Blood vessels and circulation
Blood Vessels
PART A
Blood Vessel Anatomy
Structure of vessel walls
Structure of vessel walls
Tunica externa or adventitia
Collagen fibers that protect and reinforce the vessels
Blood is carried in a closed system of vessels that begins and ends at the heart 5 types of blood vessels
Arteries – carries blood away from the heart
Arterioles – smallest arteries
Capillaries - place for diffusion
Venules - smallest veins
Veins – carries blood to the heart
Lumen – central blood-containing space
Walls of arteries and veins contain three distinct layers
Tunica intima endothelium and connective tissue Internal elastic membrane
Tunica media Smooth muscle, collagen fibers External elastic membrane Controlled by sympathetic nervous system
Vasoconstriction/vasodilation
Generalized Structure of Blood Vessels
Differences between arteries and veins
Vasavasorum Compared to veins, arteries
Have thicker walls
Have more smooth muscle and elastic fibers
Are more resilient
Histological Structure of Blood Vessels
Arteries
Capillaries
Capillaries
Continuous capillaries
Retain blood cells and plasma proteins Fenestrated capillaries
Contain pores
Sinusoids Contain gaps between endothelial cells Allow larger solutes to pass
Undergo changes in diameter
Vasoconstriction – decreases the size of the lumen
Vasodilation – increases the size of the lumen Classified as either elastic (conducting) or muscular (distribution) Small arteries (internal diameter of 30 µm or less) are called arterioles
Resistance vessels (force opposing blood flow)
An endothelial tube inside a basal lamina These vessels
Form networks
Surround muscle fibers
Radiate through connective tissue
Weave throughout active tissues Capillaries have two basic structures
Continuous
Fenestrated Sinusoids
Continuous Capillaries
Continuous capillaries are abundant in the skin and muscles
Endothelial cells provide an uninterrupted lining
Adjacent cells are connected with incomplete tight junctions
Intercellular clefts allow the passage of fluids
Continuous Capillaries
Continuous Capillaries
Continuous capillaries of the brain:
Have tight junctions completely around the endothelium
Constitute the blood-brain barrier
Continuous Capillaries
Fenestrated Capillaries
Fenestrated Capillaries
Found wherever active capillary absorption or filtrate formation occurs (e.g., small intestines, endocrine glands, and kidneys) Characterized by:
An endothelium riddled with pores (fenestrations)
Greater permeability than other capillaries
Fenestrated Capillaries
Sinusoids
Highly modified, leaky, fenestrated capillaries with large lumens Found in the liver, bone marrow, lymphoid tissue, and in some endocrine organs Allow large molecules (proteins and blood cells) to pass between the blood and surrounding tissues Blood flows sluggishly, allowing for modification in various ways
Sinusoids
Sinusoids
Capillary Beds
Collateral arteries
Many collateral arteries will fuse giving rise to one arteriole Arteriole Metarterioles
Contain smooth muscle
Precapillary sphincter
Link arterioles to capillaries
Capillary Beds
Thoroughfare channels
Arteriovenous anastomoses Connects arterioles to venules Capillaries Venules
Capillary Beds
Capillary Beds
Vascular Components
Venous System: Venules
Venules are formed when capillary beds unite
Allow fluids and WBCs to pass from the bloodstream to tissues
Postcapillary venules – smallest venules, composed of endothelium and a few pericytes (smooth-muscle cell like)
Large venules have one or two layers of smooth muscle (tunica media)
Venous System: Veins
Venous System: Veins
Veins are:
Formed when venules converge
Composed of three tunics, with a thin tunica media and a thick tunica externa consisting of collagen fibers and elastic networks
Capacitance vessels (blood reservoirs) that contain 65% of the blood supply
The Function of Valves in the Venous System
Veins have much lower blood pressure and thinner walls than arteries To return blood to the heart, veins have special adaptations
Large-diameter lumens, which offer little resistance to flow
Valves (resembling semilunar heart valves), which prevent backflow of blood Venous sinuses – specialized, flattened veins with extremely thin walls (e.g., coronary sinus of the heart and dural sinuses of the brain)
Vascular Anastomoses
Blood Flow
Actual volume of blood flowing through a vessel, an organ, or the entire circulation in a given period:
Is measured in ml per min.
Is equivalent to cardiac output (CO), considering the entire vascular system
Is relatively constant when at rest
Varies widely through individual organs
Merging blood vessels, more common in veins than arteries Arterial anastomoses provide alternate pathways (collateral channels) for blood to reach a given body region
If one branch is blocked, the collateral channel can supply the area with adequate blood supply Thoroughfare channels are examples of arteriovenous anastomoses
Blood Pressure (BP)
Force per unit area exerted on the wall of a blood vessel by its contained blood
Expressed in millimeters of mercury (mm Hg)
Measured in reference to systemic arterial BP in large arteries near the heart The differences in BP within the vascular system provide the driving force that keeps blood moving from higher to lower pressure areas
Resistance
Resistance – opposition to flow
Measure of the amount of friction blood encounters
Generally encountered in the systemic circulation
Referred to as peripheral resistance (PR) The important sources of resistance are blood viscosity, total blood vessel length, blood vessel diameter and turbulence
Resistance Factors: Blood Vessel Diameter
Small-diameter arterioles are the major determinants of peripheral resistance Fatty plaques from atherosclerosis:
Cause turbulent blood flow
Dramatically increase resistance
Resistance
Blood viscosity
The higher the viscosity the higher will be the resistance. Thus the flow will decrease Turbulence
Is the resistance due to the irregular, swirling movement of blood at high flow rates or to exposure to irregular surfaces. High turbulence decreases the flow
Resistance
Vessel diameter
Small diameter will have greater friction of blood against the vessel wall. This will decrease the flow (greater resistance)
Most of the peripheral resistance occur in arterioles. Changes in vessel diameter are frequent and significantly alter peripheral resistance
Resistance varies inversely with the fourth power of vessel radius if the radius is doubled, the resistance is 1/16 as much
Resistance
Vessel length
Increasing the length of the vessel will increase the cumulative friction and thus will decrease blood flow and pressure (greater resistance).
Resistance Factors: Viscosity and Vessel Length
Resistance factors that remain relatively constant are:
Blood viscosity – “stickiness” of the blood
Blood vessel length – the longer the vessel, the greater the resistance encountered
Blood Flow, Blood Pressure, and Resistance
Blood flow (F) is directly proportional to the difference in blood pressure (ΔP) between two points in the circulation
If ΔP increases, blood flow speeds up; if ΔP decreases, blood flow declines Blood flow is inversely proportional to resistance (R)
If R increases, blood flow decreases R is more important than ΔP in influencing local blood pressure
Systemic Blood Pressure
The pumping action of the heart generates blood flow through the vessels along a pressure gradient, always moving from higherto lower-pressure areas
Systemic Blood Pressure
Systemic pressure:
Is highest in the aorta
Declines throughout the length of the pathway
Is 0 mm Hg in the right atrium The steepest change in blood pressure occurs in the arterioles
Arterial Blood Pressure
Systemic Blood Pressure
Arterial BP reflects two factors of the arteries close to the heart
Their elasticity (compliance or distensibility)
The amount of blood forced into them at any given time Blood pressure in elastic arteries near the heart is pulsatile (BP rises and falls)
Arterial Blood Pressure
Systolic pressure – pressure exerted on arterial walls during ventricular contraction Diastolic pressure – lowest level of arterial pressure during a ventricular cycle Pulse pressure – the difference between systolic and diastolic pressure
EX: 120-80= 40 (Pulse Pressure)
Arterial Blood Pressure
Mean arterial pressure (MAP) – pressure that propels the blood to the tissues MAP = diastolic pressure + 1/3 pulse pressure
EX: for a 120 x 80 BP: MAP= 80 + 40/3 = 80 + 13 = 90 mm Hg
Venous Blood Pressure
Venous BP is steady and changes little during the cardiac cycle The pressure gradient in the venous system is only about 20 mm Hg A cut vein has even blood flow; a lacerated artery flows in spurts
Factors Aiding Venous Return
Capillary Blood Pressure
Capillary BP ranges from 20 to 40 mm Hg Low capillary pressure is desirable because high BP would rupture fragile, thin-walled capillaries Low BP is sufficient to force filtrate out into interstitial space and distribute nutrients, gases, and hormones between blood and tissues
Factors Aiding Venous Return
Venous BP alone is too low to promote adequate blood return and is aided by the:
Respiratory “pump” – pressure changes created during breathing suck blood toward the heart by squeezing local veins
Muscular “pump” – contraction of skeletal muscles “milk” blood toward the heart
Valves prevent backflow during venous return
Maintaining Blood Pressure
Maintaining blood pressure requires:
Cooperation of the heart, blood vessels, and kidneys
Supervision of the brain
Maintaining Blood Pressure
The main factors influencing blood pressure are:
Cardiac output (CO)
Peripheral resistance (PR)
Blood volume Blood pressure = CO x PR Blood pressure varies directly with CO, PR, and blood volume
Cardiac Output (CO)
Cardiac output is determined by venous return and neural and hormonal controls Resting heart rate is controlled by the cardioinhibitory center via the vagus nerves
Stroke volume is controlled by venous return (end diastolic volume, or EDV)
Cardiac Output (CO)
Under stress, the cardioacceleratory center increases heart rate and stroke volume
The end systolic volume (ESV) decreases and MAP increases
Maintaining blood pressure through Cardiovascular Regulation
Cardiac Output (CO)
Neural mechanisms – short-term control Endocrine mechanisms – mainly long-term control. Sometimes short-term also
Short-Term Mechanisms: Neural Controls
Neural controls of peripheral resistance:
Alter blood distribution in response to demands
Maintain MAP by altering blood vessel diameter
Short-Term Mechanisms: Neural Controls
Vasomotor Center
A cluster of sympathetic neurons in the medulla that oversees changes in blood vessel diameter
Maintains blood vessel tone by innervating smooth muscles of blood vessels, especially arterioles
Cardiovascular center – vasomotor center plus the cardiac centers that integrate blood pressure control by altering cardiac output and blood vessel diameter
Short-Term Mechanisms: Neural Controls
Baroreflexes Baroreceptors in: carotid sinuses, aortic arch, right atrium, walls of large arteries of neck and thorax Increased blood pressure stretches the baroreceptors
Inhibits the vasomotor center Dilate arteries
Decrease peripheral resistance, Decrease blood pressure
Short-Term Mechanisms: Neural Controls
Short-Term Mechanisms: Neural Controls
It is a integrating center for three reflex arcs:
Baroreflexes
Chemoreflexes
Medullary ischemic reflexes
Short-Term Mechanisms: Neural Controls Dilate
veins
Decrease
venous return Decrease cardiac output
Stimulate cardioinhibitory center and inhibit cardioacceleratory center Decrease heart rate Decrease contractile force
Impulse traveling along afferent nerves from baroreceptors: Stimulate cardioinhibitory center (and inhibit cardioacceleratory center)
Baroreceptors in carotid sinuses and aortic arch stimulated
Sympathetic impulses to heart ( HR and contractility)
CO
Inhibit vasomotor center R
Declining blood pressure stimulates the cardioacceleratory and vasomotor centers to:
Increase cardiac output
Constrict blood vessels Increase peripheral resistance
Stimulus: Rising blood pressure
Baroreceptors adapt to chronic high or low BP
Im
ba
CO and R return blood pressure to Homeostatic range
lan ce
Homeostasis: Blood pressure in normal range Im
CO and R return blood pressure to homeostatic range
Peripheral resistance (R)
Rate of vasomotor impulses allows vasodilation ( vessel diameter)
Arterial blood pressure rises above normal range
Vasomotor fibers stimulate vasoconstriction
Cardiac output (CO)
ba
Stimulus: Declining blood pressure
lan ce
Impulses from baroreceptors: Stimulate cardioacceleratory center (and inhibit cardioinhibitory center) Sympathetic impulses to heart ( HR and contractility)
Stimulate vasomotor center
Arterial blood pressure falls below normal range Baroreceptors in carotid sinuses and aortic arch inhibited
Short-Term Mechanisms: Neural Controls
Chemoreflexes Sensitive to low oxygen, low pH, and high carbon dioxide in the blood Prominent chemoreceptors are the carotid and aortic bodies Their primary role is to adjust respiration to change blood chemistry
Short-Term Mechanisms: Neural Controls
Medullary ischemic reflex It is an autonomic response to a drop in perfusion of the brain Cardiovascular center of the medulla oblongata sends sympathetic signals to the heart and blood vessels Cardiovascular center also receives input from higher brain centers
Hypothalamus, cortex
Hormonal Controls
The kidneys control BP by altering blood volume
Increased BP stimulates the kidneys to eliminate water, thus reducing BP
Decreased BP stimulates the kidneys to increase blood volume and BP
Short-Term Mechanisms: Neural Controls
Stimulates vasomotor and cardioacceleratory centers
Increase HR Increase CO
Reflex vasoconstriction Increases BP
Tissue perfusion increases
Hormonal Control
Hormones that Increase Blood Pressure Increase peripheral resistance
Adrenal medulla hormones – NE, E
Antidiuretic hormone (ADH) – causes intense vasoconstriction in cases of extremely low BP
Endothelium-derived factors – endothelin and prostaglandin-derived growth factor (PDGF) are both vasoconstrictors
Angiotensin II
Hormonal Controls
Kidneys act directly and indirectly to maintain long-term blood pressure
Direct renal mechanism alters blood volume Increased kidney perfusion increases filtration
Indirect renal mechanism involves the reninangiotensin mechanism
Hormonal Controls
Kidney Action and Blood Pressure
Declining
BP causes the release of renin, which triggers the release of angiotensin II
Angiotensin II is a potent vasoconstrictor that stimulates aldosterone secretion
Aldosterone enhances renal reabsorption and stimulates ADH release
Hormonal Controls
Hormones that Decrease Blood Pressure Atrial natriuretic peptide (ANP) – causes blood volume and pressure to decline Nitric oxide (NO) – is a brief but potent vasodilator Inflammatory chemicals – histamine, prostacyclin, and kinins are potent vasodilators Alcohol – causes BP to drop by inhibiting ADH
Monitoring Circulatory Efficiency
MAP Increases
Efficiency of the circulation can be assessed by taking pulse and blood pressure measurements Vital signs – pulse and blood pressure, along with respiratory rate and body temperature Pulse – pressure wave caused by the expansion and recoil of elastic arteries
Radial pulse (taken on the radial artery at the wrist) is routinely used
Varies with health, body position, and activity
Palpated Pulse
Measuring Blood Pressure
Systemic arterial BP is measured indirectly with the auscultatory method
A sphygmomanometer is placed on the arm superior to the elbow
Pressure is increased in the cuff until it is greater than systolic pressure in the brachial artery
Pressure is released slowly and the examiner listens with a stethoscope
Variations in Blood Pressure
Blood pressure cycles over a 24-hour period BP peaks in the morning due to waxing and waning levels of hormones Extrinsic factors such as age, sex, weight, race, mood, posture, socioeconomic status, and physical activity may also cause BP to vary
Hypotension
Measuring Blood Pressure
Orthostatic hypotension – temporary low BP and dizziness when suddenly rising from a sitting or reclining position Chronic hypotension – hint of poor nutrition and warning sign for Addison’s disease Acute hypotension – important sign of circulatory shock
Threat to patients undergoing surgery and those in intensive care units
The
first sound heard is recorded as the systolic pressure Korotkoff sounds
The pressure when sound disappears is recorded as the diastolic pressure
Alterations in Blood Pressure
Hypotension – low BP in which systolic pressure is below 100 mm Hg Hypertension – condition of sustained elevated arterial pressure of 140/90 or higher
Transient elevations are normal and can be caused by fever, physical exertion, and emotional upset
Chronic elevation is a major cause of heart failure, vascular disease, renal failure, and stroke
Hypertension
Hypertension maybe transient or persistent Primary or essential hypertension – risk factors in primary hypertension include diet, obesity, age, race, heredity, stress, and smoking Secondary hypertension – due to identifiable disorders, including renal disease, arteriosclerosis, hyperthyroidism, obstruction of renal artery, etc
Blood Flow Through Tissues
Blood flow, or tissue perfusion, is involved in:
Delivery of oxygen and nutrients to, and removal of wastes from, tissue cells
Gas exchange in the lungs
Absorption of nutrients from the digestive tract
Urine formation by the kidneys The rate of blood flow to the tissues is precisely the right amount to provide proper tissue function
Velocity of Blood Flow
Velocity of Blood Flow
Autoregulation: Local Regulation of Blood Flow
Types of autoregulation
Metabolic Controls Declining tissue nutrient and oxygen levels are stimuli for autoregulation Endothelial cells release nitric oxide (NO) Nitric oxide induces vasodilation at the capillaries to help get oxygen to tissue cells Other autoregulatory substances include: potassium and hydrogen ions, adenosine, lactic acid, histamines, kinins, and prostaglandins
Blood velocity:
Changes as it travels through the systemic circulation
Is inversely proportional to the cross-sectional area Total cross-sectional area It is the combined cross-sectional area of all vessel Increased total cross-sectional area will decrease blood pressure and flow
Autoregulation – automatic adjustment of blood flow to each tissue in proportion to its requirements at any given point in time Blood flow through an individual organ is intrinsically controlled by modifying the diameter of local arterioles feeding its capillaries MAP remains constant, while local demands regulate the amount of blood delivered to various areas according to need
Types of autoregulation
Myogenic Controls Inadequate tissue perfusion or excessively high arterial pressure:
Are autoregulatory
Provoke myogenic responses – stimulation of vascular smooth muscle Vascular muscle responds directly to:
Increased vascular pressure with increased tone, which causes vasoconstriction
Reduced stretch with vasodilation, which promotes increased blood flow to the tissue
Control of Arteriolar Smooth Muscle
Blood Vessels PART B
Long-Term Autoregulation
Is evoked when short-term autoregulation cannot meet tissue nutrient requirements May evolve over weeks or months to enrich local blood flow
Blood Flow: Skeletal Muscles
Local regulation Resting muscle blood flow is regulated by myogenic and general neural mechanisms in response to oxygen and carbon dioxide levels When muscles become active, hyperemia is directly proportional to greater metabolic activity of the muscle (active or exercise hyperemia)
Long-Term Autoregulation
Angiogenesis
Increased of the number of vessels to a region
enlargement of existing vessels When a heart vessel becomes partly occluded Routinely in people in high altitudes, where oxygen content of the air is low
Blood Flow: Skeletal Muscle
Systemic regulation Sympathetic activity increase Arterioles in muscles have cholinergic receptors
Muscle blood flow can increase tenfold or more during physical activity as vasodilation occurs Arterioles in organs have alpha and beta receptors
Vasoconstriction occur to divert blood to the muscles
Blood Flow: Brain
Blood flow to the brain is constant, as neurons are intolerant of ischemia Metabolic controls – brain tissue is extremely sensitive to declines in pH, and increased carbon dioxide causes marked vasodilation Myogenic controls protect the brain from damaging changes in blood pressure
Decreases in MAP cause cerebral vessels to dilate to ensure adequate perfusion
Increases in MAP cause cerebral vessels to constrict
Blood Flow: Skin
Blood flow through the skin:
Supplies nutrients to cells in response to oxygen need
Helps maintain body temperature
Provides a blood reservoir
Temperature Regulation
As temperature rises (e.g., heat exposure, fever, vigorous exercise):
Hypothalamic signals reduce vasomotor stimulation of the skin vessels
Heat radiates from the skin Sweat also causes vasodilation via bradykinin in perspiration
Bradykinin stimulates the release of NO As temperature decreases, blood is shunted to deeper, more vital organs
Blood Flow: Brain
The brain can regulate its own blood flow in certain circumstances, such as ischemia caused by a tumor increasing systemic blood pressure The brain is vulnerable under extreme systemic pressure changes
MAP below 60mm Hg can cause syncope (fainting)
MAP above 160 can result in cerebral edema
Blood Flow: Skin
Blood flow to venous plexuses below the skin surface:
Varies from 50 ml/min to 2500 ml/min, depending on body temperature
Is controlled by sympathetic nervous system reflexes initiated by temperature receptors and the central nervous system
Blood Flow: Lungs
Blood flow in the pulmonary circulation is unusual in that:
The pathway is short
Arteries/arterioles are more like veins/venules (thin-walled, with large lumens)
They have a much lower arterial pressure (24/8 mm Hg versus 120/80 mm Hg)
Blood Flow: Heart Blood Flow: Lungs
The
autoregulatory mechanism is exactly opposite of that in most tissues Low oxygen levels in the alveolus cause vasoconstriction; high levels promote vasodilation This allows for proper oxygen loading in the lungs
Blood Flow: Heart
Under resting conditions, blood flow through the heart may be controlled by a myogenic mechanism Blood flow remains constant despite wide variation in coronary perfusion pressure During strenuous exercise:
Coronary vessels dilate in response to local accumulation of carbon dioxide
Decreased oxygen in the blood will cause local release of vasodilators
Capillary Exchange of Respiratory Gases and Nutrients
Water-soluble
solutes pass through clefts and fenestrations
Lipid-soluble molecules diffuse directly through endothelial membranes
Small vessel coronary circulation is influenced by:
Aortic pressure
The pumping activity of the ventricles During ventricular systole:
Coronary vessels compress
Myocardial blood flow ceases
Stored myoglobin supplies sufficient oxygen During ventricular diastole, oxygen and nutrients are carried to the heart
Capillary Exchange of Respiratory Gases and Nutrients
Oxygen, carbon dioxide, nutrients, and metabolic wastes diffuse between the blood and interstitial fluid along concentration gradients
Oxygen and nutrients pass from the blood to tissues
Carbon dioxide and metabolic wastes pass from tissues to the blood
Capillary Exchange of Respiratory Gases and Nutrients
Capillary Exchange of Respiratory Gases and Nutrients
Capillary Exchange
Processes that move fluids across capillary walls
Diffusion of molecules happens
through adjacent endothelial cell or
through the pores or
through channels on the membrane or
through the membrane of the endothelial cells
Filtration
Capillary hydrostatic pressure (CHP)
Only small molecules will pass through the pores of the membrane or between adjacent endothelial cells
Capillary Filtration
Flow of water and solutes from capillaries to interstitial space
Plasma and interstitial fluid are in constant communication
Assists in the transport of lipids and tissue proteins
Accelerates the distribution of nutrients
Carries toxins and other chemical stimuli to lymphoid tissues
Processes that move fluids across capillary walls
Reabsorption
Through osmosis
The higher the solute concentration the greater the solution’s osmotic pressure
Blood colloid osmotic pressure (BCOP) or oncotic pressure Is the osmotic pressure of the blood
It works against hydrostatic pressure
Forces acting across capillary walls
Capillary hydrostatic pressure (CHP = 35) Blood colloid osmotic pressure (BCOP=25) Interstitial fluid colloid osmotic pressure (ICOP=0) Interstitial fluid hydrostatic pressure (IHP= 0)
Capillary filtration and reabsorption
Processes involved in filtration at the arterial end
Net hydrostatic pressure CHP – IHP= 35-0=35
Net colloid osmotic pressure BCOP – ICOP=25-0=25
Net filtration pressure 35-25=10
Net Filtration Pressure (NFP)
Capillary filtration and reabsorption
Filtration and reabsorption
Circulatory Shock
Circulatory shock – any condition in which blood vessels are inadequately filled and blood cannot circulate normally Results in inadequate blood flow to meet tissue needs
Processes involved in reabsorption at the venous end
Net hydrostatic pressure CHP-IHP=18-0=18
Net osmotic pressure BCOP-ICOP=25-0=25
Net filtration pressure 18-25=-7
NFP=(CHP-IHP) – (BCOP-ICOP)
IHP=0
ICOP=0 +NFP=fluid moves out of the capillary (arterial side) -NFP=fluid moves into the capillary (venous side)
Circulatory Shock
Three types include:
Hypovolemic shock – results from largescale blood loss
Vascular shock – poor circulation resulting from extreme vasodilation
Cardiogenic shock – the heart cannot sustain adequate circulation
Circulatory Pathways
Differences Between Arteries and Veins Arteries
Veins
Delivery
Blood pumped into single systemic artery – the aorta
Blood returns via superior and interior venae cavae and the coronary sinus
Location
Deep, and protected by tissue
Both deep and superficial
Pathways
Fair, clear, and defined
Convergent interconnections
Supply/drainage
Predictable supply
Dural sinuses and hepatic portal circulation
Developmental Aspects
Fetal circulation
The vascular system has two distinct circulations
Pulmonary circulation – short loop that runs from the heart to the lungs and back to the heart
Systemic circulation – routes blood through a long loop to all parts of the body and returns to the heart
The endothelial lining of blood vessels arises from mesodermal cells, which collect in blood islands
Blood islands form rudimentary vascular tubes through which the heart pumps blood by the fourth week of development Fetal shunts (foramen ovale and ductus arteriosus) bypass nonfunctional lungs The ductus venosus bypasses the liver The umbilical vein and arteries circulate blood to and from the placenta
Developmental Aspects
Blood vessels are trouble-free during youth Vessel formation occurs:
As needed to support body growth
For wound healing
To rebuild vessels lost during menstrual cycles With aging, varicose veins, atherosclerosis, and increased blood pressure may arise
Pulmonary circuit consists of pulmonary vessels
Arteries which deliver deoxygenated blood to the lungs Capillaries in the lungs where gas exchange occurs Veins which deliver oxygenated blood to the left atrium
Systemic arteries
Systemic Circulation
Ascending aorta
Right and left coronary arteries originate from base of aortic sinus Aortic arch
Brachiocephalic trunk Right common carotid Right subclavian
Left common carotid
Left subclavian Descending aorta
Thoracic and abdominal aortas
Systemic arteries
Pulmonary Circulation
Subclavian
Supplies arms, chest, CNS, shoulder and back
Internal thoracic Pericardium and anterior chest
Vertebral Brain Spinal cord
Systemic arteries
Axillary
shoulder Brachial
Upper arm Radial Ulnar Superficial and deep palmar archs
Arteries of the chest and upper limb
Arteries of the neck and head
Common carotid artery
Internal carotid
External carotid
Arteries of the neck and head Ophthalmic artery Basilar artery Occipital artery Vertebral artery Internal carotid artery External carotid artery Common carotid artery
Maxillary artery Facial artery
Clavicle (cut) Subclavian artery Axillary artery (b)
External Carotid
Neck
Esophagus
Pharynx
Lower jaw
face
Brachiocephalic trunk Internal thoracic artery
Arteries of the Brain and Circle of Willis Ophthalmic artery Basilar artery Occipital artery Vertebral artery Internal carotid artery External carotid artery Common carotid artery
Maxillary artery Facial artery
Clavicle (cut) Subclavian artery Axillary artery (b)
Brachiocephalic trunk Internal thoracic artery
Internal carotid
Ophthalmic eyes
Anterior cerebral Frontal and parietal lobes Anterior communicating artery
Middle cerebral Mesencephalon and lateral cerebral hemisphere
Arteries of the Brain and Circle of Willis
Circle of Willis
Vertebral arteries Basilar artery
Supply medulla oblongata
Pons
Cerebellum Basilar artery gives rise to posterior cerebral and posterior communicanting arteries
Arteries of the Abdomen
Blood Vessels PART C
Arteries of the Abdomen
Opening for inferior vena cava
Hiatus (opening) for esophagus Celiac trunk
Diaphragm Inferior phrenic artery Middle suprarenal artery Renal artery
Kidney Superior mesenteric artery Lumbar arteries
Abdominal aorta Median sacral artery
Gonadal (testicular or ovarian) artery Inferior mesenteric artery Common iliac artery Ureter
(c)
Liver (cut) Inferior vena cava Celiac trunk Hepatic artery proper Common hepatic artery Right gastric artery Gallbladder Gastroduodenal artery Right gastroepiploic artery Duodenum Abdominal aorta (b)
Major Arteries of the Trunk
Descending aorta
Thoracic For the thorax
Abdominal Celiac trunk
Left gastric
Splenic
Common hepatic
Diaphragm Esophagus Left gastric artery Left gastroepiploic artery Splenic artery Spleen Stomach Pancreas (major portion lies posterior to stomach) Superior mesenteric artery
Major Arteries of the Trunk
Abdominal aorta
Right and left Common iliacs
Internal iliac Organ of pelvic cavity
External iliac
Femoral
Popliteal Anterior tibial Posterior tibial
Fibular Dorsal and plantar archs
Superior mesenteric
Pancreas, small intestine and proximal 2/3 of the large intestine Suprarenal Renal Gonadals Inferior mesenteric
Distal 1/3 of the large intestine
Arteries of the Lower Limbs
Common iliac artery Internal iliac artery Superior gluteal artery External iliac artery Deep artery of thigh Lateral circumflex femoral artery Medial circumflex femoral artery Obturator artery Femoral artery Adductor hiatus Popliteal artery
Anterior tibial artery Posterior tibial artery Fibular artery
Popliteal artery
Posterior tibial artery Lateral plantar artery Medial plantar artery (c)
Dorsalis pedis artery Arcuate artery Metatarsal arteries (b)
Systemic Veins
Superior vena cava
Drains blood from the head and neck Inferior vena cava
Drains blood from the remainder of the body
Dural sinuses External jugular vein Vertebral vein Internal jugular vein Superior vena cava Axillary vein Great cardiac vein Hepatic veins Hepatic portal vein Superior mesenteric vein Inferior vena cava Ulnar vein Radial vein Digital veins Common iliac vein External iliac vein Femoral vein Great saphenous vein Popliteal vein Posterior tibial vein Anterior tibial vein Fibular vein Dorsal venous arch (b)
Subclavian vein Right and left brachiocephalic veins Cephalic vein Brachial vein Basilic vein Splenic vein Median cubital vein Renal vein Inferior mesenteric vein
Internal iliac vein
Dorsal digital veins
Anterior tibial artery Fibular artery Dorsalis pedis artery (from top of foot) Plantar arch
Venous return from the cranium
Veins of the Brain Superior sagittal sinus Falx cerebri Inferior sagittal sinus
Cerebral veins drain the blood into sinuses Superior sagittal sinus Inferior sagittal sinus Occipital sinus Straight sinus Left and right transverse sinuses
Straight sinus Cavernous sinus Junction of sinuses Transverse sinuses Sigmoid sinus Jugular foramen Right internal jugular vein
(c)
Venous return from the cranium
Veins of the Head and Neck Ophthalmic vein Superficial temporal vein Facial vein Occipital vein
Left and right transverse sinuses converge to form the sigmoid sinus Sigmoid sinus becomes internal jugular vein
(b)
Superficial veins of the head and neck
Temporal Facial Maxillary They drain into external and internal jugular veins
Posterior auricular vein External jugular vein Vertebral vein Internal jugular vein Superior and middle thyroid veins Brachiocephalic vein Subclavian vein Superior vena cava
Veins of neck and thorax
Internal and external jugular Brachiocephalic trunks Superior vena cava
Veins in the thorax
Veins of the arms
From lumbar vein
Azygos vein (on the right side)
Hemiazygos (on the left side) They drain into the brachiocephalic
Internal jugular vein External jugular vein
Brachiocephalic veins
Brachiocephalic Subclavian
Cephalic
Axillary Brachial Basilic
Median cubital Connects basilic and cephalic
Brachial divides in radial and ulnar
Veins of the Abdomen
Left subclavian vein
Right subclavian vein
Superior vena cava Axillary vein Brachial vein Cephalic vein Basilic vein
Hepatic veins
Hemiazygos vein Posterior intercostals
Inferior vena cava
Inferior vena cava Ascending lumbar vein
Median cubital vein Median antebrachial vein Cephalic vein Radial vein
Azygos vein Accessory hemiazygos vein
Basilic vein Ulnar vein Deep palmar venous arch Superficial palmar venous arch Digital veins
Right suprarenal vein
Inferior phrenic vein Left suprarenal vein Renal veins
Right gonadal vein
External iliac vein
Left ascending lumbar vein Lumbar veins Left gonadal vein Common iliac vein Internal iliac vein
(b)
(b)
Hepatic Portal System
Contains substance absorbed by the stomach and intestines Delivers these compounds to the liver for
Storage
Metabolic conversion
Excretion
Veins of the Abdomen Hepatic veins
Liver Hepatic portal vein
Gastric veins Spleen Inferior vena cava Splenic vein Right gastroepiploic vein Inferior mesenteric vein Superior mesenteric vein
Small intestine Large intestine Rectum (c)
Hepatic portal system
Capillaries in the digestive system Hepatic portal vein
Inferior mesenteric vein
Superior mesenteric vein
Splenic vein
Gastric veins
Cystic vein Liver capillaries Hepatic vein
Common iliac vein Internal iliac vein External iliac vein Inguinal ligament Femoral vein Great saphenous vein (superficial) Great saphenous vein Popliteal vein Anterior tibial vein Fibular (peroneal) vein
Popliteal vein
Fibular (peroneal) vein Anterior tibial vein
Small saphenous vein (superficial)
Dorsalis pedis vein Dorsal venous arch Metatarsal veins
Plantar veins
(b)
Posterior tibial vein
Plantar arch Digital veins (c)
Venous Drainage from the Lower Limb