Recently, we started talking about the cardiovascular system. The cardiovascular system includes three components. Those three components are blood, the heart and blood vessels. Blood is a connective tissue that has a liquid portion called plasma and a cellular portion that consists of many cells and cell fragments. Blood is the life maintaining fluid that circulates throughout the body’s heart, arteries, veins and capillaries. While circulating throughout the body, the blood carries difference substances. Some of these substances include nourishment, hormones and antibodies. While those substances are being carried to the body, waste matter and carbon dioxide are carried by blood out of the body. Oxygen and nutrients that are being transported by the blood diffuse into the interstitial fluid ( the fluid found between body cells ).
Blood has three main functions. Those three functions are transportation, regulation and protection.
Transportation:: Blood transports different substance throughout the body. It moves oxygen from the lungs to the cells throughout the body and it carries carbon dioxide from the cells to the lungs. Oxygen and carbon are not the only substances that are carried by blood. It is also responsible for carrying substances from the gastrointestinal tract to cells and at the same time it moves heat and waste products away from cells. It also moves hormones from endocrine glands to other cells.
Regulation:: Blood circulating helps to maintain homeostasis in all body fluids. Blood helps to maintain body temperature. This is with the help of the heat absorbing and coolant properties of the water in the blood.
Protection:: The blood has the ability to clot when there is an injury. This can be helpful in a way because it protects the body from losing too much blood. Also, white blood cells help to protect against disease by carrying phagocytes. Along with phagocytes, blood proteins such as antibodies, interferons can help to protect against disease as well.
Blood is stickier than water and also more dense. The temperature of blood is typically 30 degrees celsius. Blood counts for about 8 percent of body weight. In an average sized male there is about 5 to 6 liters of blood. In an average adult woman there is about 4 to5 liters.
Blood contains blood plasma, which is a watery liquid. This liquid is composed of dissolved substances. Blood also has formed elements. These elements are cells and cell fragments.
Blood plasma is a straw colored liquid that is about 91.5 percent water, 7 percent proteins and 1.5 percent solutes, that are not proteins. Plasma proteins are proteins in the blood. The most plentiful plasma proteins are the albiums. (about 54 percent of all plasma proteins)
Wednesday, March 18, 2009
Friday, March 13, 2009
Hormones
This past week we talked about hormones. What are hormones anyway? Hormones carry messages from glands to cells to preserve chemical levels in the bloodstream. Hormones move around in the bloodstream waiting to be recognized by a target cell. Each target cell has a receptor that can be activated by only a specific hormone. Once the target cell is activated it then knows to start it's function.
The concentration of hormones depends on three factors. The rate of production, the rate of delivery and the rate of degradation and elimination. Rate of production :: Synthesis and secretion of hormones are the most highly regulated feature of endocrine control. The management of the rate of production is controlled by both positive and negative feed back circuits. The rate of delivery :: An example of delivery would be the blood flow to an organ or a group of target cells. When there is a high blood flow more hormone is delivered and when there is a low blood flow it is the opposite. Meaning there is less amount of hormone delivered. Rate of degradation or elimination :: All hormones have featured rates of decay and are eliminate through one of several different routes. When the secretion of a hormone that has a short half-life gets shut off, the hormone concentration drops. However, when the half-life is long effective concentrations continue for more time after the secretion ceases.
We talked about the two major hormone categories. Those two groups are protein and steroidal hormones. These two groups have many differences. Protein hormones can travel easily through aqueous solutions such as blood. They also bring about rapid and instant changes within target cells. They have a short half-life which means they decompose rapidly. Protein hormones make use of their biological effect on target cells through a second messenger system.
Steroidal hormones must be transported through aqueous solutions with the help of a transport protein. Steroidal hormones like protein hormones also induce changes in target cell nuclei while doing this it alters mRNA transcription. They are hydrophobic which makes then non-polar. Unlike protein hormones, steroidal hormones have a reasonably long half-life.
As humans we need hormones. They help our bodies function and keep us healthy.
The concentration of hormones depends on three factors. The rate of production, the rate of delivery and the rate of degradation and elimination. Rate of production :: Synthesis and secretion of hormones are the most highly regulated feature of endocrine control. The management of the rate of production is controlled by both positive and negative feed back circuits. The rate of delivery :: An example of delivery would be the blood flow to an organ or a group of target cells. When there is a high blood flow more hormone is delivered and when there is a low blood flow it is the opposite. Meaning there is less amount of hormone delivered. Rate of degradation or elimination :: All hormones have featured rates of decay and are eliminate through one of several different routes. When the secretion of a hormone that has a short half-life gets shut off, the hormone concentration drops. However, when the half-life is long effective concentrations continue for more time after the secretion ceases.
We talked about the two major hormone categories. Those two groups are protein and steroidal hormones. These two groups have many differences. Protein hormones can travel easily through aqueous solutions such as blood. They also bring about rapid and instant changes within target cells. They have a short half-life which means they decompose rapidly. Protein hormones make use of their biological effect on target cells through a second messenger system.
Steroidal hormones must be transported through aqueous solutions with the help of a transport protein. Steroidal hormones like protein hormones also induce changes in target cell nuclei while doing this it alters mRNA transcription. They are hydrophobic which makes then non-polar. Unlike protein hormones, steroidal hormones have a reasonably long half-life.
As humans we need hormones. They help our bodies function and keep us healthy.
Thursday, March 5, 2009
The eyeball
Recently we started talking about the eyeball and all of its parts and its functions. There are three layers to the eyeball. The outermost layer is called the sclera. The sclera is what forms the white part of your eye. On top of the sclera is the conjunctiva. This is a thin clear covering that helps to protect your eye. It also is a lining on the inside of your eyelids. Also on the outermost layer is the cornea. The cornea is another transparent layer that allows light to enter into the eye. The cornea, together with the lens helps focus and direct light onto the retina.
The next, or middle layer is called the Choroid. It is a membrane found between the sclera and the retina, it lines the back of the eye. It contains many blood vessels that supply oxygen and nutrients to the retina, and is highly pigmented to help absorb light and prevent scattering.
The innermost layer is the retina. The retina lines the inside of the back part of the eye, and is the light-sensitive part. The retina contains millions of cells known as photoreceptors, and each photoreceptor is linked to a nerve fiber. You have a blind spot, also known as the optic disc, at the back of each eye where all of these nerve fibers come together to form the optic nerve. Once an image is detected by the photoreceptors, this information is converted into nerve impulses that are sent to the brain through the optic nerve.
The iris of the eyeball sits right on top of the ciliary body. The iris is the colored part of our eye. The black circle in the center of the iris is called the pupil and it is actually a hole.
There are six small muscles of the eye. The superior oblique is the muscle the moves the eye inward and downward. The lateral rectus moves the eye outward (away from the nose). The medial rectus is the muscle that allows you to cross your eyes (move eyes toward your nose). The superior rectus is what makes the eye moves the eye upward and slightly out. The inferior rectus moves the eye down and slightly inward. The sixth and final muscle of the eye is inferior oblique moves the eye outward and upward.
The next, or middle layer is called the Choroid. It is a membrane found between the sclera and the retina, it lines the back of the eye. It contains many blood vessels that supply oxygen and nutrients to the retina, and is highly pigmented to help absorb light and prevent scattering.
The innermost layer is the retina. The retina lines the inside of the back part of the eye, and is the light-sensitive part. The retina contains millions of cells known as photoreceptors, and each photoreceptor is linked to a nerve fiber. You have a blind spot, also known as the optic disc, at the back of each eye where all of these nerve fibers come together to form the optic nerve. Once an image is detected by the photoreceptors, this information is converted into nerve impulses that are sent to the brain through the optic nerve.
The iris of the eyeball sits right on top of the ciliary body. The iris is the colored part of our eye. The black circle in the center of the iris is called the pupil and it is actually a hole.
There are six small muscles of the eye. The superior oblique is the muscle the moves the eye inward and downward. The lateral rectus moves the eye outward (away from the nose). The medial rectus is the muscle that allows you to cross your eyes (move eyes toward your nose). The superior rectus is what makes the eye moves the eye upward and slightly out. The inferior rectus moves the eye down and slightly inward. The sixth and final muscle of the eye is inferior oblique moves the eye outward and upward.
Wednesday, March 4, 2009
Blog #4 ::::: Cranial Nerves
In my last blog I talked about spinal nerves, now I am going to talk about cranial nerves. The difference between cranial and spinal nerves is that cranial nerves emerge directly from the brain stem while spinal nerves are nerves that emerge from segments of the spinal cord. There are twelve different cranial nerves. The twelve cranial nerves can be divided into different groups. These groups being motor, sensory or mixed nerves. Sensory nerves tend to be located in the lateral brain stem. While motor nerves are located medially.
The function of the cranial nerves is for the most part similar to the spinal nerves, the nerves that are associated with the spinal cord. The motor components of the cranial nerves are derived from cells that are located in the brain. These cells send their axons out of the cranium where they will control muscles. , glandular tissue or specialized muscle. The sensory components of cranial nerves originate from groups of cells that are located outside of the brain. These collections of nerve cell bodies are called sensory ganglia. They have the same role as the dorsal root ganglia which are associated with the spinal cord.
In general, sensory ganglia of the cranial nerves send out a branch that divides into two branches. The motor components of cranial nerves transmit nerve impulses from the brain to target tissue outside of the brain while sensory components send nerve impulses from sensory organs to the brain. Without cranial nerves, we would be unable to chew, smell or see. These twelve nerves help to control many muscles of the body. All of them have their own purpose. Who knew one little nerve could control your mouth and how you chew.
The function of the cranial nerves is for the most part similar to the spinal nerves, the nerves that are associated with the spinal cord. The motor components of the cranial nerves are derived from cells that are located in the brain. These cells send their axons out of the cranium where they will control muscles. , glandular tissue or specialized muscle. The sensory components of cranial nerves originate from groups of cells that are located outside of the brain. These collections of nerve cell bodies are called sensory ganglia. They have the same role as the dorsal root ganglia which are associated with the spinal cord.
In general, sensory ganglia of the cranial nerves send out a branch that divides into two branches. The motor components of cranial nerves transmit nerve impulses from the brain to target tissue outside of the brain while sensory components send nerve impulses from sensory organs to the brain. Without cranial nerves, we would be unable to chew, smell or see. These twelve nerves help to control many muscles of the body. All of them have their own purpose. Who knew one little nerve could control your mouth and how you chew.
Tuesday, March 3, 2009
Nerves are what control the body’s functions including the vital organs, sensation and movement. Spinal nerves are the paths of communication between the spinal cord and nerves innervating specific regions of the body. There are thirty-one pairs of spinal nerves along the vertebral column. The spinal nerve is the bit that passes out of the vertebrae through the foramen. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pair of lumbar and five pairs of sacral nerves and then there is one pair of coccyx nerves.
Each nerve has two roots connecting to the spinal cord. The dorsal one is the sensory root and the ventral is the motor root. Sensory receptors send information to the spinal cord and the brain through the spinal nerve. The dorsal roots contain afferent sensory axons and the dorsal roots from both sides continue outward and form the dorsal root ganglion. The ventral roots contain efferent motor neurons. In sort of the same way as the dorsal roots, the ventral roots continue to move away from the spinal cord. They then meet up with their corresponding dorsal root at a point after the ganglion and mix.
I decided to write on this topic because of an accident that just recently happened. My cousin was in a snowmobile accident just the other day. When they took the x-ray, it showed that one of the side foramen was no longer there. They thought maybe he had a fracture. I am not sure which one they said it was, but no major damage was done due to it because of the fracture. He was however told to wear a neck brace to prevent further injury.
Each nerve has two roots connecting to the spinal cord. The dorsal one is the sensory root and the ventral is the motor root. Sensory receptors send information to the spinal cord and the brain through the spinal nerve. The dorsal roots contain afferent sensory axons and the dorsal roots from both sides continue outward and form the dorsal root ganglion. The ventral roots contain efferent motor neurons. In sort of the same way as the dorsal roots, the ventral roots continue to move away from the spinal cord. They then meet up with their corresponding dorsal root at a point after the ganglion and mix.
I decided to write on this topic because of an accident that just recently happened. My cousin was in a snowmobile accident just the other day. When they took the x-ray, it showed that one of the side foramen was no longer there. They thought maybe he had a fracture. I am not sure which one they said it was, but no major damage was done due to it because of the fracture. He was however told to wear a neck brace to prevent further injury.
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