Post on 24-Feb-2016
description
Introduction Function:
– Transport materials around body Components:
– Heart– Blood Vessels
The Heart Layers in Cross Section:
– Pericardium- outermost sac enclosing heart
– Pericardial Fluid- fluid between pericardium and epicardium
– Epicardium- tight fitting layer surrounding heart; also called visceral pericardium
– Myocardium- cardiac muscle layer– Endocardium- smooth inner layer of
heart
Heart Structure Four chambers:
– Right and left atria- receive blood into heart
– Right and left ventricle- pump blood back out of the heart
Two sides are separated by septum
Valves Four Valves in Heart:
1.Tricuspid - between right atrium and right ventricle
2.Pulmonary Semilunar - between right ventricle and pulmonary trunk
3.Mitral (Bicuspid) - between left atrium and left ventricle
4.Aortic semilunar - between left ventricle and aorta
Two Circulations of Blood Pulmonary:
– Back and forth to lungs Systemic:
– Back and forth to body
Path of Blood Through Heart
Exit Slip 1) What chamber is this? 2) Which valve is between
right atrium and right ventricle? 3) Which circuit (pulmonary or
systemic) brings blood back and forth to lungs?
1) Right atrium 2) Tricuspid 3) Pulmonary
Internal Heart
Identification
Vessels Supplying the Heart Coronary arteries
– First two branches off of the aorta
– Supply blood to heart Cardiac veins
– Return blood from heart tissues
– Drain into coronary sinus Coronary sinus
– Returns blood back to right atrium
Cardiac Cycle Sequence of events that occur during
every regular heartbeat Systole - contraction Diastole - relaxation Refer to timeline
Systole/Diastole Song
THE FLOW OF BLOOD THROUGH THE HEART
Heart Sounds Lubb - sound of atrioventricular (AV)
valves closing Dupp - sound of semilunar valves
closing
Lubb, Dubb, …. Lubb, Dubb….
made by the closing of the heart valves.
"lub" made by the contraction of the ventricles and the closing of the atrioventricular valves.
“dupp" made by the semilunar valves closing.
Reminder about Cardiac Tissue Complex network of interconnecting
cells– Connected by intercalated discs– Allows them to transfer impulse rapidly
and work together (functional syncytium)
Two sets in heart: – One in atria, one in ventricles
Kept separate from each other
Cardiac Conduction Intro Electrical impulses cause heart
structures to contract Travel down a system of specialized
fibers
33
QUICK REVIEW OF HEART Purpose Pumps blood Basic Anatomy 4 chambers 2 sides 4 valves
34
THE CONDUCTINGY SYSTEM
SA Node Inter-nodal
pathway AV Node Bundle of HIS Bundle Branches Purkinje Fibers
35
RELATIONSHIP
Why do we do an ECG? Measures:
– Any damage to the heart– How fast your heart is beating and whether it is
beating normally– The effects of drugs or devices used to control the
heart (such as a pacemaker)– The size and position of your heart chambers
Ordered if: – You have chest pain or palpitations (pounding/racing
heart)– You are scheduled for surgery– You have had heart problems in the past– You have a strong history of heart disease in the
family
Pathway for Conduction Sinoatrial node (SA node)
– Pacemaker– Causes atria to contract
Junctional Fibers – Delay impulse reaching ventricle by their
small diameter Atrioventricular node (AV node) Purkinje fibers
– Cause ventricles to contract
Electrocardiogram Also know as ECG Electrical recording
of myocardium during cardiac cycle
P wave– Atrial depolarization
QRS complex– Ventricle
depolarization and atrial repolarization
T wave– Ventricle
repolarization
Electrocardiogram (cont)
Each electrical signal begins in a group of cells called the sinus node or sinoatrial (SA) node. The SA node is located in the right atrium (AY-tree-um), which is the upper right chamber of the heart. (Your heart has two upper chambers and two lower chambers.)
In a healthy adult heart at rest, the SA node sends an electrical signal to begin a new heartbeat 60 to 100 times a minute.
From the SA node, the signal travels through the right and left atria. This causes the atria to contract, which helps move blood into the heart's lower chambers, the ventricles (VEN-trih-kuls). The electrical signal moving through the atria is recorded as the P wave on the EKG.
The electrical signal passes between the atria and ventricles through a group of cells called the atrioventricular (AV) node. The signal slows down as it passes through the AV node. This slowing allows the ventricles enough time to finish filling with blood. On the EKG, this part of the process is the flat line between the end of the P wave and the beginning of the Q wave.
The electrical signal then leaves the AV node and travels along a pathway called the bundle of His. From there, the signal travels into the right and left bundle branches. The signal spreads quickly across your heart's ventricles, causing them to contract and pump blood to your lungs and the rest of your body. This process is recorded as the QRS waves on the EKG.
The ventricles then recover their normal electrical state (shown as the T wave on the EKG). The muscle stops contracting to allow the heart to refill with blood. This entire process continues over and over with each new heartbeat.
Control of Heart Rate Cardiac Center of Medulla Oblongata
– Parasympathetic Constant braking action; acetylcholine
– Sympathetic Increases heart rate; norepinephrine
Blood Pressure Receptors– Decreases heart rate
Impulses from Cerebrum and Hypothalamus– Decrease heart rate
Changes in K and Ca concentrations
Thumbs Up, Down Coronary arteries supply blood to
heart.–UP!
The lubb of your heart is the sound of the AV closing/opening. –UP!
An ECG measures your blood pressure.–DOWN! It measures your cardiac
cycle.
Blood Vessels System of closed tubes filled with blood Arteries
– Carry blood away from heart Arterioles
– Smaller branches of arteries Capillaries
– Thin-walled vessels where nutrients, fluid, gases, and wastes are exchanged
Venules– Small veins
Veins– Large vessels returning blood to heart
Layers of Blood Vessel Walls Tunica externa
– Outermost layer composed of connective tissue with some elastic and collagenous fibers
Tunica media– Middle layer composed of smooth
muscle and elastic fibers Tunica interna (endothelium)
– Single layer of squamous epithelium
Control of Vessel Diameter Vasoconstriction– Sympathetic nervous system impulses cause
vessels to constrict Vasodialation
– Inhibition of impulse causes dialation
Arteries Carry blood away from heart under
high pressure Has the thickest tunica media and
tunica externa of all blood vessels
Arterioles Smaller branches of arteries Walls thin as the vessels get smaller Eventually lose tunic externa
Capillaries Site of exchange Only tunica interna
remains Has small openings
between endothelial cells where materials can leak out
Pre-capillary sphincters– Smooth muscle at start of
capillary that can close the capillary bed and divert blood flow
Exchange of Materials1. Oxygen and nutrients diffuse out of the
capillary2. Carbon dioxide and wastes diffuse back
into capillary3. Plasma Proteins don’t leave the blood4. Fluid is forced out of the capillary at the
arteriole side due to blood pressure5. Fluid is brought back into the capillary
due to osmotic pressure at the venule side
6. Fluid not recollected is brought back to the blood through the lymphatic system
Venules and Veins Venules
– Smaller veins Veins
– Large lumen– Thinner tunica media– Thinner tunica externa– Return blood to heart– Low pressure– Blood reservoir– Contains valves
Protect against backflow
Pumps your blood SON
G!
Heart Disorders Myocardial infarction (MI)
– Otherwise known as heart attack– Def: Blood clot obstructs a coronary
atery or one of its branches – killing part of the heart
– Causes: Diet (high in fat and/or salt)
– Causes build-up in plague (causes blood clot) Stress (usually from another illness)
– Symptoms: Pain in right arm, shortness of breath,
increased heart rate
Heart Disorders Atherosclerosis
– Def: arterial disease, hardening of arteries
– Very common– Causes:
Plague build-up (caused by diet high in fat)– Forms clots, blood has issues flowing through
Aging (older you get, more they harden) Heavy alcohol use Not exercising (EVER!) Obesity
– Can lead to heart attack or stroke
Heart Disorders Hypertension
– Def: High blood pressure Ex: 140/90 (normal – 120/80)
– Causes: Diet (high in fat and/or salt) Genetics (heart disease, diabetes) Stroke or heart attack Pregnancy/labor Kidney disease Race (African-Americans on average have
high BP) Gender
Heart Disorders Varicose veins
– Def: ruptured veins
– Causes: Abnormal
dilations– Caused by
increased blood pressure due to gravity
– Standing for abnormally long periods of time
Blood Pressure Force blood exerts on blood vessel
walls Highest in arteries; lowest in veins Max point:
– During ventricular systole; called systolic pressure
Min point: – Before next ventricular contraction;
called diastolic pressure Normal arteriole blood pressure:
120/80
Factors the Affect Blood Pressure Heart Action Blood Volume Peripheral
resistance Blood viscosity
Heart Action Stroke Volume
– Volume of blood discharged from the left ventricle during each contraction
Cardiac output– Volume of blood discharged from the left
ventricle/ minute– Cardiac Output=Stroke volume x Heart rate
(bpm) Cardiac output has proportional
relationship to blood pressure
Peripheral Resistance Blood moving against vessel walls
creates friction that impedes flow If vessels are constricted, blood
pressure raises If vessels are dilated, blood pressure
lowers
Blood Viscosity Viscosity
– Ease that a fluid flows– Increases when there are more formed
elements or plasma proteins– As viscosity increases so does blood
pressure
Controlling Blood Pressure Cardiac Output
– Strength of ventricle contraction is controlled by amount of
– Baroreceptors- send messages to medulla oblongata about how to influence SA node
Peripheral resistance– Changes in blood pressure cause changes in
medulla oblongata’s Vein reservoir
– During exercise or venoconstriction more blood