Biology Quiz #2 - Body System Heirchy - Grade 10

Specialized Cells: Stem Cells

• Stem cells can turn into any other type of cell.

• These are mostly found in embryos.

• Stem cells are undifferentiated cells with the potential to either continuously divide or become a variety of different cell types.

Specialized Cells: Differentiation

• A stem cell becomes specialized in a process called differentiation

• Once a stem cell has specialized, it cannot go back

Specialized Cells: Uses for Stem Cells

• Stem cells can be used to treat diseases and to replace damaged tissues

• Scientists are researching the use of stem cells to solve many medical problems

Specialized Cells: Types of Stem Cells

1. Embryonic stem cells

2. Adult stem cells

Specialized Cells: Embryonic Stem Cells

• Found in embryos

• Can undergo differentiation to become any type of human cell (there are over 200!).

Specialized Cells: Finding Embryonic Stem Cells

1. Sexual reproduction begins when a sperm fertilizes an egg forming a ‘zygote’ or ‘first whole cell’.

2. The zygote will undergo the cell cycle again and again forming a cell mass termed a ‘morula’

3. The morula cells divide and a blastocyst is formed which consists of an inner cell mass and an outer cell mass.

4. The outer cell mass (trophoblast) becomes part of the placenta. The inner cell mass is a collection of stem cells.

Specialized Cells: Adult Stem Cells

• We need a supply of cells to replenish cells in our body as we grow and age.

• Adult stem cells are found in different regions of the body and develop into specialized cells and tissue to support growth and repair of our tissues and organs.

• Can specialize to become a limited number of cell types.

  Specialize to become cells from their tissue of origin.

• E.g. Blood-forming stem cells can become red or white blood cells.

• Also called multipotent or tissue stem cells

Specialized Cells: What are Specialized Cells

• Specialized Cells - specialized to do 1 specific job

• What are some specialized cells that you know of?

Specialized Cells: Why do cells specialize

• Unicellular Organisms - a single-cell organism that performs ALL required functions within the cell (e.g., amoeba)

• Multicellular Organisms - much more complex and are made of many cells

• The body needs to:

  Supply food and nutrients

  Transport materials

  Remove waste

  Fight infection

• Different cells are needed to perform all of these specific functions!

Specialized Cells: Red Blood Cells

Location: Blood

Function: Carry oxygen

Specialized Design:

• Large surface area (for oxygen to pass through)

• Has NO nucleus

• Contains hemoglobin which binds with oxygen

Specialized Cells: Sperm Cells

Location: Testes

Function: Fertilize eggs

Specialized Design:

• Small and move easily

• Long tail allows for movement (needs to swim)

• The head contains enzymes, which allow the sperm to digest into an egg

Specialized Cells: Egg Cell

Location: Ovaries

Function: Be fertilized

Specialized Design:

• Large and bulky

• Contains a ‘yolk’ as a food source

• No active movement

Specialized Cells: Nerve Cell

Location: All over the body

Function: Carry nerve signals to/from brain

Specialized Design:

• Long with connections at each end

• Can carry electrical signals

Specialized Cell: Muscle Cell

Location: All over the body

Function: Body movement

Specialized Design:

• A muscle can change length

• Some are long and react quickly (skeletal)

• Some never get tired (cardiac)

• Some work automatically (smooth)

Tissues: Hierarchy of Structure in Animals

Multicellular organisms are made up of many different specialised cells. 

Each cell is specialised to perform a particular function. 

There are levels of organisation within each animal and these levels form a hierarchy, with the ‘most complex’ at the top and the ‘least complex’ at the bottom.

Tissues: What does the Heirarchy look like?

All living things are made up of CELLS 

Many cells come together to form TISSUES. 

Two or more types of tissues working together to perform a complex function are called ORGANS. 

One or more organs/structures that work together to perform vital body functions are called ORGAN SYSTEMS. 

All of the different organ systems working together form an ORGANISM.

Tissues: Types of Tissues

There are 4 major types of tissues in the body, all made up of similar cells working together.

1. Epithelial tissue

2. Muscular tissue

3. Nervous Tissue

4. Connective Tissue

Tissues: Epithelial Tissue

• Skin Tissue

• Forms a barrier by connecting cell membranes

• On the inside & outside surfaces of the body

• Fast growth/renewal rate

Tissues: Muscular Tissue

• Designed to change their shape

• Move the body or organ by contracting & relaxing

Tissue: Connective Tissue

Strengthens, supports & protects other tissues

Connective tissue can be in:

• Solid (bone)

• Liquid (blood)

• Elastic (ligaments)ens, supports & protects other tissues

Connective tissue can be in:

• Solid (bone)

• Liquid (blood)

• Elastic (ligaments)

Tissue: Nervous Tissue

• Made of neurons that send & receive signals

• Coordinates body actions & functions

Tissues: Epithelial Tissues - Squamous Cells (A₁)

• The epithelial tissue found on the body's surface is made up of flat cells called squamous cells (A1), lying on what's called the basement membrane.

• These cells provide the body with protection from dehydration and some mechanical injury. Squamous cells also make up the esophagus, the blood vessels and air sacs in the lungs.

Tissues: Epithelial Tissues - Columnar Cells (A₂)

Columnar cells (A₂), line the digestive tract (stomach, intestines), absorbing nutrients from food. Cilia on the surface of these cells provide them with massive surface areas relative to their size, which increases the rate of absorption of nutrients.

Tissues: Epithelial Tissues - Cuboidal Cells (A₃)

Cuboidal cells (A₃) make up the epithelium of kidney tubules and many glands including exocrine (sweat) glands.

Tissues: Muscular Tissues - Muscle Cells (B₁)

Muscle tissue (B) consists of long fibrous muscle cells (B₁), in which you can see dark nuclei. The muscle shown on your diagram is skeletal muscle; skeletal muscle can be found, for instance, in the arms and legs. 

Muscle tissue permits movement of the appendages and lines the hollow structures of the body such as blood vessels.

Tissues: Nervous Tissue - Nerve Cells (C₁)

Nerve tissue (C) is made of nerve cells (C₁), which are long and have numerous extensions through which nerve impulses travel on their route throughout the body. 

Nerve cells are often called neurons. An accumulation of neurons and supporting tissue exists in the brain. 

The main function of nervous tissue is to send electrical signals (impulses) throughout the body.

Tissues: Connective Tissue - Chondroblasts (D₁) and Cartilage (D₂)

The first type of connective tissue is cartilage (D₂). Cartilage is made up of chondroblasts (D₁) embedded in a rubbery substance known as condrin. It maintains the shape of organs such as the outer ear.

Tissue: Connective Tissue - Osteoblasts (D₃) and Bone (D₄)

Another type of connective tissue is bone (D₄). Bone tissue contains cells called osteoblasts (D₃), shown as dark dashes within the rings. Bone material exists in concentric rings; the osteoblasts are confined to spaces called lacunae and secrete the calcium phosphate and collagen that make bone hard. Bones provide support for the body.

Tissue: Connective Tissue - Tendon-forming Cells (D₅) and Tendons (D₆)

Tendons (D₆) and ligaments are made up of fibrous connective tissue, which in turn is made up of strands of protein produced by tendon-forming cells (D₅). 

Tissue: Connective Tissue - Ligaments (D₇)

Tendons connect muscle to bone and ligaments (D₇) connect bone to bone.

Tissue: Connective Tissue - Fat (Adipose) Cells (D₈) and Fat (D₉)

Another type of connective tissue is fat (adipose). Fat (D₉) makes up most of the internal space of fat (adipose) cells (D₈). The nuclei of the fat cells can be seen as spots along the perimeters of the cells, but the main portion of the cell is composed of fat droplets.

Tissue: Connective Tissue - Red Blood Cells (D₁₀)

Blood contains red blood cells (D₁₀), which are shaped like discs and are sometimes stacked. Red blood cells carry oxygen to cells and pick up carbon dioxide from them for expulsion from the body.

Tissue: Connective Tissue - White Blood Cells (D₁₁)

Blood also contains white blood cells (D₁₁), which act as the body's defense system, phagocytizing bacteria and other harmful organisms and producing substances used in the immune system.

Tissue: Connective Tissue - Platelet (D₁₂)

The final type of blood cell is the platelet (D₁₂). Platelets are cell fragments involved in blood clotting.