The Human Body
Circulatory System
Function
carry food, oxygen , waste substances
Parts
Heart
Blood vessels
Blood
Pump blood
When heart muscles contract, you feel heartbeat
Blood carries food particles, oxygen and waste products (carbon dioxide)
Arteries
Veins
Capillaries
Connect arteries and veins
Thick elastic muscular wall
Carry blood rich with food and oxygen from heart to body
Thin elastic muscular wall
Carry carbon dioxide from body to heart
Circulatory system of other animals
Fish
Frog
Bird
2 chambered heart
3 chambered heart
4 chambered heart
artery- carry blood from heart to body
vein- carry blood from lungs
Heartbeat and Pulse
The more active you are, the more often your heart beats to supply oxygen and food particles from the blood
can count heartbeat by counting pulse. Pulse caused by pressure
Respiratory System
Parts of respiratory system
Lungs and Breathing
nose, lungs, windpipe and diaphragm muscle
We use lungs to breathe in and breathe out
Lungs are protected by ribs
Breathing in
Air enters the body through mouth and nose
Air goes down the windpipe and into the lungs
The ribs moves upwards and outwards
Chest gets bigger and filled with air
Diaphragm muscle contracts and moves downwards
Breathing out
Diaphragm muscles relaxes and moves upwards
Chest gets smaller and is pushed out of the lungs
The ribs moves downwards and inwards
Air from the lungs moves up the windpipe
Air leaves the body through the nose or mouth
The number of times we breathe in and out in 1 minute is called breathing rate
Our breathing rate change depending how much oxygen our bodies need
Forces and electricity
Mass and Weight
Mass
Weight
amount of matter in an object
kilograms (kg) or grams (g)
Measuring scale
Force of attraction on an object caused by gravity
Newton (N)
Forcemeter
How does gravity affect weight?
Wherever you go the mass is the same
Wherever you go, the weight is not the same
Smaller the force of gravity, the lower your weight will be
Moon's gravitational force is smaller than Earth's gravitational force. Why?
The effect of forces
make an object move
slow down a moving object
stop a moving object
change the direction a moving object
change the shape of an object
Force digrams
Floating and sinking
Forces acting on objects
weight due to the force of gravity
upthrust
Causes water to be displaced or pushed out of the way
How do we know whether an object will float or sink?
If mass of the object is less than or equal to the mass of water displaced by upthrust, the object will float
If the mass of the object is greater than the mass of water displaced by upthrust, the object will sink
Force diagram arrow
How the shape of an object affects floating and sinking
The larger the surface of the container in contact with the water, the more likely the objects inside the container is to float
An object of a certain mass that has a small, compact shape will sink. An object of the same mass with a larger, flatter shape will float
Circuit diagrams
Conventional symbols
The strength of electricity is measured in units called volts (V)
The strength of electricity that a component needs for it to work is called the voltage
Types of circuit
Series circuit
Parallel circuit
A circuit which has only 1 electric current path
A circuit which has more than 1 electric current path
Each pathway receives the full circuit voltage
If the switch is open, the circuit is broken. So, lamps, buzzers will not work
The full strength of battery goes to each lamp/buzzer
Electricity need to be shared between the lamps/buzzers