Exam 2 - HD

Cardiovascular System - Urogenital System - CNS/PNS - Pregnancy/Birth - etc.

Explain the blood flow of the heart postnatally.

• Deoxygenated blood goes from right atrium → right ventricle → via pulmonary arteries → lungs

• Oxygenated blood → pulmonary veins → left atrium → left ventricle → Aorta → Body Tissue

Distinguish between Arteries, Veins and Cppilaries,

Arteries - oxygen rich blood travels from heart → body

Veins - oxygen poor blood travels back to heart

Cappilaries - oxygen and nutrients given to cells in body

Prenatal Blood-Flow

• umbilical arteries carry deoxygenated blood from fetus to placenta

• umbilical veins carry oxygenated blood from placenta to fetus

What veins and arteries does the Fetus have??

• Fetus has vein (to heart) and 2 arteries (from fetal heart) to the placenta.

Single umbilical disorder

• This is a disorder where a fetus has only one artery

• Can occur together with Down Syndrome & Failure of Kidneys

What are the two openings in the fetal heart which change from prenatal to postnatal?

• In fetal heart blood is detoured from lungs via two openings.

• Lungs are not needed because placenta provides oxygen.

• The two openings are ductus arteriosis and foramen also the umbilical vein and ductus venosous also closes.

Explain the mechanism of cephalocaudal folding.

• Folding around the formed axis.

• Embryonic disk grows not yolk sac.

• Movement of the heart crainally

• Heart is folded into embryo at the ventral part/

Which mesoderm forms cardiogenic mesoderm?

intra-embryonic mesoderm

How does the cardiac region of the embryo form??

• Embryo is a disk shape (horseshoe gap in cranial region)

• The pericardial plate is located above the cardiogenic plate infront of the embryo.

• Right now no connection between cavity and extraembryonic coelum.

• Cranial pericardium undergoes 180 rotation and now the cardiac primordium lies dorsally to the perochardial cavity.

• The pericardial cacity is bent over forward and has enclosed cardiac primordium in the front (ventrally)

• Dorsally the cardiac primordium forms two layers of the bilaminar structure.

How does the vitelline duct form??

Takes place when yolk sac becomes part of the gut tube and then forms the duct.

How do allantois form??

Form from within the connecting stalk.

How do the mesoderm cells begin to form the heart??

• Cells from mesoderm migrate through the primitive streak

  • Some of which become cardiac progenitor cells

  • Move towards head of embryo.

• Cardiac cells organise into left/right heart fields and curve around embryo (front) to form a cardiac crescent.

• BMP, Activin, TGF-B indicate mesoderm cells to differentiate into heart cells.

• From these cells two thin walled endocardial tubes emerge which then fuse at the anterior sides.

What forms the myocardium (muscle)?

Splanchnic/Visceral mesoderm

What forms the epicardium?

Surrounding mesenchyme cells thicken to form epicardium (serves as a progenitor source)

What is the purpose of the epicardium and pericardium?

• Epicardium - innermost layer of perocardium (outermost layer of heart itself)

• Pericardium - fluid filled sac which surrounds and protects the heart.

Between which layers does the coronary vasculature form?

Myoepicardium Layer: Myocardium & Epicardium

What is cardiac jelly??

• Extracellular matrix between epimyocardium and endocardial tubes

• Made from glycoproteins and collagen

• Involved in cardiac looping

What are endocardial cells?

Cells that coat the cardiac lumen surrounding the cardiac jelly.

Briefly explain how sacculations form?

• When tubular heart elongates and then forms the dilations.

What is vasculogenesis??

• Takes place in the yolk sac (early development)

• Clusters of mesodermal cells form Blood islands, which develop into:

  • Primitive blood cells

  • Endothelial cells - blood vessel walls

What are Angioblasts and what are they formed from??

• Arise from mesoderm (splanchnic and chorionic)

• They are mesenchymal cells from the yolk sac and umbilical cord

• Differentiate into blood islands

• Eventually, which form blood/blood vessels

How is the first circulatory loop formed??

Vessels from yolk sac begin to connect with vessels in embryo.

Include: dorsal aorta, umbilical arteries/veins

What is the situation of heart at 25-27 days?

• The primitive heart formed

• Looping & rotating of heart has started

• Early circulation starts

→ Heart can pump blood through the dorsal aorta and white vessels bring blood back from yolk sac to embryo.

At what stages does hematopoiesis happen in what areas of fetus??

• Formation of bloos cells

• Yolk sac 3-8 weeks

• Liver 8-22 weeks

• Then bone marrow

Thiabendazole

Compound that can lead to blood vessels falling apart.

When does the development of the aorta begin and what does it look like??

• In week 3, when main organ systems are established.

• First blood vessels are solid angioblasts then they aquire lumen to form longitudinal vessels.

Pharingeal Arches

• Aorta forms from these

• 5 pairs (1-4 & 6 - no 5)

• Have a craniocaudal development

• Form as masses of mesenchymal tissue which gets invaded by cranial neural creast cells.

• Each arch externally covered by ectoderm and internally endoderm

Pharygneal Clefts

Separate pharygneal arches

What happens to each of the Arches??

• Arch 1&2 - disappears by day 29

• Arch 3 - carotid arteries (each side of head providing blood to face neck brain & meninges)

• Arch 4 - aortic arch (left), subclavian artery (right) - arms, head, thorax

• Arch 5 - doesnt form

• Arch 6 - pulmonary arch

How do we go from pharyngeal arches to aorta?

• Due to vascularization of arches

• Run ventrally and form arteries of head neck and upper thorax on the way.

→ formation of angiogenic cluster (primordial heart)

What are the progenitor cells of coronary artery??

Epicardial cells / sinus venousus which differentiate

What does the arterial system consist of at 5 weeks??

• Left Aorta and aortic aches (3 carotid LR, 4R subclavian, 6LR pulmonary)

• Coronary

• Vitelline

• 2x Umbilical

What forms the venous system??

Sinus horn

What are the 3 systems of paired veins in the heart??

• Vitelline Veins (blood from yolk sac back to fetus, drainage of gastrontestinal tract

• Umbilical Veins (oxygenated blood from chorion and placenta to fetus - right one regresses)

• Cardinal Veins (returning blood from body)

How does the sinus venousus become part of right atrium?

• Heart starts with two equal inflow sides

• Blood shifts to the right

• Left side shrinks

• Right side becomes part of the right atrium

• Major veins (SVC, IVC) form from these structures

How do vitelline veins and the umbilical veins interact with the liver??

• Vitelline veins surround gut → form a network

• Liver grows into this network

• Network becomes hepatic sinusoids

• Umbilical veins connect to this system

• Parts of veins disappear → cleaner circulation forms

What happens to the heart after the fusion of the tubes??

• Heart tube sprouts aortic arch from outflow region

• Elongation and formation of sacculations

• New tissue growth into 4 chambers

How do the 4 chambers of the heart form?

• Within the atria ventricles form

• Openings on left & right to ventricles form

• Division between left & right atrium

• Ventricular septa forms

Cardiac Looping

How does the cardiac septa form?

• 4th week using two methods:

  • Tissue growth: fusiion of two or more actively growing masses of tissue which approach eachother

    • Fuse a single chamber into two

  • Overgrowth: growth of chamber except one narrow strip which leaves a small canal connecting two chambers.

How does the atrioventrical septum form (4th week)??

• Bulges form on dorsal & ventral walls of the AVv canal which forms the endocardial cushion septum

• Eventually, the ventricles begin to divide.

How does the atrial septa form??

Foramen Ovale

• Needs to close in newborn when air inhaled

• If open low-oxygen blood enters the left atrium

• Shunts blood from the right to the left atria via the ostium secundum

• Mostly blood via inferior vena cava and bypasses the lungs in fetus

• Associated with septum secundum

• At birth, it’s pressed against the septum premium which seals the opening.

• Can close within 18 months afterbirth otherwise surgery

Overview Steps of Ventricular Septa

• Division of ventricles

• Division of blood stream into pulmonary vein and aorta

Starting point of ventricular septa formation

One common ventricluar chamber

By end of week 4 splits into left & right ventricles

Step 1 of Ventricular septum formation

• Growth of ridge from apex towards endocardial cushion → intraventricular septum

• By week 7, the ventricles close

Step 2 of ventricular septum formation

• Begin with truncus arteriousus → splits into aorta & pulmonary trunk

• How:

  • Inside, the truncus conotruncal ridges form which grow towards eachother

  • Ridges fuse to form spiral wall called Aorticopulmonary septum.

    • Connects aorta to left ventricle and pulmonary trunk to right ventricle

  • Spiral Septum then forms aorta and pulmonary trunk.

Primitive Heart Contractions

• Begin at day 22 - unidirectional flow

• End of week 4 - rhythmic contraction

Switch from prenatal to postnatal circulation

• Ductus arteriosus closes due to muscle contractions

• Raises pressure in the left atrium

• Stops placental blood flow and decreases pressure in right atrium

• Foramen Ovale closes

• umbilical cord cut so umbilical vein and ductous venousus closes

Ductus Arteriosus

• Closure in newborn

• If it’s open mixed level of oxygenated blood enters the lungs

• Can close within 6 months after birth naturally if not then surgery is needed otherwise oxygen problems.

Atrial septum defects

1. opening below foramen ovale

2. opening at foramen ovale

Urogenital - What are reproductive organs divided into??

• Genitalia

• Subdivided into internal and external

Function of penis

Transport of urine via urethra & ejaculating sperm

What are the parts of the urethra??

• Pars prostatica (prostatic part)

• Pars membranous (membranous part)

• Pars spongiosa (spongy part)

What are some characteristics of the Urethra??

• Disadvantage at length

• Smaller risk of bladder infection

• Higher risk of uretral blockage

What is prostate enlargement??

• Frequent in men 40-50

• Growth of unknown origin

• Symptoms:

  • complaints in urination - inward swelling

  • obstruction of urethra

What are the two swelling bodies of the penis and what are their functions??

• 2x corpera cavernosa (dilation of vessels for more blood flow)

• 1x corpus spongiosum (formation of the glans penis, less swelling as that would block the urethra)

Structure of Scrotum

Spermatic Cord (function of vas deferens)??

• Tube like structure and contains vas deferens, blood vessels, and nerves

• Functions are: transport of the sperm cells from the inside to the outside.

  • Start in scrotum.

Internal Reproductive Organs

• Follows the trajectory of sperm which is testicles → epididymus → vas defers → glands.

Testicles

• Located under the epididymus

• Production of sperm cells happens here

• Connective tissue → tunica albuniginea (capsule)

Spermatogenesis

• Sperm cells in seminiferous tubules

• Leydig Cells → testosterone

• convulated tubules → straight tubules

  • Form the rete testis

What is the structure and function of the epididuymus??

• Contains the efferent ductules

• Subdivided in caput & corpus, cauda

• Function: storage of sperm cells, recycling damaged sperm cells and production of fluid.

What are the three glands in the male reproductive system??

• Seminal vesicle

• Prostate Glands

• Cowpers Glands

Ductus Deferens

• Crosses the ureter dorsally

• Drains in the ejaculatory duct and joins to form the urethrta

Seminal Vesicle

• Paired structure of 3-5cm

• Adds unto 70% fluid to semen, which contains fructose & prostaglandines.

Prostate Gland

• 30% semen

• Neutralises the acidity of the semen and improves motility.

Cowper’s Glands

• Situated near bulb of penis

• Size of a pea

• Produces alkaline fluid (lubrication) and neutralises urine

Internal vs External Genitals of Female

External - vagina, labia, pubic mound, glands

Internal - womb, ovaries, fallopian Tubes, vagina

Ovary

• Storage of egg cells

• Connected to uterus via the Fallopian Tubes

Peritoneal Cavity

• Eggs travel accross the peritonieal cavity

• Can increase risk of extrauterine pregnancy

• Possible infection

Ligaments of Ovaries

• Suspensory ligaments - contains ovarian artery

• Proper ovarian ligament- embryonic rest

• Mesovary - (part of broad ligament) fold of the peritoneal membrane.

What is the further trajectory of the egg??

• Travels through the tube

• Conception occurs in ampulla

• Implantation into the uterine wall

Uterus - Womb

• Hollow organs with tubes at both ends

• can be in specific positions (antiversion & anteflexion)

Ligaments of Uterus

• Round Ligaments - embryonic rest

• Broad Ligament - fold of peritoneum

• Cardinal Ligament - contains the uterine artery

• Uteroscaral Ligament

Vagina

• Borders the neck of the uterus

• Partially internal and external

Bartolin Glands

• Secrete mucus for lubricatrion

Skenes Glands

• Secrete mucus for lubrication

Clitoris

• Female swelling body

What does corpera cavernosa consist of??

• corpus clitoridis

• 2x crus clitoridis

Corpera spongiosa

• 2x bulbus vestbuli

• Glans Clitoridis

Peritonoeal Spaces

How does vascularisation occur in testes and ovaries and uterus??

• By testicular & ovaria artery/vein

• Both arise from aorta/vena cava (except for renal vein)

• Uterus: supplied by internal iliac artery by uterine and vaginal artery

What are the lymphoid structures??

Para aortal, iliac, inguinal

Relevant for metastasis

Somatic Innervation

• Via sacral plexus

• Efferent & Afferent

Autonomous Innervation

Inguinal Canal

Development of Inguinal Canal

Corresponsing Layers

Structure of Inguinal Canal

Contents of Inguinal Canal (male)

• Spermatic cord

• Ilionguinal nerve

Contents of Inguinal Canal (female)

round ligaments of uterus

Ilionguinal nerve

Ilionguinal nerve

Lateral Wall

Medial, Superior, Inferior Walls

Inguinal Hernia

• Protrusions of abdominal contents (through weak spots in wall.

• Can be laterl/indirect (through deep inguinal ring)

  • Or medial direct through transverse fascia.

Symptoms of Inguinal Hernia

Diagnosis of Inguinal Hernia

• Physical examination

• Use of imaging techniques (ultrasound, MRI etc)

Treatment of Inguinal Hernia

• If no strangulations → no treatment

• If strangulated then emergency surgery

Variety of Treatments