SB7 - Animal Coordination, Control & Homeostasis Flashcards
What’s the endocrine system?
A network of glands that produce and secrete hormones into the bloodstream
What is homeostasis?
The regulation of internal conditions inside cells or organisms, to create the optimum conditions for cell function
What is an endocrine gland?
Glands of the endocrine system that secrete hormones directly into the bloodstream
What glands are the endocrine system made up of?
- Pituitary gland
- Pancreas
- Thyroid
- Adrenal gland
- Ovary
- Testes
What is the Hypothalamus?
Part of the brain which controls water balance, temperature and secretion of hormones by the pituitary gland
What is the pituitary gland also known as?
The master gland
What is the purpose of the pituitary gland?
- Secretes hormones into the blood to either have an effect on the body
- Acts on other glands to stimulate them to produce different hormones
What is the purpose of the pancreas?
- Secretes insulin
- Controls blood glucose levels
What is the purpose of the Thyroid?
- Secretes thyroxine
- Controls metabolic rate, heart rate and temperature
What is the purpose of the Adrenal gland?
- Secretes adrenaline
- Involved in the ‘fight or flight’ response
—> (Body’s response to stressful situations)
What is the purpose of the Ovary?
- Secretes oestrogen
- Is involved in the menstrual cycle and the development of female secondary sexual characteristics
What is the purpose of the Testes?
- Secretes testosterone
- Is involved in the production of sperm and the development of male secondary sexual characteristics
What substance in the body transports the hormone?
Blood
What is the difference between the hormonal system and the nervous system?
- Nervous system is much faster
- Hormonal system acts for longer
What is adrenaline?
A hormone that is produced by the adrenal glands to prepare the body for a flight or flight response
What is a flight or flight response?
The body’s response to a dangerous situation
What are some aspects of the flight or flight response?
- Increased heart rate
- Increased blood pressure
- Increased blood flow to muscles
- Increased blood sugar levels
How does increased heart rate & blood pressure aid the flight or flight response?
Allows oxygen to reach the muscles more quickly, so we can move out of the path of danger
How does increased blood flow to muscles aid the flight or flight response?
Blood vessels leading to other vessels dilate - allows more blood to reach them
—> Allows them to contract with greater strength, and more quickly
How does increased blood sugar levels aid the flight or flight response?
Liver is stimulated to break down glycogen into glucose, which muscles can use to contract
What is thyroxine?
A hormone secreted by the thyroid gland that controls metabolic rate, heart rate and temperature
What is TRH?
- A hormone secreted by the hypothalamus when blood thyroxine levels are lower than normal
- Stimulates pituitary gland to release TSH
What is TSH?
A hormone secreted by the pituitary gland that stimulates the thyroid gland to release thyroxine.
What is negative feedback?
A corrective mechanism that allows only small shifts from a set point, reversing a change in conditions
How are the levels of thyroxine controlled by negative feedback?
- When the levels increase, it is detected by receptors in the brain
- This inhibits the release of TSH
- This inhibits the release of thyroxine, so levels of thyroxine fall
How are low levels of thyroxine returned to normal?
- Low levels of thyroxine stimulate production of TRH in the hypothalamus
- TRH causes the release of TSH from the pituitary gland
- TSH acts on the thyroid to produce thyroxine
- When thyroxine levels returns to normal level, thyroxine inhibits the release of TRH = stops the production of TSH
What is the menstrual cycle?
The process the body undergoes each month to prepare for a potential pregnancy
At what day does ovulation occur?
14
At what day does the cell lining break down occur?
28
What is a hormone?
Chemical messenger produced in glands and carried by the blood to specific organs in the body
What is menstruation?
The loss of blood and tissue from the lining of the uterus through the vagina during the menstrual cycle
What does FSH stand for?
Follicle stimulating hormone
What is the purpose of FSH?
Causes the maturation of an egg in the ovary
Where is FSH produced?
Pituitary gland
What does LH stand for?
Luteinising hormone
What is the purpose of LH?
Stimulates the release of the egg
Where is LH produced?
Pituitary gland
What is the purpose of oestrogen?
Involved in repairing and thickening the uterus lining
Where is Oestrogen produced?
Ovaries
What is the purpose of progestorone?
Maintains the uterine lining
Where is Progesterone produced?
Ovaries
Where is progesterone secreted from?
Egg follicle
What is a follicle?
Fluid filled ball of cells found in the ovary containing an ovum
What is the corpus luteum?
The remains of the follicle in an ovary after it has released an ovum into the fallopian tube
What hormone does FSH stimulate the production of?
Oestrogen
What hormone does Oestrogen inhibit?
FSH
What happens when oestrogen rises to a high level?
Causes a surge in LH - causes ovulation
What happens to the follicle after the egg is released?
Follicle becomes corpus luteum - Produces progesterone and oestrogen (inhibits FSH and LH)
What happens to the lining of the uterus if the egg has not been fertilised?
The corpus luteum dies and progesterone levels drop - uterus lining breaks down & menstruation happens
What is contraception?
The prevention of fertilisation
What are the types of contraceptive pills?
- Progesterone only
- Progesterone and oestrogen (mixed pill)
How does the mixed pill work?
- Oestrogen levels are constantly high = inhibits FSH so no
eggs mature - Lining also stops developing and the mucus in the cervix becomes thick = sperm cannot move through
What are some side-effects of the mixed pill?
- Changes in mood
- Breast pain / tenderness
- Increased blood pressure
Name some non-hormonal methods of contraception
- Physical barrier methods
- Spermicidal agents
- IUD
- Abstaining from intercourse
- Surgical methods
How does a male condom prevent fertilisation?
Placed over erect penis, prevents sperm entering vagina
What are the disadvantages of condoms?
They can tear or rip
How does a diaphragm or cap prevent fertilisation?
Placed over the cervix, prevents sperm from entering the vagina
What are the disadvantages of Diaphragms?
Diaphragms need to be put in just before sex and left in several hours afterwards
How does an IUD prevent fertilisation?
Prevents the implantation of an embryo or release of a hormone
What are the disadvantages of IUD?
Small chance of causing an ectopic pregnancy
How does an spermicidal agents prevent fertilisation?
Kills or disables sperm
What are the disadvantages of spermicidal agents?
Some people may have allergic reactions
What are the disadvantages of surgical methods?
Cannot be reversed - permanent
What are fertility drugs used for?
To increase the chance of pregnancy
What hormones are mainly used in fertility drugs?
FSH & LH
Name a fertility drug
Clomiphene
When is Clomiphene given to a woman?
If the woman doesn’t ovulate
How does Clomiphene work?
Increases the amount of FSH & LH released from the hypothalamus, increasing the chance that a woman will ovulate
When are IVF treatments used?
If there are issues with the quality of the man’s sperm, or if a woman has blocked oviducts
How does IVF treatment work?
- Mother is given FSH and LH
- Matured eggs are extracted from the mother and fertilised in the lab using sperm
- The fertilised eggs develop into embryos and then one or two are inserted in the uterus
Why would a woman be given FSH and LH?
To encourage the release and maturation of eggs
What are the benefits of IVF treatment?
Provides a way for an infertile couple to have a child
What are the cons of IVF treatment?
- Emotionally stressful
- Physically stressful - Women may have reactions to the hormones
- Can be expensive - if process needs to be repeated
- May lead to multiple births
What does ART stand for?
Assisted Reproductive Technology
What is ART?
The use of hormones and procedures, as fertility treatments, to help to achieve pregnancy
What are some examples of ART?
- IVF
- Fertility drugs
What does homeostasis control?
- Blood glucose concentration
- Body temperature
- Water levels
Why is homeostasis important?
Maintains enzyme action and all cell functions
What is thermoregulation?
The act of keeping internal body temperature constant
Why is thermoregulation important?
If the temperature exceeds 37 degrees the enzymes will become less effective and eventually denature
What is osmoregulation?
The act of keeping the concentration of the blood at a constant level
What will happen if the blood becomes too dilute?
And why is osmoregulation important in this case?
Water will move into cells by osmosis and they will swell, eventually bursting under the pressure
Osmoregulation keeps the blood at the same concentration
What will happen if the blood becomes too concentrated?
And why is osmoregulation important in this case?
Water will move out of cells and they will shrink
Osmoregulation keeps the blood at the same concentration
Where is the thermoregulatory centre found in the body?
Hypothalamus
What is vasodilation?
- Dilation of blood vessels near the surface of the skin
- Allows blood to flow closer to the skin surface, increasing heat loss to the surroundings
Describe what happens when the human body temperature becomes too high?
- Sweat (evaporates from skin surface resulting in increased energy transfer away
from body) is produced from sweat glands
—> The sweat is released onto the surface of the epidermis. - Vasodilation
In which part of the skin is sweat glands located?
Dermis
What is vasoconstriction?
- Constriction of blood vessels near the surface of the skin
- Less blood flows close to the skin surface, decreasing heat loss to the surroundings
Describe what happens when the human body temperature becomes too low?
- Skeletal muscles contract rapidly ( shivering ) to generate heat from respiration
- Hairs stand on end to create an insulating layer, trapping warm air
- Vasoconstriction
What is the human body temperature?
37.5 degrees Celsius
What does the thermoregulatory centre contain?
Receptors sensitive to the temperature of the blood
How does the hypothalamus respond to information related with the thermoregulatory centre?
By sending nerve impulses to effectors in the skin to maintain body temperature
What are the layers of skin?
- Dermis
- Epidermis
- Fatty tissue
What are the parts of the body control systems?
- Receptors
- Effectors
- Coordination centres
What is a Receptor?
Organ, tissue or cell that detects a stimulus
Give an example of what a effector will respond to
Temperature change
What is a Effector?
The organ, tissue or cell that produces a response
Give an example of what a effector will respond to
Temperature change
How is water lost through the body?
- Sweat from the skin
- Water vapour, from the lungs when we exhale
- Urine from the kidneys
What happens if the glucose levels in the blood are too high?
The pancreas produces insulin
What is glycogen?
A store of glucose in the liver and muscle tissues
What is glucagon?
A hormone secreted by the pancreas when blood glucose concentration is too low
—> Causes the breakdown of glycogen to glucose in the liver
What is insulin?
A hormone that regulates the level of sugar in the blood and can be produced by genetically modified bacteria
How does insulin control high blood glucose concentrations?
- Glucose to move from the blood into muscle cells for respiration
- Excess glucose to be converted into glycogen which is stored in the liver
How does glucagon control low blood glucose concentrations?
- Pancreas produces the hormone glucagon
- Glucagon binds to to the liver cells causing glycogen to be broken down into glucose
- Glucose is released into the blood, increasing the blood glucose concentration
What hormones keep blood glucose concentrations constant?
- Insulin
- Glucagon
Why can the actions of insulin & glucagon not occur continually?
Because when the blood arrives at a certain glucose concentration the other hormone is produced, resulting in the opposite effect.
What relationship does insulin & glucagon work in?
Negative feedback loop
What is diabetes?
Where the body cannot control blood sugar levels properly
What is type 1 diabetes?
Where the pancreas cannot produce enough insulin
—>This is congenital
What are the symptoms of type 1 diabetes?
- Lots of urine
- Individual may be thirsty
How can type 1 diabetes be controlled?
- Insulin injections at meal times, which results in glucose being taken up from the bloodstream
- Advised to limit the intake of simple carbohydrates
What is type 2 diabetes?
The body cells no longer respond to insulin
—> This is acquired
What are the symptoms of type 2 diabetes?
- Obesity
- Lots of urine
How can type 2 diabetes be controlled?
- Reducing the number of simple carbohydrates in diet
- Losing weight
- Increasing exercise
- Drugs are available to make insulin more effective on body cells
What is obesity?
A Body Mass Index over 30
How do you calculate BMI?
What are some ways to evaluate body mass?
- BMI
- Waist : hip ratio
If you have a high body mass are you more likely to have type 2 diabetes?
Yes
What is the urinary system?
The bodily system that removes impurities and waste products from
our blood
Describe the route for blood purification
- Blood containing impurities travels in the renal artery to the kidneys
- The kidneys regulate the levels of salt, ions and urea in the blood. —-> Any excess is sent to the ureter for excretion, and eventually the bladder
- The purified blood returns to the circulation by way of the renal vein.
Where are the kidneys located?
Both sides of the lower lumbar reigon
Label the structure of the kidney
Label the structure of the nephron
What is the functions of the kidney?
- They regulate the water content of the blood (vital for maintaining blood pressure)
- They excrete the toxic waste products of metabolism
Name the parts of the nephron?
- Bowman’s capsule
- Proximal convoluted tubule
- Loop of Henlé
- Distal convoluted tubule
- Collecting duct
What is the medulla?
Inner part of the kidney
What is the cortex?
Outer part of the kidney
What structure supplies the kidney blood?
Renal artery
What structure takes away the blood from the kidney?
Renal vein
Where does ultrafiltration occur?
The glomerulus
What is the glomerulus?
A collection of capillaries at the start of the nephron