Lecture 15: Aortic Arches And Veins Flashcards Preview

Comparative Anatomy > Lecture 15: Aortic Arches And Veins > Flashcards

Flashcards in Lecture 15: Aortic Arches And Veins Deck (18):
1

What are the components of the vertebrate cardiovascular system?

Components:
* Muscular pump:
- Heart
* Vessels carrying blood away from the heart:
- Arteries: Note that whether they are carrying oxygenated or deoxygenated blood is immaterial.
* Vessels carrying blood toward the heart:
- Veins
* A series of connecting vessels associated with the pharyngeal arches:
- Aortic arches

- See Slide 6

2

Describe the aortic arch

- Aortic arches form during embryonic development.
- Typically, there are six pairs of aortic arches.
- The embryonic pattern is relatively unchanged in fishes but is considerably modified in tetrapods.
- Six pairs of aortic arches connect: the paired dorsal aortae to the ventral aorta.
- In fishes aortic arches are interrupted by the capillary beds of gills.

3

Describe the aortic arch pattern in sharks

* First aortic arch pair is lost.
* Afferent and efferent branchials carry blood to and from gills.
* Afferent and efferent spiraculars carry blood to first pair of gills (spiracles).
- Pseudobranch.
* Arteries off efferent aortic arches:
- Hypobranchials
- External carotids

* In teleosts:
- First aortic arch pair is lost.
- Similar to pattern in shark.

4

Describe the aortic arch patterns of lungfish

- Similar to that in fishes.
- Pulmonary artery develops from arch VI.
- Arches III and IV lose their capillary beds

5

Describe aortic arch formation/fate

* Aortic arch pattern in non-mammalian tetrapods:
- Typically, first and second pairs of aortic arches form but later degenerate.
- Third pair of aortic arches form the internal carotids and common carotids.
- Note that external carotids are the cranial extensions of the paired ventral aortae cranial to the third arches.
- Fourth pair of aortic arches form the paired aortic arches.
- Fifth pair of arches degenerate.
- Sixth pair of arches become associated with the pulmonary system

6

Describe the aortic arch pattern in Amphibians and Reptiles

- Loss of arch pairs I, II, V.
- Loss of capillary beds in remainder of arches.
- Arch pair VI form pulmonary arteries.
- Arch pair IV form systemic arches.
- Arch pair III associated with carotid system.
- Ductus caroticus.

7

Describe the aortic arch pattern in Birds

- Loss of arch pairs I, II, V.
- Loss of left aortic arch IV.
- Right aortic arch IV becomes the systemic arch (arch of the aorta).
- Loss of ductus caroticus and ductus venosus.

8

Describe the aortic arch pattern in mammalian embryos

- First and second pairs of aortic arches form but later degenerate.
- Third pair of aortic arches (plus dorsal aortae cranial to third arches) form the internal carotids.
- Note that external carotids are the cranial extensions of the paired ventral aortae cranial to the third arches.
- The common carotids are derived from the ventral aortae between the third and fourth aortic arches.
- Right fourth aortic arch forms the right subclavian artery.
- Left fourth aortic arch forms the aortic arch.
- Fifth pair of arches degenerate (Just barely form—only remnants).
- Sixth pair of arches become associated with the pulmonary system.

9

Describe the aortic arch pattern in adult mammals

- Similar to pattern in birds.
- Left fourth aortic arch is retained as systemic arch (= aortic arch).
- Patent ductus venosus retained in fetus.

- See Slide 17

10

Describe the 3 aortic branches and their components

1. Dorsal intersegmentals:
- Cervical, thoracic (intercostals), lumbar intersegmentals
- Subclavians
- Iliac arteries

2. Lateral intersegmentals:
- Mesonephric arteries
- Adrenal arteries
- Renal arteries
- Gonadal Arteries

3. Ventral intersegmentals:
* Vitelline vessels:
-Celiac artery (trunk)
- Superior/inferior mesenterics
* Allantoic vessels:
- Umbilical arteries

- See Slide 20

11

Describe the dorsal aortic branch

The dorsal aorta branches are similar in all vertebrate groups.
* Paired visceral branches of the aorta:
- Renal arteries
- Gonadal arteries
* Unpaired visceral branches:
- Celiac trunk: In mammals, gives rise to the left gastric, common hepatic, and splenic arteries;
- Superior mesenteric: In humans, supplies the intestine and colon as far distal as the left colic flexure
- inferior mesenteric artery: Supplies the rest of the colon.

- See Slide 23-24

12

Describe the basic venous pattern

* The venous system in fishes is similar to the basic vertebrate venous system and to the general vertebrate embryonic venous system.
* This basic system is bilaterally symmetrical and consists of:
- A pair of anterior cardinal veins which drain the cranial region
- A pair of jugular veins which drain the head
- A pair of posterior cardinal veins draining the posterior body
- A pair of lateral veins draining the lateral body walls
- A pair of vitelline veins from the yolk sac
- An unpaired subintestinal vein.
* On each side, the anterior and posterior cardinal veins empty into one of a pair of common cardinal veins.
* The paired common cardinals, jugulars, and vitelline veins all empty into the sinus venosus.

13

Describe cardinal vein pairs, and the overall fate of the anterior cardinal veins.

* Cardinal vein pairs: Anterior, Posterior, and Common
* Fate of the anterior cardinal vein:
- Anterior cardinals form the internal jugulars.
- Connection (anastomosis) between the two is the left brachiocephalic vein.
- All blood from the head is shunted to the right and drained into the right cardinal vein --> Superior Vena Cava

* Both the anterior and the posterior pairs of cardinal veins empty into the paired common cardinals, which empty into the sinus venosus.
- See Slides 28 & 29

14

Describe additional cardinal veins and the formation of the inferior vena cava

* Additional cardinal veins:
- Subcardinals
- Supracardinals
* Formation of the inferior vena cava:
- The inferior vena cava is built as a patchwork quilt asymmetrically from remnants of the following:
-- Vitelline vein
-- Subcardinals
-- Supracardinals
-- Iliacs

* See Slides 31, & 32

15

What are the 3 portal systems?

* Portal systems are named according to the termination of the first vein in the series. The three portal systems include:
1. Hepatic portal
-- Right vitelline = hepatic portal vein
-- Proximal vitelline veins = hepatic veins
2. Renal portal
-- Proximal ends of posterior cardinals degenerate.
-- Distal ends of posterior cardinals carry blood to kidneys = renal portal veins.
-- Subcardinals return blood to sinus venosus.
3. Hypophyseal portal system

16

What is the definition of a portal system?

A system of veins that carries blood toward the heart but ends in a capillary bed in an organ other than the heart.

See Slide 36

17

Describe the hepatic portal system

* The hepatic portal system is an unpaired system of veins developed from one of the vitelline veins.
* These veins carry oxygen-poor but nutrient rich blood from the digestive tract to the liver via the hepatic portal vein.
* The nutrients are processed in the liver in a variety of ways, and the nutrient-poor blood finally passes into the sinus venosus via the hepatic veins, which are the remnants of the proximal ends of the embryonic vitelline veins.
* Note that the hepatic veins are "traditional" veins. Do not confuse them with the hepatic portal vein.
* All vertebrates have a hepatic portal system.
* This system basically involves a disintegration of certain veins and an interruption of others with capillary beds.
- The right vitelline and right branch of the subintestinal veins disintegrate posterior to the liver.
- The left vitelline and part of the old subintestinal persist as the hepatic portal vein.
- This vein leads into the liver and breaks into capillaries.
* The hepatic veins are the anterior ends of the old vitelline veins.
- They lead from the liver to the sinus venosus.

18

Describe the renal portal system

* In the formation of the renal portal system the postcardinal veins form capillary connections with the kidney.
- The renal portal system is built from a new pair of veins:
-- Subcardinals:
--- Provide an alternate path for blood flowing from the distal parts of the posterior cardinals and the caudal vein to the proximal parts of the posterior cardinals.
--- Subcardinals form between the two kidneys, pass anteriorly from the anal loop, and swing out to join the postcardinals anterior to the kidneys.
--- Subcardinals also develop capillary connections with the kidney.
--- Thus, blood may flow to the kidneys via a couple of routes.
* The subcardinals are not present in primitive mammals.
* Both the posterior cardinals and the subcardinals drain the kidneys.
- By eliminating the distal portion of each subcardinal and a middle element of each posterior cardinal, a new blood return pathway is created which forces all blood returning from the posterior part of the body into a capillary plexus in each kidney.
- From here blood enters the subcardinal remnants and finally terminates back into the posterior cardinals toward the heart.
- In this pattern, the distal parts of the posterior cardinals become the renal portal veins
* See Slide 41 and 43 (Less certain about what the objective for 43 is asking.