Homeostatic Mechanisms Flashcards
What are hormones?
Chemical messengers in the blood
Where are hormones made from?
The Endocrine organs
What is homeostasis?
This is the maintenance of constant or steady state conditions within the body
What 4 things does homeostasis control?
Blood sugar, CO2, blood pH and temperature
Why is homeostasis important (3 reasons)?
cells to function correctly,
chemical reaction to occur at correct point
allows organisms to be independent of fluctuations in external environment
What is it called when there is a change in the body?
Stimulus
What detects this change?
Receptors
What causes a response to this change?
Control centre in the brain
What responds to this change?
Efector
What is this response called?
Negative feedback
What does switching off this mechanism prevent?
Overcorrection
What organ controls blood glucose?
The pancreas
What specifically detects blood glucose change in this organ?
The Islets of Langerhans
What does the beta cells in the I.L detect?
Increase in blood glucose level
What causes an increase in blood glucose?
When a meal is being digested and absorbed into the blood
What does an increase in blood glucose cause to be released?
Insulin
What happens to all body cells when insulin is released?
They take up more glucose
What happens to the rate at which glucose is taken up when insulin is released?
It increases
What is glucose converted to when insulin is released?
Increased rate of glucose to fat storage
What also is glucose converted to for liver and muscle cells?
Glycogen
What is released when there is a decrease in blood glucose level?
Adrenaline and Glucagon
What can cause this decrease in blood glucose?
Respiration
What do liver cells do to glycogen when blood glucose decreases?
Covert back to glucose and released
What happens to amino acids when blood glucose decreases?
Convert back to glucose
What happens to rate of reactions when blood glucose level is low?
Decreases
Where is glucagon released from?
Alpha cells in the Islets of Langerhans
Where is adrenaline released from?
Adrenal glands
What happens when more adrenaline is released?
Liver cells increase rate of conversion of glycogen to amino acids to glucose
What are the 2 ways to monitor blood glucose?
Blood meter and clinistix
What colour does clinistix turn to when glucose is present?
Blue/purple
How does the blood meter detect glucose?
You prick your finger and then drop blood onto the test strip. The strip is then put into the meter and blood glucose is measured in mmoll-1
What is it called when there is excess blood glucose in the blood or urine?
Diabete Mellitus
What is diabetes?
When the blood fails to regulate blood glucose
When is type 1 diabetes often diagnosed?
Birth or later
What in the body is unable to regulate during type 1 diabetes?
The beta cells produce little or no insulin
How is type 1 treated?
Insulin injections
When is type 2 diabetes often diagnosed?
Middle age, often associated with obesity
What happens in the body with type 2 diabetes?
The body produces insulin, however the target cells are resistant so pancreas increases insulin to the point it becomes damaged
What are the 2 ways to treat type 2 diabetes?
Medication or low carb diets
Where is thyroxine released from?
Thyroid glands - pituitary gland and hypothalamus
How do you gain thyroxine in your diet?
By iodine you can get this from cod, seaweed or eggs
What does thyroxine do? (top 4)
Increases BMR
Increases heart rate
Increases cardiac output
Increases breathing rate
What is it called when there is too much thyroxine in the blood?
Hyperthyroidism from overactive thyroid creating a tumour
What are the symptoms of too much thyroxine?
Restless
Weighloss
What is the swelling on your neck called with too much thyroxine?
Goitre
How is too much thyroxine treated? (3 ways)
Drugs
Radioactive iodine
Surgery
What is an underactive thyroid called?
Hypothyroidism
What causes an underactive thyroide?
Immune disorders or drugs
What are the symptoms of an underactive thyroid?
Feeling low, weight gain and tiredness
How is an underactive thyroid treated?
Tablets which replace thyroxine
What would cause the blood to be too concentrated?
Too much sodium and too little water
What occurs when the blood is too concentrated?
Water leaves cells by osmosis and shrinks
What would cause the blood to be too dilute?
Too much water and too little sodium
What occurs when the blood is too dilute?
Water enters the cells by osmosis and the cells swell
What are sodium and chloride ions known as?
Electrolytes
How do you gain sodium and chloride ions?
Food and drink which is absorbed in ileum
How do you lose sodium and chloride ions?
Through urine and sweat
What are sodium ions needed for? (5 reasons) WIMAP
Control water balance
Muscle Contraction
Control Blood Pressure
Acid/base balance
Transmission of nervous impulses
What are chloride ions needed for? (3 reasons) WAA
Control water balance
Acid/base balance
HCL in stomach which acids digest
What can any sodium imbalance lead to?
Death or coma
What is excess sodium known as?
Hypernatremia
Name some of the symptoms of excess sodium? (5)
Muscle Twitching
High blood pressure
Brain dysfunction and confusion
Severe thirst
Heart failure
What is low sodium known as?
Hypnoatremia
What are some of the symptoms of low sodium? (4) DILS
Shock
Low blood pressure
Dehydration
Irregular heart beat
What hormone controls sodium ions?
Adolesterone
What gland detects a change in blood sodium?
Pituitary Gland
What gland releases adolesterone?
Adrenal Glands
What happens to the urine if blood sodium has increased?
More sodium excreted in urine
What do the kidneys do if sodium has increased in the blood?
Reabsorb less sodium
What hormone controls water balance?
Antidiuretic
What can the control of water balance also be known as?
Osmoregulation
What detects a change in blood concentration and where is this located?
Osmoreceptors in the hypothalamus
What gland responds to the osmoreceptors?
Pituitary gland
What does the pituitary gland release if blood is more concentrated?
More ADH
What happens to urine if the blood is more concentrated?
There is a smaller volume of concentrated urine
What does ANP stand for?
Atrial Natriuretic Peptide
Where is ANP produced?
Atrial Muscle cells
What is the normal pH range?
7.35 to 7.45
What is the definition of blood pH?
Measure of concentration of H+ ions present
Do acids have a higher or lower pH?
Lower
What happens to the concentration of H+ ions in acids?
There is a higher concentration as there are H+ ions released
What does alkalines (bases) do to blood pH?
They raise blood pH
What happens to H+ions in regards to alkalis in blood pH?
Alkalis combine with H+ ions which decreases the concentration of H+ ions.
What keeps the pH constant?
Buffer
What does the body produce during normal metabolism?
More acid waste than base
How does respiration cause more acid waste than base?
CO2 is produced which turns into carbonic acid which releases H+ ions
What 2 other factors cause more acid waste than base?
Food consumed and metabolism of proteins and fats
What are the 3 ways to control blood pH?
Buffer molecules
Respiratory mechanism
Kidney
What are the two ways that buffer molecules can control blood pH?
Can combine with H+ ions to stop pH falling
Can release H+ ions to prevent pH rising too high
What acid can release and absorb H+ ions?
Carbonic Acid
What ions can release and absorb H+ ions with carbonic acid?
Biocarbonate ions (HCO3)
Where does CO2 dissolve to form H2CO3?
Plasma
What group in haemoglobin join with H+ ions?
amino groups -NH2
What group in haemoglobin release H+ ions?
Carboxyl group -COOH
How is pH impacted during strenuous exercise?
pH falls
Why does pH fall during strenuous exercise?
CO2 is produced which increases H+ ions
What in the blood is sensitive to changes in pH?
Chemoreceptors
Where are these chemoreceptors located?
Carotid Artery and Aorta
Where are nervous impulses sent when fall of pH is detected?
Medulla in the brain
Where does the medulla then send more nervous impulses?
Inter-costal muscles and diaphragm
What happens when nervous impulses are sent to these muscles in the lung?
They contract more often and more forcefully
What happens to breathing with low pH?
Deeper and faster
What does the kidneys do if blood pH falls?
Excrete excess H+ ions
What collection of tests is used to determine blood pH?
Arterial Blood Gas Analysis
What artery is ABG usually carried out on?
Radial artery in the wrist
What is the blood analysed for during ABG?
pH
concentration CO2
concentration O2
What is a pH below 7.35 known as?
Acidosis
What is a pH above 7.45 known as?
Alkalosis
What are the 2 main categories of abnormal pH?
Malfunction of the respiratory system
Changes in level of hydrogen carbonate in blood
How is respiratory acidosis caused?
Lung disease such as asthma, pneumonia
Decreased breathing due to medications
Diseases affecting muscles or nerves of respiratory system
How is respiratory acidosis compensated?
The kidneys reabsorb more HCO3 to remove excess H+ ions from blood
What causes respiratory alkalosis?
Hyperventilation due to extreme anxiety, panic attacks, asthma attack or stress
Stroke
Pneumonia
Severe infection or fever
How is respiratory alkalosis compensated?
The kidneys reabsorb less HCO3 so less if removed from the blood
What causes metabolic acidosis?
Diabetes (ketoacidosis)
Severe diarrhoea
High levels of lactic acid due to severe over exercise
How is metabolic acidosis compensated?
Breathing rate increases to remove CO2 and therefore H+ ions from blood
What causes metabolic alkalosis?
Excessive vomiting
Overuse of diuretics
Overuse of alkaline drugs
How is metabolic alkalosis compensated?
Breathing rate decreases to retain CO2 and therefore H+ in the blood
