Week 10 CVS blood part 1 Flashcards
Cardiovascular system
Consists of;
-Blood
-Blood vessels
-Heart
Role: These components ensure that the body receives the
necessary nutrients to function properly and that waste products are efficiently
removed
Blood
Blood is the fluid that circulates through the cardiovascular system
-It consists of;
->Red blood cells (which carry oxygen)
->White blood cells (which fight
infection)
->Platelets (which help with clotting)
->Plasma (the liquid component containing nutrients, hormones, and waste products)
Blood Vessels
->Arteries: These vessels carry oxygenated blood away from the heart to the body’s tissues -The largest artery is the aorta ->Veins: These vessels return
deoxygenated blood back to the heart -The largest veins are the superior and inferior vena cava –>Capillaries: These are small, thin-walled vessels where the
exchange of gases, nutrients, and waste products occurs between blood and tissues
Heart
-The heart is a muscular organ that pumps blood throughout the body ->The heart ensures continuous blood circulation, supplying oxygen and nutrients to tissues and removing carbon dioxide and waste products
Functions of Blood
Blood is a vital fluid that sustains life by performing essential functions, particularly in
the circulatory system (CVS)
It acts as a transport carrier, providing various critical
functions including; -transportation
-protection
-regulation
Transportation (O2 and CO2)
Oxygen (O2) and Carbon Dioxide (CO2) Movement:
->Oxygen Transport: Blood carries oxygen from the lungs to the tissues throughout the body via red blood cells (RBCs) bound to haemoglobin
->Carbon Dioxide Transport: Blood transports carbon dioxide, a waste product of metabolism, from the tissues back to the lungs for exhalation
Transportation (nutrients)
Blood distributes nutrients absorbed from the digestive system to all cells in the body, providing the necessary fuel and building blocks for cellular function
Transportation (electrolytes)
Blood carries electrolytes such as sodium, potassium, calcium,
and bicarbonate, which are essential for maintaining cellular
function, nerve transmission, and muscle contraction
Transportation (metabolic waste)
Blood transports metabolic waste products such as urea and
creatinine to the kidneys for excretion, thus helping to maintain homeostasis
Transportation (hormones and cytokines)
Blood delivers hormones and cytokines, which are signalling
molecules that regulate various physiological processes, including growth, metabolism, and immune responses
Protection (immune response)
->Antibodies and Complement Proteins: Blood contains antibodies (immunoglobulins) and complement proteins that help identify and neutralise pathogens such as bacteria, viruses, and toxins
->White Blood Cells (WBCs): Blood houses various types of white blood cells (e.g., neutrophils, lymphocytes, monocytes) that are crucial for the immune response, detecting, attacking, and destroying infectious agents
Protection (prevention of blood loss)
->Clotting Mechanism: Blood has platelets and clotting factors that
initiate clot formation to prevent excessive blood loss in the event
of injury
->Platelets: These cell fragments aggregate at the site of injury to
form a plug, while clotting factors activate a cascade leading to the formation of a stable fibrin clot
Regulation (body temperature)
->Heat Distribution: Blood absorbs and distributes heat throughout the body, helping to maintain a stable internal temperature
->Heat Exchange: Blood vessels can dilate (vasodilation) to release excess heat through the skin or constrict (vasoconstriction) to retain heat, thus regulating body temperature
Regulation (pH balance)
->Buffer Systems: Blood contains buffers such as bicarbonate (HCO3-) that help maintain the pH within a narrow range (around 7.35-7.45), crucial for normal cellular functions
->Acid-Base Balance: Blood transports carbon dioxide (a by-product of metabolism) to the lungs for exhalation and helps neutralise acids produced by metabolic processes
Regulation (Circulatory Body Fluid Volume/Concentration (Osmosis))
->Fluid Balance: Blood helps regulate the volume and concentration of body fluids through osmosis, ensuring that cells receive the proper amount of water
->Plasma Proteins: Proteins such as albumin in the blood plasma maintain oncotic pressure, which helps draw water into the bloodstream and maintain fluid balance
->Electrolyte Balance: Blood maintains the proper balance of electrolytes, such as sodium, potassium, and calcium, which are essential for various cellular processes and osmotic balance
Characteristics of blood
->Blood is a unique connective tissue and the only fluid tissue in the human body
->It has distinct physical and chemical properties that enable it to perform its vital functions
Physical characteristics (nature)
->Liquid Connective Tissue: Blood is a fluid connective tissue that circulates throughout the body within the cardiovascular system
->Sticky and Viscous: Blood is a sticky, viscous fluid due to the
presence of cells, proteins, and other substances
Physical characteristics (colour)
->Scarlet Red: Blood is bright red when it is oxygen-rich, typically
found in arteries
->Dark Red: Blood is darker when it is low in oxygen, typically found in veins
Physical characteristics (volume)
Total Blood Volume: Blood constitutes about 8-10% of an
individual’s body weight
Average Volume:
->Males: Approximately 5-6 litres
->Females: Approximately 4.5 litres
Composition of blood (plasma)
It is typically divided into three main components: plasma, the buffy coat, and red blood cells (RBCs)
->Plasma (55%): Liquid Matrix: Plasma is the liquid component of blood, constituting about 55% of its total volume
Composition of blood (buffy coat)
Buffy Coat (~1%):
->Leucocytes (White Blood Cells): Part of the immune system, involved in protecting the body against infections and foreign invaders ->Types of Leucocytes: Neutrophils, lymphocytes, monocytes, eosinophils, and basophils
->Platelets (Thrombocytes): Cell fragments that play a crucial role in blood clotting and preventing blood loss
Composition of blood (RBC)
Red Blood Cells (RBCs, ~44%):
->Erythrocytes: The most abundant cells in the blood, responsible for transporting oxygen from the lungs to the tissues and carbon dioxide
from the tissues to the lungs
Blood - plasma
->Plasma is the straw-coloured, sticky fluid component of blood, making up about 55% of its total volume
It consists primarily of water and contains various soluble
components crucial for maintaining homeostasis and supporting bodily functions
Composition of plasma (water)
Water (~90%): The primary component of plasma, serving as a solvent and medium for transporting other substances
Composition of plasma
Soluble Components (~10%):
->Plasma Proteins:
-Albumin: Maintains osmotic pressure and transports hormones, vitamins, and drugs
-Globulins: Include antibodies (immunoglobulins) essential for
immune response, and transport proteins
-Fibrinogen: Essential for blood clotting
->Nutrients:
-Glucose: A primary source of energy for cells
-Amino Acids: Building blocks for protein synthesis
-Cholesterol: Involved in cell membrane structure and precursor for steroid hormones
->Gases:
-Oxygen (O2): Necessary for cellular respiration
-Carbon Dioxide (CO2): A waste product of metabolism
-Traces of Other Gases (<1%): Includes nitrogen and other gases in minor amounts
->Electrolytes:
-Sodium (Na+): Crucial for maintaining fluid balance and nerve function
-Potassium (K+): Important for nerve and muscle function
-Chloride (Cl-): Helps maintain osmotic balance and is involved in digestive processes
-Others: Include calcium, bicarbonate, magnesium, and phosphate, each with specific roles in bodily functions
->Metabolic Wastes:
-Urea: A waste product formed from the breakdown of proteins,
excreted by the kidneys
Haematopoiesis
Haematopoiesis is the process by which blood cells are formed ->This process occurs in the red bone marrow, found in specific bones within the body
->The formation of blood cells involves haematopoietic stem cells (HSCs), also known as
haemocytoblasts, which differentiate into various types of blood cells under the
influence of hormonal and growth factors
Haematopoietic stem cells (HSCs)
-HSCs are multipotent stem cells capable of giving rise to all types of blood cells, including red blood cells (RBCs), white blood cells (WBCs), and platelets
-Various hormones and growth factors determine the differentiation and maturation of HSCs into specific blood cell lineages
->Once formed, the new blood cells enter the bloodstream through blood sinusoids, which are specialised capillaries in the bone marrow
Types of blood cells formed
-Red Blood Cells (RBCs)
-White Blood Cells (WBCs)
-Platelets
Haematopoietic processes (leucopoiesis)
-Formation of white blood cells (leucocytes) in the bone marrow
->Key for the immune system, producing neutrophils, lymphocytes, monocytes, eosinophils, and basophils
Haematopoietic processes (erythropoiesis)
-Formation of red blood cells (erythrocytes) in the bone marrow
->Regulated by erythropoietin (EPO), a hormone that responds to low oxygen levels
Haematopoietic processes (thrombopoiesis)
-Formation of platelets (thrombocytes) in the bone marrow
->Involves the fragmentation of megakaryocytes
->Regulated by thrombopoietin (TPO), a hormone that stimulates platelet production
White blood cells (neutrophils)
-The most abundant type of white blood cell
-Involved in the initial immune response, particularly against bacterial infections
-Act through phagocytosis, engulfing and destroying pathogens
White blood cells (lymphocytes)
-Key players in adaptive immunity
-B-Cells: Produce antibodies to neutralise pathogens
-T-Cells: Include helper T-cells that coordinate the immune response and cytotoxic T-cells that kill infected cells
White blood cells (monocytes)
-Differentiate into macrophages and dendritic cells
-Involved in phagocytosis, engulfing pathogens and debris
-Play a role in antigen presentation to T-cells, initiating the adaptive immune response
White blood cells (eosinophils)
-Combat multicellular parasites, such as helminths
-Involved in allergic reactions and asthma
-Release cytotoxic granules to destroy parasites and modulate
inflammation
White blood cells (basophils)
-Release histamine and other mediators involved in inflammatory responses
-Play a role in allergic reactions and hypersensitivity
-Contribute to the defence against parasites
Platelets (thrombocytes) - structure
-Cell Fragments: Not whole cells, but fragments derived from
megakaryocytes in the bone marrow
-Contains Mitochondria: Have energy-producing mitochondria
-No Nucleus: Lack a nucleus, unlike most cells
Platelets (thrombocytes) - function
-Blood Clotting: Play a crucial role in the blood clotting process.
-When a blood vessel is damaged, platelets adhere to the site of injury and aggregate to form a temporary plug
-They release chemicals that activate the clotting cascade, leading to the formation of a stable fibrin clot
-Preventing Blood Loss: By forming clots, they prevent excessive blood loss from damaged vessels
WBC count
-Low WBC count : Penia: deficiency/not enough
-High WBC count : Philia:
Surplus/Excess
Cytosis: Increase
Leukopenia
A reduction in the total number of white blood cells (leucocytes)
in the blood
Risks:
-Increased Risk of Infection: A low white blood cell count impairs the body’s ability to fight infections
-Sepsis: Severe infections can lead to sepsis, a life-threatening
condition where the body’s response to infection causes
widespread inflammation
-Lethality: Without sufficient white blood cells to combat
pathogens, infections can become severe and potentially lethal
Neutropenia
A specific type of leukopenia where there is a low count of
neutrophils, the most abundant type of white blood cell
Risks:
-Risk of Bacterial Infections: Neutrophils are critical for defending against bacterial infections, low neutrophil levels increase susceptibility to bacterial infections
-Examples of Risk Factors: Chemotherapy, bone marrow disorders, severe infections, autoimmune diseases
Thrombocytopenia
A condition characterised by a low platelet count
Risks:
-Risk of Blood Loss: Platelets are essential for blood clotting, a low platelet count increases the risk of excessive bleeding, even from
minor injuries
-Autoimmune Condition in Children: Immune thrombocytopenia (ITP) is an autoimmune condition often seen in children, where the immune system mistakenly attacks and destroys platelets
-Symptoms: Easy bruising, prolonged bleeding from cuts,
spontaneous bleeding,
petechiae (small red spots on the skin)
Leucocytosis (high WBC count)
Leucocytosis is an increase in the number of white blood cells (leucocytes) in the blood, often indicating an underlying infection or inflammation
Different types of leucocytosis can suggest various types of infections or conditions
Neutrophilia (neutrophil leucocytosis)
Definition: An increased number of neutrophils in the blood
Significance: Often a sign of bacterial infection
Examples: Pneumonia, appendicitis, and bacterial sepsis
Eosinophilia
Definition: An increased number of eosinophils in the blood
Significance: Typically indicates a parasitic infection or allergic reaction
Examples: Parasitic infections like helminthiasis, allergic conditions like asthma and hay fever
Lymphocytosis
Definition: An increased number of lymphocytes in the blood
Significance: Often a sign of viral infection
Examples: Infectious mononucleosis, viral hepatitis, cytomegalovirus infection
Monocytosis
Definition: An increased number of monocytes in the blood
Significance: Indicates bacterial infection in tissues or chronic
inflammatory conditions
Examples: Tuberculosis (TB), chronic bacterial infections, and some autoimmune diseases
Red Blood Cells (RBCs) – erythrocytes
Approximately 44% of total blood volume
Cell Counts:
->Men: 4.7 to 6.1 million cells per microlitre (cells/mcL)
->Women: 4.2 to 5.4 million cells/mcL
Red Blood Cells (RBCs) – erythrocytes -> structure
Biconcave Shape:
->No Nucleus and Organelles: RBCs lack a nucleus and organelles, providing more space for haemoglobin
->Large Surface Area: The biconcave shape increases the surface area for gas exchange
->Anaerobic ATP Synthesis: RBCs generate ATP anaerobically, meaning they do not use the oxygen they transport
Red Blood Cells (RBCs) – erythrocytes -> haemoglobin content
97% of RBC Content: Haemoglobin makes up 97% of the dry weight of an RBC
->Function: Responsible for the transport of oxygen and carbon dioxide
It binds oxygen reversibly, allowing for oxygen uptake in the lungs and release in tissues
Red Blood Cells (RBCs) – erythrocytes -> spectrin
Plasma Membrane Protein: Spectrin provides flexibility to the RBC membrane
->Function: Allows RBCs to deform and pass through small capillaries without rupturing
Haemoglobin structure
Haemoglobin is the protein in red blood cells responsible for transporting oxygen from the lungs to the tissues and carbon dioxide from the tissues back to the lungs
It is composed of the red pigment haem bound to the protein globin
Haem structure
Red Pigment: Haem is the red pigment that gives red blood cells their colour, 4 heam groups -> each Hg can transport 4 O2 molecules
->Central Iron (Fe2+): Each haem molecule contains a central iron (Fe2+) ion
->Oxygen Binding: Each Fe2+ ion can bind to one oxygen (O2)
molecule, allowing haemoglobin to carry oxygen efficiently
Globlin structure
Protein Component: Globin consists of four polypeptide chains
Polypeptide Chains:
Two Alpha Chains ->there are two identical alpha (α) chains
Two Beta Chains -> there are two identical beta (β) chains.
Haemoglobin composition
Each haemoglobin molecule is composed of four polypeptide chains, with each chain containing one haem group, thus enabling one haemoglobin molecule to carry four oxygen molecules
Oxygen transport - loading
Oxygenated Blood:
->When haemoglobin binds to oxygen, it forms oxyhaemoglobin (HbO2)
->Colour: This process turns the blood bright red
->Saturation: Oxyhaemoglobin is typically 98-100% saturated with oxygen in the lungs
Oxygen transport - unloading
Deoxygenated Blood:
-When haemoglobin releases oxygen to the tissues, it becomes deoxyhaemoglobin (Hb)
->Colour: This process turns the blood dark or ruby red
->Saturation: Deoxyhaemoglobin is typically 75-80% saturated with oxygen after unloading oxygen to the tissues
Carbon dioxide transport - loading
Carbaminohaemoglobin:
->Haemoglobin also binds to carbon dioxide, forming
carbaminohaemoglobin (HbCO2)
->Proportion: About 20% of carbon dioxide in the blood is
transported bound to haemoglobin
->Function: This form allows the blood to carry CO2 from the
tissues back to the lungs for exhalation
