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 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 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 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

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 TASTE receptors in the TONGUE CHANGE OF POSITION receptors in the EARS (balance)

Responding to our environment LIGHT receptors in the EYES SOUND receptors in the EARS TASTE receptors in the TONGUE SMELL receptors in the NOSE CHANGE OF POSITION receptors in the EARS (balance)

Responding to our environment LIGHT receptors in the EYES SOUND receptors in the EARS TASTE receptors in the TONGUE 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: StimulusReceptorCoordinatorEffectorResponse

Responding to our environment The pathway: StimulusReceptorCoordinatorEffectorResponse Change in the environment Detect stimuli Central nervous system Muscles or glands Action taken

Responding to our environment The pathway: StimulusReceptorCoordinatorEffectorResponse 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: StimulusReceptorCoordinatorEffectorResponse 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 UreaProduced 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 (37 o C) 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 (37 o C) 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 (37 o C) Increase – shivering, shut down capillaries Decrease – sweating, open up capillaries Blood glucose Increase - hormone GLUCAGON Decrease – hormone INSULIN HOMEOSTASIS = maintenance of a constant internal environment

Content Lesson 7 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

LIGHT

Plant responses to the environment LIGHT MOISTURE

Plant responses to the environment LIGHT MOISTURE GRAVITY

Plant responses to the environment LIGHT MOISTURE GRAVITY PHOTOTROPISM = growth response to light

Plant responses to the environment LIGHT MOISTURE GRAVITY 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 Roots are positively geotropic – they grow in the direction of gravity Shoots are negatively geotropic – they grow away from 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 Germinating seedling Plant growth is controlled by hormones – these are produced at the growing points of shoots and roots

Plant responses to the environment GEOTROPISM – response to gravity Germinating seedling 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.

Plant responses to the environment GEOTROPISM – response to gravity Germinating seedling 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.

Plant responses to the environment PHOTOTROPISM – response to light Growing shoot LIGHT

Plant responses to the environment PHOTOTROPISM – response to light Growing shoot LIGHT

Plant responses to the environment PHOTOTROPISM – response to light Growing shoot LIGHT In shoots, light causes the hormone to accumulate on the side away from the light

Plant responses to the environment PHOTOTROPISM – response to light Growing shoot LIGHT 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 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

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 systemEndocrine system

Control of response in humans Nervous systemEndocrine system Electrical impulses Chemical messages

Control of response in humans Nervous systemEndocrine system Electrical impulses Chemical messages Very fastSlower

Control of response in humans Nervous systemEndocrine system Electrical impulses Chemical messages Very fastSlower Short lastingLonger lasting

Control of response in humans Nervous systemEndocrine system Electrical impulses Chemical messages Very fastSlower Short lastingLonger lasting Eg. moving a muscle Eg. insulin and blood sugar levels

The endocrine system

HormoneSourceRoleEffect ADH Adrenaline Insulin Testosterone Progesterone Oestrogen

The endocrine system HormoneSourceRoleEffect 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 HormoneSourceRoleEffect 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 HormoneSourceRoleEffect 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 “Fight or Flight “– a large amount of adrenaline is produced very quickly and this has a dramatic effect on the body. Adrenaline: increases the heart rate increases blood flow to the muscles Reduces blood flow to the skin and intestines Widens the bronchioles Dilates the pupils Causes fatty tissue to release fat into the blood All of this means the body is ready for action!

The endocrine system HormoneSourceRoleEffect 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 InsulinPancreas Regulates blood glucose levels Excess glucose stored in the liver Testosterone Progesterone Oestrogen

The endocrine system HormoneSourceRoleEffect 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 InsulinPancreas Regulates blood glucose levels Excess glucose stored in the liver Testosterone Progesterone Oestrogen 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 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 glucose (hormone glucagon).

The endocrine system HormoneSourceRoleEffect 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 InsulinPancreas Regulates blood glucose levels Excess glucose stored in the liver Testosterone Progesterone Oestrogen When the amount of insulin is too little (or absent altogether), or the action of insulin in the body is ineffective, 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.

The endocrine system HormoneSourceRoleEffect 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 InsulinPancreas Regulates blood glucose levels Excess glucose stored in the liver Testosterone Testicles Principal male sex hormone Development of male sexual characteristics Progesterone Oestrogen

The endocrine system HormoneSourceRoleEffect 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 InsulinPancreas Regulates blood glucose levels Excess glucose stored in the liver Testosterone Testicles Principal male sex hormone Development of male sexual characteristics Progesterone Oestrogen 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 increased muscle, bone mass and the growth of body hair.

The endocrine system HormoneSourceRoleEffect 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 InsulinPancreas 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 Oestrogen

The endocrine system HormoneSourceRoleEffect 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 InsulinPancreas 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 Oestrogen Progesterone is one of the hormones in the body that stimulates and regulates various functions. Progesterone plays a role in maintaining pregnancy. It is also produced in the adrenal glands and the placenta. It regulates the monthly menstrual cycle.

The endocrine system HormoneSourceRoleEffect 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 InsulinPancreas 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 Oestrogen Ovaries Principal female sex hormone Development of female sexual characteristics

The endocrine system HormoneSourceRoleEffect 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 InsulinPancreas 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 Oestrogen Ovaries Principal female sex hormone Development of female sexual characteristics Oestrogen is responsible for the growth and development of female sexual characteristics and reproduction. It controls growth of the uterine lining during the first part of the menstrual cycle, causes changes in the breasts during adolescence and pregnancy and regulates other metabolic processes, including bone growth and cholesterol levels in the blood

Content Lesson 7 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