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Topic 5: Homeostasis and Response - Coggle Diagram
Topic 5: Homeostasis and Response
Homeostasis
Enzyme functioning
If conditions are not optimal, enzymes can denature
Therefore, slower metabolic rate
Regulating Internal Conditions
Water levels
Internal body temperature
Blood sugar levels
Urea concentration
Carbon Dioxide levels
Components
Receptors
Detects stimuli
(changes in the environment)
Coordination Centre
Receive and process
information from receptor
Effectors
Muscles or glands
Carry out responses to external stimuli to restore optimal conditions
Negative feedback
An internal condition changes
chnage detected
Corrective Mechanisms activated
Internal conditions restored
Corrective mechanisms deactivated
The Central Nervous System
Components
Brain
Delicate
and
not well understood
Treatment
of the brain is
difficult
Made up of
millions of interconnecting neurones
Different regions of the Brain
are responsible for
certain functions
Parts of the Brain
Cerebral Cortex
Conscious thought (memory, language, intelligence)
Cerebellum
Muscle coordination
Important for
posture, balance, speech and movement
Medulla
Unconscious
activity
Breathing, heart rate
Hypothalmus
Regulates body functions
such as
temperature
Pituitary gland
Release hormones
that
control body actions
Researching
the
Brain
Types of Scans
MRI (Magnetic Resonance Imaging)
Scanners
Learn
about the areas that are active during
different activities
CT Scans
EEG Scans
Electrical stimulation
Allows us to
treat diseases such as Parkinson's disease
as
nervous system commmunicates via electrical impluses
Brain damage
We can then
map the brain
for
particular functions
Spinal Cord
Coordinating the response of effectors to stimuli
Neurones
Carry electrical impulses
throughout the CNS
Synapses
Gaps between neurones
Found at each junction of the reflex arc
Neurotransmitters diffuse
across the synapse
Transfer information between neurones
When the
electrical impulse reaches the end of the neurone
Coordinates the response of effectors
Stimulus
Receptor
Coordinator [
Relay Neurone
]
Effector
[
Sensory Neurone
]
[
Motor Neurone
]
Reflex Actions
Allow us to respond to dangerous situations rapidly and automatically
The Eye
https://www.bbc.co.uk/bitesize/guides/zprxy4j/revision/7
Optic nerve
Contains
sensory neurones,
transmits impulses from the receptor cells to the brain
Retina
Where the
light receptors are found,
where
light stimulus is detected
Made up of
Cones
and
Rods
Cones
are
sensitive to colour
Rods
are
sensitive to low light
intensity
allowing us to see in dim light
Sclera
White outer layer
of the eye. It is
tough prevent damage
Cornea
Part of sclera which is
transparent,
refracting light into the eye
Iris
Controls the
size of the pupil
Suspensory ligaments
Holds the lens in place
Cilliary Muscles
Holds the lens in place
Used to
focus on objects
Cillilary muscles contract when focusing on a near object
to cause the
suspensory ligaments to loosen.
Cilliliary muscles then relax causing the suspensory ligaments to tighten giving a thinner lens (less convex)
Loosens
when
focusing on a nearby objects
.
Lens become more convex
and
light is refracted strongly
.
Tightens
when
focusing on distant objects
so
lens become less convex
and light is
reflected less strongly.
Lens
The structure is
biconvex
and also
refracts light, focusing it onto the retina
Pupil
The hole at which light enters the eye
The
Iris
Dim
light
Pupil Dilation
Circular
muscles
relax
Radial
muscles
contract
Bright
light
Pupil Contraction
Circular
muscles
contract
Radial
muscles
relax
Common
defects
of the eye
Myopia- Short sightedness
Image is
displayed infront of retina
Treated by
concave
lens
Hyperopia - Long sightedness
Image is
displayed behind the retina
Treated by
convex lens
Treatments
Contact lenses
Lenses
which are
placed onto the surface of the eye
Can
do sports with ease
and
don't have to wear glasses
Soft lenses
cause alot of
waste disposal
and
hard lenses
need to be
kept in solution at night
Laser eye surgery
Uses
lasers
to
change the shape of the cornea
You
won't need glasses or contacts
ever again
It is
expensive
and
only available to adults
Replacement lenses
Replace your eye lens with a new one
The lens could
damage the retina, could cause cataracts and risk of infection
Operation lasts 15 mins,
can go home same day, won't need to ever wear glasses or contacts again
Hormones
Endocrine system
Pituitary gland
Releases hormones in response to changes detected by the hypothalmus
Main gland
in the endocrine systen
Pancreas
Produces
insulin and glucagon
which are involved in
regulating blood glucose
Negative feedback loop
Blood
glucose
too high
Pancreas
release
insulin
Glucose
is
taken into cells
and used for
respiration
. The
excess is converted into glycogen (which is insoluble so does not interfere with osmosis)
stored
in
liver and muscles
Blood
glucose
too low
Normal level of blood glucose
Pancreas
releases
glucagon
Glycogen is broken down
in the liver and muscles into
glucose
which
diffuses into the blood
and can be used for
respiration
Amino acids and fats
also
broken down
Normal level of blood glucose
Diabetes
Type 1
Cause
Immune cells attack pancreas
so the
pancreas can
no longer produce insulin
Risk factors
Treatment
Injecting insulin in the blood stream
before meals
so
hormone gets to the blood immediately
Taking care
with levels of
carbohydrates intake
Regular exercise
that needs to be
planned
to keep
glucose levels steady
Cures
Pancreas transplant
but
risky
and
lack of donors
and
immunosuppressant drugs
will need to be taken
Transplanting pancreatic cells
however it has had
little success
and using
embryonic stem cells is unethical
Type 2
Cause
Body
stops responding to insulin
(
immune to insulin)
RIsk factors
Being
obese
Having a
sedentary job
Eating
sugary foods
Treatment
Eating a
balanced diet
with a
controlled amount of carbohydrates
Regular exercise
Losing weight
Drugs
can be
prescribed
to
increase insulin production
in pancreas or
decrease glucose intake in the small intestine
No cure
Ovaries (female only)
Produces oestrogen
which
controls puberty
and is one of the
main hormones in the regulation of the menstrual cycle
Testes (male only)
Produces
testosterone
which stimulates
puberty and sperm production
Thyroid gland
Located in our neck
Releases
thyroxine
which
regulates our metabolism, heart rate and temperature
Regulates
growth
Production regulated by
negative feedback loop
with
Thyroid Stimulating Hormone (TSH)
Absorbs iodine
to make
thyroxine
Adrenal Glands
Located above the kidneys
Produces adrenaline
which is the
fight or flight response
when an
organism is represented with a dangerous situatuon
Changes
with
adrenaline
Increased heart rate
so blood is
circulated faster to vital organs
Increased breathing rate
so
ventilation
can move
air in and out of the lungs more quickly
Glycogen converts to glucose
in the liver so
more respiration can take place
Pupils dilate
meaning
more light can enter the eye
,
improving vision
Blood diverted away from skeletal muscles and digestive system
as
digestion is not needed
in this situation
More
oxygen and glucose
is
delivered to the brain
to
increase mental awareness
Nervous system vs Endocrine System
Endocrine
Triggers a
slower response
Uses
chemical messengers
which are
carried in the blood
Response
can be
long-lasting
Can act on
large areas
of the body
CNS
Fast
response
Uses
electrical signals
which are carried by
neurones
Response is
very short
Acts on a
precise part of the body
Menstrual cycle
Folicle stimulating hormone (
FSH
)
Produced in the
pituitary gland
Causes the
egg in the ovary to mature
Lutenising Hormone (
LH
)
Produced in the
pituitary gland
Release an egg
from the ovary
Oestrogen
Produced in the
ovaries
Stimulates the
build-up of the uterus lining
Inhibits FSH
Progesterone
Produced in the
ovaries
Maintain the uterus lining
Inhibits FSH and LH
The cycle
Day 1
-
FSH released by Pgland
and
causes egg to mature
Day 7
-
FSH stimulates ovaries to release oestrogen which causes the uterus to build up
Day 14
-
Oestrogen inhibits further release of FSH and stimulates Pgland to
release LH
Day 14-
Ovulation
(
egg is released)
Day 14
- Follicle forms
corpus luteum
which
makes progesterone
. The
progesterone maintains the uterus lining
and
inhibits FSH and LH
Contraception
Hormone based Contraception
Mixed pill
Contains
oestrogen and progesterone which inhibit LH and FSH
99% effective and easy to use
Alot of
side effects
and
have to take regularly
.
STIs
Progesterone-only pill
Thickens mucus
in cervix
preventing sperm
from getting through
Fewer side effects than mixed and 99% effective.
Take regulary.
STIs
Contraceptive implant
Small tube which releases progesterone
Don't have to take pill, 99% effective
Only
lasts 3 years
and
STIs
Contraceptive patch
Chemical
methods
Spermicides
Chemicals
that
kill or disable sperm
Readily available
Not as effective
Barrier
methods (
Condoms, diaphragm
etc )
Condoms
latex sheath over penis
which
catches semen
Offers
protection against STIs
Can
become
damaged
rendering it useless
No side effects
nor medical advice
Diaphragm
Placed over cervix before sex
to
prevent sperm from entering
Has to be
fitted by a doctor
No STI protection
No side effects
Intrauterine devices (
IUD
)
Structure inserted in uterus
by a doctor which
prevent early embyros implanting in uterus
Last 3-5 years and very effective
STIs
and can
cause problems with periods and infection
Abstinence
No sex, no pregnancy.
Some
abstain from sex around ovulation
No side effects
Rhythm method
and is
very unreliable
Surgical
methods
Vasectomy
Sperm ducts are cut
to
prevent sperm getting into semen
Permanent
Surgery needed
Sterlisation
Oviducts cut
to
prevent eggs leaving the ovaries
Permanent contraception
Surgery needed (with general anaesthetic
) and
STIs
Plant Hormones
Auxins
Gravitropism
Phototropism
Controls growth
near tips of
shoots and roots
Gibberelins
Ethene
Kidney
Kidneys act as filters
to
clean the blood
Ions
The
right amount of ions are reabsorbed
into the blood after filtration
*
Useful substances such as water
and
ions are absorbed back
into the blood. This is called
selective reabsorption
Concentration of urine controlled by
ADH
Controlled by
negative feedback loop
Receptors
detect water content is too high
Pituitary gland releases
less
ADH,
so
less water is reabsorbed
from the kidney tubules
Water content is normal
Receptors
detect water content is too low
Pituitary gland releases
more
ADH
, so
more water is reabsorbed
from the kidney tubules
Water content is normal
Urea
Excess amino acids
are
converted into fats and carbohydrates in the
liver
by
deamination
Ammonia is produced
and this is
very toxic
Ammonia converted to urea in liver
then
urea filtered out of the blood by kidney
Water
Water is balanced
by the
amount we consume
and by the
amount removed by the kidneys in urine
*
Kidney failure
Dialysis
Machines
which do the
job of kidneys
How it works
The person's
blood flows between partially permable membranes,
surrounded
by
dialysis fluid
Dialysis fluid
consists of the
same concentration of dissolved ions and glucose as healthy blood
This means that only
excess ions
,
excess water and urea
will
diffuse
across the membrane
Patients have to have a
dialysis session 3 times a week
which
lasts 3-4 hours each.
Can cause infection and clotting
Expensive
for the NHS to run
Gives the patient valuable time until an organ donor is found
Kidney transplant
Transplants
are the
only cure for kidney failure
The
donor kidney
could be
rejected
by the
immune system
meaning that the patient will have to
take **
immunosuppresant drugs**
Transplants are cheaper
(in the long run) and are
more convenient than dialysis
There is a
long waiting list for kidneys