W9 - cardiovascular system 2 the blood vessels

Question 1

Define the pulmonary and systemic circulations

Answer 1

Pulmonary circulation: The circulation between the heart and the lungs
Systemic circulation: The circulation between the heart and the body
- Consists of arteries, veins and capillaries, which are the three main types of blood vessels
Arteries = away from heart, veins = toward heart, capillaries = connect arteries and veins

Question 2

Describe the three main tunics of the wall of a typical blood vessel

Answer 2

Question 3

Compare and contrast the structure of arteries, veins and capillaries and explain how this relates to their functions

Answer 3

Arteries: Thick-walled, small lumen, high pressure; carry blood away from heart. Three types: elastic, muscular, arterioles. More elastic/collagen fibers. Round lumen. Internal & external elastic laminae aid in stretch/recoil.

Veins: Thin-walled, large lumen, low pressure; carry blood to heart. Types: large, medium-small, venules. Contain valves (from tunica intima) to prevent backflow, especially in lower limbs. Irregular/collapsed lumen.

Capillaries: Smallest vessels; connect arterioles & venules (anastomosis). Only have tunica intima (endothelium + basement membrane) for efficient gas/nutrient exchange.

Question 4

TYPES of capillaries

Answer 4

• There are three main types of capillaries, which are continuous capillaries, fenestrated capillaries and sinusoids or discontinuous capillaries.
  
  • These classifications depend on the nature of the endothelium.
  • Continuous capillaries: the endothelial cells form a complete lining with no gaps.
  • Fenestrated capillaries and sinusoids: the endothelial cells contain gaps which allow larger substances to pass through.
  • As the name suggests, these gaps are called fenestrations or pores in fenestrated capillaries.
    The gaps are larger in sinusoids than in fenestrated capillaries and the basement membrane is also discontinuous or even absent, unlike in fenestrated capillaries where the basement membrane is continuous.

Question 5

Describe the aorta and the superior and inferior vena cava
Key concepts:

Answer 5

Question 6

Aorta

Answer 6

Aorta – Largest Artery

Originates from left ventricle; carries oxygenated blood to the body.

3 Parts:

Ascending Aorta: Very short; gives off R & L coronary arteries to supply the heart.

Aortic Arch: Curves left; branches (R → L):
Brachiocephalic trunk → R common carotid & R subclavian
L common carotid
L subclavian
Carotids → head/neck; Subclavians → upper limbs

Descending Aorta: Continues down from arch
Thoracic aorta (in thorax)
Passes through aortic hiatus in diaphragm
Abdominal aorta → bifurcates at L4 into R & L common iliac arteries → pelvis/lower limbs

Question 7

Vena Cavae

Answer 7

Question 8

Head and Neck Arteries

Answer 8

• Begins with the right and left common carotid arteries
  
  • Each common carotid artery bifurcates into an external carotid artery and an internal carotid artery.
  • The internal carotid arteries form a major contribution to the blood supply of the brain, together with branches of the right and left subclavian arteries called the vertebral arteries.
  • Vertebral arteries travel in the transverse foramina of the cervical vertebrae before entering the skull through foramen magnum and uniting to form an artery called the basilar artery.
  • Branches of the basilar artery and internal carotid arteries form an anastomosis of arteries supplying the brain called the cerebral arterial circle, or the circle of Willis.

Common Carotid Arteries
- Travel superiorly through the neck and at approximately the level of the third or fourth cervical vertebra, they bifurcate into external and internal carotid arteries.
External Carotid Artery
- Supply blood to the external structures of the head and neck via many branches
Internal Carotid Artery
- Continue into the skull through openings called the carotid canals to supply blood to internal skull structures.
The internal carotid arteries do not branch until they enter the skull.

Question 9

Thorax arteries

Answer 9

Question 10

Abdomen arteries

Answer 10

Question 11

Pelvis arteries

Answer 11

Question 12

Upper limb arteries

Answer 12

Question 13

Lower Limb arteries

Answer 13

Question 14

Head and Neck veins

Answer 14

External jugular vein
- Travels inferiorly through the neck, superficial to the sternocleidomastoid muscle.
- It drains blood from the external structures of the head and neck into the subclavian vein
Internal jugular vein
- Travels inferiorly through the neck, deep to the sternocleidomastoid muscle.
- It travels firstly with the internal carotid artery and then continues with the common carotid artery.
- It arises from the continuation of one of the dural venous sinuses as it exits the skull through the jugular foramen.
The internal jugular vein drains blood from the internal skull structures and merges with the subclavian vein to form the brachiocephalic vein.

Question 15

Thorax veins

Answer 15

Coronary sinus: The vein that drains blood from the heart

Question 16

Abdomen veins

Answer 16

Arteries: Renal, Gonadal, Celiac Trunk, Superior & Inferior Mesenteric

All (except celiac trunk) have matching veins.

Renal veins drain into IVC; L renal vein crosses midline to reach IVC (right side).

R gonadal vein → IVC; L gonadal vein → L renal vein.

Superior & inferior mesenteric veins → portal venous system, not IVC.

Portal vein drains GI tract → liver for nutrient processing & detox, then blood enters systemic circulation.

Question 17

Pelvis veins

Answer 17

• Major arteries of the pelvis are the internal iliac arteries, which arise from the common iliac arteries.
  
  • There are common iliac veins that travel with the common iliac arteries and these merge to form the IVC.
    Similarly, there are internal iliac veins that travel with the internal iliac arteries.

Question 18

Define tributary, superficial vein, deep vein and venae comitantes

Answer 18