Blood Anatomy & Physiology
BLOOD STUDY NOTES
FUNCTIONS OF BLOOD
Delivery & Transport:
Oxygen (O2) and Nutrients: Essential for cellular metabolism.
Wastes and Carbon Dioxide (CO2): Removal from tissues.
Hormones: Transport of signaling molecules throughout the body.
Regulation:
Body temperature: Maintains thermal homeostasis.
pH: Maintains the acid-base balance (normal range: 7.35 - 7.45).
Fluid volume: Regulation of blood volume and pressure.
Protection:
Hemostasis: Prevents excessive bleeding through clotting mechanisms.
Immunity: Defends against pathogens through various immune responses.
COMPOSITION OF BLOOD
Approx. 5 L of fluid connective tissue (CT) composed of:
Formed Elements: Red blood cells (RBCs), white blood cells (WBCs), and platelets.
Plasma: The fluid extracellular matrix (~50% of blood volume).
DEMONSTRATION OF BLOOD COMPONENTS
Blood can be drawn into a tube containing anticoagulants (e.g., EDTA) and then centrifuged to separate components based on density.
PLASMA
The complex fluid portion of blood, accounting for approximately 50% of the total blood volume.
Composition:
~90% H2O
~10% Solutes
Serum: The fluid portion of clotted blood.
NORMAL pH of BLOOD
Normal: 7.35 - 7.45
Acidosis: pH < 7.35
Alkalosis: pH > 7.45
SOLUTES IN PLASMA
Plasma Proteins: Most synthesized in the liver.
Albumin: Major protein, maintains oncotic pressure and transports various substances (e.g., fatty acids).
Globulins: Include transport proteins and immunoglobulins (IgA, IgG, IgM).
Fibrinogen: Converts to fibrin during clotting.
Other Solutes:
Non-protein nitrogenous substances (urea, uric acid, creatinine)
Nutrients (glucose, amino acids, fatty acids)
Electrolytes (Na+, K+, Ca²+, Cl-, HCO3-)
Gases (O2, CO2)
Hormones
PLASMA PROTEINS
Albumin:
Most abundant protein, ~60% of total plasma proteins. Functions include maintaining osmotic pressure.
Globulins:
Heterogeneous group of proteins.
γ-Globulins (Immunoglobulins): Synthesized by WBCs, involved in immunity.
Clotting Proteins: Include fibrinogen and prothrombin (factors I and II, respectively).
BLOOD CLOTTING FACTORS (TABLE 17.3)
Factor I: Fibrinogen - converted to fibrin.
Factor II: Prothrombin - converted to thrombin.
Factor III: Tissue factor - initiates coagulation cascade.
Factor IV: Calcium ions (Ca²+) - necessary for all stages of the coagulation process.
(Further factors listed - detailing origin, function, and pathway)
NON-PROTEIN NITROGEN SOURCES
Urea/BUN: Product of amino acid breakdown; important renal function indicator.
Uric Acid: From nucleic acid metabolism; elevated levels can lead to gout.
Creatinine: Derived from creatine phosphates; also a measure of renal function.
NPN IMPORTANCE
Indicators of kidney function; elevated levels suggest renal impairment.
ELECTROLYTE LEVELS
Abnormalities:
Hypernatremia: Na+ > 145 mEq/L; can result from dehydration.
Hyponatremia: Na+ < 135 mEq/L; related to water retention or loss.
Hyperkalemia: K+ > 5.5 mEq/L; causes cardiac disturbances.
Hypokalemia: K+ < 3.5 mEq/L; can lead to muscle weakness.
Hypercalcemia/Hypocalcemia, Hyperphosphatemia/Hypophosphatemia, etc.
ERYTHROCYTE CHARACTERISTICS
Comprise ~45% of blood volume; specialized for O2 and CO2 transport.
Structure:
Biconcave shape, enhancing gas exchange and reducing friction.
Contains hemoglobin:
Globin: 2 alpha and 2 beta chains
Heme group: Contains iron, binding O2 and CO2.
ERYTHROCYTE LIFE CYCLE
Average lifespan of RBCs: ~120 days
Life cycle includes stages from hemocytoblast to proerythroblast to normoblast and finally reticulocyte before maturity.
REGULATION OF ERYTHROPOIESIS
Erythropoietin (EPO) released by kidneys in response to hypoxia stimulates RBC formation.
Chronic high altitude will increase EPO release and enhance erythropoiesis.
ANEMIA TYPES AND CHARACTERISTICS
Hemorrhagic Anemia: Acute/chronic blood loss (e.g., injury, ulcer).
Hemolytic Anemia: Related to destruction of RBCs (infections, transfusion reactions).
Sickle Cell Anemia: Caused by HbS, leading to RBC sickling and blockage of capillaries.
Thalassemia: Genetic disorders leading to varying severity of anemia.
LEUKOCYTES/WBCs
Function to fight infections, destroy damaged cells, and modulate immune response.
Normal WBC Count: ~4,800-10,800 cells/mm³.
Types include granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (monocytes, lymphocytes).
HEmostasis and Coagulation Processes
Phases of Coagulation: Vascular spasm, platelet plug formation, and coagulation cascade following tissue injury.
Thromboxane A2 promotes platelet aggregation and vasoconstriction; occurs via platelet release mechanisms following endothelial injury.
Clot Formation: Involves a cascade of clotting factors leading to fibrin formation, ultimately stabilizing the clot.
ABNORMAL BLEEDING DISORDERS
Thrombocytopenia: Defined as a deficiency in platelet numbers, potentially due to cancers or autoimmune diseases.
Hemophilia: Genetic conditions leading to deficiencies in coagulation factors, affecting the blood clotting ability.
DIETARY REQUIREMENTS FOR ERYTHROPOIESIS
B Vitamins: Folic acid and B12 are crucial for DNA synthesis necessary for erythropoiesis.
Iron: Essential for hemoglobin production; deficiencies lead to hypochromic anemia.
CLOT PREVENTION AND ANTICOAGULANTS
Natural inhibitors include prostacyclins, antithrombin III, and heparin.
Medications such as aspirin and vitamin K inhibitors serve in preventing unwanted clot formation during treatment protocols.
Laboratory Tests for Coagulation: Prothrombin time (PT) and partial thromboplastin time (PTT) assess health and functionality of blood clotting processes.
THE LYMPHATIC SYSTEM Overview
The lymphatic system comprises vessels and lymph organs.
Major vessels include:
Internal jugular vein
Right lymphatic duct (entrance into the vein)
Thoracic duct (entrance into the vein)
Regional lymph nodes consist of:
Cervical nodes
Axillary nodes
Inguinal nodes
Thoracic duct drains into the venous system via the subclavian vein.
Lymphatic vessels collect lymph fluid from various body tissues.
Functions of the Lymphatic SystemFluid Balance
It maintains fluid balance in the body by collecting excess interstitial fluid (IF) and returning it to the bloodstream.
Recall capillary hemodynamics:
Lymphatic ducts connect to veins to facilitate this function.
Fluid filters from capillaries under hydrostatic pressure and moves through the interstitial space, with reabsorption occurring at the venous end.
Review of Capillary HemodynamicsThe Big Picture
Fluid filtration occurs from capillaries, primarily at the arteriolar end and reabsorption at the venous end.
Capillary dynamics statistics:
20 L of fluid filters out per day - almost 7 times the total plasma volume!
17 L is reabsorbed into capillaries at the venous end, and about 3 L is drained into the lymphatic system.
Net Filtration Pressure (NFP)
NFP determines fluid movement direction. Calculated as:
NFP = (HP + OP) - (HP + OP_{c})Hydrostatic Pressure (HP):
The push of fluid against a boundary due to blood pressure in vessels.
Example: At the arteriolar end, HP = 35 mm Hg.
Osmotic Pressure (OP):
The pull of fluid across a boundary due to nondiffusible solutes (like plasma proteins).
Example: OP in capillaries = 26 mm Hg, OP in interstitial fluid = 1 mm Hg.
Calculating NFP for arteriolar end yields:
NFP = (35 + 1) - (0 + 26) = 10 ext{ mm Hg (net outward pressure)}
This confirms that fluid moves from the capillary into the interstitial space.For the venous end:
HP = 17 mm Hg, OP = 26 mm Hg.
NFP becomes:
NFP = (17 + 1) - (0 + 26) = -8 ext{ mm Hg (net inward pressure)}
This indicates fluid moves from the interstitial space back into the capillary.
Role of the Lymphatic System
In summary, fluid not reabsorbed by capillaries (3 L/day) is removed into the lymphatic system, aiding in:
Immune support
Nutrient absorption from the digestive tract.
Fat Absorption
The lymphatic system plays a crucial role in fat absorption from the intestines:
Fats, as well as other nutrients, travel into lacteals (intestinal lymphatic capillaries) and then to the bloodstream via the thoracic duct and left subclavian vein.
Mechanism of absorption includes:
Chylomicrons formed in the intestines transport fats.
Various transport mechanisms (active transport, facilitated diffusion) assist in the movement of different nutrients.
Immune Function of the Lymphatic System
Lymph nodes, as part of the lymphatic system, are critical for immune defense:
House white blood cells (WBCs) such as macrophages and lymphocytes.
Phagocytize pathogens (like E. coli).
Composition of Lymph
Once interstitial fluid enters the lymphatic system, it becomes lymph:
Similar composition to interstitial fluid but has a lower protein content and contains wastes, toxins, bacteria, viruses, and cancer cells.
Lymph Transport MechanismsLymph Capillaries and Vessels
Lymphatic capillaries have unique anatomical features:
Closed-end tubes intertwined with blood capillaries.
Lack a basement membrane.
Have flap-like mini-valves that increase permeability to allow large molecules and cells to enter.
Lymphatic Trunks and Ducts
Formed by the union of lymphatic vessels and drain specific body regions:
Include:
Lumbar trunks (2)
Intestinal trunk (1)
Bronchomediastinal trunks (2)
Subclavian trunks (2)
Jugular trunks (2)
Lymphatic ducts:
The right lymphatic duct drains the upper right body into the right subclavian vein.
The thoracic duct drains the rest of the body into the left subclavian vein.
Cisterna Chyli
Described as a "milky sac"; it is an inferior expansion of the thoracic duct that receives lymph from the lower body and drains chyle from the small intestine.
DIGESTIVE SYSTEM IUPPER GIOverview of the Digestive Tract
Terminology:
Digestive Tract = Alimentary tract = Gastrointestinal (GI) tract
Length: 9 m (30 ft) muscular tube
Extends from mouth to anus
Components of the Digestive System
Mouth (oral cavity)
Tongue
Parotid gland
Sublingual gland
Submandibular gland
Salivary glands
Pharynx
Esophagus
Stomach
Small Intestine
Duodenum
Jejunum
Ileum
Large Intestine
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Cecum
Rectum
Anus
Accessory Organs
Liver
Gallbladder
Pancreas
(Spleen)
Functions of the Digestive System
Ingestion: Food intake
Propulsion: Movement of food through the digestive tract
Digestion: Breakdown of food into absorptive units
Mechanical Breakdown: Includes chewing (mouth), churning (stomach), and segmentation (small intestine)
Chemical Digestion: Breakdown of polymers into monomers using enzymes
Absorption: Transfer of digested nutrients from the GI tract into blood and lymph
Defecation: Elimination of indigestible substances via the anus
Detailed Breakdown of Processes
Ingestion
Mechanical breakdown through chewing in the mouth.
Mechanical and enzymatic action in the stomach.
Propulsion
Swallowing (oropharynx) followed by peristalsis through the esophagus, stomach, small and large intestine
Absorption
Primarily occurs in the small intestine via blood vessels and lymph vessels (especially for lipids).
Large intestine: mainly absorption of water and electrolytes.
Defecation
Formation of feces and elimination through the anus.
Review of Digestion and Hydrolysis
Mechanism of Hydrolysis:
Water (H₂O) is used to break covalent bonds between monomers.
Example:
Monomer 1 + H₂O + Monomer 2 → Monomers linked by covalent bond.
Dehydration Synthesis:
Monomers → Formation of links with water released.
Examples of Monomers:
Glucose, Fructose, Sucrose, proteins (amino acids), triglycerides (fatty acids and glycerol), and nucleic acids (DNA/RNA).
Types of Macromolecules and Their DigestionProteins
Breakdown Process:
Enzymes: proteases break proteins into amino acids.
Example of a reaction:
Proteins + H₂O → Amino Acids (via hydrolysis).
Peptide Bonds:
Formed by dehydration synthesis between amino acids.
Carbohydrates
Example:
Starch → Amylase → Maltose + Oligosaccharides + Glucose.
Lipids
Triglycerides Breakdown:
Lipase enzyme: converts to monoglycerides and free fatty acids.
Nucleic Acids
Structure:
Comprised of nucleotides which includes a sugar, phosphate group, and nitrogenous base (Adenine, Thymine, Guanine, Cytosine).
Function:
Genetic information storage and transmission.
General Functions of the Digestive System
Absorption: The transfer of nutrients into the blood and lymphatic system.
Defecation: The excretion of waste materials.
Accessory Organs
Functionality in Digestion:
Mechanical Breakdown
Chewing and churning.
Chemical Breakdown
Secreting digestive enzymes, bile, etc.
Histology of the GI TractGeneral Overview
Layers of the Digestive Tract:
Mucosa:
Epithelium
Lamina propria
Muscularis mucosae
Submucosa:
Contains blood and lymphatic vessels, and MALT (mucosa-associated lymphoid tissue).
Nerve Plexuses:
Myenteric plexus, Submucosal plexus.
Muscularis externa:
Inner circular layer
Outer longitudinal layer.
Controls peristalsis and segmentation.
Serosa:
Connective tissue layer
Visceral peritoneum below the diaphragm.
Specific Layer Functions
Mucosa: Varies in structure based on location, typically has goblet cells for mucus secretion.
Submucosa: Composed of areolar and elastic connective tissue; contains nerves and blood vessels.
Muscularis Externa: Responsible for peristalsis and segmentation through coordinated contraction of muscle layers.
Nervous Regulation
Parasympathetic System: Stimulates saliva flow, gastric motility, and overall digestive activity.
Sympathetic System: Inhibits digestive processes, leading to reduced saliva flow and digestive activity.
Muscle Control in DigestionMuscle Arrangement
Controls Peristalsis: Waves of muscular contraction propel the bolus along the digestive tract.
Segmenting Movements: Localized rhythmic contractions for mixing and absorption in the small intestine.
Peritoneum and Cavity
Visceral and Parietal Peritoneum:
Form the peritoneal cavity, with the former covering abdominal organs and the latter lining the cavity wall.
Oral Cavity Anatomy
Boundaries:
Anterior: Oral orifice;
Posterior: Oropharynx.
Functions:
Ingestion, mastication, initial digestion of carbohydrates, and lipids.
Muscles of Mastication
Cheek and Lips: Composed of skin and skeletal muscle, which contain sensory receptors.
Main Muscles:
Masseter, temporalis, medial pterygoid (for chewing).
Palate Structure
Hard Palate: Forms the anterior roof of the mouth; consists of bony structures.
Soft Palate: Muscular arch posterior to the hard palate.
Uvula: Closes nasal passages during swallowing.
Anatomy of the Tongue
Structure: Composed of skeletal muscle; anchored to the floor by the lingual frenulum.
Taste Buds: Located in elevations (papillae) on the surface; involved in taste perception and bolus formation.
Salivary Glands Structure
Types of Salivary Glands:
Parotid, submandibular, and sublingual glands.
Serous Cells: Produce fluid with enzymes for carbohydrate digestion.
Mucous Cells: Secrete mucus to facilitate food movement.
Teeth Anatomy
Dental Structure:
Enamel: Hard outer layer of teeth.
Dentin: Lies beneath enamel and forms the bulk of the tooth.
Dentition Development
Deciduous Teeth: Temporary teeth; emerge from 6 months to 2 years, with a gradual replacement by permanent teeth (from age 6 to late teens).
Tooth Anatomy
Root: Anchored in the jaw; holds the teeth in place.
Cementum: Calcified layer encasing the root.
Pharynx
Structure and Function: Connection between oral/nasal cavities and esophagus/trachea.
Parts: Nasopharynx, oropharynx, laryngopharynx.
Muscular Action: Involuntary skeletal muscle responsible for directing bolus during swallowing.
Esophagus
Anatomy:
25 cm long tube that conveys food from pharynx to stomach.
Histology: Composed of stratified squamous epithelium in the mucosa and contains mucous secreting esophageal glands.
Lower Esophageal Sphincter
Prevents backflow of gastric contents into the esophagus (related to GERD).
Stomach Anatomy and Function
Structure:
Area for temporary storage of food; initial site of protein digestion.
Capacity: Can hold approximately 50 mL - 4 L.
Stomach Functionality
Chyme Formation: Mechanical and chemical processing of food; secretes gastric juice consisting of HCl and digestive enzymes.
Stomach Histology
Mucosa: Modified for gastric secretions including parietal cells (HCl secretion) and chief cells (pepsinogen secretion).
Stomach Emptying
Factors Influencing Rate: Gastric distension and meal composition affects gastric emptying speed.
DIGESTIVE SYSTEM II: LOWER GI Anatomy & Physiology IISMALL INTESTINE
Definition: The small intestine is where digestion is completed and absorption occurs.
Dimensions: Approximately 2.5 m in length and 2.5 cm in diameter.
Pathway: Extends from the pyloric sphincter to the large intestine.
PARTS OF THE SMALL INTESTINE
The small intestine comprises three major sections:
Duodenum
Jejunum
Ileum
Duodenum
Characteristics:
It is retroperitoneal and C-shaped, acting as the proximal end of the small intestine.
Function: Receives bile and pancreatic juice via the hepatopancreatic ampulla (ampulla of Vater).
Jejunum
Location: Situated between the duodenum and ileum.
Length: Accounts for approximately 40% of the total length of the small intestine.
Ileum
Characteristics:
This is the distal end of the small intestine.
Termination: Ends at the ileocecal valve where it joins the large intestine.
MESENTERY
Definition: A fold of visceral peritoneum that suspends the ileum and jejunum to the posterior abdominal wall.
Vascularization: Contains numerous blood and lymphatic vessels, connecting blood flow to the hepatic portal vein and the thoracic duct.
GREATER OMENTUM
Definition: A peritoneal fold that covers the small intestine anteriorly.
Associated Structures:
Stomach, spleen, and liver.
SMALL INTESTINE STRUCTUREMucosa and Surface Area
Mucosa Characteristics: The mucosa has an increased surface area to facilitate absorption.
Plicae Circulares / Circular Folds: These structures slow the flow of chyme, enhancing both absorption and surface area.
Villi and Microvilli
Villi: Finger-like projections approximately 1 mm in size that increase surface area for absorption.
Microvilli: Formed from absorptive cells, creating a "brush border" that enhances nutrient absorption.
CELLULAR STRUCTURES OF THE MUCOSA
Goblet Cells: Secrete mucus for lubrication and protection.
Absorptive Cells: Specialized for nutrient absorption.
Lacteals: Lymphatic vessels located in each villus that transport absorbed fats.
Blood Capillaries: Surround villi; responsible for transporting absorbed nutrients to the bloodstream.
Microvilli: Abundant in columnar epithelium; contribute to absorption via trans-epithelial absorption processes.
ENTEROENDOCRINE CELLS
Function: Scattered throughout the mucosa, these cells secrete hormones related to digestion which help coordinate digestive processes.
INTESTINAL GLANDS (CRYPTS OF LIEBERKUHN)
Characteristics: Found deep within the mucosa and contain goblet cells and secretory cells.
Function: Secretes intestinal juice, which is an aqueous alkaline mucus and lysozyme.
Significant Note: Unlike gastric juices, intestinal glands do not secrete digestive enzymes.
BRUNNER'S GLANDS (DUODENAL GLANDS)
Location: Present in the submucosa of the duodenum.
Function: Secrete alkaline mucus, which serves to protect intestinal lining from acidic chyme and promote enzyme functionality.
PEYER'S PATCHES
Location: Nodules of lymphatic tissue predominantly in the ileum.
Function: Aid in bacterial control and immune surveillance within the gastrointestinal tract.
MECHANICAL DIGESTION: SEGMENTATION
Definition: The primary process of mixing and breaking up the chyme.
Control Mechanism: Governed by impulses, local reflexes, and a functional "internal pacemaker" to coordinate muscle contractions, facilitating maximum nutrient absorption.
PANCREAS
Location: Extends from the spleen toward the duodenum and is retroperitoneal.
Structure: Comprises both endocrine and exocrine functions.
ENDOCRINE PANCREAS
Composition: Contains pancreatic islets (islets of Langerhans) that secrete hormones like insulin and glucagon.
EXOCRINE PANCREAS
Composition: Comprised of acinar cells.
Function: Secretes pancreatic juice containing:
Electrolytes (including NaHCO3
Digestive enzymes (EZs): Amylase, Lipases, Nucleases, Proteases (Trypsinogen, Chymotrypsinogen, Procarboxypeptidase).
SECRETION PROCESS
Pancreatic Ducts: Acinar ducts drain into the main pancreatic duct, which merges with the common bile duct.
Hepatopancreatic Ampulla (of Vater): Entry point for both bile and pancreatic juice into the duodenum, controlled by the hepatopancreatic sphincter (of Oddi).
SODIUM BICARBONATE (NaHCO3)
Function: Neutralizes the acidic chyme entering the duodenum, allowing pancreatic enzymes to function optimally.
PANCREATIC ENZYMES OVERVIEW
Amylase: Hydrolyzes starch into oligosaccharides and glucose.
Lipase: Hydrolyzes triglycerides into monoglycerides and free fatty acids.
Nucleases (DNAse & RNAse): Hydrolyze nucleic acids into simpler components.
Proteases: Hydrolyze peptide bonds between specific amino acids.
Examples: Trypsin cleaves after Arginine or Lysine; Chymotrypsin cleaves after Phenylalanine, Tryptophan, or Tyrosine.
Proteases are secreted as inactive zymogens to prevent self-digestion of the pancreas (e.g. trypsinogen is activated to trypsin).
ACTIVATION OF PANCREATIC PROTEASES
Chronology of Events:
Cholecystokinin (CCK) stimulates the release of zymogens from the pancreas.
Enterokinase (found on the small intestinal epithelial cells) converts trypsinogen into trypsin.
Trypsin activates other pancreatic enzymes to their functional forms, enabling protein digestion.
REGULATION OF PANCREATIC SECRETIONS
Nervous system (NS) stimulates pancreas secretions.
Duodenal hormones (e.g., Secretin and CCK) regulate the secretion of bicarbonate and enzyme-rich pancreatic juice.
Secretin Function: Increases secretion of NaHCO3 and promotes bile production while decreasing gastric activity.
CCK Function: Enhances enzyme secretion, bile ejection, and relaxation of the hepatopancreatic sphincter, while also decreasing gastric activity.
PANCREATIC DISORDERS
Pancreatitis: Inflammation and destruction of pancreatic tissue, often due to duct obstruction (e.g., gallstones). Release of enzymes into the blood can be detected with laboratory tests using amylase and lipase measurements.
Pancreatic Cancer: Ductal adenocarcinomas and endocrine tumors with poor prognoses due to late detection.
BILIARY SYSTEM: LIVER & GALL BLADDERLIVER FUNCTIONS
Bile Production: Essential for fat emulsification, enabling efficient lipase action.
Handles over 60 metabolic functions, including carbohydrate, lipid, and protein metabolism, detoxification, storage of vitamins and minerals, and blood filtration.
CARBOHYDRATE METABOLISM
Regulates blood glucose via glycogen storage and gluconeogenesis.
Converts excess carbs into fats for storage.