What is Lysosome?

Lysosomes

§  Originated from the Golgi apparatus 

§  Can be found in most plant and animal cells, especially phagocytic cells

§  Breaks down worn out organelles within the cell

§  Digests materials taken in through endocytosis (example: amoeba feeding) or phagocytosis (example: ingestion of bacteria by white blood cells)

Don't get confused with: Lysozomes are enzymes found in saliva, sweat, and tears. 

Lessons from OBS-Glucose Regulation

The pancreas monitors and controls the concentration of glucose in the blood using a hormone called insulin. Insulin causes glucose to move from the blood into cells. It lowers the blood glucose concentration if it has become too high. This can happen after eating a meal that is rich in carbohydrates (for example, sweets, potatoes, bread, rice or pasta).

Here is what happens in our body when the concentration of glucose is too high: 

Here is what happens in our body when the glucose regulation is too low: 

Lessons from OBS- Temperature Regulation

Our body regulates our temperature by sweating, shivering, skin capillaries and hair.

When we get too hot, our body does the following

• Sweat glands in the skin release more sweat. This evaporates, removing heat energy from the skin.
• Blood vessels to the skin become wider. They dilate allowing more blood to flow through the skin and more sweat to be lost. 
• The hairs on our skin lie flat when we are warm. 

Here is a diagram that illustrates how the hairs on our body behave when we are warm.

When we get too cold, our body does the following

• We shiver as our muscles contract rapidly. These contractions need energy for respiration and heat is given out.
• Blood vessels leading to the skin's capillaries become narrower, they constrict, letting less blood flow through the body and conserving heat. 
• The hairs on our skin rise up. They trap a layer of air above the skin which insulates our body from the cold 

Here is a diagram that illustrates how the hairs on our body behave when we are cold. 

Source:  BBC GSCE Bitesize

Lessons from OBS-Water regulation

The body adjusts its water content using its kidney. The kidney controls the volume of urine produced. Anti-Duretic Hormones (ADH) control the functions of the kidney. 

In a hot environment with a low water supply, the brain will detect a lesser amount of water concentration. This will cause ADH to be produced and the kidneys will absorb a lesser amount of water. This means a very small amount of concentrated urine will be passed out. This reduces water loss during excretion. 

This diagram below shows how the body regulates its water concentration when the water concentration falls. 

In a cool environment with sufficient water supply, the brain will detect a hight amount of water concentration. This will cause a smaller amount of ADH to be produced and the kidneys will absorb a smaller amount of water. This means a larger amount of concentrated urine will be passed out. This increases water loss during excretion.

This diagram below shows how the body regulates its water concentration when the water concentration rises.

Source: BBC Standard Grade BiteSize