Name: blood vessel connections in the body
Uploaded: 2024-07-18T13:37:06.000Z
Duration: 1 min 19 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

Anastomoses

An anastomosis is formed by joining two or more branches of an artery or vein to supply blood to a tissue or organ.
One of the critical roles of anastomoses is to establish collateral circulation, which serves as an alternate blood source if one of the arteries or veins becomes obstructed due to injury or infection.
There are three types of anastomoses &#8212; arterial, venous, and arteriovenous.
Arterial anastomoses are formed between arteries. They occur mainly in the brain and heart. The circle of Willis in the brain is an example of an arterial anastomosis, which establishes diverse pathways for blood supply to brain tissues.
However, not all arteries participate in anastomotic connections, and those that lack such interconnections are referred to as end arteries.
Venous anastomoses occur between veins and are found throughout the body.
Arteriovenous anastomoses occur between the artery and vein and are prominently observed in the vascular shunt of capillary beds.
Additionally, anastomoses can be intentionally established through surgical interventions such as bypass surgery.

anastomoses

In human anatomy, anastomosis refers to a connection or opening between two things, particularly between blood vessels or other tubular structures. The term is derived from the Greek term &#39;anastomosis,&#39; which means &#39;outlet&#39; or &#39;opening.&#39; This natural network of connections plays a critical role in the survival and functionality of the human body.
Anastomoses can be formed at arterial, venous, and lymphatic vessels.
Arterial Anastomosis: These occur between arteries. They are most common in areas of the body that require a constant and significant blood supply, such as the brain and heart. For instance, the Circle of Willis in the brain is an arterial anastomosis that provides multiple routes for blood to reach brain tissues.
Venous Anastomosis: These occur between veins and are found throughout the body. An example would be the anastomoses between veins in the forearm, which allow for the redirection of blood flow if one vein becomes blocked.
Lymphatic Anastomosis occurs between lymph vessels and plays a vital role in maintaining the body&#39;s fluid balance and overall immunity.
An artery and vein can also form an anastomosis called an arteriovenous anastomosis. The vascular shunt in the capillary bed formed between the metarteriole and thoroughfare channel, which connects the arteriole and postcapillary venule, is a prominent example.
Anastomoses can occur naturally in the body or be created surgically in procedures like bypass surgery. In both cases, they ensure that blood and other fluids can circulate effectively, even when a primary pathway is blocked or damaged.
One of the most common places where anastomosis occurs naturally is in the circulatory system. For example, the coronary arteries, which supply blood to the heart muscle, have anastomotic connections. This means that if one artery is blocked, another can often still deliver blood to the affected area, preventing heart muscle death and reducing the risk of a heart attack.
Apart from the circulatory system, anastomoses are also found in the digestive system, where they can connect different parts of the intestine, and in the respiratory system, where they link different airways.
In conclusion, anastomosis is a vital anatomical feature that helps maintain body functionality by ensuring the continuity of blood flow and the delivery of nutrients and oxygen to various tissues and organs. Whether occurring naturally or created surgically, anastomoses contribute significantly to our survival and health.

An anastomosis is formed by joining two or more branches of an artery or vein to supply blood to a tissue or organ.
One of the critical roles of ...

Education

JoVE Core

Anatomy and Physiology

Unit 1

Blood Vessels and Circulation

KEY TERMS AND CONCEPTS

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 well-known example is the Circle of Willis in the brain, which gives blood several routes to reach brain tissue.

Venous anastomoses occur between veins and are found throughout the body. In the forearm, these vein connections can redirect blood if one vein becomes blocked. Lymphatic anastomosis happens between lymph vessels and helps maintain fluid balance and support immunity.

An artery and a vein can also connect through an arteriovenous anastomosis. One example is the vascular shunt in the capillary bed between the metarteriole and the thoroughfare channel, which links the arteriole and postcapillary venule. Anastomoses may form naturally or be created during surgery, such as bypass surgery.

These connections are especially important in the circulatory system. Coronary arteries, which supply the heart muscle, have anastomotic connections. If one artery is blocked, another may still supply the area. This can help prevent heart muscle death and lower the risk of a heart attack.

Anastomoses also appear in other body systems. In the digestive system, they can connect different parts of the intestine. In the respiratory system, they can link different airways. Overall, anastomoses help preserve body function by supporting the flow of blood, nutrients, oxygen, and other fluids to tissues and organs.

Blood Vessel Connections in the Body

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...

structure of blood vessels

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...

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 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 anastomoses connect arteries, veins, and lymph vessels, help reroute blood flow, and support organs like the brain, heart, and intestines.

Blood Vessel Connections in the Body | 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.

Overview of the Cardiovascular System

The cardiovascular or circulatory system comprises the blood, the heart, and the blood vessels.
Blood is a specialized fluid comprising cells in a liquid ...

Characteristics and Functions of Blood

Approximately 8% of the body mass comprises whole blood, a specialized connective tissue vital for transportation, regulation, and protection.
The ...

Composition of Blood

Whole blood consists of the blood plasma, a fluid extracellular matrix, and formed elements, including cells and cell fragments.
Blood plasma, which makes ...

Composition of Blood Plasma

Blood plasma is a fluid that contains approximately 92% water and 8% solutes. The solutes include various types of proteins, which constitute about 7% of ...

Overview of Hematopoiesis

Hematopoiesis, or hemopoiesis, is the production of the formed elements in blood from common progenitors, called hematopoietic stem cells, or HSCs.
During ...

Production of Formed Elements

Hemangioblasts, the multipotent stem cells of mesodermal origin, give rise to hematopoietic stem cells or HSCs.
The HSCs undergo hematopoiesis to produce ...

Role of Hematopoietic Growth Factors

Hematopoietic growth factors are a group of regulatory and signaling molecules that influence the differentiation of hematopoietic stem cells, or HSCs.
...

Erythropoiesis

Factors Affecting Erythropoiesis

The cardiovascular system regulates erythrocyte numbers for optimal oxygen transport. It also prevents erythrocyte over-proliferation, maintaining blood ...

Structure and Function of Erythrocytes

There are 4.2 to 6 million erythrocytes, or red blood cells, per microliter of blood. These small cells are flattened biconcave discs with depressed ...

Hemoglobin

Hemoglobin is a tetrameric globular protein consisting of two alpha and two beta polypeptide chains.
Each of these chains has an iron-containing heme ...

Lifecycle of Erythrocytes

The circulating erythrocytes frequently squeeze through blood capillaries, damaging their plasma membrane due to constant friction.
After about 100 to 120 ...

Disorders of Erythrocytes

Erythrocyte disorders are broadly categorized into anemic and polycythemic conditions.
Anemia develops due to the low oxygen-carrying capacity of the ...

Structure and Function of Leukocytes

A healthy individual has about 4,500 to 11,000 leukocytes or white blood cells per microliter of blood, accounting for about 1% of blood volume.
Unlike ...

Classification of Leukocytes

Leukocytes are classified into two groups based on the presence or absence of cytoplasmic granules. Granular leukocytes, which contain granules, belong to ...

Disorders of Leukocytes

Leukocyte disorders are characterized by either leukopenia, an abnormally low leukocyte count, or leukocytosis, a very high leukocyte number.
Bone marrow ...

Structure and Function of Platelets

The cell fragments known as platelets are disc-shaped, with an average diameter of about 3 &#956;m and a thickness of roughly 1 &#956;m. They play a ...

Introduction to Hemostasis

Hemostasis is a series of rapid, defensive reactions triggered to stop excessive bleeding and promote healing after a vascular injury.
It is a highly ...

Vascular Spasm

The vascular phase, also known as vasospasm, is the initial stage of hemostasis, crucial for preventing excessive bleeding when a blood vessel is injured. ...

Formation of the Platelet Plug

In an injured blood vessel, the platelet phase - which overlaps with the vascular phase - begins about 15-20 seconds after the onset of vascular spasm.
As ...

Coagulation

Coagulation or clotting is the last hemostasis phase. It involves a series of chemical reactions to form a blood clot, reinforcing the initial platelet ...

extrinsic-and-intrinsic-pathways-of-hemostasis

Extrinsic and Intrinsic Pathways of Hemostasis

The extrinsic and intrinsic pathways of coagulation involve reaction cascades of clotting factors. They merge into the common pathway, eventually forming ...

Clot Retraction and Fibrinolysis

The activated platelets in a blood clot extend projections and interact with other platelets and fibrin fibers.
Within 30 to 60 minutes, the contractile ...

Disorders of Hemostasis

Thromboembolic disorders and bleeding disorders are two types of disruptions in hemostasis.
The thromboembolic disorders are characterized by the ...

The ABO Blood Group

The ABO blood group system is based on the presence of specific antigens or agglutinogens on the red blood cells, or RBCs, and antibodies or agglutinins ...

Rh Blood Group

The Rhesus or Rh antigen is a class of agglutinogen on the red blood cells or RBCs. Its presence or absence categorizes a person as Rh-positive or ...

Blood Typing

The antigens A, B, and Rh on the surface of red blood cells serve as the foundation for blood grouping.
When these antigens come in contact with their ...

Blood Transfusion

A blood transfusion is a medical procedure to replace lost whole blood or its components due to injury, surgery, or treatment for conditions like anemia ...

Bone Marrow Sampling and Transplants

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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

Overview of the Heart

The heart is a hollow muscular organ that pumps blood through the body.
It is cone-shaped and weighs about 250 to 300 grams on average.
The heart is ...

Cardiovascular System

Content elaboration: The cardiovascular system consists of the heart and blood vessels. The heart is mostly comprised of cardiac muscle which is supplied with oxygenated blood by coronary arteries. The structure of the heart includes four chambers, four valves and major vessels leading to and from the heart. The flow of blood through the heart, pulmonary and systemic circuits should be explored. Blood flows from arteries, to arterioles, to capillaries, to venules, then to veins. In the capillaries, oxygen, nutrients, and chemical messengers diffuse out (leave) and carbon dioxide and other waste products diffuse in (enter). Veins have valves that keep the blood flowing toward the heart. The primary function of the cardiovascular system is the transport of oxygen, carbon dioxide, hormones, nutrients, waste products and chemical messengers. Processes involved in the cardiovascular system include the cardiac cycle and cardiac and conductive pathway which is measured by electrocardiograms and blood pressure. Homeostatic imbalances are explored. These include, but are not limited to, a variety of cardiovascular diseases and structural imperfections of the heart, valves and vessels. Examples include, but are not limited to, myocardial infarction, aneurysm, atherosclerosis, hypertrophic cardiomyopathy, hypo/hypertension and arrhythmias. Investigations are used to understand and explain the cardiovascular system in a variety of inquiry and design scenarios that can incorporate evolutionary concepts, scientific reasoning, comparative analysis, communication skills and real-world applications.

Blood Vessel Connections in the Body

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