Lecture 1 · Blood
Blood Revision
Composition · Plasma Proteins · RBCs · WBCs · Hemostasis · Blood Transfusion
🩸 Blood — General
Volume
~5 litres
Composition
Plasma 55% + Blood cells 45%
- Transport: O₂ & CO₂ (RBCs), nutrients, waste, hormones
- Homeostatic: maintains constant internal environment
- Hemostatic: platelets prevent blood loss
- Defense: gamma globulins (antibodies) + WBCs phagocytosis
🧪 Plasma
Water
90%
Solids
Organic 9% + Inorganic 1%
Total Protein
6–8 gm/dL
Albumin
3.5–5 gm/dL — main osmotic pressure
- Albumin & Globulin: carrier functions + CO₂ transport
- Fibrinogen & Prothrombin: blood coagulation + viscosity
- γ-Globulin (antibodies): made by lymphatic tissue
- Liver: forms all plasma proteins except γ-globulins
🔴 RBCs (Red Blood Corpuscles)
- Not true cells — no nucleus, no mitochondria
- Hb = 34% of weight | Chief cation: K⁺
- Energy from anaerobic glycolysis
- Contains carbonic anhydrase enzyme (CO₂ transport)
- Main function: transport O₂ (at Hb) & CO₂
Erythropoiesis sites: Red bone marrow. Infants → all bones. Adults (>20y) → membranous bones (vertebrae, sternum, ribs).
Most important factor: Tissue oxygenation — hypoxia → ↑ erythropoietin (90% kidney, 10% liver)
Most important factor: Tissue oxygenation — hypoxia → ↑ erythropoietin (90% kidney, 10% liver)
⚪ WBCs
Normal Count
4000–11,000 /mm³
| Type | % | Function |
|---|---|---|
| Neutrophils | 60–70% | 1st defense vs bacterial infection |
| Eosinophils | — | Defense vs parasitic infection |
| Basophils | — | Release heparin & histamine |
| Lymphocytes | 20–30% | T-cell (cellular immunity), B-cell (antibodies) |
| Monocytes | — | Phagocytosis of bacteria & old cells |
🛑 Hemostasis & Clotting
- Platelets count: 150,000–400,000/mm³ | Life span: 8–12 days
- Steps: 1) Vascular spasm → 2) Platelet plug → 3) Blood clot
- Clot mechanism: Prothrombin activator → Prothrombin → Thrombin → Fibrinogen → Fibrin
| Heparin | Warfarin | |
|---|---|---|
| Route | IV injection | Oral |
| Mechanism | Facilitates antithrombin III | Inhibits Vit K (competitive) |
| Onset | Rapid (minutes) | Slow (1–2 days) |
| Antidote | Protamine | Vitamin K |
💉 Blood Transfusion
- Dangers: Incompatibility (shock, hyperkalemia, jaundice) | Allergic reactions | Disease transmission (AIDS, hepatitis, malaria)
- Indications: restore whole blood (hemorrhage), RBCs (anemia), WBCs (leucopenia), platelets (purpura), clotting factors (hemophilia)
🩸 Blood
Composition
Plasma 55% (water 90% + proteins)
Blood cells 45%
RBCs · WBCs · Platelets
Plasma Proteins
Total: 6–8 gm/dL
Albumin → osmotic pressure
γ-Globulin → antibodies
Fibrinogen → coagulation
Liver makes all except γ
RBCs
No nucleus, no mitochondria
Hb = 34% of weight
Anaerobic glycolysis (energy)
Erythropoiesis: red bone marrow
Hypoxia → erythropoietin ↑
WBCs
4000–11,000 /mm³
Neutrophils (60–70%) → bacteria
Lymphocytes (20–30%) → immunity
Basophils → heparin + histamine
Hemostasis
Vascular spasm → Platelet plug → Clot
Heparin: rapid, IV, antidote = protamine
Warfarin: slow, oral, antidote = Vit K
🫒
الزتونة — Blood
سكيمات الامتحان — لو لقيت كذا، اختار كذا
لو سألك عن الـ osmotic pressure أو سبب الـ edema في نقص البروتين
Albumin — it's responsible for maintaining plasma oncotic pressure
نقص الـ albumin → ↓ oncotic pressure → fluid leaks to tissues → edema
لو سألك أي خلية تتأثر أول في حالة hypoxia أو high altitude
Kidney releases erythropoietin (90%) → stimulates RBC production
الترتيب: Hypoxia → Kidney → Erythropoietin → Bone marrow → ↑ RBCs
لو سألك عن الـ antidote بتاع Heparin أو Warfarin
Heparin → Protamine | Warfarin → Vitamin K
Warfarin = inhibits Vit K → antidote = Vit K | Heparin = antithrombin III facilitator → antidote = protamine
لو سألك عن مصدر طاقة الـ RBCs أو سبب عدم وجود mitochondria
RBCs use anaerobic glycolysis — no mitochondria, no nucleus → called corpuscles not cells
لو سألك عن complications of blood transfusion
Incompatibility → Circulatory shock (↓ ABP) + Hyperkalemia (cardiac arrhythmia) + Jaundice
كمان: allergic reactions + disease transmission (AIDS, hepatitis, malaria)
لو سألك مين بيعمل γ-globulins (antibodies)
Lymphatic tissue (plasma cells) — NOT the liver
الكبد بيعمل كل البروتينات ما عدا الـ γ-globulins
1
Plasma
Total plasma proteins = 6–8 gm/dL. Albumin = 3.5–5 gm/dL. Main function of albumin = osmotic pressure.
2
RBCs
No nucleus → called corpuscles. Energy from anaerobic glycolysis. Hb = 34% of weight.
3
Erythropoiesis
Most important factor = tissue oxygenation. Hypoxia → erythropoietin (kidney 90%, liver 10%).
4
WBCs
Neutrophils = 1st line defense. Basophils = heparin + histamine. Lymphocytes = T-cell + B-cell immunity.
5
Anticoagulants
Heparin: IV, rapid, antidote = protamine. Warfarin: oral, slow (1-2 days), antidote = Vitamin K.
6
Clotting
Prothrombin activator → Prothrombin → Thrombin → Fibrinogen → Fibrin clot.
الأسئلة: 30
صح: 0
غلط: 0
Lecture 2 · Respiration 1
Physiology of Respiration — Ventilation
Divisions · Anatomy · Pulmonary Ventilation · Pressures · Surfactant · Compliance
🫁 Divisions of Respiration
- External respiration: pulmonary ventilation + gas exchange at alveoli
- Respiratory function of blood: carriage of O₂ & CO₂
- Internal respiration: oxidation of food → energy at cellular level
🌬️ Pulmonary Ventilation
- Normal rate: 16 breaths/min at rest
- Inspiration = ACTIVE (diaphragm + external intercostal muscles contract)
- Expiration = PASSIVE (relaxation → recoil)
- Diaphragm descends 1.5–7 cm → ↑ vertical diameter
📊 Pressures
| Pressure | Normal Values |
|---|---|
| Intrapulmonary (alveolar) | 0 at rest | −2 mmHg inspiration | +2 mmHg expiration |
| Intrapleural | −3 mmHg (end expiration) | −6 mmHg (end inspiration) | −30 mmHg (forced insp.) | +40 mmHg (forced exp. closed glottis) |
Importance of negative IPP: helps lung expansion + venous return + lymph flow + pulmonary blood flow
🧴 Surfactant
- Lipoprotein secreted from Type II alveolar cells
- ↓ surface tension between air & fluid lining alveoli
- Functions: ↓ muscular effort + prevent lung collapse + antibacterial
- Decreases in: premature babies (RDS) | cigarette smoking | cardiac surgery | premature C-section
📏 Compliance
- Ability of lung & chest to expand per unit ↑ in pressure
- Normal value: 130 ml/cmH₂O
- Affected by: elasticity, surfactant, condition of bones & muscles
🔧 Factors Affecting Ventilation
- 1) Airway resistance (bronchodilation ↓ resistance, bronchoconstriction ↑ resistance)
- Sympathetic → bronchodilation | Parasympathetic → bronchoconstriction
- 2) Pressures in thoracic cavity
- 3) Surfactant
- 4) Compliance
🫁 Respiration 1 — Ventilation
Divisions
External: ventilation + gas exchange
Blood: O₂ & CO₂ carriage
Internal: cellular oxidation
Breathing Mechanics
Inspiration = ACTIVE (diaphragm + ext. intercostal)
Expiration = PASSIVE (recoil)
Rate = 16/min at rest
Pressures
Intrapulmonary: ±2 mmHg
Intrapleural: always negative
−3 (exp) to −6 (insp)
Surfactant
Type II alveolar cells
↓ surface tension
Prevents collapse
↓ in premature babies, smoking
Autonomic Control
Sympathetic → bronchodilation
Parasympathetic → bronchoconstriction
🫒
الزتونة — Resp 1
سكيمات الامتحان
لو سألك inspiration active ولا passive
Inspiration = ACTIVE (diaphragm + external intercostal muscles contract) | Expiration = PASSIVE
لو سألك عن surfactant مكانه أو وظيفته الأهم
Made by Type II alveolar cells | Most important function = prevent lung collapse
لو سألك bronchial asthma ليه بتضيق الـ airways
↑ Parasympathetic activity → bronchoconstriction → ↑ resistance to airflow
لو سألك intrapleural pressure ليه negative
1) No air in pleural cavity 2) Continuous lung traction against rigid chest wall
لو سألك compliance ومين اللي يأثر عليه
Normal = 130 ml/cmH₂O | Affected by: elasticity + surfactant + bones & muscles condition
1
Active/Passive
Inspiration = Active (muscles contract). Expiration = Passive (muscles relax, recoil).
2
Surfactant
From Type II alveolar cells. ↓ surface tension. Prevents alveolar collapse. ↓ in prematurity & smoking.
3
IPP Values
Intrapleural: −3 (end exp) | −6 (end insp) | −30 (forced insp) | +40 (forced exp closed glottis).
4
Autonomic
Sympathetic → bronchodilation (↓ resistance). Parasympathetic → bronchoconstriction (↑ resistance).
5
Compliance
Normal = 130 ml/cmH₂O. Ability of lung + chest to expand per unit pressure change.
6
IPP Importance
Negative IPP → helps lung expansion + venous return + lymph flow + pulmonary circulation.
الأسئلة: 30
صح: 0
غلط: 0
Lecture 3 · Respiration 2
Gas Exchange & Gas Transport
Respiratory Membrane · O₂ Dissociation Curve · O₂ & CO₂ Transport · Hypoxia
🔬 Respiratory Membrane
- 6 layers: fluid lining → alveolar epithelium → epithelial BM → interstitial space → capillary BM → capillary endothelium
- Thickness: 0.6 μm | diffusion rate ∝ 1/thickness
- Surface area: 50–100 m² | diffusion rate ∝ surface area
- ↓ surface area in: pneumonectomy (half) | emphysema (alveolar wall loss)
🌬️ Gas Properties & V/P Ratio
| Parameter | PO₂ (mmHg) | PCO₂ (mmHg) |
|---|---|---|
| Alveolar air | 100 | 40 |
| Arterial blood | 100 | 40 |
| Venous blood | 40 | 46 |
CO₂ diffuses 20× faster than O₂ (high lipid solubility despite high MW)
V/P ratio = 0.8 (ventilation 4L/min ÷ perfusion 5L/min)
V/P ratio = 0.8 (ventilation 4L/min ÷ perfusion 5L/min)
🩸 O₂ Transport
O₂ in physical solution
0.3 ml/100ml (arterial) | 0.13 ml/100ml (venous)
O₂ capacity
20 ml/100ml (15g Hb × 1.33)
O₂ content (arterial)
19.5 ml/100ml
O₂ utilization coefficient
25% at rest | 75% during exercise
O₂ Dissociation Curve shifts RIGHT (Hb gives MORE O₂): ↑PCO₂ | acidosis | ↑temp | ↑2,3-DPG
Shifts LEFT (Hb gives LESS O₂): alkalosis | ↓PCO₂ | ↓temp | CO poisoning
Shifts LEFT (Hb gives LESS O₂): alkalosis | ↓PCO₂ | ↓temp | CO poisoning
💨 CO₂ Transport
| Form | Arterial CO₂ % | Tidal CO₂ % |
|---|---|---|
| Physical solution | 5% | 10% |
| Carbamino compounds | 6% | 20% |
| Bicarbonate (HCO₃⁻) | 89% | 70% |
Arterial CO₂ = 48–52 ml/100ml | Tidal CO₂ = 5ml/100ml added by tissues
⚠️ Hypoxia Types
| Type | Cause | Cyanosis? |
|---|---|---|
| Hypoxic | Defective external resp (high altitude, asthma) | Central cyanosis |
| Anemic | ↓ Hb amount or function | No cyanosis |
| Stagnant | ↓ tissue blood flow (heart failure, shock) | Central or peripheral |
| Histotoxic | Enzyme blockage (cyanide, alcohol poisoning) | No cyanosis |
🫁 Resp 2 — Gas Exchange & Transport
Resp Membrane
6 layers | thickness 0.6 μm
Surface area 50–100 m²
↓ in emphysema & pneumonectomy
O₂ Transport
98% in chemical combination with Hb
O₂ capacity = 20 ml/100ml
Utilization = 25% rest, 75% exercise
O₂ Curve Shift
Right: ↑CO₂, acidosis, ↑temp, ↑2,3-DPG
Left: alkalosis, ↓CO₂, ↓temp, CO poisoning
CO₂ Transport
89% as bicarbonate (arterial)
70% as bicarbonate (tidal)
CO₂ diffuses 20× faster than O₂
Hypoxia
Hypoxic: external resp defect
Anemic: ↓ Hb (no cyanosis)
Stagnant: ↓ blood flow
Histotoxic: cyanide (no cyanosis)
🫒
الزتونة — Resp 2
سكيمات الامتحان
لو سألك ليه CO₂ بيـdiffuse أسرع من O₂
CO₂ lipid solubility is 24× greater than O₂ → net result: CO₂ diffuses 20× faster
رغم أن MW بتاع CO₂ أكبر بس الـ lipid solubility بتغلب
لو سألك O₂ dissociation curve بتتحرك إيه في muscular exercise
Shifts RIGHT — exercising muscle is acidic + hot + high PCO₂ → Hb releases more O₂
لو سألك CO poisoning — cyanosis بتحصل ولا لأ
No cyanosis — carboxyHb is cherry red in color
لو سألك anemia cyanosis بتحصل ولا لأ
No cyanosis — threshold = 5 gm% reduced Hb, but in anemia total Hb is decreased so can't reach threshold
لو سألك main form of CO₂ transport
Bicarbonate (HCO₃⁻) — 89% of arterial CO₂ | 70% of tidal CO₂
1
CO₂ vs O₂
CO₂ diffuses 20× faster than O₂ (high lipid solubility despite high MW).
2
O₂ Capacity
20 ml/100ml blood. O₂ content: 19.5 arterial | 14.5 venous. Utilization: 25% rest.
3
Curve Shift
Right shift = ↑CO₂, acidosis, ↑temp (exercise). Left shift = CO poisoning, alkalosis.
4
CO₂ Forms
Bicarbonate = 89% (arterial) main form. Physical = 5%. Carbamino = 6%.
5
Cyanosis Rule
No cyanosis in: anemia + histotoxic + CO poisoning (cherry red). Cyanosis in: hypoxic + stagnant.
6
V/P Ratio
Normal = 0.8 (ventilation 4L/min ÷ perfusion 5L/min). Zone I (apex) = 3.3, Zone III (base) = 0.6.
الأسئلة: 30
صح: 0
غلط: 0
Lecture 4 · Respiration 3
Regulation of Respiration & Hypoxia
Respiratory Centers · Nervous & Chemical Regulation · Cyanosis
🧠 Respiratory Centers
- Located bilaterally in the brainstem
- Medullary: DRG (inspiratory) + VRG (expiratory)
- Pontine: Apneustic (lower pons) + Pneumotaxic (upper pons)
| Center | Location | Action |
|---|---|---|
| DRG (inspiratory) | Dorsal medulla | Intrinsic periodic firing → basic rhythm |
| VRG (expiratory) | Ventral medulla | Inactive in normal exp. (passive) | active in forced exp. |
| Apneustic | Lower 1/3 pons | Continuous excitatory impulses to DRG = pacemaker |
| Pneumotaxic | Upper 1/3 pons | Inhibitory impulses to apneustic + insp. center |
🔄 Generation of Rhythmic Respiration
- Apneustic → continuous stimulation to DRG
- Pneumotaxic → inhibits apneustic → stops inspiration
- DRG sends signals via phrenic nerve (C3,4,5) to diaphragm + intercostal nerves (T1-10)
🧪 Chemical Regulation (MAIN mechanism)
- ↑CO₂ = most important stimulus for respiration
- ↑H⁺ (acidosis) → ↑ respiratory rate
- Hypoxia → stimulates peripheral chemoreceptors
🫀 Nervous Regulation — Reflexes
- Hering-Breuer reflex: stretch receptors → negative feedback (stops over-inflation)
- Bainbridge reflex: ↑ venous return → ↑ HR
- Marey's law: ↑ ABP → ↓ HR (via baroreceptors)
- Respiratory sinus arrhythmia: inspiration ↑ HR | expiration ↓ HR
🔵 Cyanosis
- Threshold: 5 gm% reduced Hb in superficial capillaries
- Cyanosis occurs in: Hypoxic (central) + Stagnant (central or peripheral)
- NO cyanosis in: histotoxic | anemic | CO poisoning (cherry red carboxyHb)
🧠 Resp 3 — Regulation
Medullary Centers
DRG = inspiratory (basic rhythm)
VRG = expiratory (forced exp only)
Pontine Centers
Apneustic (lower) = pacemaker → excites DRG
Pneumotaxic (upper) = inhibits apneustic
Chemical Regulation
↑CO₂ = MOST IMPORTANT
↑H⁺ (acidosis) → ↑ RR
Hypoxia → peripheral chemoreceptors
Cyanosis
Threshold = 5 gm% reduced Hb
Present: hypoxic + stagnant
Absent: anemic, histotoxic, CO poisoning
🫒
الزتونة — Resp 3
سكيمات الامتحان
لو سألك most important stimulus for respiration
↑CO₂ (hypercapnia) — more important than hypoxia
لو سألك apneustic center لو اتحذف يحصل إيه
Loss of pacemaker → irregular breathing (apneustic breathing = prolonged inspiration)
لو سألك respiratory sinus arrhythmia
Inspiration → ↑ HR | Expiration → ↓ HR
لو سألك VRG (expiratory center) امتى بيتفعّل
Only in forced expiration (active process) — inactive in normal (passive) expiration
لو سألك Hering-Breuer reflex وظيفته
Negative feedback — stretch receptors in lung → stop over-inflation → limit tidal volume
1
Main Stimulus
↑CO₂ = most important respiratory stimulus. Then H⁺, then hypoxia.
2
DRG vs VRG
DRG = basic rhythm (always active). VRG = only in forced expiration.
3
Pontine
Apneustic (lower pons) = pacemaker. Pneumotaxic (upper pons) = inhibits apneustic.
4
Cyanosis
Threshold = 5 gm% reduced Hb. NOT in anemia, histotoxic, CO poisoning.
5
Phrenic Nerve
DRG → phrenic nerve C3,4,5 → diaphragm | intercostal nerves T1–10.
6
Sinus Arrhythmia
Inspiration → ↑ HR | Expiration → ↓ HR (respiratory sinus arrhythmia).
الأسئلة: 30
صح: 0
غلط: 0
Lecture 5 · CVS 1
Cardiovascular System & Cardiac Properties
Heart Structure · Conducting System · Cardiac Properties · Action Potential
🫀 CVS Overview
Arteries
Elastic vessels — transport blood to tissues
Arterioles
Resistance vessels
Capillaries
Exchange vessels — very thin walls
Veins
Capacitance vessels — blood to heart
| Systemic (General) | Pulmonary (Lesser) | |
|---|---|---|
| Begins at | Lt ventricle → aorta | Rt ventricle → pulmonary artery |
| Ends at | SVC/IVC → Rt atrium | Pulmonary veins → Lt atrium |
| Function | Remove waste from tissues | Oxygenate the blood |
🏗️ Heart Wall & Muscle Fibers
- 3 layers: Endocardium · Myocardium · Epicardium
- 3 types of cardiac muscle fibers: Nodal · Conducting · Contractile
| Node/Structure | Location | Role |
|---|---|---|
| SAN | Posterior wall, Rt atrium (near SVC) | Pacemaker — impulse origin (110/min) |
| AVN | Rt side of interatrial septum | Conducts to Bundle of His (90/min) |
| Bundle of His | AV fibrous ring | Only muscular connection between atria & ventricles |
| Purkinje fibers | Terminal branches | Fastest conduction 4 m/sec (35/min rhythm) |
⚡ 4 Properties of Cardiac Muscle
Rhythmicity
Regular beating — myogenic (not neurogenic)
Excitability
Ability to respond to stimuli
Conductivity
Spread excitation wave throughout heart
Contractility
Convert energy → mechanical work
⚡ Action Potential Phases
- Phase 0 (Rapid depol.): fast Na⁺ channels open → rapid Na⁺ influx
- Phase 1 (Early repol.): Cl⁻ influx + limited K⁺ efflux
- Phase 2 (Plateau): slow Ca²⁺ channels open → Ca²⁺ influx (unique to cardiac!)
- Phase 3 (Rapid repol.): K⁺ channels open → rapid K⁺ efflux
- Phase 4 (Complete repol.): Na-K pump restores resting level
🔀 Conduction Velocities
| Path | Velocity |
|---|---|
| Atrial muscle (SAN → AVN) | 1 m/sec |
| AV node (delay!) | 0.1 m/sec (slowest) |
| Purkinje fibers | 4 m/sec (fastest) |
| Ventricular muscle | 0.4 m/sec |
AV node delay allows atria to complete filling ventricles before ventricles contract
🫀 CVS 1 — Heart Structure & Properties
Heart Structure
3 layers: endo/myo/epicardium
3 fiber types: nodal, conducting, contractile
Conducting System
SAN → pacemaker (110/min)
AVN → 90/min | delay 0.1 m/sec
Purkinje → fastest 4 m/sec
4 Properties
Rhythmicity (myogenic)
Excitability
Conductivity
Contractility
Action Potential
Phase 0: Na⁺ in (rapid depol)
Phase 2: Ca²⁺ in (PLATEAU)
Phase 3: K⁺ out (repol)
Vessels
Arterioles = resistance
Capillaries = exchange
Veins = capacitance
🫒
الزتونة — CVS 1
سكيمات الامتحان
لو سألك ليه SAN هو pacemaker
Because it has the highest automaticity (110/min) — it fires before any other tissue
الترتيب: SAN 110 → AVN 90 → Bundle 45 → Purkinje 35 → Ventricles 25
لو Purkinje بقى pacemaker — heart rate هتبقى كام
35/min (its intrinsic rhythm)
لو سألك الـ plateau phase بيحصل ليه — إيه المميز في cardiac
Phase 2: slow Ca²⁺ channels open → Ca²⁺ influx — unique to cardiac muscle (not skeletal)
لو سألك AV node delay ليه مهم
Allows atria to finish contracting and fill ventricles before ventricular contraction starts
لو سألك rhythmicity بتاعت الـ heart — myogenic ولا neurogenic
Myogenic (inherent) — heart beats even if all nerves cut
1
SAN
Normal pacemaker. Highest rhythm = 110/min. Located: posterior wall Rt atrium near SVC.
2
Conduction Speed
Slowest: AVN = 0.1 m/sec. Fastest: Purkinje = 4 m/sec. Atrial muscle = 1 m/sec.
3
Phase 2 (Plateau)
Unique to cardiac muscle — slow Ca²⁺ channels open → prolonged depolarization → prevents tetany.
4
Rhythmicity
Myogenic origin (inherent) — not neurogenic. Heart beats even without neural input.
5
Bundle of His
Only muscular connection between atria and ventricles through the AV fibrous ring.
6
Vessel Types
Arterioles = resistance | Capillaries = exchange | Veins = capacitance.
الأسئلة: 30
صح: 0
غلط: 0
Lecture 6 · CVS 2
Cardiac Cycle · Heart Rate · Cardiac Output
Phases of Cardiac Cycle · Nervous & Chemical Regulation of HR · Factors Affecting COP
🔄 Cardiac Cycle
Total duration
0.8 sec
Atrial systole
0.1 sec
Ventricular systole
0.3 sec
Ventricular diastole
0.4 sec
- Ventricular systole: pressure rises from 0 → 80 mmHg (Lt) or 0 → 10 mmHg (Rt) → opens semilunar valves
- Ventricular diastole: relaxation → semilunar valves close → AV valves open → ventricular filling
- Atrial systole pumps 30% of venous return into ventricles
💓 Heart Rate Regulation
Normal HR
70 beats/min in adult male at rest
| Center | Action on HR |
|---|---|
| CAC (Cardioacceleratory) | ↑ HR via sympathetic |
| CIC (Cardioinhibitory) | ↓ HR via parasympathetic |
- Bainbridge reflex: ↑ venous return → ↑ HR (atrial baroreceptors)
- Marey's law: ↑ ABP → ↓ HR (arterial baroreceptors)
- Respiratory sinus arrhythmia: Inspiration → ↑ HR | Expiration → ↓ HR
- Oculocardiac reflex: pressure on eyeball → ↓ HR (vagal)
💊 Chemical & Physical Regulation of HR
| ↑ HR | ↓ HR |
|---|---|
| Atropine (blocks ACh) | Bile salts (inhibit SAN directly) |
| Histamine (↓ ABP → reflex tach.) | Morphine (stimulates CIC) |
| Sympathomimetics | Parasympathomimetics |
| Thyroxine (stimulates SAN) | ↑ blood temperature → +10/min per 1°C (then plateau) |
↑ Blood temperature 1°C → ↑ HR by 10 beats/min
📊 Cardiac Output (COP)
COP (normal)
5 litres/min at rest
EDV
110–130 ml (end diastolic)
ESV
40–60 ml (end systolic)
Stroke Volume
SV = EDV − ESV = 70 ml
- COP = HR × SV
- ↑ Venous return → ↑ EDV → ↑ stretch → ↑ force → ↑ SV → ↑ COP (Starling's law)
- Moderate ↑HR → SV ↓ but COP stays constant
- Extreme ↑HR or extreme ↓HR → ↓ COP
- ABP: within limits → no change in COP
🫀 CVS 2 — Cardiac Cycle & Output
Cardiac Cycle
Total = 0.8 sec
Atrial systole = 0.1 sec
Ventricular systole = 0.3 sec
Ventricular diastole = 0.4 sec
Heart Rate
Normal = 70/min
Bainbridge: ↑VR → ↑HR
Marey's law: ↑ABP → ↓HR
↑Temp 1°C → ↑10 beats
Cardiac Output
COP = 5 L/min at rest
SV = EDV − ESV = 70 ml
EDV = 110–130 ml
ESV = 40–60 ml
Factors ↑ COP
↑ Venous return (Starling)
Moderate ↑ HR
↑ Contractility
Chemicals Affecting HR
↑HR: Atropine, thyroxine
↓HR: Bile salts, morphine
🫒
الزتونة — CVS 2
سكيمات الامتحان
لو سألك Stroke Volume يتحسب إزاي
SV = EDV − ESV = 130 − 60 = 70 ml
COP = HR × SV = 70 × 70 ≈ 5000 ml = 5 L/min
لو سألك Bainbridge reflex أو لو venous return زاد
↑VR → ↑EDV → stretch → ↑contraction force → ↑SV → ↑COP (Starling's law)
لو سألك bile salts تأثيرها على الـ HR
↓ HR — directly inhibit SAN (not via nerve)
لو سألك adrenaline تأثيرها على HR في الحيوان الحي (in vivo)
Adrenaline → ↑ABP → reflex bradycardia (Marey's law) — in vivo only
In isolated heart: direct ↑ HR
In isolated heart: direct ↑ HR
لو سألك ventricular systole — الـ pressure بيوصل لكام
Lt ventricle: 0 → 80 mmHg | Rt ventricle: 0 → 10 mmHg
لو سألك COP ÷ HR = إيه
Stroke Volume (SV)
1
Cardiac Cycle
Total = 0.8 sec. Atrial systole 0.1 | Ventricular systole 0.3 | Ventricular diastole 0.4.
2
COP
Normal = 5 L/min. SV = EDV(130) − ESV(60) = 70 ml. COP = HR × SV.
3
Bainbridge
↑ Venous return → ↑ HR (atrial stretch receptors). Opposite to Marey's law (↑ABP → ↓HR).
4
Temperature
↑ 1°C blood temp → ↑ 10 beats/min HR. Opposite for ↓ temperature.
5
Starling's Law
↑ EDV → ↑ stretch → ↑ force of contraction → ↑ SV → ↑ COP.
6
Ventricular Pressure
Lt ventricle systole: 0 → 80 mmHg. Rt ventricle: 0 → 10 mmHg.
الأسئلة: 30
صح: 0
غلط: 0