Paper 2: Topic 5 Homeostasis & response - Hormonal coordination in humans (LV) Flashcards
Describe the endocrine system (2)
- Glands which produce and secrete hormones directly into the plasma
- Hormones then travel in the plasma to reach their target organs where they stimulate a response
Define the term hormone (3)
- A chemical messenger molecule
- that is produced and secreted by an endocrine gland and
- travels via the bloodstream to its target organ where it causes as response
Define the term endocrine gland (2)
An organ that produces a hormone which it secretes directly into the plasma
Define the term target organ
An organ made of cells that have specific receptors on their cell membranes that are complementary to specific hormones
State 6 differences between the nervous system and endocrine system
- Nervous system uses nerve impulse, endocrine system uses hormones
- Nervous system causes a quicker response, endocrine system causes a slower response
- Effect of the nervous system is short-lived, effect of the endocrine system is longer-lasting
- Nervous system uses neurones, endocrine system involves glands and hormones
- Nervous system uses an electrical signal, endocrine system uses a chemical messenger
- Nervous system acts on a very precise area, endocrine system acts in a more general way
Name the master gland and explain why it is called this
Pituitary gland
Reason: It produces hormones which act on other glands to make them produce different hormones
Name 4 hormones produced and secreted by the pituitary gland
- Anti-diuretic hormone
- FSH (Follicle stimulating hormone)
- Luteinising hormone (LH)
- Thyroid Stimulating Hormone (TSH)
Why is the pituitary gland called the ‘master gland’
It produces several different hormones which act on other glands to stimulate other hormones to be released and cause different effects in the body
Describe the position of the pituitary gland
The pituitary gland is no larger than a pea, and is located at the base of the brain. The pituitary gland is attached to the hypothalamus.
Describe the position of the pancreas
Part of the digestive system, located above the small intestine but below the stomach
Describe the position of the thyroid gland
Located in the neck region
(Exam/test hint: be able to identify it’s position on a diagram)
Describe the position of the adrenal glands
Located just above the kidneys (one adrenal gland per kidney)
(Exam/test hint: be able to identify it’s position on a diagram)
Describe the position of the ovaries
Part of the reproductive system, located in the pelvic region
(Exam/test hint: be able to identify their position on a diagram)
Describe the position of the testes
Part the reproductive system, located in the scrotum
Describe the function (role) of the pituitary gland
- Produces and secretes several different hormones into the plasma
- e.g. TSH, LH, FSH and ADH
Describe the function/role of the pancreas
Produces and secretes insulin and glucagon into the plasma
Describe the function/role of the thyroid gland
- Produces and secretes thyroxine into the plasma
- To regulate the heart rate, core body temperature and metabolic rate
(Exam/test hint: be able to identify it’s position on a diagram)
Describe the function/role of the adrenal glands
- Produces and secretes adrenaline into the plasma
- To increases the heart rate for ‘flight, fright and fight’
(Exam/test hint: be able to identify their position on a diagram: on top of the kidneys)
Describe the function/role of the ovaries
- Produces and secretes oestrogen into the bloodstream
- To control puberty and the menstrual cycle
Describe the function/role of the testes (3)
- Produces and secretes testosterone into the bloodstream
- To control puberty
- To control sperm production
Name the two hormones involved in regulating blood glucose levels
Insulin and glucagon
Exam/test hint: you MUST be able to spell these correctly
What is the difference between glucagon and glycogen?
- Glucagon is a hormone produced by the pancreas when blood glucose levels are low
- Glycogen is a complex, insoluble carbohydrate that is used to store energy in skeletal muscles and the liver
Describe what happens to excess glucose that is absorbed into the plasma e.g. after a carbohydrate rich meal
- The glucose is absorbed into the cells of the skeletal muscles and liver
- And it’s then converted to glycogen for storage
- This reduces the blood glucose levels in the plasma and restores the glucose concentration back to normal
Name the organ that monitors and controls the blood glucose levels
Pancreas
Name the target organs for insulin
- Liver
- Skeletal muscles
Name the target organ for glucagon
- Liver
Describe what happens if the blood glucose level falls too low
- The pancreas detects the fall in the glucose levels in the plasma
- The pancreas produces and secretes glucagon into the plasma
- Glucagon travels in the plasma to its target organ, the liver
- The cells of the liver respond to the glucagon by breaking down stored glycogen into glucose
- The glucose is released from the liver into the plasma
- This raises the plasma glucose levels and restores the plasma glucose level to normal
Describe what happens if the blood glucose level becomes too high
- The pancreas detects the rise in the blood glucose concentration in the blood
- The pancreas produces and secretes insulin into the plasma
- Insulin travels in the plasma to its target organs, the liver and skeletal muscles
- The cells of the liver and skeletal muscles respond to the insulin by absorbing more glucose from the blood plasma
- The glucose converted into glycogen inside the liver and skeletal muscle cells
- The glycogen is stored in the liver and skeletal cells
- This removes glucose from the plasma
- This lowers the blood glucose concentration and restores the plasma glucose level to normal
- This is an example of negative feedback
Name the term that describes how blood glucose levels are regulated by the body
Negative feedback
Describe a negative feedback loop (also called a negative feedback cycle)
- An internal factor e.g. blood glucose levels is elevated
- The elevated factor is detected by receptors
- The co-ordination centre receives the information
- The co-ordination centre co-ordinates a response
- The body responds by casing internal changes that lower the internal factor
- The internal factor is returned to its normal level
Remember the same happens when the internal factor is too low but the body responds causing internal changes that raise the internal factor
Explain why the negative feedback loop/cycle is referred to as a loop/cycle
- The body constantly responds to fluctuations in the internal factors of the body
- The process of detecting, responding and altering the internal factors is a continual process
Explain why the negative feedback loop/cycle is referred to as a negative process
The response that occurs is opposite to the change in the body’s internal factor
For example
- if an internal factor becomes elevated the response is to lower it
- if an internal factor becomes too low the body’s response it to raise it
State the two different types of diabetes
- Type I
- Type II
What causes type I diabetes?
The person’s pancreas fails to produce sufficient insulin for them to regulate their blood glucose levels
State the characteristics of type I diabetes
AND
Describe the symptoms of type I diabetes
Characteristic
* Uncontrolled high blood glucose levels
** Symptoms:**
* Tiredness and fatigue
* Breathlessness
* Dizziness and fainitng
* Frequent urination
* Dry mouth
* Weight loss
* Nausea and vomiting
* Blurred vision (which can lead to blindness)
Name the treatment given to type I diabetics
Insulin therapy
Describe insulin therapy
- The type I diabetic is given insulin injections
- Usually at mealtimes
Explain how insulin therapy works
- Insulin is administered at meal times
- This makes sure the blood glucose is removed from the blood as soon as the food is digested and glucose is absorbed
- This prevents the glucose levels from becoming too high (spiking)
- This form of treatment is very effective
State and explain 2 pieces of lifestyle advice is usually given to type I diabetics
- To reduce their simple carbohydrate intake i.e. reduce their intake of sugars
- To take regular exercise which will remove the excess glucose from the blood
What causes type II diabetes?
The person’s liver cells and skeletal muscle cells no longer responds to insulin produced by the pancreas
State the characteristics of type II diabetes
Uncontrolled high blood glucose levels
Describe how type II diabetes is normally treated
Follow a carbohydrate controlled diet and follow an exercise regime
Which type of diabetes increases the risk of obesity?
Type II
State 3 organs involved in the removal of waste materials/products from the body
- Skin
- Kidney
- Lungs
State 4 waste products that must be removed from the body
- Carbon dioxide
- Excess water
- Urea
- Excess ions
State 3 ways water is removed from the body
- During exhalation as water vapour
- As the solvent that forms urine via the kidneys
- As sweat from the skin
State 2 ways ions are lost from the body
From the skin as sweat In the urine via the kidneys
State 2 ways urea is lost from the body
- In the urine via the kidneys
- A small (uncontrolled) quantity is lost from the skin as sweat
Explain why the skin and lungs are less efficient as excretory organs than the kidneys
- The skin and lungs have no control over water, ion or urea lost
- The kidney has a high degree of control over how much water, ions and urea is removed from the body
Explain why it is important to regulate the internal water content of the body
- If animal cells contain too much water they will **rupture **(do NOT say ‘explode’)
- This is called cytolysis
- If animal cells contain too little water they will crenate
- In both case this will cause the cells to fail to function correctly
Explain how urea is formed
- Excess proteins in the diet are broken down during digestion
- By protease enzymes into amino acids
- The excess amino acids are then deaminated in the liver
- To form ammonia
- However, ammonia is highly soluble and very toxic
- So it is immediately converted to urea
- So that it can be safely excreted
Explain the term excretion
- The removal of waste products from the body that have been produced by cells during metabolism e.g.
- carbon dioxide (from respiration)
- urea (from deamination)
Explain the term egestion
- The removal of dead cells and undigested food from the body
- E.g. dead bacteria from the gut
State the two main processes that occur in the kidney to produce urine
- Filtration
- Selective reabsorption (exam hint: do not just say reabsorption)
State 5 molecules that are filtered out of the blood plasma into the filtrate in the kidneys
- Water
- Ions
- Glucose
- Amino acids
- Urea
Explain why cells are not filtered out of the blood plasma into the filtrate during urine formation
The cells are too big to pass through the membrane that filters the blood
State 3 molecules that are selectively reabsorbed back into the blood in the kidney
- All the glucose
- The required quantity of ions
- The required quantity of water
State 3 molecules that are excreted in the urine
- Excess ions
- Excess water
- The majority of the urea
Explain why it is important to regulate the ion levels in the blood
- If the ion content of the blood changes it alters the water potential of the blood
- This causes the cells to become crenated or to rupture
- This then prevents the cells from functioning correctly
Name the hormone involved in regulating the water content of the blood
Anti-diuretic hormone (ADH)
Name the part of the body that monitors the water content of the blood plasma
The osmo-regulatory centre of the brain
Name the receptors in the brain that detect changes in the water level of the blood plasma
Osmoreceptors