Humoral Immunity (ALL Steps) | Immunology @TaimTalksMed

Uploaded April 2019 | Updated September 2026, 1 week ago

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Content:
0:00 Introduction
0:23 Steps in Humoral Immune Response
1:22 Phagocytosis and Inflammation
9:01 Antigen Presentation (MHCII + Th0)
11:34 B Cells Differentiation
17:05 Primary and Secondary Humoral Immune Response

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All information in my immunology videos are from:
- Book: Immunology, Eighth Edition by David Male, Jonathan Brostoff, David Roth and Ivan Roitt
- Additional research in PubMed
- University lecture materials
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Types of Immune responses:
- Humoral Immune response
- Cellular Immune response
- Immunological Memory/T-cell Tolerance
- Hypersensitivity

Steps in Humoral Immunity:
1. Antigen Enter (Extracellular antigen)
2. Phagocytosis and Inflammation
3. Peptide + MHCII on cell surface presented to Th0
4. B-cell Differentiation and Ag specific antibody

Phagocytosis and Inflammation:
Phagocytosis by Professional Phagocytes:
- Neutrophils,
- Macrophages/Monocytes,
- Mast cells and
- Denditic Cell

Steps in Phagocytosis:
Step 1: Binding
- Non specific Cell Surface Receptors:
- Mannose Receptor: Bind Mannose on Cell wall of microorganisms and fungi
- Toll Like Receptor
- CD14: Bind Lipopolysaccharide of Gram negative bacteria
- C3b - C3b receptor: Indirect Opsonization (Promote binding)
- Direct Opsonization: Fc-Receptor bind to Fc portion antibody
Step 2: Engulfment
- By Pseudopods
Step 3: Phagosome:
- Oxygen Dependent Digestion: Add Reactive Oxygen Species (ROS) into phagosome to kill microorganism. ROS are free radicals
Step 4: Lysosome Fusion:
- Lysosomes fuse with phagosome (Attack Cell wall)
- Enzymes (Proteolytic, Hydrolytic)
- Antimicrobial Peptides (Defensins)
- Acidic Reaction (Low pH)
- Lactoferrin (Neutrophils)
Step 5: Antigen Presentation
- Present a part of peptide on an MHC class 2 molecule

Additionally: Macrophage release pro-inflammatory cytokines to cause inflammation.
- IL8 - Chemotaxis for Leukocytes
- IL1 - Activate T-ly and Macrophages
- IL6 - Activate T- and B-Lymphocytes
- TNFa - Activate Endothelium (Endothelium express receptors to help neutrophils to bind and get out of blood vessel and release antimicrobial proteins)
- IL12 - Activate Natural Killer Cells

- IL1, IL6, TNFa has systemic response, they act as endogenic pyrogen causing fever. They can travel to the Hypothalamus to release Prostaglandins E2 (PGE2) which causes fever. Fever helps kill microorganism and increase metabolism to heal quickly. IL6 also travel to the liver to cause release of acute phase proteins (CRP and MBL)
Incomplete Phagocytosis: Phagocyte not able to kill microorganism
Listeria: Release Listeriolysin
Mycobacterium: Release Catalase

Present MHCII to Naive T helper Cell:
3 activation signals needed to activate Lymphocyte:
- 1st signal: T cell Receptor (TCR) with CD4 and CD3 - MHCII
- 2nd signal: B7 - CD28
- 3rd signal: IL4 from mast cells, Th1
- Naive Th0 release IL2 (Autocrine) to grow
Now the naive Th0 undergoes clonal expansion and differentiation into effector Th2 cells.

Effector Th2 express CD40L and release IL10 (Suppresses function of Th1), Il4, IL5, IL6

B cells in secondary lymphoid organs:
Has BCR - B cell Receptor (IgD/IgM and signal transducers iga and igb)

B cell binds to microorganism and migrates to secondary follicule and go as close to paracortex (T cell zone) as possible to meet Th2 cell

3 activation signals needed to activate naive B-cell:
T-cell dependent B cell differentiation
- 1st signal: bind microorganism
- 2nd signal: B-cell binds to active Th2 through MHCII-TCR, CD40-CD40L
- 3rd signal: IL4, IL5, IL6, IL10, IL2, IFNg (according to what kind of antibody we need)
Now B-cell differentiate into Memory B-cell and Plasma Cell

T independent b cell differentiation:
When naive B cell binds to a microorganism (mostly carbohydrates), a strong signal activates the B cells into only miu plasma cells releasing IgM.

Primary and Secondary Humoral Immune Response:
During first exposure: IgM release first, then IgG after. The amount of IgG is higher
During second exposure of same antigen: IgM - same response, IgG give a stronger and quicker response.

Humoral Immunity (ALL Steps) | Immunology

$Wrist & Hand Bones (Carpals, Metacarpals & Phalanges) | Anatomy 🌐 Website: https://taimtalksmed.com/ 🫀 Help keep this content free: youtube.com/channel/UCEr7pkSXVsHcBLLBcJAGV-Q/join 🔬 Get 10% off anatomy lab models (affiliate link): https://anatomywarehouse.com?aff=34 📲 Other Links: Instagram: https://www.instagram.com/taimtalksmed/ Discord: https://discord.com/invite/DENMUpS8ey Content: 00:00 Introduction & Content 00:35 Carpal Bones 00:51 Proximal Row of Wrist Bones 02:51 Distal Row of Wrist Bones 05:09 Wrist Bones 05:31 Bones of the Hand 05:41 Metacarpal Bones 06:45 Phalanges 07:53 Sesamoid Bones of the Hand 09:40 Outro & Next Topic Carpal Bones (Ossa carpi) The wrist consists of 8 carpal bones arranged in two rows: a proximal row and a distal row. These short, irregular bones allow for the wrist’s flexibility and stability. Proximal row (lateral to medial): - Scaphoid (os scaphoideum) – Articulates proximally with the radius and distally with the trapezium and trapezoid. Medially connects with the lunate. Notable for its tubercle on the palmar side, contributing to the carpal tunnel’s lateral wall. - Lunate (os lunatum) – Lies between the scaphoid and triquetrum. Articulates proximally with the radius and distally with the capitate. - Triquetrum (os triquetrum) – Medial to the lunate. Articulates with lunate, pisiform (anteriorly), and hamate. - Pisiform (os pisiforme) – A sesamoid bone embedded in the tendon of flexor carpi ulnaris. Articulates with the triquetrum. Serves as the attachment for: - Pisohamate ligament - Pisometacarpal ligament - Origin for abductor digiti minimi Distal row (lateral to medial): - Trapezium (os trapezium) – Articulates with the 1st and 2nd metacarpals. Located beneath the thumb. Features: - Tubercle of trapezium - Groove for the tendon of flexor carpi radialis - Trapezoid (os trapezoideum) – Medial to the trapezium. Articulates with 2nd metacarpal, scaphoid, and capitate. - Capitate (os capitatum) – The largest carpal bone, articulates with 3rd metacarpal, lunate, scaphoid, trapezoid, and hamate. - Features: Head (proximal) and base (distal) - Hamate (os hamatum) – Medial-most bone in the distal row. - Articulates with 4th and 5th metacarpals, capitate, and triquetrum. - Features the hook of hamate, serving as an attachment for: - Pisohamate ligament - Flexor digiti minimi - Opponens digiti minimi Mnemonic used: “Scary Lions Try Pizza, Then They Chase Hamsters” (Scaphoid, Lunate, Triquetrum, Pisiform, Trapezium, Trapezoid, Capitate, Hamate) Metacarpal Bones (Ossa metacarpi) There are 5 metacarpals, numbered I–V (lateral to medial), forming the palm of the hand. - Each consists of a base, shaft, and head. - The 1st metacarpal is shorter and thicker with a saddle-shaped base that articulates with the trapezium, allowing thumb opposition. - The heads articulate with the proximal phalanges, forming the metacarpophalangeal (MCP) joints, visible as knuckles during flexion. Phalanges (Ossa digitorum) The hand contains 14 phalanges divided into: - Proximal phalanges (phalanges proximales) – Present in all 5 digits. - Middle phalanges (phalanges mediae) – Absent in the thumb. - Distal phalanges (phalanges distales) – Present in all 5 digits. Structural components: - Each phalanx has a base, shaft, and head (except distal phalanges). - Distal phalanges end in a tuberosity of the distal phalanx (tuberositas phalangis distalis) that anchors the flexor digitorum profundus tendon and supports the fingertip pulp. Sesamoid Bones (Ossa sesamoidea) - Found typically at the 1st MCP joint embedded in the tendon of flexor pollicis brevis. - Function as biomechanical levers that enhance thumb flexion force. - Can also appear at the 2nd, 3rd, or 5th MCP joints, depending on population. Radiological study mentioned: - Journal of Orthopaedics, Trauma and Rehabilitation (2017) analyzed over 300 Chinese hand X-rays. - Found sesamoid bones at the thumb MCP joint in 100% of cases. - Noted ethnic variation in occurrence at other MCP joints. - Left–right symmetry in sesamoid distribution was observed across all patients. Clinical Relevance - Scaphoid fracture – Most common carpal fracture; risk of avascular necrosis due to poor blood supply. - Hook of hamate fracture – Common in sports with racquets or bats. - First carpometacarpal arthritis – Affects thumb base; impacts opposition. - Sesamoiditis – Inflammation of sesamoid bones, often misdiagnosed. - Fractures of phalanges/metacarpals – Common due to direct trauma or punching injuries. - Thumb opposition impairment – Due to dysfunction of saddle joint or thenar muscles. Sources: - Kozlowski, T. (2017). Memorix Anatomy, 2nd ed. • Standring, S. (2020). Gray’s Anatomy, 42nd ed. • Tubbs RS, Shoja MM, Loukas M. (2016). Bergman’s Encyclopedia of Human Anatomic Variation • White TD, Folkens PA. (2005). The Human Bone Manual Programs used: Complete Anatomy, Biorender, PowerPoint$ $Femur (Thigh Bone): Landmarks, Surfaces & Muscle Attachments | Clinical Anatomy 🌐Website: https://taimtalksmed.com/ 🫀 Help keep this content free: youtube.com/channel/UCEr7pkSXVsHcBLLBcJAGV-Q/join 🔬Get 10% off anatomy lab models (affiliate link): https://anatomywarehouse.com?aff=34 📲Other Links: Instagram: https://www.instagram.com/taimtalksmed/ Discord: https://discord.com/invite/DENMUpS8ey Content: 00:00 Introduction & Content 00:47 Femur Anatomy 01:05 Proximal Femur 04:15 Shaft of Femur 06:26 Distal Femur Structures 07:48 Force Distribution Across Femur 08:26 Ending and Next Topic In this video, we go through the full anatomy of the femur, dividing it into its three major regions: the proximal end, the shaft (body), and the distal end. Structures of the Femur Proximal End of the Femur - Head of femur (caput femoris): Spherical structure that articulates with the acetabulum of the pelvis to form the hip joint. - Fovea of the head (fovea capitis femoris): Small pit on the medial surface of the femoral head where the ligament of the head of femur attaches. - Neck of femur (collum femoris): Narrow region connecting the head to the shaft, commonly fractured in elderly individuals. - Greater trochanter (trochanter major): Large lateral projection providing insertion for gluteus medius, gluteus minimus, piriformis, superior gemellus, inferior gemellus, and obturator internus. - Trochanteric fossa (fossa trochanterica): Depression on the medial side of the greater trochanter where obturator externus inserts. - Lesser trochanter (trochanter minor): Posteromedial projection for insertion of the iliopsoas muscle. - Intertrochanteric line (linea intertrochanterica): Anterior ridge running between the greater and lesser trochanters; attachment site for the iliofemoral ligament and origin of vastus medialis and vastus lateralis. - Intertrochanteric crest (crista intertrochanterica): Posterior ridge connecting the trochanters; contains the quadrate tubercle. - Quadrate tubercle (tuberculum quadratum): Site of insertion for quadratus femoris muscle. Shaft of the Femur (Corpus femoris) - Pectineal line (linea pectinea): Ridge on the posterior surface for insertion of pectineus muscle. - Gluteal tuberosity (tuberositas glutea): Posterior surface ridge for insertion of gluteus maximus. - Linea aspera (linea aspera): Prominent ridge running down the posterior shaft; composed of medial and lateral lips and an intermediate zone. - Medial lip (labium mediale): Site for origin of vastus medialis, adductor longus, adductor brevis, and insertion of adductor magnus. - Lateral lip (labium laterale): Site for origin of vastus lateralis, short head of biceps femoris, and lateral intermuscular septum. - Intermediate zone (zona intermedia): Central part of linea aspera. - Medial supracondylar line (linea supracondylaris medialis): Continuation of medial lip; attachment for adductor magnus. - Lateral supracondylar line (linea supracondylaris lateralis): Continuation of lateral lip; origin of plantaris muscle. - Anterior surface (facies anterior): Located between medial and lateral borders; origin of vastus intermedius. - Posterior surface (facies posterior): Upper back surface of the shaft. - Popliteal surface (facies poplitea): Triangular area on the posterior surface near the distal end. - Medial surface (facies medialis): Located between anterior and medial borders. - Lateral surface (facies lateralis): Located between anterior and lateral borders. - Medial border (margo medialis): Separates medial and anterior surfaces. - Lateral border (margo lateralis): Separates lateral and anterior surfaces. Distal End of the Femur - Medial condyle (condylus medialis): Large, rounded medial projection for articulation with tibia. - Lateral condyle (condylus lateralis): Large, rounded lateral projection also articulating with tibia. - Medial epicondyle (epicondylus medialis): Prominence above the medial condyle; attachment site for tibial collateral ligament. - Adductor tubercle (tuberculum adductorium): Located on medial epicondyle; insertion site for adductor magnus. - Lateral epicondyle (epicondylus lateralis): Prominence above the lateral condyle; attachment site for fibular collateral ligament. - Groove for popliteus (sulcus musculi poplitei): Small groove on lateral condyle for popliteus muscle tendon. - Intercondylar fossa (fossa intercondylaris) - Intercondylar line (linea intercondylaris) - Patellar surface (facies patellaris) Clinical Notes - Femoral neck fractures: Common in older adults, especially postmenopausal women; can compromise blood supply. - Supracondylar fractures: Common in pediatric populations; can damage neurovascular structures. - Hip flexor injuries: Involving the lesser trochanter and iliopsoas tendon. Sources: - Kozlowski, T. (2017). Memorix Anatomy, 2nd ed. - Standring, S. (2020). Gray’s Anatomy, 42nd edition - White TD, Folkens PA. (2005). The Human Bone Manual Programs used: Complete Anatomy (3D4Medical), PowerPoint, Canva, Camtasia$

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