Cardiovascular System Things to Know

Blood Vessels

     Blood is carried in a closed system of vessels that begins and ends at the heart

     The three major types of vessels are arteries, capillaries, and veins

     Arteries carry blood away from the heart, veins carry blood toward the heart

     Capillaries contact tissue cells and directly serve cellular needs

Generalized Structure of Blood Vessels

     Arteries and veins are composed of three tunics- tunica interna, tunica media, and tunica externa

     Lumen- central blood- containing space surrounded by tunics

     Capillaries are composed of endothelium with sparse basal lamina

Tunics

     Tunica interna (tunica intima)

          Endothelial layer that lines the lumen of all vessels 

          In vessels larger than 1 mm, a subendothelial connective tissue basement membrane is present

     Tunica media

          Smooth muscle and elastic fiber layer, regulated by sympathetic nervous system

          Controls vasoconstriction/vasodilation of vessels

     Tunica externa (tunica adventitia)

          Collagen fibers that protect and reinforce vessels

          Larger vessels contain vasa vasorum

Elastic (conducting) Arteries

     Thick-walled arteries near the heart; the aorta and its major branches

          Large lumen allow low-resistance conduction of blood

          Contain elastin in all three tunics

          Withstrand and smooth out large blood pressure flutuations

          Allow blood to flow fairly

Muscular (Distributing) Arteries and Arterioles

     Muscular arteries- distal to elastic arteries; deliver blood to body organs

          Have thick tunica media with more smooth muscle and less elastic tissue

          Active in vasoconstriction

     Arterioles- smalest srteries; lead to cappillay beds

          Control flow into capillary beds via vasodilation and constriction

Capillaries

     Capillaries are the smallest blood vessels

          Walls consisting of a thin tunica interna, one cell thick

          Allow only a single RBC to pass at a time

          Pericytes on the outer surface stabilize their walls

     There are three structural types of capillaries: continuous, fenestrated, and sinusoids

Venous System: Venules

     Are formed when capillary beds unite

          Allow fluids and WbCs to pass from the bloodstream to tissues

     Postcapillary venules- smallest venuels, composed of endothelium and a few pericytes

     Large venules have one or two layers of smooth muscle (tunica media)

Venous System: Veins

     Veins are:

          Formed when venules convege

          Composed of three tunics, with a thin tunica media and a thick tunica externa consisting of a collagen fibers and elastic networks

          Capacitance vessels (blood reservoirs) that contain 

     Veins have much lower blood pressure and thinner walls than arteries

     To return blod to the heart, veins have special adaptations

          Large-diameter lumens, which offer little resistance to flow

          Valves (resembling semilunar heart valves), which are 

Anastomoses

     Blood will flow where it can

Blood Flow

     Actual volume of blood flowing through a vessel, an organ, or the entire circulation in a givn period:

          Is measured in ml per min

          Is equivalent to cardiac output (CO), considering the entire vascular system

          Is 

Blood Pressure

     Force per unit area exerted on the wall of a blood vessel by its contained blood

          Expressed in millimeters of mercury (mmHg)

          Measured in reference to systemic arterial BP in large arteries near the heart

     The differences in BP within the vasclar system provide the driving forse that keeps blood moving from higher to lower pressure areas

Resistance

     Resistance- opposition to flow

          Measure of the amount of friction blood encounters as it passes through vessels

          Generally encountered in the systemic circulation

          Referred to as peripheral resistance (PR)

     The three important sources of the resistance are blood viscosity, total blood vessel length, and blood vessel diameter

Resistance Factors: Viscosity and Vessel Lenght

     Resistance factors that remain relatively constant are:

          Blood vi

Blood Vessel Diameter

     Changes in vessel diameter are frequent and significantly 

     Small-diameter arterioles are the major determinants of peripheral resistance

     Fatty plaques from atherosclerosis:

          Cause turbulent blood flow

          Dramatically increase resistance due to turbulance

Blood Flow, Blood Pressure, and Resistance

     blood flow (F) is directly proportional to the difference in blood pressure between two points in the circulation

Cardiovascular

     Over the last few week in our anatomy class we have been studing a lot about the cardiovascular system, to help us better understand how it all works. We have been doing a few labs to help us out.

Our first lab was the dissection of the cow, pig, and sheep heart.  My group dissected the pig heart. We were looking for things such as the ventricles, aorta, atriums, outer walls, and the pulmonary trunk.I not only got to see what the internal heart looked like, but it also helped me to learn how to locate the different parts of the heart. We measured each part of the heart, in order for us to compare the difference in sizes, we found out that the cow heart was the biggest out of the three.

This is a graph of the parts we had measured

We also did an EKG lab, by analizing our own hearts. This is the graphical recording of the electrical events occurring within the heart.  This allowed us to learn how to distinguish a "normal" heart rate from a "abnormal heart beat".

Before we studied this I had no idea what this ment but now i know the difference between a good heart and a bad heart.

Here is an example of a bad heart rate beacuse the Q, R, S is missing. This would be something that you would definitely need to recognize an abnormal heart which can be life threatening.

We also checked each others heart rate and we did it so it would be backwards. This is an examle of what it looked like backwards and right on the computer.



We also learned how to use a stethoscope with the sphygmomanometer to take blood pressure.  This showed the advancement of technology and how easy it is for us to listen to someones heart to make sure that everything is running correctly.  The normal blood pressure is 120/80, although women often tend to have a lower blood pressure than men.

 Me and Jill were partners and it was so hard to use a stethiscope to figure out our blood pressure. We couldn't find the heart beat at all, and my arm became so numb because it took so long.

Then we used the sphygmomanometer and at first mine still wouldn't work, and we thought somethingwas wrong with me. But we then tried it again and it worked perfect. I can't remember what my blood pressure was but it was close to normal. Jill then tried it and her blood pressure was not even close to being normal. So we tried it again and it was normal.

We also watched a video about a doctor cutting part of the heart off to help them. While he was doing this the heart beat was still beating while he was doing the surgry. I thought whoa this is crazy. He had no idea if it works. Now some doctors here in the US are doing the same procedure, but advancing it. I think this will be our future to fix our hearts if they advance it enough

Brain Dissection

Purpose:

     The purpose of the sheep brain dissection is to familiarize you with the threedimensional structure of the brain and teach you one of the great methods of studying the brain, while looking at its structure. The sheep brain will emphasize the human brain, observations that indicate that there are many similarities between the sheep brain and the human brain. Even the differences are instructive and help us to learn about the brain. Being able to locate important structures in the sheep brain was a great benefit to understanding how the structures are related to each other in the human brain. If the same structure exists in both brains, they are in the same relative location.

Materials

     Dissection pan

     Sheep Brain

     Dissection kit:

       Brain scalpel

       Probe
       Gloves

     Before beginning the dissection of the sheep brain we needed to know the terms used to specify the location and relative location of various brain structures. All these terms are both absolute and relative. Let me explain that. Let us take lateral. It both means at the side of the brain, and closer to the side. So some structure that is quite in the middle can be lateral to another structure that is even closer to the middle of the brain. To summarize,anterior or rostral mean in the front or towards the front. Posterial or caudal is at or towards the back Lateral means on the side or towards the side. Medial is at or towards the middle. Dorsal means on top, in the brain and head only, and ventral means on the bottom, in the brain and head only.

     In addition to the direction, the brain as a three dimensional object can be divided into three planes. There is the frontal or coronal planes which divides front from back. It can divide the brain and any location as long as it divides the brain from front to back.Next are the saggital planes which divides the left from the right of the brain. In the figure below, the most important saggital plane is illustrated the mid-saggital plane. However, as with the frontal planes, any plane that is parallel to the mid-saggital plane, is also a saggital plane. The last planes are the horizontal planes that divide the brain in to top and bottom portions.

      My first examine on the exterior of the entire brain. I was able to see one or two of the three layers of the meninges, the dura mater, the arachnoid layer, and the pia mater. The meninges are the protective coverings, which enclose the brain and spinal cord. The dura mater, the tough outer layer, will have been mostly removed when the brains were prepared for the dissection; however, some of the dura may stay on the brain. The arachnoid layer, the middle layer, and pia mater, the inner layer, are still likely to cover the brain. The pia mater follows the gyri and sulci and most likely is still on your specimen and may be indistinguishable from the brain. Blood vessels are between the arachnoid layer and the pia mater.

    

     My group dissected the mid-saggital cut on the brain. Which means we cut the brain from the middle going from the front of the brain to the back. When looking in the inside we noticed the cerebellum. We noticed the pattern of grey and white matter. To us it resembled a tree or bush and is called as a result the arborvitae. Then we had to cut it in sections going from the outside in from front to back, on one side of the brain we already cut.

   Our Brain Dissection

After we were done we went to look at everyone elses brain dissection. My favorite was probably Sarah's and Nicole's brain, they cut theres from front to back.



If you look on the side of the brain there is some of the dura, the extra skin that was on top of the brain.