Name: blood vessel layers and flow control
Uploaded: 2024-07-18T13:37:05.000Z
Duration: 1 min 15 s
Channel: JoVE

K12 Standards

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Human Anatomy and Physiology

Transport

Cardiovascular System

Structure of Blood Vessels

The walls of blood vessels, whether arteries or veins, have three distinct layers or tunics.
Tunica externa is the outermost layer infiltrated with several nerves and lymphatic vessels.
In larger blood vessels, the tunica externa also has a network of tiny vessels called vasa vasorum that supply blood to the cells of blood vessel walls.
The middle layer, tunica media, is the thickest layer, rich in circularly arranged smooth muscle cells and elastin sheets.
These smooth muscle cells can either contract, resulting in vasoconstriction, or relax, leading to vasodilation. This pivotal process regulates the rate of blood flow and blood pressure within the vessels.
Tunica interna is the innermost layer. It consists of the endothelium, a thin layer of flattened simple squamous epithelial cells that form the lumen of blood vessels.
The endothelium is attached to the underlying connective tissue by a basement membrane.
While the walls of arteries and veins share most components, there are two additional layers, the internal and external elastic lamina, present only in arteries

structure of blood vessels

Blood is circulated throughout the human body through a network of blood vessels called the circulatory system. This system includes arteries that transport blood from the heart to various body parts. These arterial pathways divide into smaller vessels until they reach the arterioles, which further split into capillaries. It is within these minuscule capillaries that the exchange of nutrients and waste products takes place. After this exchange, the blood is collected by venules, which fuse to form veins, returning the blood to the heart.
Certain commonalities can be discerned by examining the structures of these various types of vessels. Arteries and arterioles have thicker walls due to their proximity to the heart and the high-pressure blood they receive. Their lumens, or interior passageways through which blood flows, are smaller than those of veins, assisting in maintaining blood pressure. In contrast, the initial pressure exerted by heart contractions is significantly reduced when blood reaches the venules, having passed through capillaries. As a result, venules and veins experience lower blood pressure, have thinner walls, and larger lumens, facilitating more effortless blood flow. Many veins, especially those in the limbs, contain valves that help direct blood toward the heart. This counteracts slowing blood flow in extremities due to lower pressure and gravity.
Artery and vein walls consist primarily of living cells and their byproducts, such as collagenous and elastic fibers. These cells require nourishment and produce waste. As blood travels quickly through larger vessels, the opportunity for nourishment exchange is limited. Furthermore, large vessel walls are too thick for nutrients to permeate entirely. Larger arteries and veins contain vasa vasorum, minute vessels within the vessel walls that aid in nourishment and waste exchange. The comparatively high pressure within arteries necessitates the positioning of vasa vasorum in the outer layers of the vessel, preventing collapse due to blood pressure. However, lower pressure within veins allows the vasa vasorum to be situated nearer to the lumen. The prevalence of arterial diseases over venous diseases can be attributed to the outer positioning of the vasa vasorum, complicating nourishment delivery and waste removal. Additionally, tiny nerves, known as nervi vasorum, are found within the walls of both types of vessels and are responsible for regulating smooth muscle contraction and dilation.
The general structure of the blood vessels includes three layers. The innermost layer, the tunica intima (conventionally termed tunica interna), is composed of epithelial and connective tissues. The innermost lining consists of a specialized squamous epithelium known as the endothelium, which extends throughout the vascular system, including the heart&#39;s internal chambers. The disruption of this lining, which exposes blood to the underlying collagen fibers, significantly contributes to blood clot formation. Initially perceived merely as a demarcating layer between the vessel walls and the lumen, contemporary research accentuates the critical physiological role of the endothelium in activities like capillary exchange regulation and blood flow alteration. The endothelium produces local chemicals known as endothelins, which can constrict the muscular component of the vessel walls, thereby elevating blood pressure. Prolonged endothelin overproduction may lead to hypertension and cardiovascular disorders.
Adjacent to the endothelium lies the basement membrane or basal lamina, which effectively links the endothelium to the connective tissue. This membrane ensures strength and flexibility and allows material passage. The thin tunica intima&#39;s outer layer houses a slight amount of areolar connective tissue, mainly comprising elastic fibers for additional flexibility and collagenous fibers for strength.
The tunica media, the middle layer of the vessel wall, is the thickest layer in arteries and is notably thicker in arteries than in veins. Composed of smooth muscle layers reinforced by connective tissue, primarily elastic fibers, it contributes to the contraction and relaxation of the circular muscles, influencing the diameter of the vessel lumen. Regulated by the nervi vasorum, vasoconstriction and vasodilation alter blood flow and pressure. Hormonal and local chemical factors also monitor blood vessels, adjusting blood flow according to body conditions.
The tunica externa, the outermost tunic, forms a substantial sheath primarily composed of collagenous fibers with some elastic fibers. This is the thickest tunic, particularly in veins, and may surpass the tunica media in some larger arteries. This tunic merges with the surrounding connective tissue, stabilizing the vessel&#39;s position.

The walls of blood vessels, whether arteries or veins, have three distinct layers or tunics.
Tunica externa is the outermost layer infiltrated with ...

Education

JoVE Core

Anatomy and Physiology

Unit 1

Blood Vessels and Circulation

KEY TERMS AND CONCEPTS

blood vessel layers and flow control

Blood vessels move blood through the circulatory system, and their structure helps explain how blood flows from the heart to the body and back again. Arteries carry blood away from the heart. They branch into smaller arterioles, which then lead into capillaries. Capillaries are the tiny vessels where nutrients and waste products are exchanged. After that exchange, blood enters venules, which join together to form veins that return blood to the heart.

Arteries and arterioles have thicker walls because they are closer to the heart and receive blood under high pressure. Their lumens, or inner passageways, are smaller than those of veins. This helps maintain blood pressure as blood moves forward. Venules and veins carry blood at much lower pressure after it passes through capillaries. Their walls are thinner, and their lumens are larger, which makes blood flow easier. Many veins, especially in the limbs, also contain valves that keep blood moving toward the heart and help counter gravity.

The walls of larger blood vessels need their own supply of nutrients and a way to remove wastes. That is why larger arteries and veins contain vasa vasorum, which are tiny vessels in the vessel wall. In arteries, these small vessels are placed in the outer layers because the high pressure inside could collapse vessels closer to the lumen. In veins, where pressure is lower, the vasa vasorum can be located nearer the lumen. The transcript also notes that arterial diseases are more common than venous diseases, in part because this outer placement makes nourishment and waste removal more difficult in arteries. Tiny nerves called nervi vasorum are also present in vessel walls. They help regulate smooth muscle contraction and dilation.

Blood vessel walls have three layers, or tunics. The innermost layer is the tunica intima, also called the tunica interna. It includes epithelial and connective tissue, and its inner lining is the endothelium, a specialized squamous epithelium that continues through the vascular system and into the heart chambers. Damage to this lining exposes collagen fibers and can contribute to blood clot formation. The endothelium also has an active role in capillary exchange and blood flow. It produces endothelins, local chemicals that can constrict vessel muscle and raise blood pressure. If endothelins are made in excess for a long time, hypertension and other cardiovascular disorders may develop. Beneath the endothelium is the basement membrane, or basal lamina, which connects the lining to the connective tissue and helps provide strength, flexibility, and material passage. The outer part of the tunica intima contains areolar connective tissue with elastic fibers for flexibility and collagen fibers for strength.

The tunica media is the middle layer of the vessel wall and is the thickest layer in arteries. It is also thicker in arteries than in veins. This layer is made of smooth muscle with connective tissue support, especially elastic fibers. Its circular muscle can contract and relax to change the diameter of the lumen. These changes, called vasoconstriction and vasodilation, are regulated by the nervi vasorum and also influenced by hormones and local chemicals. The tunica externa is the outermost layer. It is a strong sheath made mainly of collagen fibers with some elastic fibers. This layer is especially thick in veins and can even be thicker than the tunica media in some larger arteries. It blends with surrounding connective tissue and helps hold the vessel in place.

Blood Vessel Layers and Flow Control

overview of blood vessels

Blood Vessel Types and Circulation

The human cardiovascular system includes five main blood vessel types: arteries, arterioles, veins, venules, and capillaries. Each type has a different job in moving blood through the body and helping maintain homeostasis. Blood vessels also help supply oxygen and nutrients, remove waste, and transport hormones. Arteries and arterioles carry blood away from the heart. Arteries are muscular and elastic, so they can handle high pressure as blood leaves the heart. Most arteries carry oxygenated...

Blood vessels move blood through the circulatory system, and their structure helps explain how blood flows from the heart to the body and back again. Arteries carry blood away from the heart. They branch into smaller arterioles, which then lead into capillaries. Capillaries are the tiny vessels where nutrients and waste products are exchanged. After that exchange, blood enters venules, which join together to form veins that return blood to the heart. Arteries and arterioles have thicker walls...

arteries and arterioles

Blood Flow Control in Arteries

Arteries carry blood away from the heart and must handle the high pressure created by each heartbeat. The arteries closest to the heart have thick walls and many elastic fibers in their three tunics. These vessels are called elastic, or conducting, arteries and are usually larger than 10 mm across. Elastic arteries expand when blood is pumped from the ventricles and then recoil. This stretching and spring back helps stop blood pressure and resistance from rising too much. It also helps keep...

capillaries and their types

How Capillaries Exchange Blood and Tissue

Capillaries are the smallest blood vessels in the circulatory system. They measure about 5 to 10 micrometers in diameter. Their thin walls let blood exchange materials with the fluid around body cells during microcirculation. A capillary wall has an endothelial layer, a basement membrane, and sometimes scattered smooth muscle fibers. These vessels are built for exchange between blood and interstitial fluid. Larger capillaries may have several neighboring endothelial cells, while smaller ones...

capillary beds

How Capillary Beds Exchange Materials

Capillary beds are tiny blood vessel networks where blood and body tissues exchange materials. They are a key part of the circulatory system. In these beds, gases, nutrients, and waste products move between the blood and the surrounding cells. Each capillary bed contains many capillaries, the smallest blood vessels in the body. Capillary walls are usually only one cell thick. This thin wall helps substances diffuse efficiently. Capillaries connect arterioles, which are small branches of...

venules

How Venules Return Blood to the Heart

Venules are small blood vessels that carry blood from capillaries into larger veins. They sit between the tiny capillary beds in tissues and the venous system that returns blood to the heart. In the microscopic circulatory system, they form an important bridge in blood flow. Venules are much smaller in diameter than veins. They are usually about 8 to 100 micrometers wide. Their walls are thin and simple. They include an endothelium, a thin layer of connective tissue, and sometimes a few smooth...

veins

Veins and How Blood Returns to the Heart

Veins are blood vessels that move blood from the body back to the heart. They are part of the circulatory system and form a network of hollow tubes. Most veins carry blood that is low in oxygen from the body’s cells to the heart so it can be reoxygenated. They also help keep blood moving through the body and support fluid balance. Veins are built for low-pressure blood flow. Their walls have three layers, or tunics. The tunica intima is the inner layer and is made of endothelial cells. Its...

veins as blood reservoirs

Venoconstriction and Venous Reserve

Veins store blood and help return it to the heart. They act as capacitance vessels, which means they can expand and hold a large volume of blood under low pressure. Because of their large diameter and thin walls, veins are much more distensible than arteries. At any given time, they contain about 64 percent of the body’s total blood volume. When the body needs blood moved quickly, the medulla oblongata activates the vasomotor center. This center sends sympathetic signals to the smooth muscle...

anastomoses

Blood Vessel Connections in the Body

Anastomoses are natural connections or openings between blood vessels and other tube-like structures in the body. The word comes from the Greek term anastomosis, meaning “outlet” or “opening.” These connections help keep blood and other fluids moving when a main pathway is blocked or damaged. Anastomoses can form between arteries, veins, and lymphatic vessels. Arterial anastomoses are found between arteries, especially in places that need a steady blood supply, such as the brain and heart. A...

blood pressure

Blood Pressure and Pulse Pressure

Blood pressure is the force blood exerts on the walls of blood vessels and the heart chambers. It is one part of blood flow, which depends on the volume of blood moving through the body each unit of time. The heart’s ventricles create this movement by contracting rhythmically and pushing blood into the arteries. Blood then moves from higher pressure to lower pressure areas. It travels from large arteries into smaller arteries, then arterioles, capillaries, venules, and veins. The venous system...

vascular resistance

How Vessel Size Changes Blood Flow

Vascular resistance explains how vessel size, blood thickness, and vessel length affect blood flow and blood pressure. It describes the force blood faces as it moves through blood vessels. This force also helps determine how hard the heart must work to keep blood moving. Vessel diameter has the biggest effect on resistance. This follows Poiseuille’s law, which shows that small changes in diameter cause large changes in resistance. If a vessel’s diameter is cut in half, resistance rises 16...

measurement of blood pressure

Blood Pressure Reading and Korotkoff Sounds

Blood pressure reading uses a cuff, a gauge, and a stethoscope to check cardiovascular health. The method used today was developed more than 100 years ago by Russian doctor Dr. Nikolai Korotkoff. The soft ticking sounds heard during the reading are called Korotkoff sounds. They come from turbulent blood flow in the vessel. The cuff is wrapped tightly around the upper arm over the brachial artery. It is placed about an inch above the point where the pulse is felt. The provider then pumps air...

venous return

How Veins Return Blood to the Heart

Venous return is the flow of blood back to the heart through the body’s veins. It is a key part of the circulatory system because it helps complete the blood circulation cycle. This movement keeps blood available to carry oxygen and nutrients to the body’s tissues. A main force behind venous return is pressure difference. Blood moves from a higher-pressure area in the peripheral veins toward the lower-pressure right atrium of the heart. If that pressure difference is too small, venous return...

pulse

How Pulse Reveals Heart Health

Pulse is the pressure wave felt in arteries after the heart pumps blood. Elastic fibers in the artery walls expand to receive blood and then recoil. This wave can be felt by hand or measured with electronic devices. As the pulse travels away from the heart, its effect becomes smaller, but parts of the systolic and diastolic waves can still be seen in smaller vessels like arterioles. In clinical care, pulse is recorded as beats per minute and used as a sign of health. Both pulse rate and pulse...

capillary exchange

How Capillaries Move Fluid and Solutes

Capillaries move gases, nutrients, wastes, and other substances between the blood and body cells. Small molecules such as gases, lipids, and lipid-soluble substances diffuse directly through the endothelial cell membranes of the capillary wall. Glucose, amino acids, and ions such as sodium, potassium, calcium, and chloride use transporters for facilitated diffusion through membrane-specific channels. Some substances also pass between cells or through special capillary structures. Glucose,...

neural regulation of blood pressure

Blood Pressure Reflexes in the Nervous System

Blood pressure reflexes in the nervous system help keep blood flow steady. The autonomic nervous system works with the cardiovascular system to make sure tissues get enough perfusion, or blood supply. These controls act through fast reflexes and slower long-term responses. Baroreceptor reflexes are a key short-term control. Baroreceptors are stretch-sensitive sensors in the carotid sinuses and aortic arch. When blood pressure rises, they fire more often and send signals to the cardiovascular...

hormonal regulation of blood pressure

Hormones That Raise and Lower Blood Pressure

Hormones help control blood pressure by changing heart activity, vessel size, and kidney function. Some hormones raise blood pressure fast, while others help lower it when blood volume is too high. Together, they keep blood flow and fluid balance within a workable range. Epinephrine and norepinephrine are released from the adrenal medulla. These catecholamines strengthen and extend the sympathetic, or fight-or-flight, response. They raise heart rate and contraction force and cause temporary...

autoregulation of blood flow

How Tissues Match Blood Flow to Need

Autoregulation helps tissues match blood flow to their own metabolic needs. It works without specific nervous stimulation or endocrine control. This local control adjusts perfusion, or blood supply, in each tissue region. Two main mechanisms guide this process: chemical signaling and myogenic control. Chemical signaling acts at the precapillary sphincter, a small ring of muscle that can open or close blood entry into capillaries. When a sphincter relaxes, blood enters the capillary bed. When...

blood pressure imbalances and circulatory shock

blood-pressure-imbalances-and-circulatory-shock

Blood Pressure Disorders and Shock Types

Blood pressure disorders can disrupt blood volume, vascular tone, and blood vessel function. These changes upset vascular homeostasis and can lead to hypertension, hemorrhage, hypotension, and shock. Normal blood pressure is 120/80 mm Hg. Elevated blood pressure is 120-129/under 80 mm Hg, and hypertension begins at 130/80 mm Hg and usually needs treatment. High blood pressure is often asymptomatic, but it can lead to serious cardiovascular events, aneurysms, peripheral arterial disease,...

exercise and cardiovascular response

How Exercise Changes Heart Function

Exercise changes heart function and blood flow in several linked steps. Light to moderate activity starts with a small rise in heart rate before exercise begins. As skeletal muscles use more oxygen, blood vessels widen, peripheral resistance falls, capillary blood flow rises, and venous return speeds up. Venous return is the flow of blood back to the heart, and it is also helped by skeletal muscle contractions and rapid breathing. These changes increase cardiac output, which is the amount of...

overview of systemic arteries

Blood Flow Through the Body

Systemic circulation moves blood through the body and keeps tissues supplied with oxygen and nutrients. It also carries waste products away from cells. Systemic arteries are the vessels that carry oxygenated blood away from the heart to the body’s tissues, and the blood later returns to the heart as deoxygenated blood. This circulation includes systemic arteries, arterioles, capillaries, venules, and veins. It covers the blood vessels of the body except those involved in pulmonary circulation.

the aorta

Aortic Anatomy and Blood Flow Path

The aorta is the main blood vessel that carries blood away from the heart. It is the largest artery in the human body. It begins at the left ventricle and continues down to the abdomen, where it later divides into two smaller arteries. The aorta has four main parts. These are the ascending aorta, the aortic arch, the thoracic aorta, and the abdominal aorta. Its average diameter is about 2 to 3 cm, but the size can change with the section of the vessel and with age, sex, and body size. The...

the arch of aorta

Aortic Arch Branches and Brain Blood Flow

The aortic arch gives off the main arteries that carry blood to the head, arms, and brain. It begins after the ascending aorta and curves toward the left side of the body. The coronary arteries also start from the ascending aorta, where they branch from two sinuses just above the aortic semilunar valve. These sinuses contain aortic baroreceptors and chemoreceptors, which help monitor blood pressure and blood chemistry. The left coronary artery and right coronary artery arise from the left...

thoracic aorta

Thoracic Aorta Branches and Blood Supply

The thoracic aorta is the part of the descending aorta that runs through the chest. It starts at the T5 vertebra and continues to the T12 level at the diaphragm. At first, it travels through the mediastinum, just left of the spinal column. Along this path, the thoracic aorta gives off several branches. These branches are grouped as visceral branches and parietal branches. Visceral branches supply internal organs. They include the bronchial, pericardial, esophageal, and mediastinal arteries,...

abdominal aorta

Abdominal Aorta Branches and Blood Flow

The abdominal aorta carries blood through the lower part of the body and gives off many major branches. It begins after the aorta passes through the aortic hiatus in the diaphragm. From there, it runs left of the spinal column, sits behind the peritoneal cavity, and is surrounded by fatty tissue. It ends at the L4 vertebra, where it divides into the common iliac arteries. Before that split, the abdominal aorta gives rise to the celiac trunk, a single artery with three main branches. These are...

arteries of the head and neck

Head and Neck Arteries for Brain Blood Flow

The arteries of the head and neck deliver oxygen-rich blood to the brain, eyes, and nearby structures. This network is complex, but it is essential for normal body function. Two major pathways are the internal carotid arteries and the vertebral arteries. The internal carotid arteries supply the anterior part of the cerebrum. They enter the cranial cavity through the carotid foramen and give off several branches. The anterior cerebral artery supplies the frontal lobe of the cerebrum, while the...

arteries of the upper limbs

Blood Flow Through the Upper Limb

The arteries of the upper limb carry blood from the chest to the shoulder, arm, forearm, and hand. The subclavian artery becomes the axillary artery as it leaves the chest and enters the axillary region. From there, it continues into the upper arm as the brachial artery. The axillary artery is important for the shoulder region. It supplies the head of the humerus through the humeral circumflex arteries. The brachial artery then supports the brachial region and divides near the elbow into...

arteries of lower limbs

Blood Flow Pathways in the Lower Limb

Blood flow pathways in the lower limb begin with the external iliac artery as it leaves the body cavity. When it passes through the body wall and enters the femoral region, it is renamed the femoral artery. The femoral artery supplies blood to the deep muscles of the thigh and to the ventral and lateral skin regions. It does this through several small branches and through the lateral deep femoral artery, which also gives rise to the lateral circumflex artery. The knee region receives blood...

overview of systemic veins

Systemic Veins Returning Blood to the Heart

Systemic veins return deoxygenated blood from body tissues to the right atrium of the heart. In the human circulatory system, three main systemic veins carry this blood back to the heart. They are the coronary sinus, the superior vena cava, and the inferior vena cava. The coronary sinus is the heart’s principal vein. It lies in the coronary sulcus on the posterior side of the heart. This broad venous channel receives nearly all venous blood from the myocardium, or heart muscle. It is supplied...

veins of thorax

Azygos Veins and Thoracic Blood Drainage

The azygos system drains most of the thorax and helps return deoxygenated blood to the heart. It is part of the body’s circulatory system. The main veins in this system are the azygos vein, the hemiazygos vein, and the accessory hemiazygos vein. The azygos vein lies just to the right of the midline and in front of the vertebral column. It begins where the right ascending lumbar vein and the right subcostal vein meet. It ends by joining the superior vena cava. This vein drains blood from the...

veins of the abdomen and pelvis

How Abdominal Blood Returns to the Heart

Blood from the abdomen and pelvis returns to the heart through the inferior vena cava. This large vein collects blood from the abdominopelvic organs and the abdominal walls before it carries it upward. Many smaller veins feed into the inferior vena cava. The lumbar veins drain the posterior abdominal wall. Some of this blood goes directly to the inferior vena cava, and some goes to the ascending lumbar veins of the thoracic azygos system. The gonadal veins also add blood, but they differ on...

veins of head and neck

Head and Neck Venous Drainage Paths

Head and neck venous drainage follows several major pathways. The external jugular, internal jugular, and vertebral veins carry blood away from different regions of the head and neck. Together, they help return blood to larger veins in the chest. The external jugular veins drain the superficial scalp and face. They pass over the sternocleidomastoid muscles and empty into the subclavian veins. The vertebral veins work differently from the nearby arteries. They drain the cervical vertebrae,...

veins of upper limbs

Upper Limb Vein Pathways

Upper limb vein pathways move blood from the hand and arm back toward the heart. These veins are grouped into deep and superficial systems. Each system follows a clear route through the hand, forearm, elbow, shoulder, and chest. The deep venous system includes the ulnar vein and the radial vein. The ulnar vein drains the fingers through the superficial palmar venous arches. The radial vein serves the palms through the deep palmar venous arches. These veins join to form the brachial vein, which...

veins of lower limbs

Lower Limb Vein Pathways

Lower limb veins carry blood from the feet and legs back toward the pelvis. They include deep veins and superficial veins. Deep veins lie farther from the skin, while superficial veins are closer to the body surface. The deep venous route begins in the foot and calf. The posterior tibial vein is formed by the union of the medial and lateral plantar veins, and it rises through the calf muscle as it takes in the fibular vein. The anterior tibial vein is a superior extension of the dorsalis pedis...

hepatic portal system

Blood Flow Through the Liver

The hepatic portal system moves nutrient-rich, deoxygenated blood from the gastrointestinal tract and spleen to the liver. This pathway helps the body maintain metabolic balance. It delivers blood to the liver before that blood returns to the rest of the circulation. The hepatic portal vein forms where the superior mesenteric vein, inferior mesenteric vein, and splenic vein join. The superior mesenteric vein drains blood from the stomach, pancreas, small intestine, and most of the large...

overview of pulmonary circulation

Pulmonary Blood Flow Through the Lungs

Pulmonary blood flow moves blood between the heart and the lungs. This circuit carries deoxygenated blood away from the right side of the heart and returns oxygen-rich blood to the left side. It connects the respiratory and cardiovascular systems through a precise route. The process starts when the right ventricle pumps deoxygenated blood into the pulmonary trunk. The pulmonary trunk is a large vessel that extends about 5 centimeters before it splits into the left and right pulmonary arteries.

development of blood vessels

How Blood Vessels Form in the Embryo

Blood vessels form very early in embryonic development. The vascular system begins about 15 to 16 days after conception. It starts outside the embryo in the mesoderm of the yolk sac, chorion, and connecting stalk. About two days later, blood vessel formation begins inside the embryo itself. This early system begins with hemangioblasts, which are precursor cells. Hemangioblasts can become angioblasts, the cells that produce blood vessels. Angioblasts gather to form blood islands across the...

fetal circulation

Placenta and Fetal Blood Flow

Placenta and fetal blood flow work together to support the developing fetus. This system moves oxygen, nutrients, and waste products between the fetus and the mother through the placenta, a special organ that acts as the exchange site. Two umbilical arteries carry blood from the fetus to the placenta. There, the blood picks up oxygen and nutrients and gives off waste products. The oxygen-rich blood then returns to the fetus through one umbilical vein. The umbilical vein splits into the fetal...

key terms and concepts

Learn how arteries, veins, capillaries, and vessel wall layers work together to move blood, control pressure, and support exchange in the circulatory system.

Blood Vessel Layers and Flow Control | JoVE K12

anatomy and physiology

JoVE Core Anatomy and Physiology showcases the anatomical and physiological details of the human body in comprehensive, clear, and engaging video animations. This collection of lessons focuses on the structures, components, functions, and requirements of the human body. It is complemented by scientist-in-action videos that demonstrate the application of this knowledge in real-world medical and research settings.

Florida Department of Education

High School

Life Science

SC.912.L.14

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SC.912.L.14.40

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Composition of Blood Plasma

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Structure and Function of Leukocytes

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Classification of Leukocytes

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Structure and Function of Platelets

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Introduction to Hemostasis

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Vascular Spasm

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extrinsic-and-intrinsic-pathways-of-hemostasis

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The ABO Blood Group

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Rh Blood Group

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Blood Typing

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Blood Transfusion

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Blood

Content elaboration: Blood is composed of plasma and the formed elements: red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes). The primary functions of blood are transportation, protection and regulation. Plasma, the most abundant component of blood, is the liquid portion that transports dissolved nutrients, waste, hormones, antibodies and proteins throughout the body. Red blood cells carry oxygen used during cellular processes throughout the body. White blood cells identify and protect the body against infectious disease and foreign cells. Platelets bind together when a blood vessel is damaged resulting in blood clot formation. The major ABO blood types, A, B, AB and O, are determined by the presence or absence of antigens on the surface of red blood cells. An additional antigen is present or absent on the surface of red blood cells determining Rh factor. Blood type antibodies are found in plasma. Processes related to blood include the production of blood cells and platelets, and hemostasis. Homeostatic imbalances are explored. These include, but are not limited to, sickle cell anemia, hemophilia, deep vein thrombosis, leukemia and lymphoma. Investigations are used to understand and explain blood in a variety of inquiry and design scenarios that can incorporate evolutionary concepts, scientific reasoning, comparative analysis, communication skills and real-world applications.

Blood

Blood Vessel Layers and Flow Control

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