Blood Vessels & CirculationCardiovascular System - 2

for student copy

Circulation of Blood• left side heart aorta branches of

aorta (arteries) arterioles capillaries venules veins vena cava right side of heart pulmonary circulation left side of heart

Arteries • any blood vessel carrying blood away from

heart• designed to withstand higher pressure than

veins• elastic: must swell to take up blood expelled by

the heart• swelling stretches elastic tissue & keeps the

blood pressure fairly high between heart beats• small arteries (arterioles)have muscles that

control their diameters (precapillary sphincters): used to control blood flow thru an organ

Capillaries • where materials delivered to/from

cells blood• walls 1 squamous cell thick: so

diffusion very fast• not elastic

Types of Capillaries

Veins • any blood vessel with blood flowing

toward the heart• low pressure vessels• can expand to accommodate

differing volumes of blood flow• contain valves to stop backflow of

blood

cross-section of vein with valve

Comparing Arteries & Veins

Blood Flow • active organs like the liver, brain,

kidneys have high blood flows @ rest• Kidney: ~25% of cardiac output• GI tract & liver: ~25%• Muscle circulation @ rest: ~20%• Brain: ~ 15%

Adaptions for Exercise• during exercise: blood flow to active

muscles greatly increases: up to 80% of cardiac output

• Blood flow to skin increases or decreases to regulate body temperature

Blood Flow Through Organs• regulated by nerves & chemical agents– both cardiac output & blood vessel

diameter controlled by hormones & nerves– controlled by ANS

• increasing blood pressure can increase blood flow increasing blood pressure increases cardiac output constricts many arterioles more blood volume to other organs

Pulmonary Circuit• circuit of blood vessels from heart

lungs heart• rt ventricle of heart pumps blood thru

pulmonary trunk branches into rt & lt pulmonary arteries smaller arterioles capillaries that surround the alveoli (little air sacs) where oxygenation of RBCs & get rid of carbon dioxide

Pulmonary Circuit cont’d• from capillaries venules which

merge into larger & larger veins until they merge into the pulmonary veins: 2 pulmonary veins from each lung empty into lt atrium

Aorta– Ascending Aorta

• begins @ aortic semilunar valve– rt & lt coronary arteries

• supply rt & lt sides of heart– Aortic Arch

• 3 important branches: brachiocephalic trunk, lt common carotid, lt subclavian

– Descending Aorta• travels posterior to heart

– portion in thorax called thoracic aorta– Portion in abdominal cavity called abdominal aorta

Common Carotids• branch into:• External Carotid arteries– supply blood to neck, esophagus,

pharynx, larynx, lower jaw, face• Internal Carotid arteries– supply blood to the brain (with the rt & lt

vertebral arteries: branches of subclavian arteries)

Arteries of Upper Extremities

• Axillary artery:– branch of

subclavian artery– becomes Brachial

artery in the arm• branches into Radial

(pulse)& Ulnar arteries in lower arm

Branches of the Abdominal Aorta• descends slightly to the left of the

vertebral column• retroperitoneal• Branches:1. Celiac Trunk (3 branches)– Lt gastric artery: stomach– Splenic artery: spleen: stomach, & pancreas– Common Hepatic Artery: liver, stomach,

gallbladder, & duodenum

Branches of the Abdominal Aorta

2. Superior Mesenteric Artery:• pancreas, duodenum, small

intestines, most of large intestines

3. Inferior mesenteric Artery:• terminal portion of the colon,

sigmoid colon, & rectum

Branches of the Abdominal Aorta

5 Paired Arteries from Abdominal Aorta

1. Inferior phrenic arteries– inferior surface of diaphragm

2. Suprarenal arteries– Adrenal glands

3. Renal arteries– kidneys

4. Gonadal arteries– Testicular or Ovarian

5. Lumbar arteries– vertebrae, spinal cord, abdominal wall

Iliac Arteries• Abdominal Aorta branches into rt & lt

Common Iliac Arteries @ L4 level• each branches internal & external

iliac arteries @ level of lumbosacral joint

• Internal Iliac Arteries:– bladder, external genitalia, uterus,

vagina• External Iliac Arteries:– blood to lower extremities

External Iliac Arteries• when cross over to medial surface of thigh

become Femoral Arteries– branches to deep femoral & superficial femoral

• when reaches knee becomes Popliteal Artery

• where it branches posterior & anterior Tibial arteries

• Posterior Tibial Artery divides Medial & Plantar Arteries

Arteries of the Lower Extremities

Superior & Inferior Vena Cava

• SVC: large vein that receives blood from upper body (head, neck, upper limbs)

• IVC: large vein that receives blood from the lower body (lower limbs, pelvis, abdomen)

• both return blood to right atrium

Systemic Veins• Internal Jugular descends parallel to

common carotid arteries brachiocephalic veins(just as they merge with the subclavian veins

Veins of the Upper Extremity

• Radial & Ulnar veins parallel arteries of same name then merge to become Brachial vein axillary vein subclavian vein

• Vein draw blood from: median cubital

Veins of the Abdomen & Pelvis• External Iliac veins

receive blood from the lower extremities --> join with Internal Iliac veins to form the rt & lt Common Iliac Veins fuses with the IVC

Hepatic Portal System• Blood leaving the digestive organs by

veins is rich in nutrients….instead of returning directly to IVC heart this blood is shunted to liver first

• This way liver can store, convert, detoxify, or excrete materials as necessary

• Hepatic Portal vein enters liver with nutrient rich blood