biology-the cardiovascular system

Created by

Bethany 123

Cards (27)

what is the function of the cardiovascular system
-it is a transportation system
-circulates blood around the body
what is the structure of the heart
what are semi lunar valves
-found in the bases of blood vessels leaving the heart
-consists of 3 cusps that prevent the backflow of blood back into the heart.
what is the bundle of His  
-a bundle of modified cardiac muscle that passes from the atrioventricular node to the ventricles by the way of the septum.
-maintans the normal sequence of the heartbeat by conducting the wave of ecitation from the right atrium to the ventricles
what is the myocardium  
heart muscle that forms tightly interconnecting cells of the cardiac muscle tissue.
what is the pericardium  
-the sac around the heart
-the sac is filled with lubricating fluid that provides protection from damage or infection
what do arteries do  
carry blood away from the heart
what do veins do
carry blood toward the heart
what is the role of the capillaries  
the place where nutrients and gases are exchanged.
why do arteries have a ticker wall than veins
they have a larger lumen so require more protection
why is the capillary being one cell thick beneficial
provides a short diffusion pathway
what is the middle and outer layer of muscle called
middle-tunica media
outer-tunica externa
describe the capillaries  
Capillary beds are present in all regions of the body but not all capillary beds are open at the same time.
• Contraction of a sphincter muscle closes off a bed and blood can flow through an arteriovenous shunt that by passes the capillary bed.
describe the sphincter muscle in the capillaries
When sphincter muscles are relaxed,
the capillary bed is open, and blood flows through the capillaries. When sphincter muscles are contracted, blood flows through a shunt that carries blood directly from an arteriole to a venule
why does blood move slowly in the capillaries
-more capillaries than arterioles
-allows time for substance exchange between the blood and the tissues
describe how capillary exchange occurs
At the arteriole end of a capillary, water moves out of the blood due
to the force of blood pressure.
• At the venule end, water moves into the blood due to osmotic
pressure of the blood.
• In the midsection of the capillary, nutrients diffuse out and wastes
diffuse into the blood.
• Substances that leave the blood contribute to tissue fluid, the fluid
between the body’s cells
what is blood made up of
55% plasma
45% formed elements
what are the components of the blood
-plasma: liquid part of the blood
-red blood cells: carry oxygen to the body
-white blood cells: fight infection
-platelets: responsible for the formation of blood clots
describe the cardiac cycle
stage 1
-both venticles relax
-the atria contracts forcing blood through the valves into the venticles
stage 2
-both atria relax
-the venticles contract
-blood is ejected into the aorta and pulmonary artery
stage 3
-relaxation of both the atria and the ventricles
-atria fills back up and the cycle starts again.
what is the extrinsic control of the heart  
• A cardiac control center in the medulla oblongata speeds up or slows down the heart rate by way of the autonomic nervous system branches:
parasympathetic system (slows heart rate) and the sympathetic system (increases heart rate).
• Hormones epinephrine and norepinephrine from the adrenal medulla also stimulate faster heart
rate.
what is the intrinsic contol of the heartbeat
The SA (sinoatrial) node, or pacemaker, initiates
the heartbeat and causes the atria to contract on average every 0.85 seconds.
• The AV (atrioventricular) node conveys the stimulus and initiates contraction of the ventricles.
• The signal for the ventricles to contract travels from the AV node through the atrioventricular bundle to the smaller Purkinje fibers.
what is the autonomic nervous system  
A part of the nervous system that regulates key
involuntary functions of the body, including the activity of
the heart muscle; the smooth muscles, including the
muscles of the intestinal tract; and the glands. The autonomic nervous system has two divisions: the
sympathetic nervous system, which accelerates the heart rate, constricts blood vessels, and raises blood
pressure, and the parasympathetic nervous system, which slows the heart rate, increases intestinal and gland
activity, and relaxes sphincter muscles.
what happens if the sinoatrial node fails to work properly how is this fixed
the heart still beats due to impulses generated by the AV node, but the beat is slower (40 to 60 beats per minute). To correct this condition, it is possible to implant an artificial pacemaker, which automatically gives an electrical stimulus to the heart.
what is an electrocardiogram
An electrocardiogram (ECG) is a
recording of the electrical changes
that occur in the myocardium during a
cardiac cycle.
• Atrial depolarization creates the P
wave, ventricle depolarization creates
the QRS wave, and repolarization of
the ventricles produces the T wave.
how many vascular pathways is there
1)Pulmonary circuit which circulates blood through the lungs
2) Systemic circuit which circulates blood to the rest of the body.
what is the pulmonary system
• The pulmonary circuit begins with the pulmonary trunk from the right ventricle which branches into two
pulmonary arteries that take oxygen-poor blood to the lungs.
• In the lungs, oxygen diffuses into the blood, and carbon
dioxide diffuses out of the blood to be expelled by the lungs.
• Four pulmonary veins return
oxygen-rich blood to the left atrium.
what is the systematic circuit
• The systemic circuit starts with the aorta carrying O2
-rich blood from the left ventricle.
• The aorta branches with an
artery going to each specific organ.
• Generally, an artery divides into
arterioles and capillaries which then lead to venules.