Topic 7: Animal Coordination, Control and Homeostasis Flashcards
What is the endocrine system?
A network of glands that produce and secrete hormones into the bloodstream
What is a hormone?
A cell signalling molecule produced by endocrine glands and released into the blood and travels to a target organ and binds to receptors on effectors initiating a response
Describe the endocrine system
Uses hormones, hormones travel in the bloodstream to the target organ, slower response and lasts until all hormones have broken down which takes a long amount of time
Describe the nervous system
Uses nerve impulses, nerve impulses travel via neurones to the effectors, faster response and lasts until the nerve impulse stops which takes a short amount of time
What is the pituitary gland?
Described as the ‘master gland’ and endocrine gland that produces hormones which control other glands
What are the adrenals glands?
Endocrine glands that produce adrenaline
Where are the adrenal glands located?
Above the kidneys
Where is adrenaline?
A hormone produced by the adrenal glands that is involved in the ‘fight or flight’ response
What are the effects of adrenaline on the body?
Increases heart rate, blood pressure, blood flow to muscles and blood glucose levels
How does adrenaline increases heart rate and blood pressure?
Secreted by the adrenal glands, travels in the blood to the heart, binds to specific red on cells in the heart, causes heart muscle to contract more forcefully and frequently so heart rate and blood pressure increases
How does adrenaline increases respiration at muscle tissues?
Adrenaline binds to specific receptors on cells in the liver, triggers breakdown of glycogen stores and release of glucose so blood glucose levels increases, increase heart rate causes greater blood blood flow to muscles and muscle cells receive more oxygen and glucose for respiration
What is negative feedback?
A corrective mechanism that allows only small shifts from a set point and it reverse a change in conditions
What is the thyroid gland?
Endocrine gland that produces thyroxine
Where is the thyroid gland located?
In the neck
What is thyroxine?
A hormone secreted by the thyroid gland that controls metabolic rate, heart rate and temperature
What is metabolic rate?
The rate at which biochemical reactions occur in cells
How is thyroxine released?
Hypothalamus secretes TRH, TRH stimulates secretion of TSH from pituitary gland and TSH stimulates the release of thyroxine from the thyroid gland
Hat does TRH stand for?
Thyrotropin releasing hormone
What does TSH stand for?
Thyroid-stimulating hormone
How does a negative feedback system controls blood thyroxine levels?
If blood thyroxine levels increase above a set point, TRH and TSH secretions is inhibited, less thyroxine is produced by the thyroid gland so thyroxine levels return to normal and if blood thyroxine levels decreases below a set point, TRH and TSH secretion is increased, more thyroxine is produced by the thyroid gland so thyroxine levels return to normal
How do the ovaries act as an endocrine gland?
They secrete oestrogen into the bloodstream
How do the testes act as an endocrine gland?
They secrete testosterone into the bloodstream
What is homeostatic?
The maintenance of a stable internal environment in the body despite fluctuations in internal and external conditions
Why is homeostasis important?
To ensure optimum conditions for enzymes and cellular processes in the body
What three conditions within the body that must be controlled by homeostasis?
Temperature, blood glucose concentration and water levels
What is thermoregulation?
The maintenance of core body temperature
Why must body temperature be controlled?
Enzymes work best at their optimum temperature, deviations from this optimum temperature decrease the rate of enzymes-controlled reactions
What is the optimum temperature for enzymes in the human body?
37C
What does the maintenance of an ideal body temperature depend on?
A negative feedback system involving: receptors, hypothalamus and effectors
Where are temperature-sensitive receptors located?
Skin - epidermis (outer layer) and dermis (below epidermis)
Hypothalamus
What is the function of receptors in the skin and I’m the hypothalamus?
They detect changes in blood temperature and send information to the hypothalamus
What is the function of the hypothalamus?
It coordinates information from the receptors and sends instructions to the effectors
What is the function of the effectors?
They produce a response to counteract the change in blood temperature and return it to the set point
What are the responses of the body to an increase in temperature above 37C?
Vasodilation, sweating and erector muscles relax, hairs lie flat
What structure produces sweat?
Sweat glands found in the dermis
How is sweat released from the skin?
Pores in the epidermis release sweat onto the skins surface which then evaporates
How does sweating help to reduce body temperature?
Heart energy is used to evaporate sweat, increased heat transfer from the skin to the environment decreases body temperature
What is vasodilation?
Dilation of blood vessels near the skin surface, blood flows closer to the skin surface and greater heat loss to the surrounding
What are the responses of the body to a decrease in temperature below 37C?
Vasoconstriction, shivering, hair erector muscles contract and little sweat is produced
How does shivering help to increase body temperature?
Involuntary contraction of muscles generates heat energy from respiration
How does the contraction of hair erector muscles help to increase body temperature?
Hairs stand on the end creating pockets of air between hairs and a layer of insulation
What is vasoconstriction?
Constriction of blood vessels near skin surface, less blood flows close to the skin surface and less heat loss to the surroundings
Which organ is responsible for the maintenance of blood glucose concentrations?
Pancreas
How are blood glucose concentrations controlled?
Controlled by the hormones insulin and glucagon which are secreted by the pancreas
What does insulin and glucagon are antagonistic hormones mean?
They have opposite effects which counteract one another
What is the role of insulin in the regulation of blood sugar levels?
Causes liver and muscle cells to increase their uptake of glucose from the blood and glucose is converted into glycogen, a storage molecule
What is the role of glucagon in the regulation of blood sugar levels?
Causes the breakdown of glycogen to glucose in the liver and glucose is released into the blood
What is the control of blood glucose concentration an example of?
Negative feedback
What happens when blood glucose concentrations becomes too high?
Blood glucose concentration increases above a set point, pancreas secretes insulin and stops producing glucagon, liver and muscle cells increase uptake of glucose, glucose is converted to glycogen and stored, some glucose may be stored as lipids in tissues and blood glucose concentration decreases, returning to normal level
What happens when blood glucose concentrations become too low?
Blood glucose concentration decreases below a set point, pancreas secrets glucagon and stops producing insulin, liver cells convert glycogen into glucose which is released into blood and blood glucose concentration increases returning to normal level
What is diabetes?
A condition where the homeostatic control of blood glucose levels stops working
What is the cause of type 1 diabetes?
Pancreas doesn’t produce enough insulin
How is type 1 diabetes treated?
Daily insulin injections at meal times, limiting intake of refined sugars and regular exercise
What is the cause of type 2 diabetes?
Person develops insulin resistance or doesn’t produce enough insulin (often due to obesity)
How is type 2 diabetes treated?
Balanced diet, exercise and medication or insulin injection
How does exercise help to control diabetes?
Exercise increases respiration in muscle cells, excess glucose is removed from the blood to produce energy in the form of ATP
Why are type 2 diabetes advised to replace simple carbohydrates with more complex carbohydrates?
Simple carbohydrates are broken down quickly so can raise blood glucose levels rapidly and complex carbohydrates take longer to break down so have a reduced effect on blood glucose levels
What is the body mass index?
A value based on height and mass used to categorise an individual as underweight, normal weight, overweight or obese
How is BMI calculated?
Mass / height2
What BMI values indicate obesity and an increased risk of type 2 diabetes?
BMI value larger than 30
How is an individual waist-to-hip ratio calculated?
Waist circumference/ hip circumference
What does a waist-to-hip ratio higher than 1.0 in males or 0.85 in females indicate?
Abdominal obesity and increased risk of developing type 2 diabetes
What is osmoregulation?
The maintenance of constant water levels in the body fluids of an organism
Why is osmoregulation important?
Prevents cells bursting or shrinking when water enters or leaves by osmosis
What happens to an animal cell if it’s placed into a solution with a higher water concentration?
Higher concentration of water in surrounding solution, water molecules move down their water concentration gradient into the cell by osmosis and pressure inside the cell increases, cell bursts (lysis)
What happens to an animal cell if it’s placed into a solution with a lower water concentration?
Lower concentration of water in surrounding solution, water molecules move down their water concentration gradient out of the cell by osmosis and pressure inside the cell decreases, cell shrinks (crenation)
What happens to an amino cell if it’s placed into a solution with an equal waters concentration?
No net movement of water molecules into or out of the cell
What is the function of the kidneys?
Removes toxic waste substances from the body, alters blood water levels and alters blood ions levels
What is urine?
Waste product of the kidney that contains urea, excess water and excess ions
How is urea produced?
In the liver, urea is produced from the breakdown of excess amino acids
What is the function of the renal artery?
Supplies blood to the kidneys
What is the function of the renal veins?
Drains blood from the kidney
What is the function of the ureter?
Takes urine to the bladder from the kidneys
What is the function of the urethra?
Releases urine from the bladder, out of the body
What is a nephron?
Functional unto, of the kidney where filtration and selective reabsorption takes place
What is the filtration in the kidney?
Blood flows through the glomerulus under high pressures and small molecules, water and ions are filtered out of thr blood and into the Bowman’s capsule of the nephron
Why do large molecules remain in the blood?
They are too large to fit through the pores in the capillary walls
Which substances are selectively re absorbed from the nephron tubule?
All sugars, some water and ions
What happens to the molecules not selectively reabsorbed?
They travel down the kidney tubule as urine and are transported to the bladder via the uerter, here they are stored and eventually excreted
How is the concentration and volume of urine controlled?
Controlled by the secretion of anti-diuretic hormones (ADH)
What produces ADH?
Pituitary gland
How does ADH affect the reabsorption of water from the kidney tubules?
ADH increases the permeability of the collecting ducts, enabling more water to be reabsorbed into the blood
What is required to maintain the ideal water content of blood?
A negative feedback system involving: receptors in the hypothalamus, hypothalamus and effector
What is the negative feedback loop which occurs when blood water concentration is detected?
Receptors detect low blood water content and send information to the hypothalamus, this coordinationto the information and sends instructions to the pituitary gland and pituitary gland increased ADH secretion, ADH increases collecting ducting permeability so more water is reabsorbed and blood water content increases so more concentrated urine is produced
What is the negative feedback loop which occurs when high blood water concentration is detected?
Receptors detect high blood water content and send information to the hypothalamus, this coordinationto the information and sends instructions to the pituitary gland and pituitary gland secreted less ADH, collecting duct become less permeable so less water is reabsorbed and blood water content decreases so more dilute urine is produced
How can kidney failure be treated?
Kidney dialysis and transplant
What is kidney dialysis?
A machine artificially filters a patients blood
How does kidney dialysis work?
Selectively permeable barriers separate patients blood from dialysis fluid, materials are exchanged across the barrier and large cells and proteins remains in the blood
What is the composition of dialysis fluid?
Same concentration of glucose and ions as in normal blood plasma and no urea
What does a kidney transplant involve?
Taking a kidney from a living donor or someone recently deceased and implanting it into the patient
What is the risk associated with kidney transplants?
Risk of the body rejecting the transplanted kidney
What precautions are taken to minimise the risk of rejection?
Tissue typing ensures that the transplanted organ is ‘compatible’ with the recipient and immunosuppressant drugs help prevent the immune system from rejecting the organ
What is the menstrual cycle?
The cycle in women that involves: shedding of uterus lining, repair of uterus lining, release of an egg and maintenance of uterus lining
What are the stages of the menstrual cycle?
Days 1-4: if fertilisation and implantation don’t occur the uterus lining sheds and the egg is expelled with it
Days 4-14: uterus lining thickens and blood vessels grow in preparation for the implantation of an egg
Day 14: egg released from a follicle into the oviduct
Days 14-28: uterus lining maintained so implantation can occur
What are the names of the hormones that control the menstrual cycle?
Follicle stimulating hormone, oestrogen, luteinising hormone and progesterone
What is the role of FSH in the menstrual cycle?
Secreted by the pituitary gland, transported in the bloodstream to the ovaries and triggers the development of a follicle in the ovaries which release oestrogen
What role does oestrogen play in the menstrual cycle?
Secreted by the ovaries, repairs and thickens the uterus lining, inhibits secretion of FSH from the pituitary gland and stimulates secretion of ZLH from the pituitary gland
What is the role of LH in the menstrual cycle?
Secreted by the pituitary gland, transported in the bloodstream to the ovaries, surge in LH triggers ovulation and stimulates follicle remains to develop into a corpus luteum which then secretes progesterone
What is a corpus luteum?
Temporary endocrine structure, mass of cells that release progesterone and degenerate after a few days
What is the role of progesterone in the menstrual cycle?
Secreted by the corpus luteum, stimulates the growth of blood vessels in the uterus lining, inhibits the release of FSH and LH and if no implantation occurs, progesterone levels decrease and the uterus lining sheds, FSH increases and the cycle starts again
What happens to progesterone levels if fertilisation and implantation occur?
The placenta produces progesterone so levels remain high, this prevents further ovulation and maintains the uterus lining
What are contraceptives?
A method or device utilised to prevent pregnancy
Which hormones can be taken to prevent pregnancy?
Progesterone taken on its own and progesterone combined with oestrogen
How does progesterone prevent pregnancy?
Spermicide find it more difficult to enter the uterus as the cervical mucus is thickened, thins the uterine lining, reducing the likelihood of egg implantation and prevents ovulation in some women
How does oestrogen prevent pregnancy?
Oestrogen inhibits FSH preventing ovulation
How can progesterone be administered as a contraceptive?
Mini-pill taken daily or injection
How can progesterone and oestrogen be administered as a contraceptive?
Combined pill or skin patch
What are the benefits of hormonal contraception methods?
99% effective when used properly, generally longer lasting than non-hormonal methods and used to treat other conditions
What are the risks of hormonal contraception methods?
Side effects, don’t protect against STIs, may involve uncomfortable medical procedures and not effect if used incorrectly
What is the barrier methods of contraception?
Prevent the spermicide and egg meeting
What are the benefits of barrier methods of contraception?
Condoms are simple and quick to use, condoms prevent the spread of STIs and no side effects
What is the main risk of barrier methods of contraception?
Less effective than hormonal methods
What two methods are used to treat infertility?
Clomifene therapy and IVF
What is the role of hormones in IVF?
FSH and LH given to a women to stimulate egg production and ovulation, eggs retrieved from the woman’s ovaries and fertilise in vitro and resultant embryo transferred to the woman’s uterus
What is clomifene therapy?
Prescription of clomifene drug to women who don’t ovulate regularly and stimulates secretion of more FSH and LH which triggers egg production and ovulation
