Human Heart and Blood Vessels
Intro to the circulatory system
Blood Vessels: The Vascular System
• Purpose: Taking blood to the tissues and back
• Include– Arteries– Arterioles– Capillaries– Venules– Veins
Figure 11.8a
The Vascular System
Figure 11.8b
Artery
Vein
Veins– Carry blood to the
heart from the body– Most veins have
oxygen poor (deoxygenated) blood
– Have valves to prevent the backflow of blood
– Veins branch off to venules
Pulmonary Vein
Major Veins• Jugular veins drain
the head/brain• Superior and inferior
venae cavae are the largest veins that drain into the heart
• The ONLY vein that carries oxygenated blood is the Pulmonary Vein
WHY?
Figure 11.12
Arteries
– Carry blood away from the heart to the body
– Most carry oxygenated blood to body cells
– They have thick muscular walls and you can feel a pulse in them
– Arteries branch off to form Arterioles
Major Arteries• Aorta is the largest
artery in the body.• Coronary arteries
supply blood to the heart itself
• Femoral artery supplies blood to the legs
• The ONLY artery that has deoxygenated blood is the pulmonary artery
Why??
Figure 11.11
How are the blood vessels all connected?
ARTERYVEIN
CAPILLARIES
arteriole
endothelium
connective tissue
smooth muscle
venule
valve
From Heart To heart
Capillaries– The walls are thin (one cell thick) so diffusion
of gases, nutrients, & wastes can take place– Red blood cells travel through one cell at a
time, single file
From the heart
Towards the heart
Why do capillaries need to be one cell thick?• So that diffusion can take place.
Capillary Bed – exchange vesselsInteraction of molecules flowing in and out of blood at a capillary bed.
• Oxygen and nutrients cross to body cells• Carbon dioxide and metabolic waste products cross into blood
Gas/nutrient exchange happens at the site of the capillary
GA
S E
XC
HA
NG
ES
O2
CO2
Glucose
What Influences Capillary Exchange?
There are 3 processes: 1.Blood pressure – created by the heart pumping
blood. It’s the pressure of blood against the walls of vessels
2.Diffusion – movement of substances from an area of GREATER concentration to an area of LESSER concentration
3.Osmotic Pressure – A force caused by the difference in solute concentration on either side of a membrane
Diffusion at Capillary Beds
Figure 11.20
Example: Movement of CO2 from areas of higher concentration (body cells) to areas of lower concentration (interstitial fluid and then even lower in the blood)
The lymphatic system • an extension of the circulatory system consisting of a fluid known
as lymph (a watery fluid derived from plasma that has seeped out of the blood system capillaries and mingled with the cells).
• helps regulate blood volume and pressure
How do capillaries interact with the lymphatic system?
How do capillaries interact with the lymphatic system?
• Rather than returning to the heart through the blood veins, this lymph enters a series of one-way lymphatic vessels/ducts that return the fluid to the circulatory system.
http://www.cancerresearchuk.org/about-cancer/cancers-in-general/what-is-cancer/body/the-lymphatic-system
How do capillaries interact with the lymphatic system?
• The vessels/ducts pass through hundreds of tiny, capsule-like bodies called lymph nodes. Located in the neck, armpits, and groin, the lymph nodes contain cells that filter the lymph and phagocytize foreign particles.
http://www.cancerresearchuk.org/about-cancer/cancers-in-general/what-is-cancer/body/the-lymphatic-system
Blood Vessel Disorders: What are Varicose Veins?
• Varicose veins are abnormal and irregular dilations in superficial (near the surface) veins.
• Varicose veins in the rectum are hemorrhoids
Blood Vessel Disorders: What is Phlebitis?
Phlebitis - the inflammation of a vein. Sometimes this inflammation causes a thromboembolism (clot) to form on the wall of the vein.Sometimes the clot breaks off (embolus) and travels through the body.
Do Now: 1.What is the function of an artery? What type of blood flows in arteries?
2.What is the function of a vein? What type of blood flows in veins?
3.What is the function of a capillary? What occurs here? How?
The Human HeartMuscular organ that contracts rhythmically and pumps blood through blood vessels
What are the functions of the heart?
1.Keeps O2-poor blood separate from O2-rich blood2.Keeps blood flowing in one direction3.Creates blood pressure to move blood through the body
Why is the mammalian circulatory system called a double pump system?
One half of the heart pumps blood to the lungs and then the other half pumps blood to the rest of the body.
Pulmonary Circuit-To and from the lungs-Oxygenates blood-Drops off CO2
Systemic Circuit-To and from rest of body-Drops off oxygen & nutrients-Picks up nutrients, wastes, & CO2
The LEFT side of the heart drives the Systemic Circuit. It pumps blood to the entire body (except lungs)
•To deliver oxygen and nutrients to body cells•To pick up waste (CO2)
from body cells•This is called “nutrient-for-waste” exchange
The RIGHT side of the heart drives the Pulmonary Circuit. It pumps blood to the alveoli in lungs for gas diffusion
•To release CO2 •To oxygenate the blood
Pulmonary Circulation System
Red portion of heart and red blood vessels carry oxygen-rich blood.
Blue portion of heart and blue blood vessels carry oxygen-poor blood.
Pump Your Blood Song
The heart is surrounded by a double-layered, sac-like structure called the pericardium. The space between the layers normally contains a very small amount of fluid.
DISORDER:
Pericarditis - inflammation of the pericardium
Coverings of the Heart
The wall of the heart is composed of 3 distinct layers.
The inner endocardium is smooth and is made up of connective tissue and epithelium, and is continuous with the endothelium of major vessels joining the heart.
The endocardium contains the Purkinje fibers.
The middle layer called myocardium consists of cardiac muscle and is the thickest layer of the heart wall.
The outermost layer, the epicardium, is made up of connective tissue and epithelium, and houses blood and lymph capillaries along with coronary arteries. It is the same as the visceral pericardium.
Chambers of the HeartThe heart has 4 internal chambers: • 2 Atria on top • 2 Ventricles below.Atria receive blood returning to the heart
and have thin walls Ventricles are thick walled and pump
blood out of the heart the body.
A septum divides the atria from each other and ventricles from each other.
Atria of the HeartThe Right Atrium receives blood
from the body• The Superior Vena Cava brings
blood from the upper parts of the body
• The Inferior Vena Cava brings blood from the lower parts of the body
The Left Atrium receives blood from the lungs by way of the pulmonary veins Septum
Ventricles of the HeartVentricles are thick walled and
pump blood out of the heart to the body.
The right ventricle pumps blood via the pulmonary artery to the lungs to be oxygenated
The left ventricle pumps blood out to the whole body via the aorta
DO NOW
List the structures of the heart that have deoxygenated blood.
List the structures of the heart that have oxygenated blood.
Label the Heart
Valves Prevent the Back Flow of Blood
Atrioventricular (A-V) valve ensures one way flow of blood from the atrium to the ventricles
• The right A-V valve is called the tricuspid
• The left A-V valve is called the bicuspid or mitral valve
Valves Prevent the Back Flow of Blood
Semilunar valves are found where the blood exits the heart. They are called “semilunar” because they resemble half moons
• Right side has a pulmonary semilunar valve
• The Left side has an aortic semilunar valve
Do Now:
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conducting_system_of_the_heart.html
What makes the heart beat?The conduction system of the heart is a route of specialized cardiac muscle fibers that initiate and stimulate contraction of the atria and the ventricles
Nodal tissue – the heart is controlled by nodal tissue
1.Sinoatrial node (S-A node or pacemaker), located on the posterior right atrium, generates the impulses for the heartbeat.
2.Atrioventricular node (A-V node) located in the septum.
Branches of the A-V bundle give rise to Purkinje fibers leading to papillary muscles; these fibers stimulate contraction of the papillary muscles at the same time the ventricles contract.
1. SA node sends out a stimulus, which causes the atria to contract
2. When this stimulus reaches the AV node, it signals the ventricles to contract
3. Impulses pass down the two branches of the atrioventricular bundle to the Purkinje fibers
4. After the stimulus reaches the Purkinje fibers the ventricles contract Purkinje Fibers
An electrocardiogram (EKG or ECG) is a test that checks for problems with the electrical activity of your heart.
http://allnurses.com/general-nursing-student/ekg-its-alphabetical-952130.html
https://my.clevelandclinic.org/services/heart/diagnostics-testing/electrocardiograph-tests/electrocardiogram-ekg
Ways to determine how well the heart is functioning
The sounds of the heart are caused by the closing of the
valves.
A normal heartbeat produces the familiar “LUB-DUP” sound as the chambers contract and the valves close.
The “lub” sound- quieter, longer, lower pitched- caused by the bicuspid and tricuspid valves (A-V valves) closing. The “dub” or “dup” sound- louder, shorter, higher pitched- caused by the semilunar valves closing.
Ways to determine how well the heart is functioning
What is a Heart Murmur?
Heart murmurs are the clicking or the swishing sound after the “LUB”. The valve doesn't close properly and “leaks”
Listen to heart sounds
What is a mitral valve prolapse?• 1 in 20 americans
have this
• The defective heart valve leaflet can cause blood to flow back into the atrium
Mitral Valve Prolapse
• What are mitral valve prolapse symptoms?– Feeling like your heart is racing or is skipping beats – Heart palpitations – Chest pain that comes now and then – Shortness of breath – Dizziness – Anxiety
• Diagnosis?• When listening to your heart with a stethoscope, your
doctor may hear a clicking sound. The defective heart valve leaflet can make a pronounced "click" as it opens and closes. If blood is flowing back into the atrium, your doctor will hear a "whooshing" sound. This sound is called a heart murmur and is caused by the mitral valve prolapse.
Disorders of the heart
• Arrhythmia – Irregular heart beat– Bradycardia =<60bpm– Tachycardia =>100bpm
• Fibrillation – fast but uncoordinated contractions
Coronary Disorders• Atherosclerosis or
Arteriosclerosis - slow and progressive building up of plaque, fatty substances, cholesterol, cellular waste products, calcium and fibrin in the inner lining of an artery.
• This building up of plaque may lead to thickening and hardening of the arteries, subsequently blocking the blood flow either partially or totally in an artery.
Medmovie of atherosclerosis
Angina• Angina is chest pain or
discomfort that occurs if an area of your heart muscle doesn't get enough oxygen-rich blood.
• This pain is due to plaque in arteries
• Angina may feel like pressure or squeezing in your chest. The pain also can occur in your shoulders, arms, neck, jaw, or back. Angina pain may even feel like indigestion.
Thromboembolism• Thromboembolism is when a blood clot
breaks away from its place of origin and is carries to a new location. Thromboembolism leads to a heart attack when the embolus (traveling clot) blocks a coronary artery and a portion of the heart dies due to a lack of oxygen.
• A heart attack is called a myocardial infarction
AngioplastyAngioplasty is the technique of
mechanically widening a narrowed or obstructed blood vessel, the latter typically being a result of atherosclerosis. An empty and collapsed balloon on a guide wire, known as a balloon catheter, is passed into the narrowed locations and then inflated. The balloon crushes the fatty deposits, opening up the blood vessel for improved flow, and the balloon is then deflated and withdrawn.
Coronary Bypass Surgery• Coronary Bypass
surgery is when a surgeon grafts segments of another vessel between the aorta and the coronary vessels, bypassing the areas that have a blockage
PulseYour pulse is your heart rate, or
the number of times your heart beats in one minute. Pulse rates vary from person to person. Your pulse is lower when you are at rest and increases when you exercise (more oxygen-rich blood is needed by the body when you exercise). Monitored at “pressure points” where pulse is easily palpated
• A normal resting pulse is 60-100 beats per minute
Figure 11.16
The Heart:Regulation of Heart Rate• Increased heart rate is regulated by:
– Sympathetic nervous system• Crisis• Low blood pressure
– Hormones• Epinephrine• Thyroxine
– Exercise can increase heart rate– Decreased blood volume
• Decreased heart rate is regulated by– Parasympathetic nervous system– High blood pressure or blood volume– Decreased venous return
Blood Pressure
• Measurements by health professionals are made on the pressure in large arteries
– Systolic – pressure at the peak of ventricular contraction
– Diastolic – pressure when ventricles relax
• Pressure in blood vessels decreases as the distance away from the heart increases
Measuring Arterial Blood Pressure
Figure 11.18
Variations in Blood Pressure• Human normal range is variable
– Normal• 140–110 mm Hg systolic• 80–75 mm Hg diastolic
– Hypotension• Low systolic (below 110 mm Hg)• Often associated with illness
– Hypertension• High systolic (above 140 mm Hg)• Can be dangerous if it is chronic
Figure 11.17
Comparison of Blood Pressures in Different Vessels
Blood Pressure: Effects of Factors• Temperature
– Heat has a vasodilation effect so pressure decreases– Cold has a vasoconstricting effect so pressure
increases
• Chemicals– Various substances can cause increases or decreases
• Diet• Neural factors
– Autonomic nervous system adjustments (sympathetic division)
• Renal factors– Regulation by altering blood volume– Renin – hormonal control
Animation: The Cardiac Cycle (Quiz 1)
Major blood supply to the body1. Brain2. Thyroid gland3. Thyroid artery4. Pulmonary circulation5. Pulmonary vein6. Aorta7. Splenic artery8. Spleen9. Superior mesenteric artery10. Renal artery11. Kidney12. Intestine13. Renal vein14. Portal vein15. Liver16. Inferior vena cava17. Hepatic veins18. Pulmonary artery19. Superior vena cava20. Thyroid vein
Capillary Beds
Figure 11.10
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