B7 - animal co-ordination, control and homeostasis Flashcards
what are hormones?
chemical messengers released directly into blood and carried around the body
what do hormones effect?
particular cells in particular organs (target organs)
what do hormones control?
substances in organs and cells that require constant adjustment
where are hormones produced (and secreated)?
endocrine glands
what do endocrine glands make up?
endocrine system
name the 6 endocrine glands
- pituitary gland
- thyroid gland
- adrenal glands
- pancreas
- ovaries
- testes
pituitary gland
- in the brain
- produces many hormones that regulate body conditions
- sometimes called ‘master gland’ because these hormones act on other glands, directing them to release hormones that bring about change
thyroid gland
- in neck just infront of trachea
- produces thyroxine
- thyroxine is envolved in regulation of metabolic rate, heartrate, temperature
adrenal glands
- produce adrenaline used to prep body for fight or flight response
pancreas
- produces insulin and glucagon used to regulate blood glucose level
ovaries
- produce oestrogen involved in the menstrual cycle
testes
- produce testosterone (male sex hormone)
- testosterone contols puberty and sperm production
nervous response (neurones)
- very fast action
- act for short time
- precise area
hormonal response
- slower action
- act for a long time
- act in a more general way
how to tell if response is nervous?
if it is really quick info is passed to effectors quickly eg. hot surface
how to tell if response is hormonal?
lasts a long time eg. adrenaline kicks in quiclky but effects last for a while after (feel wobbly)
where is adrenaline secreated?
adrenal glands above the kidneys
function of adrenaline?
prepares body for fight or flight response
what is fight or flight response?
standing ground, or runnung away from a threat
how does adrenaline induce fight or flight respone?
- binds to specific receptors in the heart causing heart muscle to contract with more frequency and force causing heart rate and blood pressure to increase
- this increases blood flow to muscles, and cells recieve more O2 and glucose for increased respiration
- also binds to receptors in liver, liver breaks down glycogen stores releasing glucose
- increases blood glucose levels, more glucose in the blood to be transported to cells
what causes adrenaline to be realeased?
- brain detects stressful situation
- sends nervous impulse to adrenal glands
- adrenal glands release adrenaline, body preps for action
adrenaline target organs?
heart and liver
negative feedback?
when body detects the level of a substance has gone above/below average level triggers response to bring it back to normal
why does body use negative feedback?
contol levels of hormones and substances in blood
where is thyroxine released?
thyroid gland
function of thyroxine?
important role regulating metabolic rate
define metabolic rate
the speed at which oxygen and food products react to release energy
what is the effect of thyroxine on metabolic rate?
underactive thyroid gland can cause weight gain as less thyroxine is produced and metabolic rate drops.
lower metabolic rate = less glucose is broken down in respiration and more is stored as fat
what causes blood thyroxine levels to be kept at the right level?
negative feedback system
low blood thyroxine - negative feedback?
- low levels stimulate hypothalmus to release TRH
- TRH stimulates pituitary gland to release TSH
- TSH stimulates thyroid gland to release thyroxine and levels rise
high blood thyroxine - negative feedback?
- release of TRH from hypothalmus inhibited
- reduces TSH production
- thyroid produces less thyroxine
- thyroxine levels fall
TRH
thyrotropin releasing hormone
TSH
thyroid stimulating hormone
hypothalmus
a structure in the brain that produces hormones
thyroxine target organ
most tissues
what is the mestrual cycle?
monthly sequence of events where female body releases an egg and preps uterus for if the egg is fertilised
stage 1 menstrual cycle
day 1- menstruation begins , lining of uterus breaks down and is released (period)
stage 2 menstrual cycle
day4-14 - uterus lining is repaired, becomes thick, spongy full of blood vessels ready for (possible) fertilised egg to implant
stage 3 menstrual cycle
day 14- ovulation occurs, (egg develops and released by ovary)
stage 4 menstrual cycle
day14-28 - lining maintained, if no fertilised egg implants, breaks down
what are th 4 hormones in menstrual cycle?
FSH
LH
oestrogen
progesterone
FSH (follicle stimulating hormone)
- released by pituitary gland
- causes follicle (egg and surrounding cells) to mature in an ovary
- stimulates production of oestrogen
oestrogen
- released by ovaries
- causes uterus lining to thicken and grow
- high levels stimulate LH surge (rapid increase)
LH (luteinising hormone)
- released by pituitary gland
- stimulates ovulation, follicle ruptures and egg is released
- stimulates remains of follicle to develop into corpus luteum which secrestes progesterone
progesterone
- released by corpus luteum after ovulation
- maintains uterus lining
- inhibits release of FSH and LH
- when levels fall (due to no fertilisation), and theres low oestrogen lining breaksdown
- low progesteron = FSH increase and cycle restarts
why period stop when pregnant?
if fertilised egg implants (pregnant) progesterone levels stay high (placenta produces progesterone) to maintain lining during pregnancy
what does infertile mean?
when a person cannot reproduce naturally
what are the 2 ART?
- clomifene therapy
- in vitro fertilisation (IVF)
clomifene therapy
- if infertile because of no or irregular ovulation
- take drug called clomifene
- causes more FSH and LH to be realeased into the body stimulating egg maturation and ovulation
- by knowing person is ovulating, couple can have intercourse inc. chance of pregnancy
IVF
- collecting egg from ovaries fertilising in lab with sperm and grown into embryos
- when one or two are balls of cells, transferred back to uterus to inc chance of pregancy
- FSH and LH given before egg extraction to stim egg production (+1 egg collected)
ART
assisted reproductive technonlogy
hormonal contraceptive - oestrogen
- used to prevent the release of an egg
-even though oestrogen helps stimulate the release of eggs. If taken every day, the level remains high and inhibits FSH production.
- After a while egg development and production stops
Hormonal contraceptive – progesterone
- can be used to reduce fertility
- Stimulates production of cervical mucus, preventing any sperm getting through the cervix and reaching egg
- high progesterone means inhibits production of FSH and LH so no egg is developed / released
oestrogen and progesterone contraceptive
combined pill and contraceptive patch
progesterone only contraceptive
mini-pill and contraceptive injection
what is a barrier method
putting a physical barrier between the sperm and egg so they dont meet
examples of barrier methods
condoms (male and female)
diaphragm (fit over opening of uterus) must be used with spermicide (chemical that kills sperm)
pros of hormonal contraceptives
more effective at preventing pregnancy than barrier methods
cons of hormonal contraceptive
side effects eg. headaches, acne, moodchanges
don’t protect against STI’s (only condoms do))
pros of barrier method
prevents sti (CONDOMS ONLY)
cons of barrier methods
can tear
other methods of contraception
intrauterine method (eg. IUD)
abstinence (not having intercourse)
surgical methods (irreversible)
define homeostatsis
the body’s maintaining of a constant internal environment so everything works properly
why is maintaining a constant enternal environment important?
cells need right conditions to function properly and for enzymic action
how does the body maintain a constant internal environment?
Homeostasis typically involves negative feedback loops that counteract changes of various conditions
examples of homeostasis
- blood glucose regulation
- osmoregulation (water content)
- thermoregulation (body temp regulation)
- NEGATIVE FEEDBACK RESPONSES
how does glucose enter the body? (levels increase)
when eating foods that contain carbohydrates
how does glucose enter the blood?
from the small intestine
how is glucose removed from blood? (levels decrease)
normal metabolism of cells eg. respiration
exercising vigourously
what is glycogen?
the store of excess glucose in the muscles and LIVER
made up of many connected glucose molecules
how does weight gain (glucose related) occur? (idk if relevant)
when glycogen stores are full, excess glucose is stored as lipid (fat) in tissue
what does the pancreas do?
monoitors and controls blood glucose levels
what hormones does pancreas secrete?
insulin (high blood glucose)
glucagon (low blood glucose)
high blood glucose process
- high blood glucose detected
- pancreas secretes insulin
- insulin moves glucose from blood into liver (amd muscle cells)
- liver turns glucose into glycogen
- blood glucose is reduced
low blood glucose process
- low blood glucose detected
- pancreas secretes glucagon
- glucagon makes liver break glycogen down to glucose
- glucose released bck into blood
- blood glucose increases
insulin and glucagon target organ
liver
what is type 1 diabetes?
condition where pancreas produces little-no insulin (inadequete amount), can cause persons blood glucose levels to rise to a fatal amount
how type 1 diabetes is treated?
inulin injections into fatty tissue beneath skin so it can enter bloodstream
done at mealtimes to remove glucose from blood quickly once digested
very effective
amount depends on persons diet and physical activity
life style treatments for type 1 diabetes?
limiting intake of foods with high simple carb content (sugar)
regular exersie (glucose used up more)
causes of type 1 diabetes
genetics
thought cause: immune system attacking healthy insulin-producing betacells
symptoms of type 1 diabetes
frequent urination, always thirsty, tired, weight loss
hypogycaemia
low blood sugar
cause confusion, unconciousness even coma (extreme)
hyperglycaemia
high blood sugar
cause exhastion and blurred vision
what is type 2 diabetes?
condition when a person becomes insulin resistant (body doesn’t respond to insulin)
how type 2 diabetes is treated?
healthy diet, exercise, weight loss (if needed)
risk factors of type 2 diabetes
40+ years, obesity eg.excess fat around abdomen
what is classified as obese
30+ BMI
BMI formula
BMI = mass (kg)/ height² (m)
waist-to-hip ratio formula
waist-to-hip ratio = waist circumference (cm) / hip circumference (cm)
what waist-to-hip ratio cause inc risk of type 2 diabetes?
1.0 men
0.85 women
what does waist-to-hip ratio indicate?
how fat is stored in body
