CIE iGCSE Co-ordinated Sciences-B13.1 Coordination and response- Study Notes- New Syllabus
CIE iGCSE Co-ordinated Sciences-B13.1 Coordination and response – Study Notes
CIE iGCSE Co-ordinated Sciences-B13.1 Coordination and response – Study Notes -CIE iGCSE Co-ordinated Sciences – per latest Syllabus.
Key Concepts:
Core
- State that electrical impulses travel along neurones
- Describe the mammalian nervous system in terms of:
(a) the central nervous system (CNS) consisting of the brain and spinal cord
(b) the peripheral nervous system (PNS) consisting of the nerves outside of the brain and spinal cord - Describe the role of the nervous system as coordination and regulation of body functions
- Identify in diagrams and images sensory, relay and motor neurones
- Describe a simple reflex arc in terms of: receptor, sensory neurone, relay neurone, motor neurone and effector
- Describe a reflex action as a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)
- Describe sense organs as groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals
CIE iGCSE Co-Ordinated Sciences-Concise Summary Notes- All Topics
Electrical Impulses in Neurones
📌 Key Point
Electrical impulses travel along neurones to carry messages around the body.
🌱 Explanation
- A neurone is a nerve cell.
- It transmits information in the form of tiny electrical signals called nerve impulses.
- Impulses travel quickly along the neurone’s length (axon).
- This allows the nervous system to coordinate fast responses (e.g. reflexes, movement, sensing).
📊 Summary
| Term | Meaning |
|---|---|
| Neurone | Nerve cell |
| Nerve impulse | Electrical signal |
| Direction | Travels along the neurone (axon) |
| Function | Rapid communication in the body |
⚡ Quick Recap
Neurones = nerve cells.
Carry electrical impulses along their length.
Enable fast communication between body and brain.
Mammalian Nervous System
📌 Introduction
The mammalian nervous system is a communication network that controls and coordinates body activities. It is divided into two main parts:
🏙️ Central Nervous System (CNS)
- Consists of the brain and spinal cord.
- Acts as the control centre:
- Brain → processes information, makes decisions.
- Spinal cord → relays information between brain and body, controls reflexes.
- Function: Receives information from sense organs, processes it, and sends out instructions.
🌐 Peripheral Nervous System (PNS)
- Consists of all the nerves outside the brain and spinal cord.
- Links the CNS to the rest of the body.
- Two main roles:
- Sensory nerves → carry impulses from receptors (sense organs) to the CNS.
- Motor nerves → carry impulses from the CNS to effectors (muscles, glands).
📊 Summary Table
| Part | Main Structures | Function |
|---|---|---|
| CNS | Brain + Spinal cord | Processes information, sends responses |
| PNS | Nerves outside CNS | Connects CNS with body (senses + actions) |
⚡ Quick Recap
Nervous system = CNS + PNS.
CNS = brain + spinal cord (control centre).
PNS = nerves outside CNS (connects body to CNS).
Memory tip: “CNS = Central control, PNS = Peripheral pathways.”
Role of the Nervous System
📌 Introduction
The nervous system is the body’s fast communication and control system. It ensures the body works smoothly by coordinating and regulating different functions.
🌱 Main Roles
- Coordination
- Brings together information from sense organs (stimuli).
- Processes this information in the brain/spinal cord.
- Sends out responses to muscles and glands so the whole body works in harmony.
- Example → touching something hot: hand pulls away quickly.
- Regulation
- Maintains steady internal conditions (homeostasis).
- Controls involuntary processes like heartbeat, breathing rate, and digestion.
- Adjusts responses to changes in the environment (light, sound, temperature).
📊 Summary Table
| Function | How it works | Example |
|---|---|---|
| Coordination | Connects stimulus → response | Eye sees ball → muscles move hand |
| Regulation | Keeps conditions stable | Brain controls breathing/heartbeat |
⚡ Quick Recap
Nervous system = fast control + communication.
Coordination = links sense organs to effectors for quick responses.
Regulation = maintains body functions automatically.
Memory tip: “Nervous system = think, act, balance.”
Types of Neurones
📌 Introduction
Neurones are specialised cells that carry electrical impulses. They differ slightly in structure depending on their role.
👁️ Sensory Neurone
- Carries impulses from receptors → CNS (brain/spinal cord).
- Structure features to spot in diagrams:
- Long dendron (from receptor to cell body).
- Cell body usually off to the side.
- Short axon (to CNS).
🔄 Relay Neurone (Interneuron)
- Found inside the CNS.
- Connects sensory neurones to motor neurones.
- Structure features to spot in diagrams:
- Small, often short axon and dendrites.
- Cell body in the centre.
- Entirely inside brain/spinal cord.
💪 Motor Neurone
- Carries impulses from CNS → effectors (muscles or glands).
- Structure features to spot in diagrams:
- Cell body at one end with many dendrites.
- Long axon extending to effector.
- Ends in axon terminals connecting to muscle/gland.
📊 Summary Table
| Neurone type | Direction of impulse | Key diagram feature |
|---|---|---|
| Sensory | Receptor → CNS | Cell body to the side, long dendron |
| Relay | Within CNS | Small, central cell body, short axon |
| Motor | CNS → Effector | Cell body at one end, long axon to effector |
⚡ Quick Recap
Sensory = receptors → CNS. (cell body side branch).
Relay = link in CNS. (short, central).
Motor = CNS → effector. (cell body at one end).
Memory tip: “See (Sensory) → Relay → Move (Motor).”
Simple Reflex Arc
📌 Introduction
A reflex action is a fast, automatic response to a stimulus. It protects the body from harm and does not involve conscious thought. The pathway of this response is called a reflex arc.
🌱 Pathway of a Reflex Arc
- Receptor
- Detects the stimulus (e.g. skin detects heat from a hot object).
- Sensory neurone
- Carries an electrical impulse from receptor → spinal cord (CNS).
- Relay neurone (in CNS)
- Passes the impulse directly to a motor neurone, without involving the brain in decision making.
- Motor neurone
- Carries the impulse from CNS → effector.
- Effector
- Muscle or gland that produces the response (e.g. muscle contracts to pull hand away).
📊 Summary Table
| Step | Structure | Function |
|---|---|---|
| 1 | Receptor | Detects stimulus |
| 2 | Sensory neurone | Sends impulse to CNS |
| 3 | Relay neurone | Transfers impulse within CNS |
| 4 | Motor neurone | Sends impulse from CNS to effector |
| 5 | Effector | Produces response (muscle/gland) |
⚡ Quick Recap
Reflex arc = Receptor → Sensory → Relay → Motor → Effector
Response is fast, automatic, protective.
Example: Touching something hot → hand pulls away.
Memory tip: “R-S-R-M-E = Rapid Safe Reflex Movement Every time.”
Reflex Action
📌 Definition
A reflex action is a way for the body to automatically and rapidly integrate and coordinate stimuli with the responses of effectors (muscles or glands).
🌱 Key Features
- Automatic → happens without conscious thought.
- Rapid → protects the body from harm by producing a quick response.
- Involves effectors:
- Muscles → contract (e.g. pulling hand away).
- Glands → secrete (e.g. saliva secretion when smelling food).
- Uses a reflex arc: stimulus → receptor → sensory neurone → relay neurone (CNS) → motor neurone → effector → response.
📊 Example Reflexes
| Stimulus | Receptor | Effector | Response |
|---|---|---|---|
| Touching hot object | Skin | Arm muscles | Hand pulled away |
| Bright light | Eye receptor cells | Iris muscles | Pupil contracts |
| Food smell | Nose receptors | Salivary glands | Saliva produced |
⚡ Quick Recap
Reflex = fast, automatic link between stimulus & response.
Coordinates stimuli → effectors.
Protects the body or helps survival.
Memory tip: “Reflex = Rapid Response.”
Sense Organs and Receptors
📌 Introduction
Sense organs are groups of specialised receptor cells that detect specific stimuli from the environment and send impulses to the brain via sensory neurones.
🌱 Types of Receptors and Their Stimuli
- Eyes 👁️
Receptor cells: Light receptors (rods and cones) in the retina.
Stimulus: Light.
Function: Detect light intensity and colour → vision. - Ears 👂
Receptor cells: Sound receptors in the cochlea.
Stimulus: Sound vibrations.
Function: Hearing.
Also contain balance receptors in the semicircular canals. - Skin ✋
Receptor cells: Different nerve endings in skin.
Stimuli: Touch, pressure, pain, temperature.
Function: Sense of touch, awareness of temperature changes, pain detection. - Tongue 👅
Receptor cells: Taste buds.
Stimulus: Chemicals in food/drink.
Function: Detect tastes (sweet, sour, salty, bitter, umami). - Nose 👃
Receptor cells: Olfactory receptors.
Stimulus: Chemicals in air (smells).
Function: Sense of smell.
📊 Summary Table
| Sense organ | Receptors | Stimulus | Function |
|---|---|---|---|
| Eye | Rods & cones | Light | Vision |
| Ear | Cochlear cells & balance receptors | Sound & balance | Hearing & balance |
| Skin | Nerve endings | Touch, temp, pain | Sensation & protection |
| Tongue | Taste buds | Chemicals in food | Taste |
| Nose | Olfactory receptors | Chemicals in air | Smell |
⚡ Quick Recap
Sense organs = groups of receptors.
Stimuli: light, sound, touch, temperature, chemicals.
Link: Receptors → sensory neurones → brain → response.
Memory tip: “Eye-Light, Ear-Sound, Skin-Touch/Temp, Tongue-Taste, Nose-Smell.”