1
Q
What are the two types of hormones?`
A
- Steroid
- Protein
2
Q
Describe what a protein hormone is.
A
- Not soluble in PL memb and do not enter the cell
- need to bind on the outside and secrete a messenger
3
Q
Describe what a steroid hormone is.
A
- can pass through memb and enter cell and nucleus
- have direct effect on DNA inside nucleus
4
Q
What is the endocrine system?
A
- hormones are released directly into the blood from endocrine glands
- ductless glands
- consist of cells that manufacture the hormone into capillaries
5
Q
What is the exocrine system?
A
- groups of cells surrounding ducts
- secrete products into the ducts
6
Q
State the name of the cells which receive endocrine signals
A
Target cells
7
Q
Describe the structure and function of target cells.
A
- may be grouped in a target tissue
- may be more widely dispersed e.g receptors for adrenaline and tissues intervated by the PNS
8
Q
What must the target cells possess in order to receive non-steroid hormones?
A
- A specific receptor on the surface of the PM
9
Q
What are the two types of receptors?
A
- Alpha
- Beta
10
Q
Where are alpha receptors found?
A
- Excitatory in SM and gland cells, cause relaxation of intestinal smooth muscles
11
Q
Where are beta receptors found?
A
- produce an inhibitory response
- in heart muscle= excitatory
12
Q
Name a use of beta receptors
A
- beta blockers
- used to inhibit the response of these receptors to adrenalin
- controls heart conditions
13
Q
What is a first messenger?
A
- Non seroid hormones
- Cause the release of another signalling molecule
14
Q
Where is a first messenger found?
A
- outside the cell that bind to the CSM and initiate an internal effect
15
Q
What does the secondary messenger do?
A
- stimulates a change in the activity of a cell
16
Q
Summarise the action of steroid hormones
A
- Steroid hormone passes through CM of the target cell
- Steroid hormone binds with a specific receptor in cytoplasm
- Receptor/ steroid hormone complex enters nucleus of target cell and binds to another recetpor on chromosomal material
- Binding stimulates production of mRNA which codes for production of proteins
17
Q
How are steroid hormones produced?
A
- Adrenal cortex uses cholesterol to produce hormones which are steroid based
18
Q
Why can’t adrenaline pass directly through the PM?
A
- It is hydrophillic so it binds to receptor cells on the surface
- Polar molecule derived from tyrosine
19
Q
Describe the method of action of adrenaline
A
- Adrenaline binds to comp receptor
- Activates a G protein which is associated with the receptor
- G protein activates adenyl cyclase and converts ATP to cyclic adenosine monophosphate
- cAMP acts as a second messenger which activates an enzyme cascade
- Results in hydrolysis of glycogen into glucose
20
Q
What are the 2 main secretions of the pancreas?
A
- pancreatic juice containing enzymes secreted into small intestine
- hormones secreted from islets of Langerhans into the blood
21
Q
Describe the structure/ features of Islets of Langerhans
A
- Good blood supply
- made up of a and b cells
- cells are able to detect glucose concentration as it passes through capillaries in the islets
22
Q
What do the a cells in islet of Langerhans do?
A
- Glucagon is secreted into blood
- causes glycogen to be converted into glucose
- liver releases glucose into blood
23
Q
What do the b cells in islet of Langerhans do?
A
- insulin secreted into blood
- causes accelerated take up of glucose
- decreased glycogen breakdown
24
Q
What is the exocrine function of the pancreas?
A
- to secrete and synthesise digestive enzymes
25
Describe the structure of exocrine cells in the pancreas.
- small groups
- each group is called an acinus
- acini are grouped into lobules separated by connective tissue
- cells of the acini secrete the enzymes they synthesise into the tubule
26
What does the pancreatic duct do?
- carries fluid containing enzymes into first part of small intenstine called duodenum
27
What does the fluid from the pancreatic duct contain?
- pancreatic amylase
- trypsinogen
- lipase
28
What is the endocrine function of the pancreas?
- the A and B cells that make up the endocrine tissue
- involves secreting glucagon and insulin
29
Why should blood glucose levels be maintained at the optimum level?
- to provide glucose for respiration (brain cells ONLY respire using glucose, cant store glycogen)
- high glucose concentrations affect blood WP, cells lose water by osmosis
30
How is blood glucose increased?
- digestion
- the liver hydrolyses stored glycogen into glucose
- the liver converts lipids and fats into glucose and releases it
31
How is blood glucose decreased?
- lack of food intake
- respiration by cells
- conversion into glycogen by liver and muscle cells
32
What monitors blood glucose levels?
a and b cells in islets of Langerhans
33
What is meant by negative feedback?
The mechanism that detects and reverses a change, bringing the system back to the optimum state.
34
What is the saying for when there is no more glucose
if glucose is gone you need glucagon
35
How do beta cells control insulin secretion?
| briefly
1. Pottasium channels are open so ions flow out via diffusion
2. When blood glucose is too high it moves into the cell via a glucose transporter
3. glucose is metabolised inside the mitochonria to produce ATP which closes the k+ ion channels (atp sensitive channels)
4. depolarisation causes the inside to be less negative, change in potential difference opens calcium channels
5. calcium ions cause insulin vesicles to fuse with CM, exocytosis
36
How does the liver respond to blood glucose levels?
- more transport proteins in CM
- glycogenesis
- glucose converted into fats
- more glucose used in respiration by increasing the rate of respiration
37
How do liver cells respond when blood glucose levels fall?
1. liver cells have glucagon receptors
2. hydrolysing glycogen to glucose (glycogenlysis)
3. removing glucose transport proteins from CM so less glucose is absorbed
4. using more fatty acids in respiration
5. amino acids and fats are converted into additional glucose by gluconeogenesis
38
Define glycogenesis
The formation or synthesis of glycogen
39
Define gluconeogenesis
The synthesis of glucose from other sources
40
Define glycogenolysis
The biochemical breakdown of glycogen to glucose
41
Define glucokinase
An enzyme that catalsyses the phosphorylation of glucose
42
How does insulin lower blood glucose concentration?
- increases rate of glucose absorption
- increasing respiratory rate of cells
- increasing rate of glycogenesis
- inhibiting the release of glucagon from alpha cells of islet of Langerhans
43
How does glucagon increase blood glucose?
- glycogenolysis
- reducing glucose absorption
- increasing gluconeogenesis
44
Why is tiredness a symptom of diabetes?
- no glucose uptake and glycogen conversion by liver
- no stored glycogen to be hydrolysed and released back into the blood
- cells lack glucose for respiration and fatigue occurs
45
What is hyperglycaemia?
High blood glucose
46
What is hypoglycaemia?
Low blood glucose
47
What is type 1 diabetes?
Stops producing insulin
48
What is type 2 diabetes?
Receptor cells don't respond to insulin
49
How is type 1 and 2 diabetes caused and treated?
Cause 1= beta cells destroyed by immune system or infection
Cause 2= obesity, high fat diet, family history, lack of exercise
Treat 1= insulin injection or pump, pancreatic transplant, islet of Langerhans transplant
Treat 2= lose weight, change lifestyle, take meds which reduce amount of glucose released, drugs to slow absorption in the intestine
50
Compare treatment VS cure
Treatment manages the condition whilst a cure stops the condition
51
Name possible cures for diabetes
Pancreas transplant
Beta cell transplant
Stem cells
Stem cells from somatic cell nuclear transplant
52
What is the issue with possible cures for diabete?
1. Pancreas trans= immuno drugs, risks, high success
2. Beta cell trans= immuno drugs, not highly success
3. Stem cells= rejection problems, moral objections
4. Stem cells from somatic cell= no rejection issues as it is patient's nucleus
53
Name advantages of bacterial insulin compared to pig and cow insulin
1. exact copy of human insulin (allergic reaction not likely)
2. mass produced to meet demand
3. cheaper
4. lower risk of infection
5. no religious objections
54
Name 5 physiological changes due to the fight or flight response
1. Blood vessels constrict to the digestive system, dilate to the liver and muscles
2. pupils dilate
3. deep breaths, increased ventilation
4. heart rate increases
5. blood glucose increases
55
Briefly explain how the fight or flight response is coordinated.
Sensory input -> detected by receptors -> NS coordinates a response which is carried out by effectors -> adrenal medulla (noradrenaline), glands and SM activate, secretion of ACTH by pituitary gland stimulates adrenal cortex which releases 30 hormones
56
What are the 3 layers of the adrenal gland and what do they secrete?
1. Zona glomerulosa= outermost, secretes mineralocorticoids like aldosterone
2. Zona fasciculata= middle layer, secretes glucocorticoids like cortisol
3. Zona reticularis= inner, secretes precursor molecules to make sex hormones
57
What is the adrenal medulla and what does it secrete?
Found at the centre of the adrenal gland
Secretes adrenaline and noradrenaline
58
What effect does the hormone from the zona glomerulosa have?
- raises blood glucose levels in times of stress
- regulates immune response, surpresses inflammatory reactions
- aldosterone acts on the kidney distal tubules, effecting selective reabsorption (controls conc of NA+ and K+ ions), maintains BP
- mineralocorticoids
59
What effect does the hormone from the zona fasciculata have?
- glucocorticoids= cortisol, stimulate increase in blood glucose
- cortisol stimulates glucose production from glycogen
- controls metabolism of respiratory substrates
60
What effect does the hormone from the zona reticularis have?
- Small amounts of male and female sex hormones are released
- precursor androgens if correct enzymes arent present for cortisol
- precursors are used to make sex hormones
- important in women after menopause
61
What effect does noradrenaline have?
- works with adrenaline
- increases heart rate, narrowing blood vessels in non essential organs like the digestive system
62
What do the 2 centres in the medulla oblongata do?
1. Increases HR by sending impulses through SNS which is transmitted by accelerator nerve
2. Decreases HR by sending impulses through parasympathetic NS transmitted by vagus nerve
63
What do baroreceptors do and where are they found?
- detect changes in blood pressure
Located in= aorta, vena cava, carotid arteries
64
Briefly describe how chemoreceptors respond to low blood pH
When CO2 is in the blood it reacts with water to form carbonic acid which lowers pH
This is detected by chemoreceptors
causes heart rate to increase
increased blood flow to lungs so CO2 is exhaled
65
What do chemoreceptors do?
- detect changes in blood pH, particularly due to carbon dioxide concentration
Located in= aorta, carotid artery, medulla
66
Briefly describe how chemoreceptors respond to a decrease in CO2 concentration
Causes a higher pH
decreases the fequency of impulses sent to medulla oblongata
nerve impulses which stimulate SAN/ activity decrease
HR returns to normal
67
Briefly describe how baroreceptors monitor blood pressure
Increase in blood pressure causes impulses to be sent to medulla oblongata centre
decreases HR
MO sends impulses along parasympathetic neurones to SAN
Decreases HR
Bp back to normal
Biology
flashcards
Decks in class (24)
# Cards
-
Biological membranes33
-
Communicable diseases65
-
Biological molecules54
-
Nucleic acids33
-
Enzymes32
-
Exchange surfaces32
-
Cell structure30
-
Cell organelles22
-
Cell division40
-
Transport in animals57
-
Transport in plants49
-
Classification and evolution51
-
Biodiversity57
-
Homeostasis69
-
Ecosystems31
-
Plant hormones27
-
Hormones67
-
Photosynthesis33
-
Nerves44
-
Nerves- the brain regions6
-
Respiration34
-
Inheritance38
-
Manipulating genomes23
-
Cellular control33
