Lesson Notes By Weeks and Term v4 - SHS 3
ANATOMY AND PHYSIOLOGY
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ANATOMY AND PHYSIOLOGY
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Subject: Biomedical Science
Class: SHS 3
Term: 2nd Term
Week: 10
Grade code: 3.2.1.LI.2
Strand code: 2
Sub-strand code: 1
Content standard code: 3.2.1.CS.1
Indicator code: 3.2.1.LI.2
Theme: HUMAN BODY SYSTEMS
Subtheme: ANATOMY AND PHYSIOLOGY
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This lesson explores the remarkable partnership between two of our body's most vital systems: the respiratory system (our breathing system) and the cardiovascular system (our blood circulation system). We often think of breathing and our heartbeat as separate, but they work together in a perfectly coordinated way to deliver everything our cells need to survive. In Ghana, understanding this connection is crucial. When we eat our banku or fufu, play football, or even just sit in class, our cells are constantly demanding energy. This energy comes from the food we eat, but it can only be released with the oxygen we breathe.
This topic can be understood as a three-part process: Pick-up, Transport, and Delivery. Part 1: The "Pick-Up" Stations
Our body has two main "pick-up stations" to get essential substances from the outside world into our internal transport system (the blood).
A. The Respiratory System: Picking Up Oxygen Function: The primary role of the respiratory system in this context is to get oxygen (O₂) from the air into the blood and remove carbon dioxide (CO₂) from the blood. Key Structure: The Alveoli: Deep inside our lungs are millions of tiny, balloon-like air sacs called alveoli (singular: alveolus). These are the actual sites of gas exchange. Imagine them as the loading bay for oxygen. The Process of Gas Exchange (at the Alveoli): Inhalation: When you breathe in, air rich in oxygen fills the alveoli. Diffusion: The walls of the alveoli are extremely thin (only one cell thick). They are also surrounded by a dense network of tiny blood vessels called capillaries, which also have walls that are one cell thick. Concentration Gradient: The concentration of oxygen is very high in the alveoli (from the fresh air) and low in the blood that has just returned from the body. Due to this difference, oxygen naturally moves (diffuses) from the area of high concentration (alveoli) across the thin walls into the blood in the capillaries. Haemoglobin: Once in the blood, most of the oxygen doesn't just dissolve. It binds to a special protein in red blood cells called haemoglobin. Haemoglobin acts like a special "seat" on the red blood cell bus, specifically for oxygen. One red blood cell can carry about a billion oxygen molecules! This greatly increases the blood's oxygen-carrying capacity.
B. The Digestive System: Picking Up Nutrients and Water Function: After we eat, the digestive system breaks down complex foods into simple, soluble molecules that can be absorbed into the blood. Key Structure: The Small Intestine (Villi) The inner wall of the small intestine is not smooth. It is covered in millions of tiny, finger-like projections called villi (singular: villus). These villi are further covered by even smaller projections called microvilli. This massively increases the surface area for absorption. Think of it like trying to mop up water with a flat cloth versus a towel with many threads – the towel absorbs more because of its larger surface area. The Process of Absorption (at the Villi): Digestion: Foods like carbohydrates (e.g., from kenkey, rice) are broken down into simple sugars like glucose. Proteins (e.g., from fish, beans) are broken down into amino acids. Absorption into Blood: Each villus has its own network of capillaries. The simple nutrients (glucose, amino acids, vitamins, minerals) and water pass from the small intestine across the thin wall of the villus and into these capillaries. This happens through processes like diffusion and active transport. Transport: This nutrient-rich blood then travels from the small intestine, goes to the liver for processing, and then enters the main circulation. Part 2: The "Transport" System - The Cardiovascular System