Lecture 10: Heart

Question 0

Embryonic heart tube
Septation
When is it complete by?
What does it separate?

Answer 0

You have blood come in the venous end then gets pumped out the arterial end. Refer to slide 9
Separation- septa develop to separate atrium and ventricle. Complete by end of 5th week. Septum doesn’t close communicating between L & R atria = foramen ovale. Important for embryos because blood goes through there.

Question 1

Development of the heart.
When does development begin?
When does it begin to contract?
Look at slide 8 and learn it

Answer 1

3rd week
Day 21blood is circulating
Day 22: heart starts pumping
Day 35 bending complete

Question 2

Aortic arches. How do we end up with the varies arteries.

What are the derivatives?

Answer 2

1st pair: become part of maxillary artery in head
2nd pair: largely disappears
3rd: common and internal carotid arteries
4th: right subclavian artery and aortic arch
5th pair: degenerates
6th pair: ductus arteriosus and part of pulmonary arteries
Slide 12

Question 3

What is the course of recurrent laryngeal nerves?

Answer 3

It is a branch of CN 10 vagus nerve.
Right recurrent laryngeal nerve hooks around the right subclavian artery (from 4th aortic arch)
Left recurrent laryngeal nerve remains hooked around 6th aortic arch which becomes the ductus arteriosus. In adult, nerve hooks around ligamentum arteriosum and the arch of the aorta.
They supply the laryngeal muscles
Slide 14
They are current because there like an electric fence carrying current ready to zap the laryngeal muscles

Question 4

Fetal circulation differences
Slide 16
Fetus receives oxygenated blood from mother via?
How does the blood bypass the liver?
Blood from IVC enters RA and some flows to LA directly through?
Most of blood in pulmonary trunk is shunted via?

Answer 4

• Foetus receives oxygenated blood from mother via umbilical vein
• blood mostly bypasses the liver via ductus venous.
• ductus arteriosus takes blood from pulmonary trunk and dumps it straight into the aorta, coz babies don’t breath capish. When born, this ductus shut the hell up

Question 5

Describe the blood flow through the heart

Answer 5

SVC + IVC - right atrium - right ventricle -pulmonary trunk- pulmonary arteries -lungs-pulmonary veins-left atrium- left ventricle - aorta - body

Question 6

Surface projections of the heart.
Describe we’re you can locate the aortic valve auscultation point, pulmonary valve auscultation point, also mitral and tricuspid valve auscultation points. Slide 18

Answer 6

Aortic- right side in 2nd intercostal space. Right ➡Ate Rat shit
Pulmonary valve left side 2nd intercostal space
Tricuspid -right side 5th intercostal space-sternal margin ➡tri 3 +2 =5 fifth space, good maths. Everyone Tries to be R handed coz its cooler
Mitral- 5 intercostal space further down near end of cartilage -in line with middle of clavicle

Question 7

Label the diagram on slide 20, 21, 22, 23, 24, 25, 26

Answer 7

Do it

Question 8

Phrenic nerve. It also carries sensory fibres from wear?

Answer 8

Primary source of sensory fibres from pericardium.

Pain sensation carried by phrenic nerve is refer to C3-C5 dermatomes

Question 9

Coronary arteries supply what?

Label diagram on slide 27 and 28

Answer 9

Supply myocardium and epicardium

Originate at base if ascending aorta

Question 10

Cardiac veins and coronary sinuses.

Label diagram slide 30 and 31

Answer 10

Yeeeep

Question 11

What is the Name of the remnant of the foramen ovale?

Answer 11

Fossa ovalis

Slide 32, know how to label

Question 12

What is the function of the moderator band

Answer 12

Keeps the ventricles from over stretching

Slide 33

Question 13

Label slide 34, and 35

Question 14

Describe how conduction is spread through the heart

Answer 14

• sinoatrial node fires 70 x/min
• cardiac muscle of right atrium conducts and contracts
• impulses reach AV node
• impulses travel from AV node down the IV septum via AV bundles
• AV bundles branch to purkinje fibres that supply papillary muscles and walls of ventricles

Question 15

What is the sympathetic innervation of the heart?

Answer 15

• Pre-sympathetic fibres from IML of T1-T5
• post-synaptic sympathetic fibres from cervical and superior thoracic sympathetic ganglia and end in SA and AV nodes
• sympathetic stimulation: ⬆HR, ⬆force of contractions, indirectly dilates coronary arteries by inhibiting their constriction ➡supplies more oxygen and nutrients to myocardium during increased activity

Question 16

What is the parasympathetic innervation of the heart?

Answer 16

• pre-synaptic fibres from vagus nerve
• post-synaptic fibres from intrinsic ganglia located near SA and AV nodes and along coronary arteries
• parasympathetic stimulation ⬇Hr, ⬇force of contractions, constricts coronary arteries
• saves energy between period of increased demand

Question 17

Label and understand diagram on slide 41 :)

Question 18

Can refer to text book pg 139

Answer 18

He

Question 19

What is the embryonic heart structure of these adult derivatives? 
Pulmonary trunk and aorta 
Smooth part of right and left ventricle 
Pectinated part of r and l ventricles 
Pectinate walls of r and l atrium

Answer 19

Meh slide 13