3.5.9
Reflex Arc
Components of a Reflex Arc
Components of a Reflex Arc
The different parts of a reflex arc are:
Stimulus
Stimulus
- A stimulus can be any change in the environment to which the body needs to respond.
- The stimulus is detected by a receptor.
Receptor
Receptor
- Receptors are found all over the body.
- They detect the change in the environment and initiate (start) a signalling process within the body.
- The signal is picked up by a neurone (nerve cell).
Coordinators
Coordinators
- There are three types of neurone (nerve cell):
- The sensory neurone, which carries the signal in the form of an electrical impulse to the central nervous system (CNS).
- The relay neurone (in the CNS) relays the electrical impulse from the sensory neurone to the appropriate motor neurone.
- The motor neurone is another type of nerve cell that carries the electrical impulse from the CNS to an effector.
Effector
Effector
- An effector is a muscle or gland that brings about an action in response to the change in the internal or external environment.
Response
Response
- The response can be any action that helps the organism to avoid the harmful situation.
1The Nature & Variety of Living Organisms
1.1Characteristics of Living Organisms
2Structure & Functions in Living Organisms
2.1Organisation Structure
2.1.1Cells
2.1.2Tissues
2.1.3Organs
2.1.4Organ Systems
2.1.5Organisms
2.1.6Animal cells
2.1.7Plant cells
2.1.8Cell Differentiation
2.1.9Stem Cells
2.1.10Uses of Stem Cells
2.1.11Disadvantages of Stem Cells
2.1.12End of Topic Test - Cell Types & Structures
2.1.13Exam-Style Questions - Cells
2.1.14Diffusion
2.1.15Factors affecting Diffusion
2.1.16Surface Area to Volume Ratio
2.1.17Diffusion - Experiment
2.1.18Osmosis
2.1.19Required Practical - Osmosis
2.1.20Active Transport
2.1.21Transport in Cells
2.1.22End of Topic Test - Cell Transport
2.1.23Grade 9 - Cell Transport
2.1.24Exam-Style Questions - Substance Exchange
2.2Biological Molecules
2.3Nutrition
2.3.1Photosynthesis
2.3.2Photosynthesis Equation
2.3.3Factors affecting Rate of Photosynthesis
2.3.4Photosynthesis - Calculations
2.3.5Investigating Photosynthesis
2.3.6Testing Leaves for Starch
2.3.7Grade 9 - Photosynthesis Experiment
2.3.8Exam-Style Questions - Rate of Photosynthesis
2.3.9Leaf Adaptations
2.3.10Ion Deficiencies
2.3.11Human Diet
2.3.12Vitamins and Minerals
2.3.13Dietary Needs
2.3.14Human Digestive System
2.3.15Peristalsis
2.3.16Villi
2.3.17Digestive Enzymes
2.3.18Amylase
2.3.19Protease
2.3.20Lipase
2.3.21Bile
2.3.22End of Topic Test - Enzymes & Nutririon
2.3.23Exam-Style Questions - Enzymes & Digestion
3Organism Functions
3.1Respiration
3.2Gas Exchange
3.3Transport
3.3.1Surface Area to Volume Ratio
3.3.2Exchange Surfaces
3.3.3Examples of Exchange Surfaces
3.3.4Root Hair Cells
3.3.5Transpiration
3.3.6Rate of Transpiration
3.3.7Measuring Transpiration
3.3.8Xylem
3.3.9Translocation
3.3.10Blood Components
3.3.11Plasma
3.3.12Red Blood Cell
3.3.13Platelets
3.3.14The Immune System
3.3.15Antibodies
3.3.16Vaccination
3.3.17Types of Blood Vessel
3.3.18Blood Vessels - Arteries
3.3.19Blood Vessels - Veins
3.3.20Blood Vessels - Capillaries
3.3.21Function of the Heart
3.3.22Structure of the Heart
3.3.23Heart Rate
3.3.24Heart Disease
3.3.25Double Circulatory System
3.3.26Important Blood Vessels
3.3.27End of Topic - Transport
3.3.28Exam-Style Questions - The Heart
3.4Excretion
3.5Coordination & Response
3.5.1Homeostasis
3.5.2Regulating Internal Conditions
3.5.3Coordinated Responses
3.5.4Types of Tropisms
3.5.5Auxin and Phototropism
3.5.6Nervous System
3.5.7Synapses
3.5.8Reflex Actions
3.5.9Reflex Arc
3.5.10Sense Organs
3.5.11The Eye
3.5.12Eye - Focusing
3.5.13Eye - Adapting to Light
3.5.14Thermoregulation
3.5.15Sweating and Shivering
3.5.16Thermoregulation - Blood Vessels
3.5.17Exam-Style Questions - Homeostasis
3.5.18Endocrine Glands
3.5.19Hormones
3.5.20Nervous vs Endocrine
3.5.21Adrenaline
3.5.22Glucose
3.5.23Puberty
3.5.24Menstruation
3.5.25Menstrual Cycle
3.5.26Menstrual Hormones
3.5.27Grade 9 - Hormonal Coordination
3.5.28End of Topic Test - Coordination & Response
4Reproduction & Inheritance
4.1Reproduction
4.2Genetics
4.3Variation
4.3.1Alleles
4.3.2Phenotype
4.3.3Monohybrid Inheritance
4.3.4Punnett Square
4.3.5Sex Determination
4.3.6Codominance
4.3.7Cystic Fibrosis Punnett Square
4.3.8Cystic Fibrosis Pedigree Diagram
4.3.9Variation
4.3.10Mutations
4.3.11Natural Selection
4.3.12Evolution
4.3.13Resistant Bacteria
4.3.14End of Topic Test - Variation
4.3.15Grade 9 - Evolution
4.3.16Exam-Style Questions - Cystic Fibrosis
5Ecology
5.1Ecosystems
5.1.1Ecosystems
5.1.2Resources
5.1.3Interdependence
5.1.4Growth Factors
5.1.5Assessing Ecosystems
5.1.6Quadrats
5.1.7Required Practical
5.1.8Exam-Style Questions - Sampling
5.1.9Energy Flow
5.1.10Food Chains
5.1.11Trophic Levels
5.1.12Decomposers
5.1.13Pyramids of Biomass
5.1.14Transfer of Biomass
5.1.15Reasons for Wastage
5.1.16End of Topic Test - Food and Trophic Levels
5.1.17Recycling Materials
5.1.18Carbon Cycle
5.1.19Exam-Style Questions - Carbon Cycle
5.1.20Nitrogen Cycle
5.1.21The Nitrogen Cycle and Microorganisms
5.1.22End of Topic Test - Ecosystems
5.1.23Grade 9 - Ecosystems
6Biological Resources
6.1Food Production
6.1.1Intensive Farming - Crop Yield
6.1.2Intensive Farming - Ion Deficiency
6.1.3Intensive Farming - Pest Control
6.1.4Intensive Farming - Fish Farming
6.1.5Microorganisms in Food
6.1.6Factors Affecting Microorganism Growth
6.1.7Industrial Fermentation
6.1.8Selective Breeding
6.1.9Selective Breeding Process
6.1.10Uses of Selective Breeding
6.1.11Exam-Style Questions - Selective Breeding
Jump to other topics
1The Nature & Variety of Living Organisms
1.1Characteristics of Living Organisms
2Structure & Functions in Living Organisms
2.1Organisation Structure
2.1.1Cells
2.1.2Tissues
2.1.3Organs
2.1.4Organ Systems
2.1.5Organisms
2.1.6Animal cells
2.1.7Plant cells
2.1.8Cell Differentiation
2.1.9Stem Cells
2.1.10Uses of Stem Cells
2.1.11Disadvantages of Stem Cells
2.1.12End of Topic Test - Cell Types & Structures
2.1.13Exam-Style Questions - Cells
2.1.14Diffusion
2.1.15Factors affecting Diffusion
2.1.16Surface Area to Volume Ratio
2.1.17Diffusion - Experiment
2.1.18Osmosis
2.1.19Required Practical - Osmosis
2.1.20Active Transport
2.1.21Transport in Cells
2.1.22End of Topic Test - Cell Transport
2.1.23Grade 9 - Cell Transport
2.1.24Exam-Style Questions - Substance Exchange
2.2Biological Molecules
2.3Nutrition
2.3.1Photosynthesis
2.3.2Photosynthesis Equation
2.3.3Factors affecting Rate of Photosynthesis
2.3.4Photosynthesis - Calculations
2.3.5Investigating Photosynthesis
2.3.6Testing Leaves for Starch
2.3.7Grade 9 - Photosynthesis Experiment
2.3.8Exam-Style Questions - Rate of Photosynthesis
2.3.9Leaf Adaptations
2.3.10Ion Deficiencies
2.3.11Human Diet
2.3.12Vitamins and Minerals
2.3.13Dietary Needs
2.3.14Human Digestive System
2.3.15Peristalsis
2.3.16Villi
2.3.17Digestive Enzymes
2.3.18Amylase
2.3.19Protease
2.3.20Lipase
2.3.21Bile
2.3.22End of Topic Test - Enzymes & Nutririon
2.3.23Exam-Style Questions - Enzymes & Digestion
3Organism Functions
3.1Respiration
3.2Gas Exchange
3.3Transport
3.3.1Surface Area to Volume Ratio
3.3.2Exchange Surfaces
3.3.3Examples of Exchange Surfaces
3.3.4Root Hair Cells
3.3.5Transpiration
3.3.6Rate of Transpiration
3.3.7Measuring Transpiration
3.3.8Xylem
3.3.9Translocation
3.3.10Blood Components
3.3.11Plasma
3.3.12Red Blood Cell
3.3.13Platelets
3.3.14The Immune System
3.3.15Antibodies
3.3.16Vaccination
3.3.17Types of Blood Vessel
3.3.18Blood Vessels - Arteries
3.3.19Blood Vessels - Veins
3.3.20Blood Vessels - Capillaries
3.3.21Function of the Heart
3.3.22Structure of the Heart
3.3.23Heart Rate
3.3.24Heart Disease
3.3.25Double Circulatory System
3.3.26Important Blood Vessels
3.3.27End of Topic - Transport
3.3.28Exam-Style Questions - The Heart
3.4Excretion
3.5Coordination & Response
3.5.1Homeostasis
3.5.2Regulating Internal Conditions
3.5.3Coordinated Responses
3.5.4Types of Tropisms
3.5.5Auxin and Phototropism
3.5.6Nervous System
3.5.7Synapses
3.5.8Reflex Actions
3.5.9Reflex Arc
3.5.10Sense Organs
3.5.11The Eye
3.5.12Eye - Focusing
3.5.13Eye - Adapting to Light
3.5.14Thermoregulation
3.5.15Sweating and Shivering
3.5.16Thermoregulation - Blood Vessels
3.5.17Exam-Style Questions - Homeostasis
3.5.18Endocrine Glands
3.5.19Hormones
3.5.20Nervous vs Endocrine
3.5.21Adrenaline
3.5.22Glucose
3.5.23Puberty
3.5.24Menstruation
3.5.25Menstrual Cycle
3.5.26Menstrual Hormones
3.5.27Grade 9 - Hormonal Coordination
3.5.28End of Topic Test - Coordination & Response
4Reproduction & Inheritance
4.1Reproduction
4.2Genetics
4.3Variation
4.3.1Alleles
4.3.2Phenotype
4.3.3Monohybrid Inheritance
4.3.4Punnett Square
4.3.5Sex Determination
4.3.6Codominance
4.3.7Cystic Fibrosis Punnett Square
4.3.8Cystic Fibrosis Pedigree Diagram
4.3.9Variation
4.3.10Mutations
4.3.11Natural Selection
4.3.12Evolution
4.3.13Resistant Bacteria
4.3.14End of Topic Test - Variation
4.3.15Grade 9 - Evolution
4.3.16Exam-Style Questions - Cystic Fibrosis
5Ecology
5.1Ecosystems
5.1.1Ecosystems
5.1.2Resources
5.1.3Interdependence
5.1.4Growth Factors
5.1.5Assessing Ecosystems
5.1.6Quadrats
5.1.7Required Practical
5.1.8Exam-Style Questions - Sampling
5.1.9Energy Flow
5.1.10Food Chains
5.1.11Trophic Levels
5.1.12Decomposers
5.1.13Pyramids of Biomass
5.1.14Transfer of Biomass
5.1.15Reasons for Wastage
5.1.16End of Topic Test - Food and Trophic Levels
5.1.17Recycling Materials
5.1.18Carbon Cycle
5.1.19Exam-Style Questions - Carbon Cycle
5.1.20Nitrogen Cycle
5.1.21The Nitrogen Cycle and Microorganisms
5.1.22End of Topic Test - Ecosystems
5.1.23Grade 9 - Ecosystems
6Biological Resources
6.1Food Production
6.1.1Intensive Farming - Crop Yield
6.1.2Intensive Farming - Ion Deficiency
6.1.3Intensive Farming - Pest Control
6.1.4Intensive Farming - Fish Farming
6.1.5Microorganisms in Food
6.1.6Factors Affecting Microorganism Growth
6.1.7Industrial Fermentation
6.1.8Selective Breeding
6.1.9Selective Breeding Process
6.1.10Uses of Selective Breeding
6.1.11Exam-Style Questions - Selective Breeding
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