Download Lesson 7 - iGCSE Science Courses

IGCSE BIOLOGY
SECTION 2 LESSON 7
Content
Section 2
Structures
and
functions
in living
organisms
a) Levels of organisation
b) Cell structure
c) Biological molecules
d) Movement of substances
into and out of cells
e) Nutrition
f) Respiration
g) Gas exchange
h) Transport
i) Excretion
j) Coordination and response
Content
Lesson 7
j) Coordination
and
response
j) Coordination and response
2.77 understand that organisms are able to respond to changes in their
environment
2.78 understand that homeostasis is the maintenance of a constant internal
environment and that body water content and body temperature are both
examples of homeostasis
2.79 understand that a coordinated response requires a stimulus, a receptor and
an effector
Flowering plants
2.80 understand that plants respond to stimuli
2.81 describe the geotropic responses of roots and stems
2.82 describe positive phototropism of stems
Humans
2.83 describe how responses can be controlled by nervous or by hormonal
communication and understand the differences between the two systems
2.84 understand that the central nervous system consists of the brain and spinal cord
and is linked to sense organs by nerves
2.85 understand that stimulation of receptors in the sense organs sends electrical
impulses along nerves into and out of the central nervous system, resulting in rapid
responses
2.86 describe the structure and functioning of a simple reflex arc illustrated by the
withdrawal of a finger from a hot object
2.87 describe the structure and function of the eye as a receptor
2.88 understand the function of the eye in focusing near and distant objects, and in
responding to changes in light intensity
2.89 describe the role of the skin in temperature regulation, with reference to
sweating, vasoconstriction and vasodilation
2.90 understand the sources, roles and effects of the following hormones: ADH,
adrenaline, insulin, testosterone, progesterone and oestrogen.
Content
Lesson 7
j) Coordination
and
response
j) Coordination and response
2.77 understand that organisms are able to respond to changes in their
environment
2.78 understand that homeostasis is the maintenance of a constant internal
environment and that body water content and body temperature are both
examples of homeostasis
2.79 understand that a coordinated response requires a stimulus, a receptor and
an effector
Flowering plants
2.80 understand that plants respond to stimuli
2.81 describe the geotropic responses of roots and stems
2.82 describe positive phototropism of stems
Humans
2.83 describe how responses can be controlled by nervous or by hormonal
communication and understand the differences between the two systems
2.84 understand that the central nervous system consists of the brain and spinal cord
and is linked to sense organs by nerves
2.85 understand that stimulation of receptors in the sense organs sends electrical
impulses along nerves into and out of the central nervous system, resulting in rapid
responses
2.86 describe the structure and functioning of a simple reflex arc illustrated by the
withdrawal of a finger from a hot object
2.87 describe the structure and function of the eye as a receptor
2.88 understand the function of the eye in focusing near and distant objects, and in
responding to changes in light intensity
2.89 describe the role of the skin in temperature regulation, with reference to
sweating, vasoconstriction and vasodilation
2.90 understand the sources, roles and effects of the following hormones: ADH,
adrenaline, insulin, testosterone, progesterone and oestrogen.
Content
Lesson 7
j) Coordination
and
response
j) Coordination and response
2.77 understand that organisms are able to respond to changes in their
environment
2.78 understand that homeostasis is the maintenance of a constant internal
environment and that body water content and body temperature are both
examples of homeostasis
2.79 understand that a coordinated response requires a stimulus, a receptor and
an effector
Flowering plants
2.80 understand that plants respond to stimuli
2.81 describe the geotropic responses of roots and stems
2.82 describe positive phototropism of stems
Humans
2.83 describe how responses can be controlled by nervous or by hormonal
communication and understand the differences between the two systems
2.84 understand that the central nervous system consists of the brain and spinal cord
and is linked to sense organs by nerves
2.85 understand that stimulation of receptors in the sense organs sends electrical
impulses along nerves into and out of the central nervous system, resulting in rapid
responses
2.86 describe the structure and functioning of a simple reflex arc illustrated by the
withdrawal of a finger from a hot object
2.87 describe the structure and function of the eye as a receptor
2.88 understand the function of the eye in focusing near and distant objects, and in
responding to changes in light intensity
2.89 describe the role of the skin in temperature regulation, with reference to
sweating, vasoconstriction and vasodilation
2.90 understand the sources, roles and effects of the following hormones: ADH,
adrenaline, insulin, testosterone, progesterone and oestrogen.
Responding to our environment
Responding to our environment
LIGHT
receptors in
the EYES
Responding to our environment
LIGHT
receptors in
the EYES
SOUND
receptors in
the EARS
Responding to our environment
LIGHT
receptors in
the EYES
SOUND
receptors in
the EARS
CHANGE OF
POSITION
receptors in
the EARS
(balance)
Responding to our environment
LIGHT
receptors in
the EYES
SOUND
receptors in
the EARS
CHANGE OF
POSITION
receptors in
the EARS
(balance)
TASTE
receptors in
the TONGUE
Responding to our environment
LIGHT
receptors in
the EYES
TASTE
receptors in
the TONGUE
SOUND
receptors in
the EARS
SMELL
receptors in
the NOSE
CHANGE OF
POSITION
receptors in
the EARS
(balance)
Responding to our environment
LIGHT
receptors in
the EYES
TASTE
receptors in
the TONGUE
SOUND
receptors in
the EARS
SMELL
receptors in
the NOSE
CHANGE OF
POSITION
receptors in
the EARS
(balance)
TOUCH,
PRESSURE and
TEMPERATURE
receptors in
the SKIN
Responding to our environment
The pathway:
Responding to our environment
The pathway:
Stimulus
Receptor
Coordinator
Effector
Response
Responding to our environment
The pathway:
Stimulus
Change in
the
environment
Receptor
Coordinator
Effector
Response
Detect
stimuli
Central nervous
system
Muscles
or glands
Action
taken
Responding to our environment
The pathway:
Stimulus
Receptor
Coordinator
Effector
Response
Change in
the
environment
Detect
stimuli
Central nervous
system
Muscles
or glands
Action
taken
Hot pan
Temperature
receptors in
the skin
Central nervous
system
Muscles
in arms
Hand
pulled
away
Responding to our environment
The pathway:
Stimulus
Receptor
Coordinator
Effector
Response
Change in
the
environment
Detect
stimuli
Central nervous
system
Muscles
or glands
Action
taken
Hot pan
Temperature
receptors in
the skin
Central nervous
system
Muscles
in arms
Hand
pulled
away
Responses can be either conscious or
reflex
Controlling our internal environment
Removal
Carbon
dioxide
Product of
respiration,
removed by
the lungs
Controlling our internal environment
Removal
Carbon
dioxide
Product of
respiration,
removed by
the lungs
Urea
Produced by
the liver,
removed by
the kidneys
Controlling our internal environment
Controlled
Water
content
Loss – lungs,
sweating, urine
Gain - drinking
Controlling our internal environment
Controlled
Water
content
Loss – lungs,
sweating, urine
Gain - drinking
Ion content
(eg. sodium)
Loss – lungs,
sweating, urine
Gain – drinking,
eating
Controlling our internal environment
Controlled
Water
content
Loss – lungs,
sweating, urine
Gain - drinking
Ion content
(eg. sodium)
Loss – lungs,
sweating, urine
Gain – drinking,
eating
Temperature
(37oC)
Increase – shivering,
shut down capillaries
Decrease – sweating,
open up capillaries
Controlling our internal environment
Controlled
Water
content
Loss – lungs,
sweating, urine
Gain - drinking
Ion content
(eg. sodium)
Loss – lungs,
sweating, urine
Gain – drinking,
eating
Temperature
(37oC)
Increase – shivering,
shut down capillaries
Decrease – sweating,
open up capillaries
Blood glucose
Increase - hormone
GLUCAGON
Decrease – hormone
INSULIN
Controlling our internal environment
Controlled
Water
content
Loss – lungs,
sweating, urine
Gain - drinking
Ion content
(eg. sodium)
Loss – lungs,
sweating, urine
Gain – drinking,
eating
Temperature
(37oC)
Increase – shivering,
shut down capillaries
Decrease – sweating,
open up capillaries
Blood glucose
HOMEOSTASIS
= maintenance of a
constant internal
environment
Increase - hormone
GLUCAGON
Decrease – hormone
INSULIN
Content
Lesson 7
j) Coordination
and
response
j) Coordination and response
2.77 understand that organisms are able to respond to changes in their
environment
2.78 understand that homeostasis is the maintenance of a constant internal
environment and that body water content and body temperature are both
examples of homeostasis
2.79 understand that a coordinated response requires a stimulus, a receptor and
an effector
Flowering plants
2.80 understand that plants respond to stimuli
2.81 describe the geotropic responses of roots and stems
2.82 describe positive phototropism of stems
Humans
2.83 describe how responses can be controlled by nervous or by hormonal
communication and understand the differences between the two systems
2.84 understand that the central nervous system consists of the brain and spinal cord
and is linked to sense organs by nerves
2.85 understand that stimulation of receptors in the sense organs sends electrical
impulses along nerves into and out of the central nervous system, resulting in rapid
responses
2.86 describe the structure and functioning of a simple reflex arc illustrated by the
withdrawal of a finger from a hot object
2.87 describe the structure and function of the eye as a receptor
2.88 understand the function of the eye in focusing near and distant objects, and in
responding to changes in light intensity
2.89 describe the role of the skin in temperature regulation, with reference to
sweating, vasoconstriction and vasodilation
2.90 understand the sources, roles and effects of the following hormones: ADH,
adrenaline, insulin, testosterone, progesterone and oestrogen.
Plant responses to the environment
Plant responses to the environment
LIGHT
Plant responses to the environment
LIGHT
MOISTURE
Plant responses to the environment
LIGHT
GRAVITY
MOISTURE
Plant responses to the environment
LIGHT
GRAVITY
MOISTURE
PHOTOTROPISM = growth response to light
Plant responses to the environment
LIGHT
GRAVITY
MOISTURE
PHOTOTROPISM = growth response to light
GEOTROPISM = growth response to gravity
Plant responses to the environment
Roots are positively
geotropic – they grow
in the direction of
gravity
Plant responses to the environment
Shoots are negatively
geotropic – they grow
away from the
direction of gravity
Roots are positively
geotropic – they grow
in the direction of
gravity
Plant responses to the environment
Shoots are positively
phototropic – they
grow in the direction
of light
Plant responses to the environment
GEOTROPISM – response to gravity
Germinating seedling
Plant responses to the environment
GEOTROPISM – response to gravity
Plant growth is controlled
by hormones – these are
produced at the growing
points of shoots and roots
Germinating seedling
Plant responses to the environment
GEOTROPISM – response to gravity
In the shoot, the hormone is produced
at the tip. It travels down through
the shoot and stimulates the growth
of cells on the lower side. The shoot
therefore grows upwards, away from
gravity.
Germinating seedling
Plant responses to the environment
GEOTROPISM – response to gravity
In the shoot, the hormone is produced
at the tip. It travels down through
the shoot and stimulates the growth
of cells on the lower side. The shoot
therefore grows upwards, away from
gravity.
In the root the hormone is again
produced at the tip. It travels up
through the root and slows down the
growth of cells on the lower side. The
root therefore grows downwards,
towards the force of gravity.
Germinating seedling
Plant responses to the environment
PHOTOTROPISM – response to light
LIGHT
Growing shoot
Plant responses to the environment
PHOTOTROPISM – response to light
LIGHT
Growing shoot
Plant responses to the environment
PHOTOTROPISM – response to light
In shoots, light causes the
hormone to accumulate on the
side away from the light
LIGHT
Growing shoot
Plant responses to the environment
PHOTOTROPISM – response to light
LIGHT
Growing shoot
The hormone
stimulates the
growth of cells on
the side away from
the light, so the
shoot grows towards
the light.
Plant responses to the environment
Commercial uses of plant hormones:
Plant responses to the environment
Commercial uses of plant hormones:
• rooting compound – encourages the growth
of roots in stem cuttings.
Plant responses to the environment
Commercial uses of plant hormones:
• rooting compound – encourages the growth
of roots in stem cuttings.
• ripening hormone – enables plants to ripen
at the same time. Sprayed on the crop, often
while being transported.
Plant responses to the environment
Commercial uses of plant hormones:
• rooting compound – encourages the growth
of roots in stem cuttings.
• ripening hormone – enables plants to ripen
at the same time. Sprayed on the crop, often
while being transported.
• selective weedkillers – act on target plants,
disrupting their growth.
Content
Lesson 7
j) Coordination
and
response
j) Coordination and response
2.77 understand that organisms are able to respond to changes in their
environment
2.78 understand that homeostasis is the maintenance of a constant internal
environment and that body water content and body temperature are both
examples of homeostasis
2.79 understand that a coordinated response requires a stimulus, a receptor and
an effector
Flowering plants
2.80 understand that plants respond to stimuli
2.81 describe the geotropic responses of roots and stems
2.82 describe positive phototropism of stems
Humans
2.83 describe how responses can be controlled by nervous or by hormonal
communication and understand the differences between the two systems
2.84 understand that the central nervous system consists of the brain and spinal cord
and is linked to sense organs by nerves
2.85 understand that stimulation of receptors in the sense organs sends electrical
impulses along nerves into and out of the central nervous system, resulting in rapid
responses
2.86 describe the structure and functioning of a simple reflex arc illustrated by the
withdrawal of a finger from a hot object
2.87 describe the structure and function of the eye as a receptor
2.88 understand the function of the eye in focusing near and distant objects, and in
responding to changes in light intensity
2.89 describe the role of the skin in temperature regulation, with reference to
sweating, vasoconstriction and vasodilation
2.90 understand the sources, roles and effects of the following hormones: ADH,
adrenaline, insulin, testosterone, progesterone and oestrogen.
Control of response in humans
Control of response in humans
Our responses are controlled by
both the nervous system and the
endocrine system
Control of response in humans
Our responses are controlled by
both the nervous system and the
endocrine system
So what are the
differences
between the two?
Control of response in humans
Nervous system
Endocrine system
Control of response in humans
Nervous system
Endocrine system
Electrical
impulses
Chemical
messages
Control of response in humans
Nervous system
Endocrine system
Electrical
impulses
Chemical
messages
Very fast
Slower
Control of response in humans
Nervous system
Endocrine system
Electrical
impulses
Chemical
messages
Very fast
Slower
Short lasting
Longer lasting
Control of response in humans
Nervous system
Endocrine system
Electrical
impulses
Chemical
messages
Very fast
Slower
Short lasting
Longer lasting
Eg. moving a
muscle
Eg. insulin and
blood sugar levels
The endocrine system
The endocrine system
Hormone
ADH
Adrenaline
Insulin
Testosterone
Progesterone
Oestrogen
Source
Role
Effect
The endocrine system
Hormone
Source
Role
Effect
ADH
Pituitary
gland
Control water
levels in the
blood
When ADH is
present, more water
is reabsorbed back
into the blood
Adrenaline
Insulin
Testosterone
Progesterone
Oestrogen
The endocrine system
Hormone
Source
Role
Effect
ADH
Pituitary
gland
Control water
levels in the
blood
When ADH is
present, more water
is reabsorbed back
into the blood
Adrenaline
Adrenal
glands
Maintains normal
blood pressure.
Fight or flight
Stimulates liver
to change
glycogen to
glucose
Insulin
Testosterone
Progesterone
Oestrogen
The endocrine system
Hormone
Source
Role
Effect
ADH
Pituitary
gland
Control water
levels in the
blood
When ADH is
present, more water
is reabsorbed back
into the blood
Adrenaline
Adrenal
glands
Maintains normal
blood pressure.
Fight or flight
Stimulates liver
to change
glycogen to
glucose
“Fight or Flight “– a large amount of adrenaline is produced
Insulin
very quickly and this has a dramatic effect on the body.
Adrenaline:
Testosterone
• increases the heart rate
• increases blood flow to the muscles
• Reduces blood flow to the skin and intestines
Progesterone
• Widens the bronchioles
• Dilates the pupils
• Causes fatty tissue to release fat Oestrogen
into the blood
All of this means the body is ready for action!
The endocrine system
Hormone
Source
Role
Effect
ADH
Pituitary
gland
Control water
levels in the
blood
When ADH is
present, more water
is reabsorbed back
into the blood
Adrenaline
Adrenal
glands
Maintains normal
blood pressure.
Fight or flight
Stimulates liver
to change
glycogen to
glucose
Pancreas
Regulates
blood glucose
levels
Excess glucose
stored in the
liver
Insulin
Testosterone
Progesterone
Oestrogen
The endocrine system
Hormone
Source
Role
Effect
ADH
Pituitary
gland
Control water
levels in the
blood
When ADH is
present, more water
is reabsorbed back
into the blood
Adrenaline
Adrenal
glands
Maintains normal
blood pressure.
Fight or flight
Stimulates liver
to change
glycogen to
glucose
Pancreas
Regulates
blood glucose
levels
Excess glucose
stored in the
liver
Insulin
Testosterone
When the bloodstream contains glucose, the pancreas is
stimulated to produce the hormone insulin. Insulin causes
glucose to be usable by the body cells
and excess to be
Progesterone
stored in the liver as glycogen. If the body later needs
glucose and none is available in the blood, the liver can
convert glycogen back into glucoseOestrogen
(hormone glucagon).
The endocrine system
Hormone
Source
Role
Effect
ADH
Pituitary
gland
Control water
levels in the
blood
When ADH is
present, more water
is reabsorbed back
into the blood
Adrenaline
Adrenal
glands
Maintains normal
blood pressure.
Fight or flight
Stimulates liver
to change
glycogen to
glucose
Pancreas
Regulates
blood glucose
levels
Excess glucose
stored in the
liver
Insulin
Testosterone
When the amount of insulin is too little (or absent
altogether), or the action of insulin in the body is ineffective,
Progesterone
the disease diabetes (correctly known as Diabetes mellitus)
will result. It is not a curable disease but can be controlled
so that most sufferers can lead a full
and normal life.
Oestrogen
The endocrine system
Hormone
Source
Role
Effect
ADH
Pituitary
gland
Control water
levels in the
blood
When ADH is
present, more water
is reabsorbed back
into the blood
Adrenaline
Adrenal
glands
Maintains normal
blood pressure.
Fight or flight
Stimulates liver
to change
glycogen to
glucose
Pancreas
Regulates
blood glucose
levels
Excess glucose
stored in the
liver
Testicles
Principal male
sex hormone
Development
of male sexual
characteristics
Insulin
Testosterone
Progesterone
Oestrogen
The endocrine system
Hormone
Source
Role
Effect
ADH
Pituitary
gland
Control water
levels in the
blood
When ADH is
present, more water
is reabsorbed back
into the blood
Adrenaline
Adrenal
glands
Maintains normal
blood pressure.
Fight or flight
Stimulates liver
to change
glycogen to
glucose
Pancreas
Regulates
blood glucose
levels
Excess glucose
stored in the
liver
Testicles
Principal male
sex hormone
Development
of male sexual
characteristics
Insulin
Testosterone
Progesterone
Testosterone plays a key role in the development of male reproductive tissues such as
the testes and prostate as well as promoting secondary sexual characteristics such as
Oestrogen
increased muscle, bone mass and the
growth of body hair.
The endocrine system
Hormone
Source
Role
Effect
ADH
Pituitary
gland
Control water
levels in the
blood
When ADH is
present, more water
is reabsorbed back
into the blood
Adrenaline
Adrenal
glands
Maintains normal
blood pressure.
Fight or flight
Stimulates liver
to change
glycogen to
glucose
Pancreas
Regulates
blood glucose
levels
Excess glucose
stored in the
liver
Testosterone
Testicles
Principal male
sex hormone
Development
of male sexual
characteristics
Progesterone
Ovaries
(corpus
luteum)
Female
menstrual cycle
and pregnancy
Prepares body for
conception and
pregnancy
Insulin
Oestrogen
The endocrine system
Hormone
Source
Role
water
Pituitary Control
levels in the
ProgesteroneADH
is one of thegland
hormones in the
blood
body that stimulates and regulates various
Maintains normal
Adrenal
functions.
Progesterone
plays a roleblood
in pressure.
Adrenaline
Fight or flight
maintaining pregnancy. It glands
is also produced
in
the adrenal glands and the placenta. Regulates
It
blood glucose
regulatesInsulin
the monthlyPancreas
menstrual cycle.
levels
Testosterone
Progesterone
Oestrogen
Effect
When ADH is
present, more water
is reabsorbed back
into the blood
Stimulates liver
to change
glycogen to
glucose
Excess glucose
stored in the
liver
Testicles
Principal male
sex hormone
Development
of male sexual
characteristics
Ovaries
(corpus
luteum)
Female
menstrual cycle
and pregnancy
Prepares body for
conception and
pregnancy
The endocrine system
Hormone
Source
Role
Effect
ADH
Pituitary
gland
Control water
levels in the
blood
When ADH is
present, more water
is reabsorbed back
into the blood
Adrenaline
Adrenal
glands
Maintains normal
blood pressure.
Fight or flight
Stimulates liver
to change
glycogen to
glucose
Pancreas
Regulates
blood glucose
levels
Excess glucose
stored in the
liver
Testosterone
Testicles
Principal male
sex hormone
Development
of male sexual
characteristics
Progesterone
Ovaries
(corpus
luteum)
Female
menstrual cycle
and pregnancy
Prepares body for
conception and
pregnancy
Ovaries
Principal
female sex
hormone
Insulin
Oestrogen
Development of
female sexual
characteristics
The endocrine system
Hormone
Source
Role
Oestrogen is responsible for the growth and
Control water
development of female sexual
characteristics
Pituitary
levels in the
ADH
and reproduction. It controls
growth of the
gland
blood
uterine lining during the first part of the
Maintains normal
Adrenal
menstrual
cycle, causes
changes in the
blood pressure.
Adrenaline
Fight or flight
glands
breasts during adolescence and pregnancy
and regulates other metabolic processes,
Regulates
glucose
Insulin
Pancreas
including bone
growth and
cholesterolblood
levels
levels
in the blood
Testosterone
Progesterone
Oestrogen
Effect
When ADH is
present, more water
is reabsorbed back
into the blood
Stimulates liver
to change
glycogen to
glucose
Excess glucose
stored in the
liver
Testicles
Principal male
sex hormone
Development
of male sexual
characteristics
Ovaries
(corpus
luteum)
Female
menstrual cycle
and pregnancy
Prepares body for
conception and
pregnancy
Ovaries
Principal
female sex
hormone
Development of
female sexual
characteristics
Content
Lesson 7
j) Coordination
and
response
j) Coordination and response
2.77 understand that organisms are able to respond to changes in their
environment
2.78 understand that homeostasis is the maintenance of a constant internal
environment and that body water content and body temperature are both
examples of homeostasis
2.79 understand that a coordinated response requires a stimulus, a receptor and
an effector
Flowering plants
2.80 understand that plants respond to stimuli
2.81 describe the geotropic responses of roots and stems
2.82 describe positive phototropism of stems
Humans
2.83 describe how responses can be controlled by nervous or by hormonal
communication and understand the differences between the two systems
2.84 understand that the central nervous system consists of the brain and spinal cord
and is linked to sense organs by nerves
2.85 understand that stimulation of receptors in the sense organs sends electrical
impulses along nerves into and out of the central nervous system, resulting in rapid
responses
2.86 describe the structure and functioning of a simple reflex arc illustrated by the
withdrawal of a finger from a hot object
2.87 describe the structure and function of the eye as a receptor
2.88 understand the function of the eye in focusing near and distant objects, and in
responding to changes in light intensity
2.89 describe the role of the skin in temperature regulation, with reference to
sweating, vasoconstriction and vasodilation
2.90 understand the sources, roles and effects of the following hormones: ADH,
adrenaline, insulin, testosterone, progesterone and oestrogen.
End of Section 2 Lesson 7
In this lesson we have covered:
Overview of co-ordination and Response
Plant responses to the environment
Comparison of nervous and endocrine systems
The endocrine system