Science - Grade 5
Human Body Systems, Ecosystems, and Matter & Energy
Table of Contents
1. Introduction to Body Systems
The human body is made up of organ systems that work together to keep us alive and healthy. Each system has specific functions and is made up of organs working together.
| Body System | Main Function | Key Organs |
|---|---|---|
| Circulatory | Transports blood, oxygen, nutrients | Heart, blood vessels, blood |
| Digestive | Breaks down food for energy | Mouth, stomach, intestines |
| Respiratory | Gets oxygen, removes CO2 | Nose, lungs, diaphragm |
| Skeletal | Provides structure and protection | Bones, cartilage, joints |
| Muscular | Movement and posture | Muscles (skeletal, smooth, cardiac) |
| Nervous | Controls body, processes information | Brain, spinal cord, nerves |
| Excretory | Removes waste from body | Kidneys, bladder, skin |
How Systems Work Together:
Example: When you run, your muscular system moves your legs, your respiratory system breathes faster to get more oxygen, your circulatory system pumps blood faster to deliver oxygen to muscles, and your nervous system coordinates all these actions!
2. The Circulatory System
The circulatory system (also called cardiovascular system) is like a delivery service that transports blood throughout your body, bringing oxygen and nutrients to cells and removing waste products.
The Heart
- * A muscular organ about the size of your fist
- * Located slightly left of center in your chest
- * Has 4 chambers: 2 atria (upper) and 2 ventricles (lower)
- * Beats about 100,000 times per day!
- * Right side pumps blood to lungs; left side pumps to body
Blood Vessels
Arteries
Carry oxygen-rich blood AWAY from heart
Thick walls, high pressure
Veins
Carry blood back TO the heart
Thinner walls, have valves
Capillaries
Tiny vessels connecting arteries to veins
Where exchange happens
Blood Components
- Red Blood Cells - Carry oxygen (contain hemoglobin)
- White Blood Cells - Fight infections and diseases
- Platelets - Help blood clot when you get a cut
- Plasma - Liquid part that carries nutrients and waste
The Path of Blood:
Heart → Arteries → Capillaries (oxygen delivered) → Veins → Heart → Lungs (get oxygen) → Back to Heart
3. The Digestive System
The digestive system breaks down food into nutrients that your body can use for energy, growth, and repair. It's like a food processing factory!
The Journey of Food:
Mouth
Teeth chew food; saliva starts breaking down starches
Esophagus
Tube that pushes food to stomach using muscle movements (peristalsis)
Stomach
Churns food and mixes with digestive juices (acids); kills bacteria
Small Intestine
About 6 meters long! Nutrients are absorbed into blood here
Large Intestine
Absorbs water; forms solid waste
Rectum & Anus
Stores and eliminates waste
Helper Organs:
Liver
Produces bile to break down fats
Pancreas
Makes enzymes to digest food
Gallbladder
Stores bile from liver
4. The Respiratory System
The respiratory system is responsible for breathing - taking in oxygen (O2) and releasing carbon dioxide (CO2). Every cell in your body needs oxygen to produce energy!
Parts of the Respiratory System:
- Nose/Mouth - Air enters; nose filters and warms air
- Pharynx (Throat) - Passageway for air and food
- Larynx (Voice Box) - Contains vocal cords for speaking
- Trachea (Windpipe) - Tube leading to lungs; lined with cilia
- Bronchi - Two tubes branching into each lung
- Bronchioles - Smaller tubes within lungs
- Alveoli - Tiny air sacs where gas exchange happens (300 million!)
How Breathing Works:
Inhale (Breathe In)
- * Diaphragm contracts (moves down)
- * Rib cage expands
- * Lungs fill with air
Exhale (Breathe Out)
- * Diaphragm relaxes (moves up)
- * Rib cage gets smaller
- * Air pushed out of lungs
Gas Exchange in Alveoli:
In the alveoli, oxygen passes from air into the blood (carried by red blood cells), and carbon dioxide passes from blood into the air (to be exhaled). This happens because of diffusion - gases move from high to low concentration.
5. Food Chains and Food Webs
A food chain shows how energy flows from one organism to another through feeding relationships. It starts with producers and moves through various consumers.
Levels in a Food Chain:
Make their own food through photosynthesis (plants, algae)
Herbivores that eat producers (grasshopper, rabbit, deer)
Carnivores that eat herbivores (frog, snake, small birds)
Apex predators (eagle, lion, shark)
Break down dead organisms (bacteria, fungi, worms)
Example Food Chain:
Grass →Grasshopper →Frog →Snake →Eagle
Food Web:
A food web is more realistic than a food chain. It shows how multiple food chains connect because most organisms eat more than one type of food.
Example: A rabbit eats grass AND vegetables. A hawk eats mice AND snakes AND rabbits.
6. Ecosystems
An ecosystem is a community of living organisms (biotic) interacting with their non-living environment (abiotic). It includes all the relationships and energy flow in an area.
Biotic Factors (Living)
- * Plants and trees
- * Animals (predators, prey)
- * Fungi and bacteria
- * Insects and microorganisms
Abiotic Factors (Non-living)
- * Sunlight
- * Water
- * Temperature
- * Soil and minerals
- * Air and wind
Types of Ecosystems:
Terrestrial (Land)
Forest, desert, grassland, tundra
Aquatic (Water)
Ocean, lake, river, pond, coral reef
Philippine Ecosystems:
- Coral Reefs - Tubbataha, Apo Reef (rich marine biodiversity)
- Mangroves - Coastal areas protecting shorelines
- Rainforests - Sierra Madre, Palawan (endangered species home)
- Freshwater - Laguna de Bay, lakes and rivers
7. Properties of Matter
Matter is anything that has mass and takes up space. All objects around us are made of matter. Matter has different properties that help us identify and describe it.
Physical Properties:
Can be observed without changing the substance.
Mass
Amount of matter (measured in grams, kg)
Volume
Space it takes up (mL, L, cm³)
Density
Mass per unit volume (g/mL)
Color, Shape, Texture
Observable characteristics
States of Matter:
🧊
Solid
Fixed shape & volume
Particles tightly packed
💧
Liquid
Fixed volume, takes container's shape
Particles slide around
💨
Gas
No fixed shape or volume
Particles move freely
Density Formula:
Density = Mass ÷ Volume
Example: If an object has mass of 20g and volume of 5mL, its density = 20 ÷ 5 = 4 g/mL
8. Changes in Matter
Matter can undergo two types of changes: physical changes and chemical changes. Understanding the difference is important in science!
Physical Changes
Change in form or appearance, but not in composition.
- * Cutting paper
- * Melting ice
- * Dissolving sugar in water
- * Boiling water
- * Breaking glass
Reversible in most cases
Chemical Changes
New substance formed with different properties.
- * Burning paper (ash formed)
- * Rusting iron
- * Cooking food
- * Digesting food
- * Milk turning sour
Usually irreversible
Signs of Chemical Change:
- * Color change - Banana turning brown
- * Gas production - Bubbles when baking soda meets vinegar
- * Temperature change - Heat released when burning
- * Precipitate forms - Solid forms in liquid
- * Light produced - Fireworks
Changes of State:
| Process | From | To | Example |
|---|---|---|---|
| Melting | Solid | Liquid | Ice → Water |
| Freezing | Liquid | Solid | Water → Ice |
| Evaporation | Liquid | Gas | Water → Steam |
| Condensation | Gas | Liquid | Steam → Water drops |
| Sublimation | Solid | Gas | Dry ice → CO2 gas |
Key Takeaways
Body Systems
- * Circulatory: heart, blood, vessels
- * Digestive: mouth to intestines
- * Respiratory: lungs, gas exchange
- * All systems work together!
Food Chain
- * Producers → Consumers → Decomposers
- * Energy flows one direction
- * Food web shows connections
Ecosystems
- * Biotic (living) + Abiotic (non-living)
- * Terrestrial and aquatic types
- * Philippines: reefs, mangroves, forests
Matter
- * 3 states: solid, liquid, gas
- * Density = Mass ÷ Volume
- * Physical vs Chemical changes