Regulation Flashcards
(80 cards)
1
Q
What does a feedback system operate? What are the two types of feedback systems?
A
They operate the response to a stimulus which in turn modifies the original stimulus. Positive and negative.
2
Q
What are the 6 stages in a feedback system?
A
- Stimulus
- Receptor
- Modulator
- Effector
- Response
- Feedback
3
Q
What is the dynamic equilibrium?
A
The fluctuations around the normal or optimum level.
4
Q
What is the set point in the equilibrium?
A
The level around which the conditions fluctuate.
5
Q
What is thermoregulation?
A
Heat generated by cells carrying out cell respiration.
6
Q
Are humans endotherms?
A
Yes.
7
Q
What is the equation of thermoregulation?
A
Glucose + Oxygen = Energy + CO2 + H20
8
Q
How much energy produced is heat energy?
A
Over half.
9
Q
What is metabolic rate?
A
The rate at which cell respiration occurs.
10
Q
What are two factors the increase metabolic rate?
A
Stress and exercise.
11
Q
How do mammals produce and lose heat?
A
They produce heat in their cells. They loss heat to their environment.
12
Q
How do you maintain a constant body temperature?
A
The amount of heat produced must be exactly the same as the amount of heat lost.
HEAT INPUT = HEAT OUTPUT
13
Q
What are the steps in the negative feedback system in thermoregulation?
A
Stimulus = change in body temperature Receptors = thermoreceptor Modulator = hypothalamus Effectors = blood vessels and sweat glands Response = vasodilation/vasocontriction, perspiration rate Feedback = change in body temperature
14
Q
Where are the thermoreceptors found in the peripheral section?
A
Found in the skin and some mucous membranes; either cold or heat receptors.
15
Q
Where are the thermoreceptors found in the central section?
A
Found in the hypothalamus, spinal cord and abdominal organs.
16
Q
What do the peripheral blood vessels carry to the surface of the skin?
A
Warm blood.
17
Q
If you reduce the amount of blood flowing to the skin what happens?
A
You reduce the amount of heat lost to the environment.
18
Q
What does vasoconstriction of the peripheral vessels do?
A
Makes the skin go paler and less heat is lost.
19
Q
What does vasodilation of the peripheral vessels do?
A
Makes the skin go redder and more heat is lost.
20
Q
What are 3 different points to reduce or increase heat loss?
A
- Peripheral vasocontriction or vasodilation
- Reduce or increase surface area to volume ration (behavioural response)
- Reduce or increase amount of sweat
21
Q
What are 3 different points to reduce or increase heat production?
A
- Increase or decrease adrenalin production
- Increase or decrease thyroxine production
- Increase muscle activity (voluntary or shivering)
22
Q
What are behavioural response to temperature? What is it?
A
A conscious change to behaviour to increase or decrease heat loss. Put a jumper on, sit in the shade, reduce surface area.
23
Q
What is heat exhaustion?
A
Dehydration and vasodilation can cause low blood pressure; making a person collapse (even though temperature is still normal.
24
Q
What is heat stroke?
A
Dehydration, high environmental temperatures and high humidity make it difficult for the body to lose heat. Heat is retained making thermoregulation cease and body temperature rises.
25
What is hypothermia?
If the body temperature falls below 33C, then the metabolic rate is too slow to maintain body temperature. Heat lost is greater than heat produces, the body temperature continues to fall.
26
What is surface area to volume ratio?
Surface area : volume ratio = surface area/volume
EG
SA= 1.5cm, V= 3mL
Ratio = 1.5/3 = 0.5 cm/ml
27
Why do smaller organisms lose heat faster than large organisms?
Small organisms have a large surface area to volume ratio. compared to their body size, they have a lot of skin
28
How fast do organisms lost heat if they have a high SA:V? A low SA:V?
High SA:V = lose heat faster
| Low SA:V = lost heat slower
29
What are the 3 different body shapes in humans?
Endomorph
Mesomorph
Ectomorph
30
What are the four ways heat can be lost or gained?
1. Conduction - through one solid to another
2. Convection - through fluids (liquid/gases)
3. Evaporation - Change of state removes heat
4. Radiation - through space
31
What is excretion?
The removal of waste products of metabolism from the body. As they are toxic
32
What do excretory organs include?
Lungs, sweat glands, alimentary canal (bile pigments), kidneys.
33
Is faeces counted as excretion? Why?
No. It is not the waste product of cells. It is elimination
34
What are the 3 types of fluid?
1. Intracellular fluid - inside cells
2. Extracellular fluid - outside cells
3. Extracellular fluid - may be either interstitual (intercellular) fluid or plasma
35
How do you maintain optimum osmotic pressure?
Fluid input = fluid output
36
What is the negative feedback system for fluid balance?
```
Stimulus = change in osmotic pressure
Receptors = hypothalamus
Modulator = hypothalamus
Effectors = cells lining tubules in nephron (DCT and Collecting duct)
Response = change in amount of water reabsorbed by nephron
Feedback = change in osmotic pressure
```
37
What is homeostasis?
The process of keeping the environment inside the body fairly constant, the maintenance of a constant internal environment despite changes to the external environment
38
What is the main function of the endocrine system?
To maintain homeostasis with help from hormones and feedback loops
39
What is the difference between negative and positive feedback?
Negative: the response reduces or minimises the original stimulus
Positive: the response increases or maximises the original stimulus
40
Can you explain the 6 stages in a feedback system?
1. Stimulus:
A change occurs in the environment
2. Receptor:
The stimulus is detected by sensory cells
Message:
Sensory cells generate a message in the form of a nerve impulse or hormone
3. Modulator:
A control centre processes the message received from the receptor
Message:
A new message is sent out by the modulator
4. Effector:
Muscles or glands receive the message from the modulator
5. Response:
The effector organs bring about an appropriate reaction
6. Feedback:
The response changes the original stimulus
41
What are the hormones responsible for regulation of the menstrual cycle?
Progesterone, luteinising hormone, oestrogen, follicle stimulating hormone
42
What is dehydration? Symptoms?
When water loss exceeds water intake. Lost through sweating, vomiting, or diarrhoea. Symptoms include servers thirst, low blood pressure, dizziness and headaches. Person can become delirious, lose consciousness or die
43
What is water intoxication? Symptoms?
Too much water in the body. Body fluids become too diluted and cells take in extra water (osmosis). Symptoms lightheadedness, headache, vomiting, collapse, death.
44
Define osmotic pressure.
The measure of the tendency of a solution to take in water by osmosis
45
What are the key methods of water intake?
Food (700mL)
Metabolic water (200mL)
Drink (1600mL)
46
What are the key methods of water loss?
Lungs (300mL)
Skin (500mL)
Kidneys/urine (1500mL)
Alimentary canal/faeces (200mL)
47
What are the 3 processes that occur in the nephron? Explain them.
Blood centres the glomerulus under high pressure.
Filtration:
The high blood pressure forces water and small dissolved molecules out of the blood and into the capsule. Large molecules and blood cells are retained in the blood.
The filtrate is collected by the glomerulus capsule
Reabsorption:
The filtrate passes through the proximal convoluted tubule, the loop of Henle, the distal convoluted tubule and the collecting duct. Water and other useful substances are reabsorbed into the peritubular capillaries.
Secretion: Some materials that need to be removed from the body are secreted into the kidney tubule from the peritubular capillaries.
Urine:
The water and dissolved substances that remain make up the urine, it is carried by the collecting duct to the ureter and then to the bladder.
48
What is ADH? What does it do?
Antidiuretic hormone, it controls the permeability of the walls of the distal convoluted tubule and collecting duct.
49
What is the feedback loop for ADH?
1. Water concentration of blood plasma decreases; osmotic pressure of the blood is increased
2. Osmoreceptors in the hypothalamus are stimulated
3. Posterior lobe of the pituitary gland is stimulated to release ADH
4. Permeability to water of the distal convoluted tubules and collecting ducts is increased
5. Increased amount of water is reabsorbed into the blood plasma
6. Water Concentration of the blood plasma increases; osmotic pressure of the blood is decreased
50
What is the feedback system from the thirst centre?
1. Water concentration of blood plasma decreases; osmotic pressure of the blood is increased, mouth becomes dry
2. Osmoreceptors in the thirst centre of the hypothalamus are stimulated
3. The person feels thirsty
4. The person responds to the feeling of thirst by drinking
5. Water drunk is absorbed into the blood from the alimentary canal
6. Water leaves the blood and the extracellular and intercellular fluids return to their normal concentrations
51
What is glucose essential for?
To keep the body functioning, all cells need a constant supply of glucose, it is the source of energy for all cell activities
52
What is hyperglycaemia?
Blood glucose levels are too high
53
What is hypoglycaemia?
Blood glucose levels are too low
54
Where is insulin produced? What is its role? How does it do this?
The b cells in the pancreas, it causes a decrease in blood sugar levels. It accelerates the transport of glucose (from blood to cells) and it accelerates the conversion of glucose into glycogen, it also stimulates the conversion of glucose into fat as adipose tissue and increases protein synthesis.
55
Where is glucagon produced? What is its role?
The a cells in the pancreas, it causes an increase in blood sugar levels.
56
Where is adrenaline and cortisol produced? What do they do
The adrenal cortex.
Cortisol regulates carbohydrate metabolism (making sure enough energy is available to cells), they stimulate the conversion of glycogen to glucose, it also increases the rate at which amino acids are removed from cells and transported to the liver (this can be converted into glucose if glycogen and fat levels are low.
Adrenaline produces the same effects of the autonomic nervous system, it elevates blood glucose levels and counteracts the effects of insulin, it stimulates the production of lactic acid from glycogen in muscle cells.
57
What is glycogenesis?
The formation of glycogen from other carbohydrates (glucose), influenced by insulin from the pancreas.
Glucose ----> Glycogen (stored in the liver and muscle cells)
58
What is glycogenolysis?
The breakdown of glycogen to glucose, influenced by glucagon from the pancreas.
Glycogen ----> Glucose (release back into the bloodstream)
59
What is gluconeogenesis?
Conversion of fats or proteins into glucose, influenced by glucagon/adrenaline/cortisol.
Amino acids/Fats ----> Glucose
60
What is the feedback loop for when blood glucose rises?
```
Stimulus:
Rise is blood glucose levels
Receptor:
B cells in pancreas
Modulator:
Pancreas
Response:
Secretion of insulin by b cells
Effect:
Uptake of glucose by liver/muscle cells and glycogenesis
Feedback:
Decrease in blood glucose levels
```
61
What is the feedback loop for when blood glucose is too low?
```
Stimulus:
Low blood glucose levels
Receptor:
A cells in pancreas
Modulator:
Pancreas
Response:
Secretion of glucagon by a cells
Effect:
Release of glucose by lover/muscle cells by glycogeneolysis
Feedback:
Increase in blood glucose levels
```
62
Is breathing involuntary?
Yes, but you can consciously change it.
63
What muscles are responsible for breathing? How are they controlled?
Diaphragm and intercostal muscles. They are controlled by the nerve impulses from the respiratory centre in the medulla; controlling inspiration and expiration.
64
Where do these breathing impulses travel on?
Travel along the phrenic nerve to the diaphragm and along the intercostal nerves to the intercostal muscles.
65
Why does CO2 concentration have a greater influence on breathing than O2
Because when CO2 dissolves, it forms carbonic acid and then hydrogen ions which cause blood pH to decrease (more acidic) as it builds up.
66
What do the chemoreceptors do? Location?
They detect changes to plasma CO2 levels. They are located in the medulla (centrally) and aortic/carotid bodies (peripherally)
67
What do chemoreceptors do when they detect change?
They send impulses to the respiratory centre; which then produces more impulses (increasing breathing movements.
68
Do O2 levels have to be very low in order to have an effect on breathing? What are the receptors?
Yes (very, very low), aortic/carotid bodies are the receptors (the medulla is also sensitive to greatly lowered O2 concentration in plasma. Nerve impulses are then sent to the respiratory centre and so on.
69
Where are the stretch receptors located? What do they do? When are they important?
They are located in the lungs. They send impulses to the RC (which then inhibits inspiration). Only important when heavy breathing occurs (helps stop over-inflation).
70
What is voluntary control of breathing important for?
Speech and holding breath etc
71
How does involuntary control take over?
Too much CO2 in the body, RC is stimulated by the low pH of the plasma (due to hydrogen ions). The stimulatory impulses from the RC dominate the inhibitory impulses from the cerebrum.
72
What is hyperventilation? What can cause it?
Extreme breathing movements which removes from CO2 than normal in turn removing the factor that stimulates breathing in the first place. (Artificially lowering blood CO2 levels inhibiting breathing). Emotions or consciously thought can control if this happens.
73
Why is hyperventilation dangerous if you do it before diving?
Holding your breathing after you've removed to much CO2, the amount of CO2 is still to low to stimulate breathing, do you don't. Not enough oxygen gets to your brain, you faint and then drown.
74
What is the feedback loop for the concentration of CO2 and hydrogen ions?
Decrease in breathing rate
- --> Increase in concentration of CO2 ---> chemoreceptors in medulla oblongata
- --> Decrease in pH ---> chemoreceptors in aortic and carotid bodies
- -----> Respiratory centre
- --> Increased activity of respiratory muscles
- --> Decreases concentration of CO2
75
Name 2 disruptions to homeostasis.
Diabetes and thyroid issues.
76
Type 1 Diabetes:
When does it occur?
What is the cause?
How can it be treated or managed?
It usually begins in childhood. It occurs because a fault in the patients immune systems which causes the destruction of beta cells in the islet of lagerhands of the pancreas. As beta cells produce insulin, the person does not produce insulin. It can be manages through insulin injections/insulin pump.
77
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Type 2 Diabetes:
When does it occur?
What is the cause?
How can it be treated or managed?
What happens if left untreated?
```
```
It usually develops in people over the age of 45. This people are able to produce insulin their body just doesn't respond to it. It is a lifestyle disease usually caused by:
- Lack of physical activity
- Being overweight/obese
- A diet high in fat/sugar/salt/low in fibre
- High blood pressure
- High blood cholesterol
- Smoking
Management aims to keep blood glucose levels within the normal range, this is done by:
- Careful diet
- Regular exercise
- Healthy body weight
- Monitoring blood glucose
- Medication
```
If untreated the person may be in risk of:
- Heart disease
- Stroke
- Kidney disease
- Eye problems
- Nerve damage
- Skin/foot problems
78
Hyperthyroidism:
What is its cause?
What are the symptoms?
How is it treated/managed?
To much thyroxine is produced by thyroid gland. Symptoms include:
- Rapid heart beat
- Fatigue
- Weight loss
- Increased appetite
- Sweating
- Anxiety
- Protruding eyeballs
Treatment includes:
- Drugs that block thyroid glands use of iodine
- Surgery to remove some/all of the gland
- Drinking radioactive iodine (only harmful to thyroid cells)`
79
Hypothyroidism:
What is its cause?
What are the symptoms?
How is it treated/managed?
```
It occurs through problems with the thyroid gland or pituitary glans or hypothalamus. Usually caused due to lack of iodine (not enough hormones produced) or track by the immune system (Hashimoto's disease) or surgery of cancer (thyroid removal).
Symptoms:
- Slow heart rate
- Unexplained weight gain
- Fatigue/lack of energy
- Intolerance to cold
- Swelling to face/Goitre
Treatment:
- Increase iodine intake
- Tablet containing thyroid hormone (must be taken for the rest of their life)
```
80
What is graves disease?
The enlargement of the thyroid due to an immune system reaction, some genetic predisposition but not inherited.
