
What are insulins target cells?
Liver, muscle and other body cells including those in the brain
68
How many amino acids does glucagon contain?
29
69
What are glucagons target cells?
Hepatocytes
70
What are the effects of glucagon?
Glycogen is converted into glucose More fatty acids used in respiration Amino acids and fats are converted into glucose
71
What is the process of glycogen into glucose?
Glycogenolysis
72
What is the process of converting glucose to glycogen?
Glycogenesis
73
What is the process of amino acids and fats converted into glucose?
Gluconeogenesis
74
How can the hormones insulin and glucagon be described?
Antagonistic
75
What is diabetes mellitus?
A condition in which the body is no longer able to produce sufficient insulin to control its blood glucose concentration
76
When are diabetic people at risk?
After a meal rich in carbohydrates and sugars | After exercise or fasting
77
How is type 1 diabetes also known?
Insulin dependent or juvenile onset
78
What is thought to be the cause of type 1 diabetes?
An autoimmune response In which the body's immune system attacks beta cells Or A viral attack
79
What can a person with type 1 diabetes no longer do?
Synthesise sufficient insulin | Store glucose as glycogen
80
What is type 2 diabetes also known as?
Non insulin dependent
81
What problem occurs with type 2 diabetes?
As people age their receptors become less responsive to the insulin hormone
82
What is the blood glucose concentration like in a person with type 2 diabetes?
Permanently raised
83
Danger of a high blood glucose concentration
Organ damage
84
What factors can bring an early onset of type 2 diabetes?
``` Obesity Lack of exercise High refined sugar diet Family history Being of Asian or Afro-Caribbean origin ```
85
How is type 1 diabetes normally treated?
Insulin injections
86
What are the alternatives to insulin injections?
Insulin pump therapy Islet cell transplantation Pancreas transplant
87
What is an insulin pump?
A small device which pumps insulin into the bloodstream through a needle permanently inserted under the skin
88
What is islet cell transplantation?
Healthy beta cells are implanted from a dead donor
89
What has new research into type 1 diabetes treatment found?
That stem cells could be used to grow new islets of langerhans
90
How is type 2 diabetes usually treated?
Life style changes- diet, exercise and weight loss
91
How can insulin be gained?
Extracted from the pancreas of animals | By genetic modification of Escherichia bacteria
92
What are the advantages of the genetic modification method?
Less chance of rejection from immune system Lower risk of infection It is cheaper to manufacture More morally accepted

A2 Biology (11 decks)

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