SNC 2P - Biology - Digestive System

Learning Goals:

The respiratory system carries oxygen to & removes carbon dioxide from the blood.

The circulatory system transports dissolved gases & nutrients through the body.

The digestive system breaks down food, absorbs nutrients & eliminates solid waste.

Organ systems working together carry out important tasks in the body.

 

Success Criteria:   

I can...

...label the parts of the respiratory, circulatory & digestive systems.

...follow the path through each system.

...explain how the systems work together.

 

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As we have already seen, there are numerous organ systems found in the human body (and the bodies of other animals).  Over the next few lessons, we will be taking a look at three of them: the digestive system, the circulatory system and the respiratory system.

Let's begin with the digestive system.  

The digestion process begins in the mouth, which uses the teeth and tongue to break down food mechanically.  The salivary glands produce saliva, which begins to break down the food chemically.

The food passes into the esophagus, which is a tube that uses peristalsis (muscular contractions) to push the food down to the stomach.

The stomach has two jobs: to hold the food and churn it to further the digestion process.  The stomach lining produces acid and enzymes, which further break down the food chemically.

The contents of the stomach empty into the small intestine, which is 6 m long and fairly narrow.  Most digestion occurs here, allowing nutrients to diffuse through the wall of the small intestine into the bloodstream.

The large intestine is 1.5 m long and larger in diameter.  The large intestine absorbs water from indigestible food.

The remaining solid matter is condensed in the rectum and then passes out through the anus as waste, known as feces.

There are three accessory organs that contribute to the digestion process, although food never passes through them.   The liver, pancreas and gall bladder all produce digestive enzymes, which are delivered to the digestive tract where they mix with the partially digested food. 

 

Let's make like a system and digest some more info - click here. 

 

 

SNC 2P - Biology - Hierarchy of Structure in Animals

Multicelullar organisms (like humans and dogs) are made up of various specialized cells.  Unlike single celled organisms, single specialized cells cannot survive on their own.  Specialized cells are one small component of larger groups of cells that make up the organism’s body.

Multicellular organisms are organized into levels that become increasingly complex, from cells at the most basic level, to tissues, organs, organ systems, and the whole organism itself. 

This image was obtained from here.  Go there if you want to see a nifty power point on the hierarchy of structure in animals.  Be aware that the information in this link is far beyond the course curriculum.

 

Cells - the smallest structural unit of an organism 

ex.  In humans, there are several different types like skin cells, red blood cells, etc.

Tissues – a collection of similar cells that perform a particular, but limited, function.

ex.  In humans there are four major types: epithelial, connective, muscle and nerve tissue.

 

Organs – a structure composed of different tissues working together to perform a complex body function.

ex.  In humans, the digestive system contains the stomach, intestines, etc.

 

Organ Systems – a system of one or more organs and structures that work together to perform a complex body function.

ex.  In humans there are the digestive, circulatory, respiratory, musculoskeletal and nervous systems.

 

Organism -  an individual animal

ex.  A human being.

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Your mission:

1. Using p. 44-47, fill in the following table.  When you finish, send me (on Edsby) the completed PDF or take pictures of your work.  
2.  Time to do some sorting.
   

p. 45

p. 46

p. 46

p.47

SNC 2P - Biology - Specialized Cells

Learning Goals:

All cells begin alike & differentiate into specialized cells.

Specialized cells have different structures that allow them to perform unique functions.

Groups of cells working together form tissues.

Groups of tissues working together form organs, which work together in systems.

 

Success Criteria:  

I can...

...explain specialized cells & why they are important to an organism.

...explain how cells, tissues, organs and systems are related & provide examples of each.

 

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Specialized Cells

All cells begin their existence as identical cells called stem cells. Each stem cell has the same DNA and has the potential to become one of many different types of cells (red blood cells or bone cells or heart muscle cells, etc) as it matures.

During this maturation, a series of events, called cell differentiation, occurs to turn the stem call into a specialized cell.  

So, specialized cells just have certain portions of the DNA turned on and other portions turned off.  This allows these cells to perform a specialized function .

 

Click on this picture to go to a website that shows magnified images of these different types of cells.  The text that goes along with each image is quite advanced, so you can ignore it.

The characteristics of a cell often provides insight into its job in the body.  For instance, muscle cells are long and thin, and contain a high concentration of mitochondria.  Skin cells are flat and thin, and layered atop each other. 

 

Question of the Day #3:  Why do muscle cells have more mitochondria than other types of cells?  Explain your reasoning.  Send me your answer on Edsby.

 

SNC 2P - Biology - Cancer

Unchecked Cell Growth

We have learned about the cell cycle in previous lessons.  A typical cell goes through the cell cycle in one to two days. The cell cycle is told to start or stop by chemical signals.  For instance, if you get a paper cut, the cells in your finger get the message to start dividing to repair the damage.

If a cell ignores the message to stop dividing, unchecked cell growth can occur.  Over time, a mass of cells, or tumour, can form.

So, why do some cells get confused and refuse to stop dividing?

The typical answer is that a mutation occurs.  A mutation is a permanent change in a cell's DNA. Sometimes a mutation results in a cell going deaf to the signal to stop dividing.  Some mutations are inherited, while others are the result of exposure to environmental conditions.  More about that later.

Tumours

Not all tumours are cancerous.  Different mutations will produce different types of tumours. 

Benign Tumour

• cell division is unchecked
• cell division occurs at a moderate rate
• tumour does not invade adjacent cells, but may crowd out its neighbours
• does not spread throughout the body
• fairly harmless (unless in the brain, where it may cause traumatic pressure)
  
  

Cancerous Tumour

• cell division is unchecked
• cell division occurs rapidly (a very small amount of time is spent in interphase)
• tumour invades adjacent cells and damages them
• may spread to throughout the body
• may interfere with the proper function of other cells
• may result in death if the tumour is not destroyed or removed

 

Cancer cell being attacked by lymphocytes (a type of white blood cell).

Staying Healthy

So, how can you lessen the likelihood that you will get cancer? 

Click on this picture to go to an activity.

 

 

To read more on this topic (only if you choose to do so), click on this picture.

 

SNC 2P - Biology - Mitosis

Recall that the cell cycle consists of the following steps:

• interphase
• mitosis
• cytokinesis

 

Mitosis can be further broken down into four phases:

• prophase
• metaphase
• anaphase
• telophase

 

So, all the stages of the cell cycle, in order are:

Interphase🠞Prophase🠞Metaphase🠞Anaphase🠞Telophase🠞Cytokinesis

(or just using the first letter of each phase: I🠞P🠞M🠞A🠞T🠞C) 

Click here to continue to learn about the cell cycle and mitosis. 

 

 

SNC 2P - Biology - Cell Life Cycle

Why Cell Division is Important

Cell division is important to an organism for three reasons:

• growth – an organism must get larger after birth
• maintenance – replacement of lost cells
• repair – healing of wounds

 

Cell Cycle

The cell cycle is the series of events from one cell division to the next.

The cell prepares for division by duplicating its chromosomes in the nucleus since each new cell needs a copy.

Stages of the Cell Cycle

Interphase → Most of the cell's life cycle is spent in interphase.  During interphase the cell grows and engages in its regular functions.  The mother cell also duplicates its organelles and the DNA (in the nucleus) in order to be ready for division.

Mitosis → Mitosis occurs during cell division.  In this stage the contents of the nucleus are separated into two identical copies.

Cytokinesis → Cytokinesis is the final process in cell division.  During cytokinesis, the cytoplasm and organelles divide into two, genetically identical cells (daughter cells).  Each daughter cell now begins its own cell cycle.

Notice that the cell spends the majority of its time in interphase.

 

Question of the Day #2: Do you think cell division occurs more often in a 4 year old or a 40 year old?  Explain your reasoning.  Send me your answer on Edsby.