Goodwin Exam 2

What embryonic tissue forms the primary heart tube?

Splanchnic layer of later plate mesoderm

When does the heart start beating?

Day 22

What is the first septation of the heart?

Septum Primum

What is the function of the foramen ovale?

Fetal R/L shunt, bypasses fetal lungs

When is atrial septation completed?

First breath

What are the two parts of the ventricular septum?  

Muscle and membranous

What are the two right-to-left shunts of fetal circulation?

Foramen ovale and ductus arteriosus

When do the fetal shunts close?

shortly after birth

How do the fetal shunts close?

Oxygen pressure on first breath

What are the two kinds of heart valves and what is the difference between them?

AV valves (tri, chordae tendinae) and semilunar (bi) valves

What is the function of the conduction system of the heart and what are its main components?

Causes heart to beat -> SA, AV, His, Purkinje

What is the blood supply to the heart?

Coronary arteries

Why is the Anterior Interventricular Artery so important? (Hint: It has another name.)

Widow Maker (LAD), blockage causes severe heart attacks

What is the innervation to the heart?

Both sympathetic and parasympathetic

What causes the “Plateau” in the action potential of a non-pacemaker cardiac myocyte?

Caused by calcium channels opening and extending the contraction.

How are action potentials of “pacemaker” cells different than other cardiac myocytes?

Special Na2+ and K+ channels that slowly leak until they reach threshold and spontaneously contract

Where in the conduction system of the heart is the contractile impulse slowed down and why?

AV node slows impulse, which allows atria to finish contracting before the ventricles are stimulated to contract

What is being measured in an ECG?

Summed electrical activity of all cells recorded from the surface of the body (projection of a time-varying cardiac dipole vector onto different lead directions)

What is Einthoven’s Law of ECGs?

Lead 1+ Lead 3 = Lead 2

In an ECG, what is happening during the P wave, QRS complex, and T wave?

-              P wave: atrial depolarization

-              QRS: ventricular depolarization and ventricular contraction

-              T wave: ventricular repolarization

What is the significance of the P-R and Q-T intervals?

-              PR: conduction through AV node and A-V bundle (time for electrical signals to travel from atria to ventricles) (Conduction delay)

-              QT: time for ventricular depolarization and repolarization (total ventricular activity)

Why are so many leads used in ECGs?

Additional leads provide more clinical insight on heart function

How are arrythmias different from normal as measured by ECGs?

Differences in PQRST complexes from normal, abnormal rhythm and timing

Why are mechanical pacemakers needed?

Needed to provide electrical stimulation when normal conduction system fails

Draw a Pressure/volume loop for the left ventricle.

How is stroke volume of a ventricle determined?

End diastolic volume – end systolic volume = stroke volume   (EDV – ESV = stroke volume)

How is ejection fraction determined?

Stroke volume/EDV = ejection fraction

How is Cardiac Output determined?

Cardiac Output = Heart Rate x stroke volume

How does sympathetic stimulation affect heart rate?

Increases heart rate

How does parasympathetic stimulation affect heart rate?

Decreases heart rate

What determines the End Diastolic Volume?

Venous return

-              Skeletal muscle pump, respiratory pump, sympathetic innervation

What are the two types of vessels that have major contributions to the “Pressure Reservoir” in the arterial system? 

Elastic arteries and muscular arteries

How is Mean Arterial Pressure calculated and why is one value divided by three?

 MAP = [SBP + 2(DBP)]/3

• heart spends 2/3 in diastole and 1/3 in systole

*Mean arterial pressure = cardiac output x resistance

If Cardiac output decreases what happens to Mean Arterial Pressure?

Decreases

Where are the baroreceptors and where do they send their signals?

Baroreceptors are in the aortic arch and carotid sinus (adventitia of internal carotid)  receptors, signals are sent to the medullary cardiovascular control center

What is the short-term system of regulating Blood Pressure?

Baroreceptor reflex -> maintains stable blood pressure by detecting arterial stretch

What is the long-term system of regulating Blood Pressure?

Renin-angiotensin system -> regulates blood volume via the kidneys by adjusting the glomerular filtration rate

What vessels have the largest cross-sectional area in the body?

Capillaries

What vessels only have a tunica intima?

Capillaries

Compare and contrast transcytosis from paracellular transport

Transport through endothelial cells vs between cells

When blood is being “filtered’ in capillaries, which way is water flowing?

Fluid is moving out of the capillaries

What is “pitting edema”, and what is it a sign of?  

Fluid leakage from capillaries -> fluid uptake by venules and lymphatics

• Pitting edema in a patient with right ventricular heart failure

Describe the volume reservoir in the vascular system, and how is it activated?

Stimulated to constrict by the sympathetic nervous system (increases EDV, which increases stroke volume)

During the development of atherosclerotic plaques, which vessel cell type secretes Extracellular Matrix protein fibers?

Smooth muscle cells

hat is the lack of Red blood cells called?

Anemia

What stimulates erythropoiesis?

Erythropoietin (EPO)

What do megakaryocytes produce?

Platelets

What would be the problem with thrombocytopenia?

Lack of platelets, blood can’t clot

What stimulates the production of leukocytes?

Stimulated by a number of colony-stimulating factors

What blood cell type is increased during bacterial infections and can reveal a person’s sex?

Neutrophils (Barr Body)

What would be observed in a blood smear of acute vs chronic leukemia?

More precursor cells in acute leukemia, more differentiated cells in chronic leukemia

Where does hematopoiesis take place in the fetus/adult

Takes place in liver in the fetus, bone marrow in adults

What is the result of hypoplastic bone marrow

Reduced ability to produce blood cells, bone marrow failure

What is the result of hyperplastic bone marrow?  

Conversion of yellow (fatty) marrow back to red marrow

What is the difference between the Myeloid lineage and the Lymphoid lineage in hematopoiesis?

-              Myeloid: innate

-              Lymphoid: active

What are the two pathways that can initiate the coagulation cascade?

Extrinsic or intrinsic pathways

What accumulates during thrombus formation?

Platelets and fibrin

What dissolves clots?

Plasmin

What structures are located on the apical side of respiratory epithelium?

Ciliated cells and goblet cells

In what part of the respiratory system does olfaction take place?

Superior nasal cavity

What holds the trachea and bronchi open so that their radius remains constant?

Cartilage rings

Part of the respiratory tract can dilate and contract and what cells are responsible for this activity?

Bronchioles, smooth muscle cells

What muscles are involved in inspiration?

Diaphragm and intercostals

What muscles are involved with expiration?

Passive (intercostals, abdominal muscles for forced expiration)

What prevents lungs from collapsing?

Negative pleural pressure

What is the function of alveolar surfactant, and which cells produce it?

Decreases surface tension, type 2 pneumocytes

What is responsible for the difference between total pulmonary ventilation and total alveolar ventilation?

Dead space

What dilates bronchioles? What contacts bronchioles?

CO2 and sympathetic, also CO2 and parasympathetic

How do lung arterioles react to increased oxygen tension? And how is this different than most of the body’s other arterioles?

Dilate, other arterioles contract

Where does reserve lung capacity come from?

Ability of muscles to forcibly expand or compress lungs beyond normal tidal volume

Which is more soluble in water, O2 or CO2?

CO2

What process does gas use to move from the alveoli to a red blood cell?

Diffusion

What factors affect diffusion of gases between alveoli and blood?

Pressure

How is most O2 moved from the alveoli to other tissues in the body?

Hemoglobin

How is most CO2 moved from the tissues to the alveoli?

Bicarbonate

How does Fick’s Law relate cardiac output to O2 utilization?

Links O2 consumption with cardiac output, QO2 = CO(A[O2] – v[O2])

Which has a higher affinity for O2 Fetal hemoglobin of adult hemoglobin?

Fetal hemoglobin

What innervates the diaphragm and where is its origin?

Phrenic nerve (C3-C5) cervical nerve

What structure controls the rate of ventilation?

Medulla oblongata

What structure regulates inspiration and expiration?

Insp: DRG, Exp: VRG

What structure establishes the breathing rhythm or rate?

Botzinger Complex

What part of the GI system is derived from endoderm?

epithelium

Where does the rest of it come from?

Mesoderm + neural crest

What parts of the GI system become secondarily retroperitoneal?

Pancreas, duodenum, ascending colon

Is it normal for the gut tube leave the body during development?

Yes

What is an omphalocele?

Congenital abdominal wall defect where baby’s abdominal organs protrude outside belly button area

If all of the large bowel is located on the left side of the body, what did not happen normally?

Normal rotation and fixation of intestines did not occur

What are the four layers of the gut wall from the esophagus to the rectum?

(Innermost) mucosa, submucosa, muscularis externa, serosa (outermost)

What is contained in the mucosa?

Epithelium, lamina propria, muscularis mucosa

What kind of epithelium does the esophagus have?

Stratified squamous epithelium

What kind of muscle is in the muscularis externa of the esophagus?

Smooth muscle

What cells protect the stomach from digesting itself?

Surface mucus cells

What cells produce stomach acid?

Parietal cells

What cells produce pepsinogen and what dose it do?

Chief cells, protein digestion

What bacteria can cause stomach ulcers?

H. pylori

What is the difference between a liver lobule and a liver Acinus?

lobules are organized into acini

Where does all of the venous drainage from the gastrointestinal system go to before it goes to the heart?

hepatic portal system

What happens if GI venous blood is restricted from flowing into the liver?

Portal hypertension

What is the role of the exocrine function of the pancreas?

Producing and secreting digestive enzymes

What is the role of the endocrine function of the pancreas?

Regulates blood sugar