Anatomy Exam 2 (Heart and Lungs)

Heart and Lungs Slides 1, 2, and 3

Heart Anatomy

• Superior Vena Cava

• Right Atrium

• Right Ventricle

• Aorta

• Pulmonary Trunk

• Left Atrium

• Left ventricle

• Coronary Vessels

Valves of the heart

• Semilunar valves

• tricuspid valve (right ventricle)

• mitral valve

• bicuspid valve (left ventricle)

Where does blood returning from the body enter?

the right atrium, then flows through the tricuspid valve into the right ventricle, then pumped through the pulmonary artery to the lungs to pick up oxygen.

How does blood leave the heart to the rest of the body?

oxygen-rich blood returns from the lungs into the left atrium, then passes through the mitral valve into the left ventricle, and then is forcefully pumped through the aorta to distribute oxygen to the rest of the body.

LUB

Atrioventricular valves close

DUP

Aortic and pulmonary valves close

Systole (pumping)

1. Isovolumetric contraction: atria relaxed, ventricles contract, AV valves closed.

2. Ejection: atria relaxed, ventricles contract

Diastole (filling)

1. Isovolumetric relaxation: atria relaxed, ventricles relaxed, semilunar valves closed

2. Rapid filling: atria relaxed, ventricles relaxed

3. Atrial contraction: atria contract, ventricles relaxed

Fetal Circulation

• Comes from mother’s blood, placenta

• Ductus arteriosus

• Foramen ovale

• Ductus venosus

• bypasses lungs

Sinoatrial (SA) Node

• Pacemaker

• located in the wall of the right atrium

• spontaneously generates electrical impulses that set the pace for the heartbeat

Atrioventricular (AV) node

• impulse spreads across both atria, causing them to contract and push blood into the ventricles

• the signal converges at the AV node, which introduces a brief delay to ensure the ventricles have enough time to fill completely

Atrioventricular Bundle (Bundle of His)

• Emerges from the AV node

• the signal enters the bundle of His located within the interventricular septum

Right and left bundle branches

• The bundle splits into right and left bundle branches, racing rapidly down either side of the septum toward the apex of the heart.

Purkinje Fibers

• At the apex, the signal fans out into specialized Purkinje fibers that course upward through the ventricular myocardium. This triggers a powerful, coordinated contraction from the bottom up, efficiently ejecting blood into the aorta and pulmonary artery.

P wave

• initial small upward bump

• represents the depolarization of the atria

• As the electrical impulse travels from the SA node across both atria, it causes them to depolarize and contract, pushing blood down into the ventricles.

QRS complex

• Sharp, positive spike

• represents the depolarization of the ventricles

• ventricles have larger muscle mass than atria, so this electrical sweep creates a large deflection

• signal triggers powerful ventricular contraction

• atria get repolarized, but that signal is hidden in this large complex

T wave

• final, smooth wave

• represents the repolarization of the ventricles

Pacemaker Potential: Membrane continuously polarizes due to what channels for what?

HCN channels for Na+

H (Hyperpolarization) is open at what polarization?

low!

CN (Cyclic Nucleotide) is open more under stimulation of ________ __________ by _________ and ________. what response?

1. beta-adrenergic receptors

2. epinephrine and norepinephrine

3. sympathetic response

Ca+ channels open at ______, Ca+ floods _____

1. -40 mV

2. in

K+ channels open, K+ floods ____

out

Parasympathetic vagus nerve ______ rate

decreases

Sympathetic cardiac nerves _____ rate and force

increase

Myocardial action potentials spread from ______ to _______, sweeping across the ______ ________.

1. cell to cell

2. entire heart

Cardiac Output (CO) = what?

Heart Rate (HR) * Stroke Volume (SV)

Frank-Starling Law

• Increased volume = increased stretch = increased force of contraction

• increased preload volume means increased resistance in after load, and therefore increased force of attraction is required to overcome resistance

In arteries, blood can flow ______ ways.

both

In veins, blood can flow ____ way.

one

Artery has a ______, while vein has a ______

• Lumen

• Valve

The right lung has _____ lobes

3

The left lung has ____ lobes

2

Bronchiole anatomy

1. Trachea

2. primary bronchus

3. secondary (lobar) bronchus

4. tertiary (segmental) bronchus

5. bronchiole

6. terminal bronchiole

7. respiratory bronchiole

Alveoli are covered with ______

capillaries

Alveolar wall is coated with ______

surfectant

Inflow of oxygen depleted blood is in the _______

arteriole

Outflow of oxygenated blood is in the ________

venule

Liters of O2 per Hour = what?

Surface Area * Change in Partial Pressure / Distance * Resistance

Alveolar wall is _____ ______ and ________ thick!

1. one cell

2. 0.001 mm

Alveolar surface area is _____ square meters

75 (tennis court size)

Thoracic Cavity Pressure

-3mm Hg (intrapleural pressure is subatmospheric)

Thorax and Lung expansion creates ______ pressure. Sucks ____ in.

1. negative

2. air

Diaphragm is? What nerve innervation?

1. the primary muscle of breathing

2. phrenic

Ribcage, what mechanisms?

Pump Handle and Bucket Handle mechanisms

H2O: Inspired Air?

Variable

H2O: Alveolar Air?

47 mmHg

CO2: Inspired Air?

000.3 mmHg

CO2: Alveolar Air?

40 mmHg

O2: Inspired Air?

159 mmHg

O2: Alveolar Air?

10 mmHg

N2: Inspired Air?

601 mmHg

N2: Alveolar Air?

568 mmHg

Total Pressure (Inspired and Alveolar Air)?

760 mmHg

Atmosphere

159 atm

Airway

149 atm

Alveolus

104 atm

Pulmonary Capillary

100 atm

Tissue and Vein

40 atm

In the alveoli, oxygen goes ______ and CO2 goes _____

1. in

2. out

In the Alveoli capillaries, PO2 is _____ and PCO2 is ______

1. 104

2. 40

As we transition to pulmonary vein, PO2 is _____ and PCO2 is _____

1. 100

2. 40

(pulmonary vein)

As we go past left heart and into systemic arteries, PO2 is ______ and PCO2 is ______

1. 100

2. 40

(systemic arteries, same as pulmonary vein)

In body cells, PO2 is _____ and PCO2 is _____

1. 40

2. 46

(body cells)

When we get to body cells, oxygen goes ____ and CO2 goes _____

1. out

2. in

As we go back to alveoli, PO2 is ______ and PCO2 is ______

1. 40

2. 46

(stays the same as body cell)

PO2 of blood only reflects O2 dissolved in ______

plasma (much more in red blood cells)

Plasma is?

mostly water, proteins like Albumin, Globulins, and Fibrinogen (which is an important clotting factor produced by the liver)

Leukocytes

immune system

Erythrocytes

Red blood cells, carries oxygen

Plasma is what percent of blood?

55%

Buffy coat (leukocytes, platelets) is what percent of blood?

less than 1%

Erythrocytes is what percent of blood?

45%

What is Hematopoiesis?

Making blood cells!

How many blood cells are made per day?

500 billion!

Where are blood cells made?

bone marrow! (liver in fetus)

Red blood cell homeostasis is a ______ feedback loop.

negative.

Kidneys and liver sense low oxygen and produce what hormone (red blood cell homeostasis)?

Erythropoietin (EPO), stimulates red blood cell production in kidneys in adults. liver in fetus

Oxygen levels ______, EPO _______

1. rise

2. inhibited

How many hemoglobin per red blood cell, and how many O2 molecules can it carry?

1. 280 million per red blood cell

2. carries 0 to 4 O2 molecules

Heme group with O2 is…

oxyhemoglobin

heme group without O2 is…

deoxyhemoglobin

Amount of O2 unloaded to tissues

CO2 in 3 forms in the blood:

• Dissolved CO2 in plasma

• carbaminohemoglobin

• bicarbonate

Inside red blood cell…

1. CO2 + H2O → w/ carbonic anhydrase, becomes H2CO3 → H+ (binds to hemoglobin) + HCO3-, which leaves RBC, Cl enters, chloride shift

Dissolved CO2 is

acidic

bicarbonate is

alkaline (basic)

inadequate ventilation leads to…

decreased pH (acidosis). regulate pH balance (7.4). kidneys help as well, producing bicarbonate and excreteing H+

How does brain use chemoreception to sense blood pH?

with carotid body and aortic bodies in aortic arch

Bohr effect:

O2 affinity changes with pH, makes it easier to load oxygen in the lungs and unload at peripheral tissues

Higher affinity

• O2 loading (loads in lungs)

• pH 7.6 (lung)

• higher pH (more basic)

lower affinity

• pH 7.2

• O2 unloading (leaves to tissues)

• lower pH (more acidic)

Temperature effect

• O2 affinity decreases at higher temperature

• makes it easier to unload oxygen into exercising muscle

Myoglobin

• left-shifted O2 curve

• higher affinity for O2

Fetal hemoglobin

• left-shifted O2 curve

• higher affinity for O2

• pulls oxygen from mother’s red blood cells

Evolution as hunter gatherers means…

selection for increased physical activity and increased energy metabolism (kcal/day). Need increased cardiac output!

Human left ventricle is more ____ ______. We have more ______ muscle, more _____, and more efficiency.

1. Endurance adapted

2. compact

3. twist (to “wring” out blood")

What is the most common blood type allele in humans?

O type

Earliest hominins had what blood type?

A type

Blood type B evolved how many years ago?

3.5 mya

Blood type O evolved how many years ago?

1.1 mya