CHAPTER 14 - HORMONAL COMMUNICATION Flashcards
1
Q
What is an endocrine gland
A
A group of cells that are specialised to secrete chemicals
2
Q
What does the pituitary gland do
A
Produces
growth hormone, which controls growth of bones and muscles;
anti-diuretic hormone, which increases reabsorption of water in the kidneys
and Gonadotrophins which control development of ovaries and testes
3
Q
What does the thyroid gland do
A
Produces thyroxine which controls rate of metabolism and rate that glucose is used up in respiration and promotes growth
4
Q
What does the Adrenal gland do
A
produces adrenaline, which increases heart and breathing rate and raises blood sugar level
5
Q
What do the testis do - endocrinally
A
Produce testosterone which controls sperm production and secondary sexual characteristics
6
Q
What does the pineal gland do
A
Produces melatonin which affects reproductive development and daily cycles
7
Q
What does the thymus do
A
Produces thymosin which promotes production and maturation of white blood cells
8
Q
What does the pancreas do
A
produces insulin which converts excess glucose into glycogen in the liver, and glucagon, which converts glycogen back to glucose in the liver
9
Q
What does the ovary do endocrinally
A
Produces oestrogen which controls ovulation and secondary sexual characteristics and progesterone, oestrogen which controls ovulation and secondary progesterone, which prepares the uterus lining for receiving an embryo
10
Q
What are hormone often referred to
A
Chemical messengers because they carry information from one part of the body to another
11
Q
What do exocrine glands do
A
Secrete chemicals through ducts into organs eg. sweat through sweat ducts onto the skin or digestive enzymes into the digestive system
12
Q
What types of hormones are there
A
Steroids, proteins, glycoproteins, polypeptides, amines or tyrosine derivatives
13
Q
What events can lead to hormones being secreted
A
Glands are secreted into the blood to alter the concentration of a substance eg. blood glucose
Or as a result of another hormone or a nerve impulse
14
Q
What are target cells
A
The cells on organs that have receptors that a hormone will bind to
15
Q
What are steroid hormones and where are their receptors
A
They pass through the lipid component of the cell membrane and bind to steroid hormone receptors to form a hormone-receptor complex. The receptor may be in the cytoplasm or the nucleus depending on the hormone. The H-RC formed acts as a transcription factor which in turn facilitates or inhibits the transcription of a specific gene. Oestrogen is an example of a hormone which works this way
16
Q
How do non-steroid hormones
A
Hydrophilic so they cannot pass directly through the cell membrane. Instead they bind to receptors on the cell surface membrane of the target cell. This triggers a cascade reaction by chemicals called second messengers. Adrenaline is an example of a hormone which works this way
17
Q
Which are longer lasting and why - Hormonal or neuronal communication
A
Hormones arent released directly onto their target cells, so there is a slower and less specific form of communication, and as they are not broken down as quickly as neurotransmitters, it results in a much longer lasting and widespread effect
18
Q
Hormonal system qualities vs Nervous system Qualities
A
Hormones:
Communication by hormones
Transmission in blood
Relatively slow transmission
Travel to all parts of body, but only target organs respond
Response is widespread
Response is slow
Long-lasting response
Effect may be permanent and irreversible
Nervous system:
Communication by nerve impulses
Transmission by neurones
Rapid transmission
Impulses only travel to specific parts of the body
Localised response
Rapid response
Short-lived response
Effect is temporary and reversible
19
Q
Where are the adrenal glands located
A
On top of each kidney
20
Q
What are the adrenal glands two parts
A
Adrenal cortex - outer region of the glands. This produces hormones that are vital to life, such as cortisol and aldosterone
Adrenal Medulla - the inner region of the glands. This produces non-essential hormones, such as adrenaline which helps the body react to stress
21
Q
What is the production of hormones in the adrenal gland controlled by
A
Pituitary glands
22
Q
What are the main type of hormones produced by the adrenal cortex
A
Glucocorticoids
Mineralocorticoids
Androgens
23
Q
What do glucocorticoids do
A
These include cortisol which helps regulate metabolism by controlling how the body converts fats, proteins and carbohydrates into energy. It also helps regulate blood pressure and cardiovascular function in response to stress.
Another glucocorticoid hormone released is corticosterone. This works with cortisol to regulate immune response and suppress inflammatory reactions.
Release of these hormones is regulated by hypothalamus
24
Q
What do mineralocorticoids do
A
Main one produced is Aldosterone which helps control blood pressure by maintaining the balance between salt and water concentrations in the blood and bodily fluids.
Its release is mediated by signals triggered by the kidney
25
What do androgens do
Small amounts of male and female sex hormones are released - their impact is relatively small compared with the larger amounts of hormones eg. oestrogen and testosterone from ovaries or testes after puberty, but they are still important, especially in women after the menapause
26
When are the hormones that are released from the adrenal medulla
When the sympathetic nervous system is stimulated eg. when the body is stressed
27
What are the hormones secreted from the medulla
Adrenaline and Noradrenaline
28
What does Adrenaline do
Increases the heart rate sending blood quickly to the muscles and brain. It also rapidly raises blood glucose concentration levels by converting glycogen to glucose in the liver
29
What does noradrenaline do
Works with adrenaline in response to stress, producing 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 (raising blood pressure)
30
Using a named example, explain the function of an endocrine gland
Produce and secrete hormones
e.g., adrenal gland and adrenaline
31
Describe the pathway triggered by a stimulus in hormonal communication
stimulus detected → gland stimulated → hormone secreted → travels in blood (plasma) → target cell → binds to receptor/triggers response
32
Bright light causes the iris muscles to contract in your eye, constricting the pupil and preventing damage. State and explain whether hormonal or neuronal communication would be used in this response
Neuronal communication
faster response needed to prevent damage / electrical impulses travel
faster than hormones in blood stream/response is temporary
33
A person falls into a fast-flowing river. State and explain the changes that may occur in the body and increase a person's chances of survival in this situation
Detected by sympathetic nervous system
triggers the adrenal glands to secrete hormones
from the adrenal medulla
named hormone – adrenaline / noradrenaline
effect of hormone on body – raises heart rate / increases blood glucose concentration / widens air passages / narrows blood vessels in non-essential organs / raises blood pressure
explanation of how hormonal effect
increases chance of survival e.g., increased rate of respiration / muscles are able to work harder / longer
34
What is a glandular organ
An organ whose role is to produce and secrete hormones and digestive enzymes
35
What are the two main functions of the pancreas
Exocrine gland - to produce enzymes and release them via a duct into the abdomen
Endocrine gland - to produce hormones and release them into the blood
36
What are the important types of enzymes produced by the pancreas
Amylases - Break down starch into simple sugars eg. pancreatic amylase
Proteases - Break down proteins into amino acids eg. trypsin
Lipases - breaks down lipids into fatty acids and glycerol eg. pancreatic lipase
37
Where is the alkaline fluid known as pancreatic juice and enzymes secreted into
Ducts which eventually lead into pancreatic duct and eventually into the duodenum, the top part of the small intestine
38
What is most of the pancreas made up of
Exocrine glandular tissue
39
What hormones is the pancreas responsible for producing
Insulin and Glucagon - controlling blood glucose concentration
40
Within the exocrine tissue, what are the small regions of endocrine tissue called and where do they secrete hormones to
Islets of Langerhans,
Secrete directly into bloodstream
41
What do the islets of langerhans look like, what type of tissue are they and what is its function
Lightly stained, large spherical clusters
Endocrine pancreatic tissue
Produces and secretes hormones
(pg 387)
42
What do the pancreatic acini look like, what type of tissue are they and what is its function
Darker stained, small berry-like clusters
Exocrine pancreatic tissue
Produces and secretes digestive enzymes
(pg 387)
43
What are the two types of cell in the Islets of Langerhans and what do they do
Alpha cells - Produce and secrete Glucagon
Beta cells - produce and secrete insulin
44
State the difference between endocrine and exocrine glandular tissue
Hormones are produced by endocrine tissue
whereas substances such as enzymes are produced by exocrine tissues
45
State two features which would enable you to identify the Islets of Langerhans through a cross-section of pancreatic material, when viewed under a light microscope
Lighter stained / appear whiter than surrounding tissue
larger cluster of cells
when viewed under high power an acinus is visible / small groups of cells are visible surrounding a duct
46
What is the normal blood glucose concentration
90 mg cm-3
47
What factors lead to an increase in blood glucose
Diet - eating carbohydrate rich foods and sweet foods - starch and sugar which are broken down into glucose
Glycogenolysis - breaking down of glycogen in liver and muscles releasing glucose into blood stream
Gluconeogenesis - production of glucose from non-carbohydrate sources eg. liver makes glucose from glycerol or amino acids
48
What is glycogenolysis
Glycogen stored in the liver and muscle cells is broken down into glucose which is released into the bloodstream
49
What us Gluconeogenesis
The production of glucose from a non-carbohydrate source
eg. liver making glucose from glycerol and amino acids, releasing glucose into the blood
50
How does blood glucose concentration decrease
Respiration - some of the glucose in the blood is used up by cells to release energy. either in normal bodily functions or during exercise
Glycogenesis - Production of glycogen, when blood glucose concentration is too high, excess glucose is taken in through the diet and converted into glycogen in the liver
51
What is glycogenesis
The production of glycogen from glucose, when it is take out of the blood when concentrations are too high when excess is consumed, converted into glycogen, stored in liver
52
What are one of the only bodily cells to not have insulin receptors on their cell surface membrane
Red blood cells
53
What happens when insulin binds to a glycoprotein
Changes in tertiary structure of glucose transport protein channels
Causes channels to open, allowing more glucose to enter the cell
Also activates enzymes within some cells to convert glycogen to fat
54
How does Insulin lower blood concentration
Increases rate of absorption of glucose by cells, especially skeletal muscle cells
Increase respiratory rate of cells - increasing need for glucose, taking from blood
Increasing rate of glycogenesis - insulin stimulates the liver to remove glucose from the blood by turning glucose into glycogen
Increasing rate of glucose to fat conversion
Inhibiting release of glucagon from alpha cells in the islets of langerhans
55
What is Insulin broken down by
Enzymes in the liver - so to maintain its effect it must constantly be secreted
56
What is the type of feedback seen in the regulation of blood glucose concentration
Negative
Too high - Secretes Insulin
Too Low - Secretes Glucagon
57
What are the only cells in the body that have glucagon receptors
Liver and fat cells
58
How does glucagon raise blood glucose concentration
Glycogenolysis - breakdown of glycogen into glucose
Reducing amount of glucose absorbed by cells
Increasing Gluconeogenesis - conversion of amino acids and glycerol into glucose
59
Why are Insulin and Glucagon antagonistic hormones
They work against each other
60
What happens to blood glucose concentration and why when adrenaline is released
Raises blood glucose concentration to allow more respiration to occur
61
What is the mechanism for which insulin is secreted
Normal blood glucose levels:
potassium channels in the plasma membrane of beta cells are open and K+ diffuse out of the cell - -70 mV potential
Rising blood glucose conc:
Glucose enters cell by glucose transporter
Glucose metabolised inside mitochondria, producing ATP
ATP binds to K+ channels, closing them (ATP-sensitive potassium channels)
K+ ions cannot diffuse out of cell, potential is -30mV and depolarisation occurs
Depolarisation causes Voltage-gated Calcium channels to open
Calcium ions enter cell and cause secretory vesicles to release insulin they contain by exocytosis
(pg 392)
62
What is negative feedback
Negative feedback is feedback which causes any corrective measures to be reduced or switched off, allowing the system to return to its original (normal) level
63
Describe the role of glucagon in the control of blood glucose concentration
Glucagon is responsible for increasing blood glucose concentration
binds to receptors on liver cells
causes glycogenolysis
64
Describe the changes which take place inside a beta cell to cause the release of insulin in the presence of high blood glucose concentration
Glucose enters the cell via a glucose transporter
Glucose is metabolised / ATP generated
ATP binds to potassium channels / potassium channels close
Cell becomes depolarised
Calcium ion channels open
Calcium ions cause vesicles to release insulin / exocytosis of secretory vesicles
65
Explain how hormones return blood glucose concentration to normal after a meal
Cause blood glucose concentration level to rise
Rise in blood glucose concentration is detected by β cells in islet of Langerhans
β cells release insulin into blood
insulin binds to glycoprotein receptors / receptors on cell surface membrane
cells take up / absorb more glucose
cell respiration rate increases
increases glycogenesis / conversion of glucose into glycogen
results in a decrease in blood glucose concentration
66
What is the broad condition for diabetic people
They are unable to metabolise carbohydrates properly - in particular, glucose
67
What is hyperglycaemia
Raised blood sugar - which over time can lead to serious damage to many body systems, including nerves and blood vessels
68
What is the overview for type 1 diabetes
Unable to produce insulin - due to beta cells in islets of langerhans unable to produce insulin
No prevention or cure, no known cause
Evidence suggests the condition arises as a result of an autoimmune response where body own immune system attacks the beta cells
Normally develops in childhood
69
What are the symptoms of diabetes
High blood glucose concentration
Glucose present in urine
Excessive need to urinate (polyuria)
Excessive thirst (polydipsia)
Constant hunger
Weight loss
Blurred vision
Tiredness
70
What is the overview for patients with type 2 diabetes
Cannot effectively use their insulin and hence cannot control their blood sugar levels
Either because beta cells dont produce enough insulin or the body cells dont respond properly to insulin - usually due to the glycoprotein insulin receptor not working properly
Cells lose responsiveness to insulin, so dont take up enough glucose, leaving it in blood
90% of people who have diabetes globally have type 2
Mostly due to excess body weight, physical inactivity, overeating of carbohydrates
Risk of T2 increases with age but now also occurs in children
71
What is the treatment for type 1 diabetes
Injections of insulin - hence called insulin-dependant
Regularly test their blood glucose concentration- usually by pricking the finger, then a drop of blood is analysed by machine, and then can work out the amount of insulin to be administered
Injection allows glucose to be absorbed by cells and causes glycogenesis to occur, resulting in a reduction of blood glucose conc
OR TRANSPLANT
72
What are the main issues with injecting insulin
Can cause Hypoglycaemia- too much insulin resulting in very low blood glucose concs
Or hyperglycaemia, not enough insulin resulting in high glucose concs
73
What is the treatment for type 2 diabetes
Exercise and managing diet/carbohydrate intake
If this isn't enough to control blood glucose conc. drugs ALSO have to be used, to slow the rate at which the body absorbs glucose from intestine and then if this doesn't work ultimately insulin injections
74
How was insulin previously obtained
pancreas of cows and pigs
75
Since 1955 when the structure of insulin was identified, how is it now made and what are the advantages of this
Genetically modified bacteria
Human insulin is produced in a pure form - less likely to cause allergic reactions
Insulin can be produced in much higher quantities
Production costs are much cheaper
Peoples concerns over using animal products in humans are overcome
76
What is a new treatment for diabetes
Using stem cells to replace the loss of the single cell type (islet (beta) cells)
77
How are stem cells obtained
Destroying a human embryo,
To get around this, using embryos that would have been destroyed anyway eg.
spare embryos from infertility clinics, or terminated pregnancies
or using preserved umbilical stem cells
78
What are the advantages of stem cells over current therapies for treating T2 diabetes
Donor availability wouldn't be an issue - stem cells would produce unlimited new source of beta cells
People no longer have to inject themselves with insulin
Reduced likelihood of rejection
79
Explain why people with T1 diabetes have to constantly monitor their blood glucose concentration
Blood glucose concentration varies throughout the day / as a result of diet and exercise
eg. increased exercise will cause blood glucose concentration to decrease / eating carbohydrates will cause blood glucose conc to increase
Necessary to not become either hypo or hyperglycaemic and suffer a coma or unconsciousness
80
Explain why some who suffer from diabetes mellitus who can produce insulin cannot control their blood glucose concentration
They are suffering from type 2 diabetes
their body cells do not respond to insulin/not sensitive to insulin/cell surface receptors do not bind to insulin
cells do not take up enough glucose from the blood
so blood glucose concentration remains high
81
What is the fight or flight response
When a potentially dangerous situation is detected, the body automatically triggers a series of physical responses. These are intended to help mama survive by preparing the body to either run or fight for life, hence the name of the response.
82
Describe the events in the fight or flight response
Autonomic nervous system detects stimulus
Hypothalamus communicates with the sympathetic nervous system and the adrenal cortical system.
The sympathetic nervous system using neural pathways to initiate body reactions. Where is the adrenal-cortical system uses hormones in the bloodstream
The sympathetic nervous system sends out impulses to glands and smooth muscles, and tells the adrenal medulla to release adrenaline and noradrenaline into the bloodstream. The stress hormones cause several changes in the body, including increased heart rate.
The release of all the stress hormones which have a longer action from the adrenal cortex is controlled by hormones produced by the Pituitary gland in the brain. The hypothalamus stimulates PG to secrete adrenocorticotropic hormone (ATCH) which bloodstream to the adrenal cortex, where it activates the release of many hormones to prepare the body to deal with a threat
83
In a flight or fight response, what is the purpose of:
Increased heart rate
pupil dilation
Arterioles in skin constricting
Blood glucose level increase
smooth muscle of airways relax
Non-essential systems (eg. digestion) shut down
Difficulty focusing on small tasks
Pump more oxygenated blood around the body
In as much light as possible for better vision
More blood to major muscle groups, brain, heart and muscles of ventilation
Increase respiration to provide energy for muscle contraction
To allow more oxygen into the lungs
Focus resources on emergency functions
Green solely focused only on where the threat is coming from
84
Is adrenaline a hydrophilic or hydrophobic hormone and where are the receptors
Hydrophilic, so its receptors are on the cell surface membrane
85
What is the main job of adrenaline
Liver cells to undergo glycogenolysis glucose is released into the bloodstream to allow for more respiration therefore energy for muscle contraction
86
As adrenaline cannot pass through the cell membrane of a liver cell, it must bind to receptors on the outside and trigger a chain reaction. Describe the events in this chain reaction.
When adrenaline binds to its receptor, the enzyme adenylyl cyclase is activated
This triggers the conversion of ATP into cAMP on the inner surface of the cell membrane in the cytoplasm
The increase in CAMP levels activate specific enzymes called protein kinases which phosphorylate and hence activate other enzymes. This example, enzymes are activated which trigger the conversion of glycogen into glucose.
(pg 398 and 399 VERY IMPORTANT)
87
State and explain two physical responses which occur as a result of the fight and flight response
Eg. Heart rate increase – to pump oxygenated blood around the body (1);
pupil dilation – to take in as much light as possible for better vision
88
Explain why people often feel cold in times of stress
Less blood in the skin to keep it warm, hence the skin feels cold
as the blood has been redirected to muscles to aid movement/ability to run
89
Explain how the nervous and endocrine system work together to enable the body to respond to danger
Danger detected by the autonomic nervous system
hypothalamus triggers sympathetic nervous system
nervous impulse triggers release of hormones from adrenal medulla
adrenaline causes glycogenolysis in liver cells
credit detail of second messenger model
increased blood glucose used for respiration/create energy for muscle contraction
other appropriate hormone and response
pituitary gland stimulates the adrenal-cortical system
hormones release from adrenal cortex
90
Which nervous system is heart rate controlled by
Autonomic
91
Which part of the brain is responsible for controlling heart rate
Medulla oblongata
92
What do the two centres in the medulla oblongata do
One centre increases heart rate by sending impulses through the sympathetic nervous system, these impulses are transmitted by the accelerator nerve to the SAN
One centre decreases heart rate by sending impulses through the parasympathetic nervous system, these impulses are transmitted by the vagus nerve to the SAN
93
What are the two types of receptors which provide information that affect heart rate and what do they do
Baroreceptors - detect changes in blood pressure, e.g. if a persons blood pressure is too low, heart rate needs to increase to prevent fainting. Baroreceptors are present in the aorta, vena cava and carotid arteries
Chemoreceptors - these receptors detect changes in the level of particular chemicals in the blood such as carbon dioxide. Chemo receptors are located in the aorta, the carotid artery and the medulla.
94
What happens if there is too much CO2 in the blood and how do chemoreceptors help
pH of blood decreases as carbonic acid is formed when CO2 reacts with H2O in blood.
Change is detected, and heart rate is increased so blood flows quicker to the lungs so CO2 can be exhaled
ORA if pH drops
(pg 401)
95
How do Baroreceptors prevent extreme blood pressures
If BP is too high, pulses are sent to the medulla oblongata centre which decreases heart rate. The medulla oblongata sends impulses longer parasympathetic neurones to the SA and which decreases the heart rate which reduces blood pressure back to normal.
ORA for low BP
96
What is the affect of adrenaline and noradrenaline on the heart
They affect the pacemaker region of the heart itself and speed up the heart rate by increasing the frequency of impulse is produced at the SAN
97
Explain why an athletes heart rate may increase just before a race has begun
Stress
leads to release of adrenaline / noradrenaline
which increases the frequency of impulses from SAN
98
Explain why blood pH values vary during exercise
Increased respiration leads to increased production of CO2
CO2 dissolves in the blood to form carbonic acid, which lowers blood pH
99
Explain why an increase in the pH of the blood leads to a decrease in Heart rate
Chemoreceptors detect decrease in blood pH
frequency of impulses sent to medulla decrease
decrease in impulses sent to SAN
SAN decreases heart rate
