mammalian lecture 04-16

Sodium Influx: During excitation contraction coupling, sodium enters the cardiac cell when sodium channels open. This results in an increase in calcium permeability, which is crucial for cardiac muscle contraction.
Calcium Channel Blockers: Medications that block calcium channels are used to alleviate force of contractions and lower blood pressure.

Calcium Depletion: If a drug is used to remove all calcium from outside a cardiac cell, this could severely affect cardiac function.
Exam Insight: Chapter 14, Question 12 related to the effects of calcium depletion is crucial for exam preparation. It is emphasized as an important point for students to understand.

Length-Tension Relationship: The relationship affects how much force the cardiac muscle can generate at varying lengths of the sarcomeres. Athletes can achieve better contraction due to training that enhances heart efficiency.
- Example: An athlete may have a resting heart rate of 50 beats per minute, indicating a highly efficient heart.
Preload: Increased preload allows for a more effective contraction, which can be influenced by the volume of blood returning to the heart.
Skeletal Muscle Pump: Strong skeletal muscles assist in returning blood to the heart, increasing stroke volume and efficiency.
Respiratory Pump: Breathing mechanics help return blood to the heart.
Sympathetic Innervation: The density of sympathetic receptors in veins affects their ability to constrict and facilitate blood return to the heart.

Concept: The heart pumps all the blood that returns to it, meaning more blood entering the heart during diastole leads to greater stroke volume during systole.

Coronary Artery Disease: Narrowing of coronary arteries decreases blood flow to the heart, leading to various conditions including myocardial infarction (heart attack).
- Velocity & Resistance: Increased resistance in the coronary arteries leads to a decreased blood flow velocity.
Symptoms: In a clinical example, a patient exhibited ST segment depression on an ECG, indicative of reduced blood flow.

Troponin Levels: Elevated levels of cardiac troponin in peripheral blood indicate muscle damage (myocardial infarction), aiding in diagnosis.
Types of Myocardial Infarction:
- NSTEMI: Non-ST Elevation Myocardial Infarction indicated by specific ECG changes.

Nitroglycerin: Administered to relieve angina by relaxing coronary arteries and increasing blood flow.
Coronary Angiogram: Used to visualize narrowed arteries via injecting dye through a catheter, demonstrating arterial health and presence of atherosclerotic plaques.

Kidney Structures: The kidney comprises structures including Bowman's capsule, where initial filtration occurs. Afferent and efferent arterioles play essential roles in blood flow to and from the nephron.
Filtration Process: Understanding the filtration mechanism at Bowman's capsule is critical.

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