Homeostasis Flashcards
what 3 components are your automatic control systems made up of to maintain a steady condition
- cells called receptors
- coordination centres
- effectors
example of coordination centres
- brain
- spinal chord
- pancreas
what does your automatic control system use to keep your internal environment stable
negative feedback
negative feedback
when the level of something (water or glucose) gets too high of too low your body uses negative feedback to bring it back to normal
what does your receptor do if your level is too high
receptors detect a stimulus (change in the environment)
what does your coordination centre do if your level is too high
receives and processes the information then organised a response
what does your effector do if your level is too high
produces a response which counteracts the change and restores the optimum level (level decreases)
what does your receptor do if your level is too low
detects a stimulus (change in the environment)
what does your coordination centre do if your level is too low
received and processed information then organised a response
what does your effector do if your level is too low
produces a response which counteracts the change and restores the optimum level (level increases)
what different parts make up the nervous system
- central nervous system
- sensory neurones
- motor neurones
- effectors
what are sensory neurones
neurones that carry information as electrical impulses from the receptors to the central nervous system
what are motor neurones
neurones that carry electrical impulses from the central nervous system to effectors
what are effectors
all your muscle and glands, which respond to nervous impulses
why does nervous system exist
- allows humans to react to their surroundings
- and coordinate their behaviour
what can receptors form
- larger, complex organs
(retina of the eye is covered in light receptor cells
what is the Central Nervous System (CNS)
a coordination centre that receives information from receptors and then coordinate a response, carried out by effectors
synapses
the connection between two neurones
in a synapse how is signal transferred
- by chemicals which diffuse (move) across the gap
- chemicals then set off a new electrical signal in the next neurone
reflexes
rapid, automatic responses to stimuli that don’t involve conscious part of your brain
(helps reduce chances of being injured, survival reflex)
example of reflex
when light is shined into ur eye, pupils automatically become smaller to decrease amounts of light getting in ur eye, stops it getting damaged
what is the passage of information in a reflex (from receptor to effector) called
reflex arc
example of reflex arc going through CNS
1) bee stings finger
2) stimulus detected by receptors
3) impulses travel along sensory neurone
4) then travel along relay neurone, via a synapse
5) then travel along motor neurone, via a synapse
6) impulses reach muscles and contract
reaction time
time taken to respond to a stimulus
how can reaction time be affected
- age
- gender
- drugs
example of measuring reaction time (ruler practical)
1) sat arm rested on edge of table
2) ruler held vertically between thumb and forefinger and let go
3) person try and catch ruler as quick as can
4) measure by what number on the ruler it’s caught at
5) repeat test several times to get mean distance ruler fell
6) person drink caffeine, wait 10 mins, test again
control variables of ruler practical to make it a fair test
- same person
- same hand
- ruler dropped from same height
- person being tested hasn’t had caffeine at all today
ways of sending information around the body
- nerves
- hormones
hormones
chemical molecules released directly into the blood
what are hormones carried in and what do they only affect
- carried in blood to other parts of body
- only affect particular cells in particular organs (called target organs)
what do hormones control that need constant adjustment
organs and cells
where are hormones produced and secreted by
various glands, called endocrine glands which make your endocrine system
are hormone effects long or short lasting
long-lasting
examples of glands
- pituitary gland
- thyroid
- adrenal gland
- pancreas
- ovaries
- testes
hormones and nerves have differences: nerves
- very fast action
- act for a very short time
- act on a very precise area
hormones and nerves have differences: hormones
- slower action
- act for a long time
- act in a more general way
what does pituitary gland (glands) do
- produces hormones that regulate body conditions
- act on other glands, directing them to release hormones that bring about change
thyroid (glands)
produces thyroxine which is involved in regulating the rate of metabolism, heart rate and temperature
what does adrenal gland (glands) do
produces adrenaline used to prepare the body for a “fight or flight” response
pancreas (glands)
produces insulin used to regulate blood glucose levels
ovaries (glands)
produces oestrogen which is involved in the menstrual cycle
the two hormones that control blood glucose level
- insulin
- glucagon
what is added when blood glucose levels are too high
insulin
what is added when blood glucose levels are too low
glucagon
how can glucose get into ur blood from ur gut
by eating foods with carbohydrates
what removes glucose from the blood
- exercise
- normal metabolism
diabetes
a condition that affects your ability to control your blood sugar level
what does the pancreas produce (type 1 diabetes)
little or no insulin
if a person has little or no insulin what could happen to them and their blood glucose levels (type 1 diabetes)
can rise to a level that can kill them
what is insulin therapy (type 1 diabetes)
several injections of insulin through the day, which makes sure glucose is removed from blood quickly once food has been digested, stops level getting too high
what is type 2 diabetes
person becomes resistant to their own insulin (still produce it but body cells don’t respond properly to hormone)
what can being resistant to your own insulin cause (type 2 diabetes)
a person’s blood sugar level to rise to a dangerous level
how can type 2 diabetes be controlled
- eating carbohydrate-controlled diet
- regular exercise
being overweight
can increase your chance of developing type 2 diabetes because obesity is a major risk factor in the development of the disease
monthly release of an egg from a woman’s ovaries is part of what cycle
menstrual cycle
what does your body start doing at puberty
releasing sex hormones that trigger sexual characteristics (development of facial hair) and can cause eggs to mature in women
what is the main reproductive hormone in men
testosterone
what is testosterone
- produced by testes
- stimulates sperm production
what is the main reproductive hormone in women
oestrogen
what is oestrogen
- one of the main female sex hormones needed for puberty
- involved in the menstrual cycle
4 stages of menstrual cycle
1) menstruation starts
2) uterus lining builds up again
3) egg develops and is released
4) wall is then maintained
stage 1- menstruation start…
uterus lining breaks down for about 4 days
stage 2- uterus lining builds up again…
from day 4-14 into a thick spongy layer full of blood vessels, ready to receive a fertilised egg
stage 3- egg develops and is released…
from the ovary at day 14 (called ovulation)
stage 4- wall is then maintained…
- for about 14- to 28 days
- if no fertilised egg has landed on uterus wall by day 28, spongy lining starts to break down and cycle starts again
what is ovulation
when an egg develops and is released from the ovary at day 14
menstrual cycle is controlled by 4 hormones
- oestrogen
- progesterone
- FSH
- LH
progesterone
- produced by the empty follicle in the ovary after the egg has been released
- maintains the lining of the uterus during the second half of the menstrual cycle
FSH (Follicle-stimulating hormone)
- produced in the pituitary gland
- causes an egg to mature in one of the ovaries (in a structure called follicle)
- stimulates the ovaries to produce oestrogen
LH (luteinising hormone)
- produced by the pituitary gland
- stimulates the release of an egg at day 14 (ovulation)
contraceptive patch
- contains oestrogen and progesterone
- small patch that sticks on skin, lasts one week
contraceptive implant
- inserted under the skin of the arm
- released a continuous amount of progesterone (stops ovaries releasing eggs) make it hard for sperm to swim to egg and stop any fertilised egg implanting in the uterus
- can last for 3 years
intrauterine device
- t- shaped device that is inserted into the uterus to o kill sperm and prevent implantation of a fertilised egg
- plastic IUDs, release progesterone
- copper IUDs prevent sperm surviving in uterus
non-hormonal forms of contraception
- condoms (male and female)
- diaphragm (shallow plastic cup fits over cervix
- spermicide
pros of FSH and LH given to a women in a fertility drug to stimulate ovulation
helps lots of women get pregnant
cons of FSH and LH given to a women in a fertility drug to stimulate ovulation
- doesn’t always work, try multiple times which is expensive
- too many eggs could be stimulated, results in unexpected multiple pregnancies
IVF process
- collecting eggs from woman’s ovaries and fertilising them in a lab using the man’s sperm
- fertilised eggs then grown into embryos in a lab incubator
- once embryos are tiny balls of cells they are transferred to woman’s uterus (to improve chance of pregnancy)
pros of IVF
gives an infertile couple a child
cons of IVF
- multiple births can happen if multiple embryos grow into a baby (risky for mother and babies, higher chance of miscarriage)
- success rate is low makes process stressful and often upsetting
- physically stressful as well (vomiting, dehydration)
adrenaline
hormone released by the adrenal glands
what is adrenaline released in a response to
stressful or scary situations
how does adrenaline prepare your body for “fight or flight”
triggering mechanisms that increase supply of oxygen and glucose to cells in the brain and muscles (increases heart rate)
thyroxine
a hormone released by the thyroid gland (in the neck)
what is thyroxine’s important role
- regulating the basal metabolic rate
- stimulates protein synthesis for growth and development
In a simple reflex action, chemicals are released at two synapses: one between a sensory neurone and a __________ neurone, and one between a __________ neurone and a motor neurone. What one word completes both gaps?
relay
Which system has longer lasting effects: the nervous system or hormonal system?
hormonal system
What is the word for an organ or tissue that brings about the response in a reflex action?
effector
Where in the nervous system is information from receptors taken to for processing?
central nervous system
Which system is able to respond to change faster: the nervous system or hormonal system?
nervous system
Automatic control systems always include three things: receptors, __________ and effectors. What one word completes the sentence?
coordination centres
Aside from the spinal cord, give an example of a coordination centre in an automatic control system.
brain
In a simple reflex action, a chemical is released in the synapse between a relay neurone and a __________ neurone, which sends an impulse along the __________ neurone to an effector. What one word completes both gaps?
motor neurone
Blood sugar levels of the body need to be maintained, along with what other internal condition?
temperature
What is the word for a change in the environment that a receptor cell responds to?
stimulus
The brain coordinates the __________ to a stimulus. What word completes this sentence?
response
What is the name of the junction between two neurones?
synapse
What type of cell in the nervous system detects a change in the environment?
receptor
What is the name of the system that enables humans to react to their environment?
central nervous system
What is the name of the cells found in nerves that carry information?
neurones
Effectors can be either muscles or what?
glands
What is the common reflex action in the eye usually called?
blinking
What does muscular tissue do to bring about movement?
contract
One word to describe a reflex action is automatic. What is the other word that means you cannot control it?
unconscious
What stimulus is a receptor in the eye sensitive to?
light
Glands secrete __________ in reflex actions. What is the missing word?
chemicals
How does the speed of reflex actions compare to normal responses? Are they faster or slower than normal responses?
faster
What type of actions involving the nervous system are automatic and very fast?
reflex
What part of the CNS is not usually involved in an unconditioned reflex?
brain
What stimuli are receptors in the nose and tongue sensitive to?
chemicals
In a reflex action, impulses from a receptor cell travel along what kind of neurone first?
sensory neurone
In a reflex action, muscles respond by doing what?
contracting
True or false? Thyroxine prepares the body for “fight or flight”.
false
Type 1 diabetes can be controlled by injecting… what?
insulin
What type of tissue produces hormones?
gland
Carl is diabetic and injects insulin every day. What is likely to happen to his blood glucose level following an injection of insulin?
fall
True or false? Adrenaline increases the glucose concentration in the blood.
true
Name a hormone released into the bloodstream in humans in response to a dangerous situation.
adrenaline
What are the missing TWO words? “The process that allows homeostatic mechanisms to self-adjust around a normal value, so keeping the body’s internal environment stable, is known as __________ __________”
negative feedback
Which hormone lowers blood sugar levels when they are too high?
insulin
Name the disease condition where a person’s blood glucose level is not properly controlled.
diabetes
Where is adrenaline produced?
adrenal gland
What type of structures secrete hormones?
gland
Name the hormone that increases the heart rate.
adrenaline
What type of molecule is the hormone insulin made from?
protein molecules
True or false? People with type 1 diabetes need to give careful attention to their diet and exercise levels.
true
True or false? If a large, sugary dessert is eaten, the body will respond by producing less insulin.
false
True or false? Adrenaline decreases the pulse rate.
false
What is the missing word? “The organs or tissues that respond to a particular hormone are known as __________ organs or tissues.”
target
Where is thyroxine produced?
thyroid gland
Where in the body is the hormone glucagon produced?
pancreas
Name a hormone that controls the concentration of glucose in the blood.
insulin
Carl’s diabetes is caused by his body not producing enough insulin. Which of Carl’s organs is not functioning properly?
pancreas
If someone takes an overdose of heroin, a doctor might treat them by checking their heart rate and giving them an injection of adrenaline. What would the injection do to their heart rate?
increase it
Thyroxine is controlled by what type of feedback?
negative feedback
If people with diabetes are not treated, what problem with their blood glucose level are they most likely to have?
too high
Carl is diabetic. He injects insulin in the morning but then doesn’t have time for lunch. What problem is most likely to occur with his blood glucose level?
too low
The hormone glucagon causes __________ to be converted into glucose. What is the missing word?
glycogen
Hormones are usually transported to their target organs in the __________. What is the missing word?
blood
Name a glucose-regulating hormone produced by the pancreas.
glucagon
The organ that a particular hormone acts on is known as the __________ organ. What one word completes this sentence?
target organ
Name the organ that monitors the concentration of glucose in the blood.
pancreas
What type of protein is a chemical messenger that travels in the blood?
hormone
What chemical substances coordinate many processes in the body?
hormone
Other than oxygen, the level of what substance needs to be maintained to give cells a constant supply of energy?
sugar or glucose
When glucagon acts upon liver cells, it stimulates the cells to convert glycogen into a soluble carbohydrate that is then released into the bloodstream. What is the name of this carbohydrate?
glucose
What is sometimes called the “master gland” because of its important role in the endocrine system?
pituitary gland
Which hormone is responsible for the development of secondary sexual characteristics in girls during puberty?
oestrogen
The process of development of secondary sexual characteristics that teenagers go through is called what?
puberty
Apart from LH, name another hormone that is involved in the menstrual cycle.
FSH
Which hormone is primarily responsible for stimulating ovulation?
LH
What is the monthly shedding of the lining of the womb in the menstrual cycle called?
menstruation or period
Women with fertility issues may have low levels of which hormone?
FSH
Early birth control pills contained large amounts of hormones and could lead to blood clots. The blood clots are an example of a __________ effect of a drug. What word completes the sentence?
side
In the menstrual cycle, the release of an ovum is called what?
ovulation
Which hormone is responsible for the development of secondary sexual characteristics in boys during puberty?
testosterone
What does LH stand for?
luteinising hormone
A disadvantage to fertility treatment is that it can lead to multiple births. Who does this pose a risk to?
the mother and the babies
True or false? Fertility treatment decreases the chance of twins or triplets.
false
The function of FSH is to cause an ovum to __________. What one word completes this sentence?
mature or develop
Does IVF guarantee that a woman will become pregnant?
no
True or false? Modern contraceptive pills have fewer side effects than earlier pills.
true
Oestrogen stops or slows the production of what hormone?
FSH
The first birth control pills contained large amounts of what hormone?
oestrogen
After an egg is released, the empty follicle in the ovary secretes __________, which inhibits both FSH and LH. What word completes the sentence?
progesterone
What does IVF stand for?
in vitro fertilisation
A vasectomy is an example of which method of contraception?
surgical
Fertility is the measure of the ability to become __________. What one word completes the sentence?
pregnant
Name the organ where oestrogen is made
ovaries
Name a natural method of birth control
abstinence
Name a surgical method of birth control.
vasectomy
Does the oral contraceptive pill directly affect the maturation of ova?
yes
The lining of the uterus will be shed if the egg released at ovulation is not what?
fertilised
What does FSH stand for?
follicle stimulating hormone
What gland secretes FSH and LH?
pituitary gland
Some methods of birth control (like skin patches and injections) work by slowly releasing a hormone that inhibits the maturation and release of eggs for months or years. What hormone is this?
progesterone
Ovulation occurs approximately every how many days?
28
Name a mechanical method of birth control.
condom
Condoms are an example of which type of contraception?
mechanical
Spermicide is an example of which type of contraception?
chemical
what if you have too much oestrogen?
it can increase your risk of blood clots and stroke
what is the speed at which chemical reactions in the body occur while the body is at rest?
basal metabolic rate
what is the basal metabolic rate?
the speed at which chemical reactions in the body occur while the body is at rest
