BiologyPhylum Chordata

Module 11

What is an Endoskeleton? A skeleton on the inside of a

creature’s body, typically composed of bone or cartilage

Name some organisms that have endoskeletons

What is the difference between cartilage and bone?

A bone is made up of living cells surrounded by a hard substance called the bone matrix

Cartilage is a usually translucent somewhat elastic tissue that composes most of the skeleton of vertebrate embryos and except for a small number of structures (as some joints, respiratory passages, and the external ear) is replaced by bone during ossification (the natural progress of bone formation)

Three types of bone cells; Osteoblasts: cells that promote function

of bone tissue by producing the bone matrix

Osteocytes: mature bone cells surrounded by the bone matrix

Osteoblasts: continue to produce new bone tissue

Inside the Bone

Two types of tissue: Compact bone tissue Spongy bone tissue

Periosteum: a dense membrane that contains blood vessels that supply oxygen and nutrients to the cells in the bones and contains nerves

Spongy Bone Tissue

Compact Bone Tissue

There is Life in your Bones

Why are bones so important to our lives? <Discuss>

Bone marrow: a soft tissue inside the bone that produces blood cells

The Circulatory System

Closed Circulatory System: A system in which the oxygen-carrying blood cells never leave the blood vessels

Arteries – referred to as “red” Veins – referred to as “blue” Capillaries – look at the white part of

your eye – you will see capillaries

The Heart and Blood

Let’s compare the blood and heart like a commuter train that picks up and drops off people and goods all day long as it goes around the tracks

Blood picks up oxygen from the lungs and drops it off in the tissues

At the same time it picks up carbon dioxide from the tissues and drops it off in the lungs

It is also transporting nutrients from the small intestine to the liver first, then to all body cells

Simultaneously, it transports wastes from the tissues to the kidneys, and hormones from the endocrine glands to the cells throughout the body

It is a SUPER multi-tasker!!!

Your blood goes through your heart, even when you are at rest – Thank The Lord!

It travels at a quick pace – it travels through the heart about every 15-20 seconds

Trained athletes blood may be able to travel five or six times as fast as it does at rest

Blood is not only a transport medium, it is a regulatory tissue

It regulates fluid volume Blood picks up fluid from the intestines

and quickly moves it around the body, so that all tissues receive the fluids they require

It also equalizes temperature differences between warm and cold parts of the body

To help regulate the body’s temperature, the blood vessels of the skin constrict, squeezing the blood away from the surface to the deeper, warmer parts of the body

But if the skin gets too cold, the vessels open up and allow blood to return to the surface to warm up the skin again

All this – without US thinking about it – What a mighty God we have!

Blood is also a protective tissue

It protects against tissue loss

When you get a cut and begin to bleed, there are mechanisms within the blood to stop the bleeding (platelets)

This process is called hemostasis

Blood is also protective against infection because of the function of the white blood cells

They are like a very well oiled defensive army – they circulate through the body, detecting foreign invaders and calling for reinforcements (other white blood cells), to fight infections – such as bacteria or viruses

Makeup of Blood

As you know, the blood is liquid. One of the most descriptive aspects of a liquid is its viscosity.

Viscosity: The resistance to flow and alteration of shape due to cohesion

Viscosity is basically thickness Example: Honey and water – if you tip a

glass of water over the water flows freely. However, if you have a glass with honey in it and you tip it over, it does not flow freely, but slowly and seems to ooze out of the glass

Although blood has plenty of water in it, it is denser than water

This is because RBC’s contain iron, which is very dense compared to water

Discuss donating blood and checking for iron deficiency or anemia

Denser blood drops faster when placed in water

Human Endoskeleton

Look at Figure 13.4 on page 398 Axial Skeleton

The portion of the skeleton that supports and protects the head, next, and trunk

Appeendicular Skeleton The portion of the skeleton that

attaches to the axial skeleton and has the limbs attached to it

The Nervous System

Controlled by the brain Once a brain cell is damaged – it

cannot be repaired

Stem Cell Research – A Lot of Talk!

Pros and Cons of Stem Cell Research - What are Stem Cells?

“Stem" cells can be contrasted with "differentiated" cells.

They offer much hope for medical advancement because of their ability to grow into almost any kind of cell.

For instance, neural cells in the brain and spinal cord that have been damaged can be replaced by stem cells.

In the treatment of cancer, cells destroyed by radiation or chemotherapy can be replaced with new healthy stem cells that adapt to the affected area, whether it be part of the brain, heart, liver, lungs, or wherever.

Dead cells of almost any kind, no matter the type of injury or disease, can be replaced with new healthy cells thanks to the amazing flexibility of stem cells.

As a result, billions of dollars are being poured into this new field.

Where Do They Come From?To understand the pros and cons of stem cell research, one must first understand where stem cells come from.

There are three main sources for obtaining stem cells: adult cells cord cells and embryonic cells

Adult stem cells can be extracted either from bone marrow or from the peripheral system.

Bone marrow is a rich source of stem cells. However, some painful destruction of the bone marrow results from this procedure.

Peripheral stem cells can be extracted without damage to bones, but the process takes more time.

With health issues, time is often of the essence Although difficult to extract, since they are taken

from the patient's own body, adult stem cells are superior to both umbilical cord and embryonic stem cells.

They are plentiful. There is always an exact DNA match so the body's immune system never rejects them. And as we might expect, results have been both profound and promising.

Stem cells taken from the umbilical cord are a second very rich source of stem cells.

Umbilical cells can also offer a perfect match where a family has planned ahead.

Cord cells are extracted during pregnancy and stored in cryogenic cell banks as a type of insurance policy for future use on behalf of the newborn.

Cord cells can also be used by the mother, the father or others. The more distant the relationship, the more likely it is that the cells will be rejected by the immune system's antibodies.

However, there are a number of common cell types just as there are common blood types so matching is always possible especially where there are numerous donors.

The donation and storage process is similar to blood banking.

Donation of umbilical cells is highly encouraged. Compared to adult cells and embryonic cells, the

umbilical cord is by far the richest source of stem cells, and cells can be stored up in advance so they are available when needed.

Further, even where there is not an exact DNA match between donor and recipient, scientists have developed methods to increase transferability and reduce risk.

The pros and cons of stem cell research come to the surface when we examine the third source of stem cells - embryonic cells.

Embryonic stem cells are extracted directly from an embryo before the embryo's cells begin to differentiate.

At this stage the embryo is referred to as a "blastocyst."

There are about 100 cells in a blastocyst, a very large percentage of which are stem cells, which can be kept alive indefinitely, grown in cultures, where the stem cells continue to double in number every 2-3 days.

A replicating set of stem cells from a single blastocyst is called a "stem cell line" because the genetic material all comes from the same fertilized human egg that started it.

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President Bush authorized federal funding for research on the 15 stem cell lines available in August 2001.

Other stem cell lines are also available for research but without the coveted assistance of federal funding.

So, what is the controversy all about?

Those who value human life from the point of conception, oppose embryonic stem cell research because the extraction of stem cells from this type of an embryo requires its destruction.

In other words, it requires that a human life be killed. Some believe this to be the same as murder.

Against this, embryonic research advocates argue that the tiny blastocyst has no human features.

Further, new stem cell lines already exist due to the common practice of in vitro fertilization.

Research advocates conclude that many fertilized human cells have already been banked, but are not being made available for research.

Advocates of embryonic stem cell research claim new human lives will not be created for the sole purpose of experimentation.

Others argue against such research on medical grounds.

Mice treated for Parkinson's with embryonic stem cells have died from brain tumors in as much as 20% of cases.

1. Embryonic stem cells stored over time have been shown to create the type of chromosomal anomalies that create cancer cells.

2. Looking at it from a more pragmatic standpoint, funds devoted to embryonic stem cell research are funds being taken away from the other two more promising and less controversial types of stem cell research mentioned above.

The Brain

The brain is the most important part of our anatomy.

It tells all the other parts what to do, and when to do it.

The brain works as part of a network that includes the spinal cord and peripheral nerves.

Together, they transmit and control any information sent to and from the other areas of the body. Nonetheless, the brain is the master controller.

Special types of cells called neurons, or nerve cells, make up the content of the brain.

These cells form a network throughout the body as well. The brain uses this network to send messages and receive feedback from the body using electrochemical charges.

As such, neurons send messages to each other through the spinal cord and peripheral nerves.

It's the electrochemical aspect of neurons that allows the brain to coordinate all the body's functions.

The physical characteristics of neurons are what make electrical transmissions throughout the brain and body possible.

A neuron cell consists of a cell body, an axon and dendrites.

While the cell body holds the cell's instructions, the axons and dendrites extend out from the cell body like branches and carry the electrical charges, or impulses, from one nerve cell to another.

The brain itself contains three groupings, or sections of neurons, that coordinate the body's functions.

They are the:Brain stemCerebellumCerebral hemispheres (cerebral

cortex)

The brain stem connects with the spinal cord.

Contained in the brain stem are the medulla, pons, midbrain and thalamus.

Each section carries out specific functions in terms of processing and sending information to and from the brain.

The areas of the body controlled by the brain stem are the heart rate, blood pressure, arm and leg movements, digestion and basic reflexes.

The cerebellum, located behind the brain stem, processes information having to do with our sense of balance and arm-leg coordination.

The cerebellum makes up about one third of the total brain mass.

Sitting atop the brain stem and cerebellum are the two cerebral hemispheres responsible for thought, speech and memory abilities.

What most distinguishes the human brain from all others is it's two cerebral hemispheres.

Fundamentally, all mammal brain structures consist of the sections needed to sustain the life of the animal.

The areas of the brain that regulate breathing, digestion, blood pressure, limb coordination and reflexes are represented in all mammalian brains.

Not only is the cerebral cortex a new addition to the brain structure, it's made up of two intra-dependent portions.

Reproduction

In all vertebrates, the sexes are separate

Two types of fertilization Internal: the process by which the male

places sperm inside the female’s body, where the eggs are fertilized

External: the process by which the female lays eggs and the male fertilizes them once they are outside of the female

While external fertilization occurs in most aquatic vertebrates, internal fertilization occurs in most land-dwelling vertebrates

Oviparous development: occurs in an egg that is hatched outside the female’s body

Ovoviviparous development: occurs in an egg that is hatched inside the female’s body

Viviparous development: occurs inside the female, allowing the offspring to gain nutrients and vital substances from the mother through a placenta

Class Amphibia

Amphi = both sides Bio = life Amphibia = dual life

Characteristics

Endoskeleton mostly made of bone Smooth skin with many capillaries and

pigments No scales Two pairs of limbs with webbed feet As many as four organs for respiration Three-chambered heart Oviparious with external fertilization

Salamanders Small and have

little color Exception – the

giant salamander of Japan (5 feet and has bright color

Most salamanders have no lungs 90% of respiration occurs through

their skin Can spend a great deal of time

under water

Frogs

Frogs have smooth, shiny skin that dries easily

Spend a great deal of time in the water

Toads have dry, bumpy skin They return to the water to

reproduce Toads do NOT cause warts