Exam 1 Study Guide PDF

**Unit 1: The Heart** Anatomy - Pulmonary circulation vs. Systemic circulation - Systemic: right side of heart receives oxygen poor blood from systemic circulation - Pulmonary: to the lungs - Chambers and Valves - Oxygenated vs. Unoxygenated - Cardiac muscle vs. Sk...

**Unit 1: The Heart** Anatomy - Pulmonary circulation vs. Systemic circulation - Systemic: right side of heart receives oxygen poor blood from systemic circulation - Pulmonary: to the lungs - Chambers and Valves - Oxygenated vs. Unoxygenated - Cardiac muscle vs. Skeletal muscle (similarities and differences) - Cell size: Cardiac muscle cells are much smaller than skeletal muscles cells - Branching: Cardiac muscle cells are branched - Number of nuclei: cardiac muscle cells have a single nucleus located in the center of the cell - T-tubules: In the cardiac muscle are much larger and more branched - Sarcomeres: not ordered the same way in cardiac muscle cell as it is in the skeletal muscle cell. The striations are not as distinct. - Sarcoplasmic Reticulum: It is less extensive in the cardiac muscle which enables the heart muscle to be more flexible and allow it to beat over and over. - Mitochondria: Cardiac muscle cells have more mitochondria comprising up to a third of the intracellular volume. More mitochondria are needed because cardiac muscle cells derive all of their energy from aerobic respiration. - Conduction System - SA node -- pacemaker: composed of autorhythmic cells that generate the action potentials that initiate contraction. These action potentials then spread through the right and left atria, causing them to contract. - AV node- slows down conductance - Smaller size - Fewer gap junctions - Bachmann's bundle -- delivers SA signal to left atrium - Bundle of HIS, bundle branches, purkinje fibers -- fast conductions system of ventricles Function - Action Potentials - Compare and contrast contractile myocyte vs. autorythmic cell vs. neuron - **Contractile Myocytes (Heart Muscle Cells)** -- These are the muscle cells in your heart that actually contract to pump blood. - **Autorhythmic Cells (Pacemaker Cells)** -- These are special heart cells that generate their own electrical signals to set the heart rate. - **Neurons (Nerve Cells)** -- These send signals in the brain, spinal cord, and nerves. - What are the differences? Similarities? - Ions (Na+, K+, Ca++) - Resting membrane potential - IRK channels - Funny channels (HCN): **Funny Channels (HCN Channels) Open** -- These channels let **Na+ leak in** when the cell is too negative, slowly making the inside more positive. - L-type Ca++ channels: Big surge of **Ca++** rushes in, causing the full action potential (the \"spike\"). - T-type Ca++ channels: More positivity! These open briefly and push the cell toward the threshold. - Plateau phase: (due to Ca++ influx, prevents rapid firing) - What drives the pacemaker potential in the autorythmic cells? How does it work? How is heartbeat regulated? The **pacemaker potential** is how autorhythmic cells generate their own action potentials **without needing a signal from the brain. Since the funny channels open automatically after repolarization, the cycle repeats, setting a steady rhythm for the heartbeat.** The **sympathetic nervous system (fight or flight)** speeds it up (more Na+ and Ca++ enter the cell). The **parasympathetic nervous system (rest and digest)** slows it down (more K+ leaves the cell, making it take longer to reach threshold). - Cardiac Cycle - Systole vs. diastole - Systole: the contraction of the chambers. Atrial systole before ventricular systole - Diastole: Relaxation of the heart. - How does pressure change in the ventricles during a heartbeat? In the atria? - **In the ventricles**: - At the start, the ventricles are relaxed, and pressure is **low**. - When they contract (squeeze), pressure **rises a lot** to push blood out. - Once they relax again, pressure **drops** so they can fill with blood again. - **In the atria**: - When atria contract, pressure **increases slightly** to push blood into the ventricles. - Once the atria relax, pressure **drops**, and they start filling up again. - What activates the valves? Valves in the heart open and close based on **pressure differences** between chambers. They work kind of like doors that only open one way. - When are semi-lunar valves open? Closed? - **Open**: When the ventricles squeeze and pressure is high, the valves open to let blood out. - **Closed**: When ventricles relax and pressure drops, the valves close to prevent blood from coming back in. - When are atrioventricular valves open? Closed? - - **Open**: When ventricles relax, and pressure is low, allowing blood to flow in. - **Closed**: When ventricles squeeze, pressure rises, and the valves shut to stop blood from flowing backward. - What is "Isovolumetric" contraction? This is a fancy way of saying that the ventricles are squeezing **but no blood is leaving yet**. - The ventricles start to contract, increasing pressure. - The **AV valves close** (so no blood can go back into the atria). - The **semi-lunar valves stay closed** because pressure isn\'t high enough to open them yet. - The volume of blood in the ventricles stays the same (**iso = same, volumetric = volume**), but the pressure builds up fast. - What are the heart sounds? When do they occur? The "**lub-dub**" sound you hear in your heartbeat comes from **valves closing**: - **Lub (S1)** -- Happens when the **AV valves close** (ventricles are starting to contract). - **Dub (S2)** -- Happens when the **semi-lunar valves close** (ventricles are relaxing). - Passive vs. active filling - **Passive filling (80%)** -- When the ventricles relax, blood just **flows in naturally** from the atria (no squeezing needed). - **Active filling (20%)** -- The atria contract at the end to **push in the last bit** of blood. - Stroke volume, end-diastolic volume, cardiac output, ejection fraction - **Stroke Volume (SV)** -- The amount of blood pumped **out of one ventricle per heartbeat** (\~70mL). - **End-Diastolic Volume (EDV)** -- The amount of blood **in the ventricle before it contracts** (\~120mL). - **Cardiac Output (CO)** -- The total amount of blood **pumped per minute**. - CO = **Stroke Volume × Heart Rate** - **Ejection Fraction (EF)** -- The percentage of blood pumped **out of the ventricle per beat**. - EF = (**SV / EDV**) × 100 - Normal is around **55-70%**. - EKG: it represents currents flowing through the extracellular fluids as the charges associated with the heart change. - How do you read it? - What makes a deflection positive or negative? - What is a dipole? - Regulation of Cardiac Function - Intrinsic: If you increase the end-diastolic volume, stroke volume increases - Relationship between end diastolic volume and stroke volume - Preload: the degree of stretch at the end of diastole, - Alignment of thick and thin filaments within sarcomere:  Maximum force is achieved when the starting position of the sarcomere is such that the thick filament is at the very end of the thin filament allowing the greatest range of movement and still allowing each myosin head to bind to actin - Extrinsic - Autonomic Nervous System: **Automatic Heart Regulation** - Sympathetic: (\"Fight or Flight\") - Uses **sympathetic cardiac nerves** and **β1 adrenergic receptors** to **increase heart rate and contraction strength**. - Opens more ion channels in pacemaker cells, making them fire faster. - Increases **calcium release** in heart muscle cells, leading to stronger contractions and higher **stroke volume**. - Parasympathetic: (\"Rest and Digest\") - Uses the **Vagus nerve** and **acetylcholine (Ach)** to **slow down heart rate** by making it harder for heart cells to reach threshold. - At rest, there is constant parasympathetic activity keeping the heart rate lower than its natural rhythm. - If parasympathetic input is suddenly lost, heart rate increases. - Homeostatic reflexes: Keeping Heart Rate Balanced - Baroreceptors: Detect blood pressure changes and adjust heart rate accordingly. - Chemoreceptors: Monitor oxygen and CO2 levels, influencing heart rate when needed. **Unit 2: Blood** Blood - Plasma vs. Formed Elements - **plasma (55% of blood volume)** - **92% water** and contains **proteins** (colloid mixture). - Key **plasma proteins**: - **Albumin** (60%): Maintains **osmotic pressure** and transports substances. - **Globulins**: Help transport substances and include **antibodies**. - **Fibrinogen**: Involved in **blood clotting**. - Plasma without clotting factors is called **serum**. - Formed Elements - **Red Blood Cells (RBCs) -- 45% of blood volume** - Carry **oxygen** and determine **hematocrit** percentage. - Higher hematocrit in **males, high elevations, and trained athletes**. - **White Blood Cells (WBCs) & Platelets** - Make up a small fraction of blood. - Found in the **buffy coat** (thin white layer between RBCs and plasma). - Platelets = **cell fragments** for **blood clotting**. - Erythropoiesis: HSC -\> proerythroblast -\> reticulocyte -\> erythrocyte - Red blood cells (RBCs) develop in the bone marrow. - Reticulocytes are immature RBCs that enter circulation and mature into erythrocytes. - Role of erythropoietin (from kidney) - **EPO is a hormone from the kidneys** that stimulates RBC production when oxygen levels are low. - Hemoglobin: globin + heme - Made of **globin (protein) + heme (iron-containing pigment)**. - **Function**: Carries oxygen (O₂) in the blood. - Function = carry oxygen - Recycling - Globin portion degraded and recycles - Heme cannot be recycled - Iron removed = biliverdin -\> bilirubin - "free" bilirubin: Fat-soluble, transported to the liver. vs. "conjugated" bilirubin: Water-soluble, excreted in bile. - Function - Transport: O₂, nutrients, waste, hormones - pH regulation: buffers maintain acid-base balance - Fluid regulation: maintains blood volume & osmotic balance - Temperature: distributes heat throughout the body - Hemostasis: blood clotting to prevent bleeding Hemostasis 1. Vascular spasm -- temporary smooth muscle contraction a. Reflex from local pain receptors 2. Platelet plug b. vWF activation: Platelets stick to the injured site. c. Platelet adhesion: Platelets release chemicals (Ca++, ADP, vWF) to attract more platelets. d. Platelet activation: Platelets stick together via receptors, activated by thromboxane. i. Increased Ca++ causes granule release ii. Induced by ADP, vWF iii. Inhibited by healthy endothelial cells 1. Nitric oxide, prostacyclin, ADPase e. Platelet aggregation iv. Platelets stick together via "aggregation receptor" v. Activated by thromboxane 3. Blood Clot Formation f. Cross-linking of platelet plug by fibrin g. Fibrin activated by thrombin h. Plasmin activated by intrinsic and extrinsic clotting pathways vi. Intrinsic pathway: XII -\> XI -\> IX + VIII -\> X vii. Extrinsic pathway: thromboplastin -\> VII -\> X viii. Common pathway: X + V -\> thrombin (from prothrombin i. Role of vitamin K: is needed for clotting factors. 4. Clot Dissolution j. Plasminogen binds to (and is stabilized by) fibrin k. Plasminogen converted to plasmin ix. tPA l. Plasmin degrades fibrin Blood Typing Blood antigens and antibodies - ABO blood group system: Based on A and B antigens - Rh blood group system : Determines + or -- blood type. - Hemolytic Disease of the Newborn (HDN): Rh-negative mother's immune system attacks Rh-positive fetal blood. Blood Vessel Structure - Three tunicas: - Adventitia: (outer, connective tissue) - Media: (middle, smooth muscle & elastic fibers) - Intima: (inner, endothelial cells) - Smooth muscle components, elastic components - Types of arteries/veins - Elastic, muscular, arterioles and venules, capillaries - Which have valves? Viens - Which are responsible for diastolic pressure? -  **Elastic arteries (like the aorta & major arteries)** maintain **diastolic pressure** by recoiling after systole (heart contraction). -  Their **elasticity** helps sustain blood flow even when the heart is relaxed. - Which can be regulated? -  **Arterioles** are the **primary regulators** of blood flow and **resistance**. -  They adjust diameter via **vasoconstriction** (increases BP) and **vasodilation** (decreases BP). - Compliance: Ability of blood vessels to expand/contract. - Relationship between pressure, diameter, and resistance - What determines systolic blood pressure? Diastolic blood pressure? -  **Systolic BP** = Force during heart contraction. -  **Diastolic BP** = Force when the heart is relaxed. Capillary Exchange - Arteriole end of capillary bed vs. venule end -  **Arteriole End:** Higher **hydrostatic pressure** pushes nutrients & fluids out. -  **Venule End:** Higher **blood colloid osmotic pressure (BCOP)** pulls fluids back in. - Regulation by pre-capillary sphincter - Hydrostatic pressure - Blood colloid osmotic pressure (BCOP) - Interstitial colloid osmotic pressure (ICOP) - Interstitial fluid pressure (IFP)- "juice box" effect caused by lymph maintains balance Regulation of Blood Pressure - Short term vs. long term - Baroreceptors: detects BP changes - Chemoreceptors: monitors oxygen and CO2 - Adrenal medullary reflex: Fight or flight response - CNS ischemic response: responds to low oxygen in brain - Renin-angiotensin-aldosterone: increases BP - Anti-diuretic hormone: retains water to increase BP - Atrial naturetic hormone: Lowers BP by releasing excess fluid - Fluid shift: adjusts blood volume