Animal Coordination, Control and Homeostasis Flashcards
What are hormones?
A product of cells that circulates in body fluids and produces a specific effect on other cells or tissues
What is a target organ?
A specific organ on which a hormone acts
What are endocrine glands?
Glands of the endocrine system that secrete hormones directly into the blood stream
What are the two ways the body communicates organ to organ?
Hormones (slower response) Nervous system (fast response)
What is the function of the pituitary gland?
Produces hormones that regulate body conditions. These hormones act on other glands and cause them to release hormones
What is the function of the thyroid gland?
Produces thyroxine, which regulates the rate of metabolism, heart rate and temperature
What is the function of the adrenal glands?
Produce adrenaline, used for the ‘flight or fight’ response
What is the function of the ovaries?
Produces oestrogen, involved in the menstrual cycle
What is the function of the pancreas?
Produces insulin, which regulates blood glucose levels
What is the function of the testes?
Produces testosterone, which controls puberty and sperm production
What is the ‘fight or flight’ response?
The brain tells the sympathetic nervous system to start working, which tells the adrenal glands to release adrenaline into the bloodstream. This makes the body more able to respond to a threat, by increasing heart rate and blood pressure among other things. These responses mean the body is more able to run or fight a threat
What responses are caused in the ‘fight or flight’ response?
Adrenaline binds to receptors in the heart, causing it to beat faster and increase blood pressure, increasing blood flow to muscles
Adrenaline binds to receptors in the liver, causing it to break down glycogen into glucose, increasing blood sugar levels
What is homeostasis?
The mechanism that keeps the internal environment constant, so that cells are at optimal conditions to operate
What are the responses when the body is too hot?
Erector muscles relax so hairs lie flat
Lots of sweat is produced
Vasodilation occurs
What are the responses when the body is too cold?
Erector muscles contract
Little sweat is produced
Vasoconstriction occurs
You shiver
How is body temperature controlled?
The hypothalamus contains receptors sensitive to blood temperature in the brain and skin. When a change is detected, it causes a response in the skin
What is vasoconstriction?
Vasoconstriction reduces blood flow near the surface of the skin by constricting blood vessels. This reduces heat loss from the blood by radiation through the skin. It is used in cold weather.
What is vasodilation?
Vasodilation increases blood flow near the surface of the skin by dilating blood vessels. This increases heat loss from the blood by radiation through the skin. It is used in hot weather.
What is osmosis?
The diffusion of water molecules across a semi-permeable membrane
What is osmoregulation?
The active regulation of water content in the body
What is BMI?
A measure of body fat based on height and weight
How is BMI calculated?
Weight (kg) / height (m) ^2
What is negative feedback?
When changes happen in a control system, processes happen so that the changes are reversed
How does insulin regulate glucose levels?
Glucose in the blood increases
The pancreas detects this and releases insulin
Insulin tells muscles to take in more glucose and the liver to convert glucose into glycogen
Glucose levels decrease
How does glucagon regulate glucose levels?
Glucose in the blood decreases
The pancreas detects this and releases glucagon
Glucagon tells the liver to change glycogen back into glucose, which is released into the bloodstream
Glucose levels increase
What causes type 1 diabetes?
The body’s immune system attacks beta cells in the pancreas, so the body cannot produce insulin. This causes dangerously high blood sugar levels.
What are symptoms of type 1 diabetes?
Excessive urination, increased thirst and hunger, a dry mouth, fatigue, and unexpected weight loss. Diabetic ketoacidosis
How is type 1 diabetes managed?
Insulin is injected into subcutaneous tissue using an insulin pen or pump, usually around meal times. A healthy lifestyle and a diet low in carbohydrates is important
What causes type 2 diabetes?
The pancreas cannot produce enough insulin to function properly, or when the body develops a resistance to insulin. An unhealthy lifestyle, including being overweight or obese, having a poor diet, having a high waist-hip ratio, or smoking, causes this
What are symptoms of type 2 diabetes?
Frequent urination, increased thirst and hunger, weight loss, blurred vision, itchiness, and fatigue.
How is type 2 diabetes managed?
Medicine are prescribed to improve the sensitivity of tissues to insulin, increase insulin production, and lower glucose production. In extreme cases insulin injections are used. A healthy lifestyle is needed
What are the three main roles of the kidney?
Removal of urea
Adjustment of ion levels
Adjustment of water levels
What do the renal vein and artery do?
The renal vein carries blood that has been filtered by the kidney
The renal artery carries unfiltered blood to the kidney
What does the ureter do?
Carries urine from the kidney to the bladder
How do the kidneys filter blood?
Blood enters through the renal artery into nephrons
The liquid part (water, urea, ions, glucose) is forced out of the glomerulus into the Bowman’s capsule at high pressure (ultrafiltration)
Bigger molecules like proteins and blood cells cannot pass through and remain in the blood
All glucose is selectively reabsorbed, and sufficient ions and water are reabsorbed at the correct level
Excess water and ions and urea continue out of the nephron via the collecting duct, passing into the ureter and into the bladder
‘Clean’ blood is left, with ions, water, blood cells, glucose, and bigger molecules
What is ADH?
A hormone released by the pituitary gland. It makes the collecting ducts of nephrons more permeable, so more water is reabsorbed into the blood, stopping the body from becoming dehydrated.
What is dialysis?
An artificial method used to filter blood for people who have kidney failure. Fluid contains the same concentration of salts and glucose as blood plasma, but lower concentrations of ions and waste substances. Waste substances move out of the blood, while essential parts remain.
The barrier is semipermeable, so big molecules like proteins remain.
It is done regularly.
What is a kidney transplant?
When someone gives a healthy kidney to somebody whose kidneys have failed.
An organ is removed from someone who has died suddenly or who does not need it
What are advantages/ disadvantages of kidney transplants vs dialysis?
Advantages:
Cheaper
Quality of life is better
Disadvantages: Must take immune-suppressant drugs, increasing chance of infection Kidneys last 8-9 years Risk of rejection or failure Shortage of donors
What is TRH?
A hormone released by the hypothalamus that stimulates the pituitary gland to release TSH
What is TSH?
A hormone released by the pituitary gland that stimulates the thyroid gland to release thyroxine
What is FSH?
A hormone released from the pituitary gland that stimulates egg maturation and oestrogen production
What is oestrogen?
A hormone released from the ovaries that stops FSH from being released. It builds up the uterus lining and a high amount causes an LH surge on day 14
What is LH?
A hormone released from the pituitary gland on day 14 that causes an egg to be released and stimulates the follicle remains to develop into a corpus lutem
What is progesterone?
A hormone released by the corpus lutem that maintains the uterus lining and inhibits the release of FSH and LH
What is clomifene therapy?
A oral medication and hormone therapy for people with irregular menstrual cycles. It blocks the effect of oestrogen, allowing for higher levels of FSH and LH, so eggs ripen and are released
What is IVF?
A method used when there is a physical problem with the uterus, or if the male’s sperm is too weak. A woman has extensive hormone therapy, which stimulates the ovaries to produce a number if ova at once. Eggs are collected by a needle, ova and sperm are mixed together and incubated for 18 hours. The fertilised embryos are placed in the uterus where implantation can take place
What are the advantages/ disadvantages of hormonal vs barrier contraceptives?
Advantages:
Typically more effective
Couple does not have to think about contraception
Disadvantages:
Possible unpleasant side effects
Protects against STIs
How do oral contraceptives work?
Some contain progesterone (mini pill and contraceptive injection) and some also contain oestrogen (combined pill and contraceptive patch). Oestrogen inhibits the production of FSH, stopping egg development and production after a while. Progesterone stimulates the production of thick cervical muscles, stopping sperm from getting through.
