Human Circulatory System Quiz

Book Information

• Book Title: Seeley's Essentials of Anatomy & Physiology
• Edition: Eleventh
• Authors: Cinnamon VanPutte, Jennifer Regan, Andrew Russo
• Publisher: McGraw-Hill

Chapter 13: Blood Vessels and Circulation - Lecture Outline

Objectives

• Identify anatomical and physiological deviations of the circulatory system.
• Explain the clinical significance of blood vessels and blood circulation.
• Describe the structure and function of arteries, capillaries, and veins.

Blood Vessels

• Blood vessels (outside the heart) are divided into two classes:
  • Pulmonary vessels: transport blood from the right ventricle to the lungs and back to the left atrium.
  • Systemic vessels: transport blood from the left ventricle to all parts of the body and back to the right atrium.

Blood Vessel Functions

• Carry blood
• Exchange nutrients, waste products, and gases within tissues.
• Transport substances
• Regulate blood pressure
• Direct blood flow to tissues

Vessel Structures

• Arteries:
  • Carry blood away from the heart
  • Thick walls with a lot of elastic tissue.
• Veins:
  • Carry blood toward the heart
  • Thinner walls with less elastic tissue.
• Capillaries:
  • Site of exchange between blood and tissue fluids.

Blood Flow

• Blood flows from arteries to arterioles, then into capillaries, then into venules, and finally into veins. Veins return blood to the heart.

Blood Vessel Walls

• Tunica Intima: innermost layer, simple squamous.
• Tunica Media: middle layer, smooth muscle with elastic and collagen fibers
• Tunica Adventitia: outermost layer, connective tissue.

Types of Arteries

• Elastic Arteries:
  • Largest diameter
  • Thickest walls
  • Example: aorta and pulmonary trunk
• Muscular Arteries:
  • Medium to small size
  • Thick in diameter
  • Contain smooth muscle cells
  • Control blood flow to body regions

Capillaries

• Blood flows from arterioles into capillaries.
• Capillaries form networks.
• Blood flow regulated by smooth muscle cells (precapillary sphincters).

Capillary Structure

• Walls consist of a single layer of endothelium surrounded by delicate loose connective tissue.

Types of Veins

• Small veins: All three tunics are present.
• Medium-sized veins: Collect blood from small veins and deliver to large veins.
• Large veins: Contain valves.

Pulmonary Circulation Vessels

• Pulmonary circulation: Blood vessels carrying blood from the right ventricle to lungs and back to the left atrium.
• Pulmonary trunk: Blood pump from right ventricle towards lungs.
• Pulmonary veins: Exit lungs, carrying oxygen-rich blood to left atrium.

Systemic Circulation Vessels

• Systemic circulation carries blood from the left ventricle to the tissues of the body and back to the right atrium.
• Oxygenated blood from the pulmonary veins passes to the left atrium, then to the left ventricle, and then to the aorta.
• Arteries distribute blood from the aorta to all portions of the body.

Blood Flow Through Circulation (Figure 13.5)

• Details the flow of oxygenated and deoxygenated blood through the heart, lungs, and body tissues.

Parts of the Aorta (Figure 13.5)

• Ascending aorta: Passes superiorly from left ventricle.
• Aortic arch: Three major arteries carry blood to the head and upper limbs.
• Descending aorta: Extends through thorax and abdomen to pelvis.
• Thoracic aorta: Part of descending aorta extending through thorax to diaphragm
• Abdominal aorta: Descending aorta from diaphragm to common iliac arteries

Major Arteries (Figure 13.6)

• Diagram displays locations of various arterial branches supplying different parts of the body.

Branches of the Aorta (Figure 13.7)

• Illustration shows the various arteries branching off from the aorta, including specific named branches.

Arteries of the Head and Neck

• Branches of aortic arch: brachiocephalic, left common carotid, left subclavian arteries
• Brachiocephalic artery: First branch off aortic arch, supplies blood to right side of head and neck.
• Left common carotid artery: Second branch, supplies left side of head and neck.
• Left subclavian artery: Third branch, supplies left upper limbs.
• Right common carotid artery: Branches off brachiocephalic artery, supplies right side of head and neck.
• Right subclavian artery: Branches off brachiocephalic artery, supplies right upper limbs.
• Details of specific arteries: Superficial temporal, Posterior auricular, Occipital, Maxillary, Internal carotid, External carotid, Carotid sinus, Vertebral, Facial, Lingual, Superior thyroid, Common carotid, Thyrocervical trunk.

Arteries of the Upper Limbs

• Axillary arteries: Continuation of subclavian, supply blood deep in clavicle
• Brachial arteries: Continuation of axillary, where blood pressure measurements are taken.
• Ulna arteries: Branch of brachial, near elbow
• Radial arteries: Branch of brachial, supply blood to forearm and hand, pulse taken here

Arteries of the Lower Limbs

• Femoral arteries: Supply thigh
• Popliteal arteries: Supply knee
• Anterior and posterior tibial arteries: Supply leg and foot
• Fibular arteries: Supply lateral leg and foot

Veins (general information)

• Return blood to the heart.
  • Systemic circulation - Deoxygenated blood
  • Pulmonary circulation - Oxygenated blood

Superior and Inferior Vena Cava

• Superior vena cava: Blood return from head, neck, thorax, and right upper limbs to right atrium.
• Inferior vena cava: Blood return to right atrium from abdomen, pelvis, and lower limbs.

Major Veins(Figure 13.14)

• A diagram illustrating major veins with labeled names and positions.

Veins of the Head and Neck

• External jugular vein: Drains head and neck, empties into subclavian veins.
• Internal jugular vein: Drains blood from brain, face, neck, empties into subclavian veins.
• Subclavian veins: Forms brachiocephalic veins
• Brachiocephalic veins: Joins to form superior vena cava.

Veins of the Upper Limbs

• Brachial veins: Empty into axillary vein
• Cephalic veins: Empty into axillary and basilic vein
• Median cubital veins: Connect to cephalic vein, near elbow

Veins of the Thorax

• Right and left brachiocephalic veins: Drain blood from thorax to superior vena cava.
• Azygos veins: Drain blood from thorax to superior vena cava
• Internal thoracic veins: Empty into brachiocephalic veins
• Posterior intercostal veins: Drain posterior thoracic wall, into azygos vein on right, hemiazygos on left.

Veins of the Abdomen and Pelvis

• Common iliac vein: Formed from external and internal iliacs, empties into inferior vena cava.
• External iliac vein: Drains lower limbs, empties into common iliac vein.
• Internal iliac vein: Drains pelvic region, empties into common iliac vein.
• Renal vein: Drains blood from kidneys.

Hepatic Portal System

• Liver processes substances absorbed by the intestinal tract.
• Portal system: vascular system from capillaries in viscera to capillaries in liver.
  • Uses splenic vein and superior mesenteric vein

Veins of the Lower Limbs

• Femoral veins: Drain blood from thigh, empty into external iliac vein.
• Great saphenous veins: Drain from foot, empty into femoral vein.
• Popliteal veins: Drain blood from knee, empty into femoral vein.

Blood Pressure

• Measurement of force blood exerts against vessel walls.
• Systolic pressure: Pressure during heart contraction.
• Diastolic pressure: Pressure during heart relaxation.
• Average blood pressure: 120/80 mmHg
• Pulse pressure: Difference between systolic and diastolic pressure.

Measuring Blood Pressure

• Procedure for measuring blood pressure (using a sphygmomanometer).

Capillary Exchange

• Most exchange across capillary walls occurs by diffusion.
• Factors affecting fluid movement across capillary walls include blood pressure, capillary permeability, and osmosis.
• Net movement of fluid from blood to tissues.
• Excess fluid removed by lymphatic system.

Local Control of Blood Flow

• Regulated by relaxation and contraction of precapillary sphincters
• Controlled by metabolic needs of tissues
• Blood flow increased by decreased oxygen levels, concentration of nutrients

Nervous Control of Blood Flow

• Vasomotor center (sympathetic division) controls blood vessel diameter
• Vasomotor tone: state of partial blood vessel constriction. Increased tone leads to vasoconstriction and increased blood pressure.

Hormonal Control of Blood Flow

• Sympathetic division regulates blood flow through the release of epinephrine and norepinephrine from the adrenal medulla.
• In most vessels, hormones cause constriction, reducing blood flow. In certain tissues like skeletal and cardiac muscle, they cause dilation, increasing blood flow.

Mean Arterial Pressure (MAP)

• Calculated measure of average arterial pressure.
• MAP changes in response to changes in heart rate (HR), stroke volume (SV), and peripheral resistance (PR)

Baroreceptor Reflexes

• Respond to stretch in arteries caused by increased pressure.
• Located in carotid sinuses and aortic arch.
• Activate responses to maintain blood pressure within normal range.

Chemoreceptor Reflex

• Sensitive to changes in blood oxygen, carbon dioxide, and pH.
• Located in carotid bodies and aortic bodies near carotid sinuses and aortic arch.
• Send action potentials to medulla oblongata for appropriate response.

Adrenal Medullary Mechanism

• Increased sympathetic stimulation to adrenal medulla leads to release of epinephrine and norepinephrine into blood.
• Increased heart rate, stroke volume, and vasoconstriction.
• Vasodilation in skeletal and cardiac muscle.

Renin-Angiotensin-Aldosterone Mechanism

• Reduced blood flow triggers kidneys to release renin, converting angiotensinogen to angiotensin I, further converted by an enzyme to angiotensin II
• Angiotensin II causes vasoconstriction and stimulates adrenal cortex to secrete aldosterone.
• Aldosterone conserves sodium and water, resulting in less water lost through urine and maintaining blood pressure.

Antidiuretic Hormone Mechanism

• Nerve cells in the hypothalamus release ADH when plasma solute concentration or blood pressure decreases.
• ADH causes kidneys to absorb more water, reducing urine volume.
• Result is maintenance of blood volume and blood pressure.

Long-Term Control of Blood Pressure

• Blood pressure regulated by changes in blood pH, and by chemoreceptors in the medulla, carotid, and aortic bodies.
• Increased pH inhibits vasomotor and cardioregulatory centers, leading to vasodilation and decreased heart rate/stroke volume.
• Decreased pH stimulates vasomotor and cardioregulatory centers, causing vasoconstriction and increased heart rate/stroke volume.

Aging and Blood Vessels

• Arteriosclerosis: Arteries lose elasticity
• Atherosclerosis: Type of arteriosclerosis (from plaque deposits in artery walls).
• Factors contributing to atherosclerosis include lack of exercise, smoking, obesity, high cholesterol/trans fat diets, and certain genetics.

Test your knowledge on the human circulatory system with this quiz. Covering blood vessels, their functions, and blood pressure concepts, it will challenge your understanding of how blood circulates throughout the body. Ideal for biology students or anyone interested in human anatomy.