Physiology of Cardiac and Respiratory Systems

Levels of Organization

• Biological structures range from atoms to organisms
• Atoms combine to form organelles
• Organelles combine to form cells
• Cells combine to form tissues
• Tissues combine to form organs
• Organs combine to form organ systems
• Organ systems combine to form organisms

Organ Systems

• Respiratory system
• Nervous system
• Reproductive system
• Skeletal system
• Digestive (Gastrointestinal) system
• Lymphatic system
• Integumentary (skin, hair, nails) system
• Circulatory (Cardiovascular) system
• Endocrine system
• Excretory (Urinary) system

Physiology and Cytology

• Physiology = study of how organ systems function
• Cytology = study of cells
• Homeostasis = maintaining a stable internal environment

Cell Structure

• Extracellular Fluid (ECF) = fluid outside the cell
• Intracellular Fluid (ICF) = fluid inside the cell
• Plasma membrane = separates the ICF from the ECF
• Nucleus = contains genetic material
• Mitochondria = where glucose, fatty acids, and oxygen combine to create ATP
• Endoplasmic reticulum = internal passageways
• Plasma membrane = semipermeable membrane
• Ribosomes = organelles that synthesize proteins
• Lysosomes = organelles involved in digestion

Cell Membrane Functions

• Physical isolation — barrier separating ICF from ECF
• Regulation of exchange with environment— monitors external conditions
• Structural support — gives shape and support
• Sensitivity — monitors signals and triggers responses

Cell Membrane Structure

• Phospholipid bilayer = hydrophilic heads toward the watery environment and hydrophobic tails inside the membrane.
• Integral proteins = within the membrane
• Peripheral proteins = bound to the inner or outer surface of the membrane
• Glycoproteins = embedded within the membrane and act as markers for cell identification & communication

Transport Mechanisms

• Facilitated diffusion is passive transport — molecules moving across a membrane through a channel or carrier protein

Transport Mechanisms, Continued

• Active transport = requires energy for molecules to move against the concentration gradient

Polysaccharide Breakdown and Transport

• Mouth = Salivary amylase breaks down polysaccharides into smaller chains

• Stomach = Amylase is inactivated; no further carbohydrate digestion

• Small Intestine =Pancreatic amylase breaks down polysaccharides to disaccharides. Brush border enzymes (e.g. Maltase, sucrase) convert disaccharides into monosaccharides like glucose.

• Absorption → Glucose is absorbed into intestinal cells via active transport (SGLT proteins), then into the bloodstream via facilitated diffusion (GLUT proteins)

• Glucose is transported in bloodstream to provide energy for tissues or storage.

Mitochondria and Nucleus

• Mitochondria = where aerobic respiration (using oxygen) occurs to produce ATP (energy)
• Nucleus = contains the genetic information (DNA) organized into chromosomes for making protein and cell function programming

Tissues

• Connective = supports, binds, and protects organs and tissues (e.g, bone, cartilage)
• Epithelial = covers body surfaces and internal cavities that form glands
• Nervous = transmits electrical signals, including brain, spinal cord & nerves
• Muscle = responsible for movement through contraction and relaxation (e.g, skeletal, smooth & cardiac)

The Heart

• Right atria = receives deoxygenated blood from the body via the superior and inferior vena cava
• Left atria= receives oxygenated blood from the lungs through pulmonary veins
• Right ventricle = pumps blood to the lungs via the pulmonary artery
• Left ventricle = pumps oxygenated blood to the rest of body via the aorta
• Atrioventricular (AV) valves = prevent backflow of blood between atria and ventricles
• Semilunar valves = prevent backflow of blood into the ventricles from the aorta

Layers of the Heart Wall

• Pericardium: two-layered membrane surrounding the heart
• Pericardial fluid: lubricates the heart, reducing friction
• Epicardium: outermost layer of the heart wall
• Myocardium: thick, muscular middle layer of the heart wall
• Endocardium: innermost layer of the heart wall

Heart Contractile and Conducting Myocytes

• Cardiac myocytes are responsible for contracting to pump blood
• Conducting myocytes initiate and conduct electrical impulses throughout the heart
• Muscles are involuntary, making the heart an effective pump.

Blood Vessels

• Arteries = carry blood away from the heart with thick walls, high pressure, and no valves.
• Arterioles = smaller branches of arteries leading to capillaries (regulation of blood flow)
• Capillaries = sites of exchange between blood and tissues
• Venules = small veins that drain blood from capillaries
• Veins = carry blood toward the heart with thin walls, low pressure, and valves

Blood Vessel Histology

• Tunica intima: innermost layer, composed of endothelial cells
• Tunica media: middle layer, contains smooth muscle and elastic fibers
• Tunica adventitia: outermost layer, composed of connective tissue

Capillaries

• Continuous: uninterrupted endothelial, present in muscles and the skin.
• Fenestrated: contain pores, found in the intestines and endocrine glands

Vascular Resistance

• Factors influencing vascular resistance: radius, blood viscosity, and length of vessel

Blood Pressure

• Systolic pressure: highest pressure in the aorta during ventricular contraction.
• Diastolic pressure: lowest pressure in the aorta during ventricular diastole.
• Pulse pressure: difference between systolic and diastolic pressure.
• Mean arterial pressure (MAP) = average pressure in the aorta during a cardiac cycle.

Pulmonary System

• Pulmonary ventilation: movement of air into and out of the lungs
• Gas exchange: between alveoli and pulmonary capillaries for oxygen and carbon dioxide
• Acid-base balance: regulating blood pH
• Thermoregulation: helping regulate body temperature
• Respiratory pump - aids venous return in aiding blood through the body
• Renin-angiotensin-aldosterone system (RAAS) - hormone system that regulates blood pressure when low
• Defenses against infection: contains structures protecting lungs and air from foreign bodies.

Alveoli

• Type I pneumocytes: thin, simple squamous epithelium for gas exchange.
• Type II pneumocytes: secrete surfactant, reducing surface tension in alveoli, preventing them from collapsing.
• Alveolar macrophages: remove debris and pathogens

Rate of Gas Diffusion

• Proportional to surface area and partial pressure difference
• Inversely proportional to thickness

Oxygen Transport

• Dissolved in plasma: small amount.
• Bound to hemoglobin: most of the oxygen is carried bound to hemoglobin (oxyhemoglobin) inside red blood cells

Oxygen Dissociation Curve

• Describes the relationship between % saturation of hemoglobin vs pO2.
• Sigmoidal curve = indicates that hemoglobin is not a linear carrier
• Left shift: increased affinity - more oxygen taken up (at higher temperature, CO2)
• Right shift: reduced affinity - more oxygen unloaded (during exercise, lower pH, ↑temp, and ↑CO2)

Altitude Training

• Adaptations: Increased hemoglobin, improved oxygen-carrying capacity of blood, increased lung ventilation (breathing), and increased affinity between hemoglobin and oxygen.
• Training protocols: "Live high, train low," "Train High, live high."

Carbon Dioxide Transport

• Dissolved in plasma: small amount
• Bound to hemoglobin: some is bound.
• Bicarbonate ions: most transported this way H2CO3 → HCO3 + H+

Control of Ventilation

• Central and peripheral chemoreceptors are important in maintaining Homeostasis for breathing rate
• Lung stretch receptors are important for breathing rate
• Proprioceptors provide input to maintain breathing during exercise & other sensory input is important

Acid-Base Balance of Blood

• Acidosis: blood pH falls below 7.35.
• Alkalosis: blood pH rises above 7.45.
• Regulation important for maintaining appropriate electrochemical and enzyme functions.

Nervous System

• Central nervous system (CNS) = brain and spinal cord
• Peripheral nervous system (PNS) = nerves that branch off from CNS
• Receptors: specialized cells that detect stimuli
• Sensory neurons: carry impulses to CNS
• CNS: processes and transmits impulses
• Motor neurons: carry impulses away from CNS
• Effectors: respond to stimuli (muscles, glands)

Sensory Neurons

• Types of sensory receptors in body: visceral, somatic and proprioceptive sensory receptors
• Sensory neuron is a complete neuron from distal part of body to the CNS, with cell bodies, dendrites and axons.
• Electrical impulses are sent down the sensory neuron along the axon to the CNS
• Chemical signal is released at synapse and travels across to the next neuron

Motor Neurons

• Motor neurons: carry impulses away from CNS
• Effectors: respond to stimuli (muscles, glands)
• Motor neurons are part of both somatic (voluntary) and autonomic (involuntary) systems

Muscle Contraction

• Neuromuscular junction: where motor neuron and muscle fiber meet
• Action potential: electrical signal that travels along the nerve and muscle
• Excitation-contraction coupling: process where electrical signal is converted into mechanical response causing muscle contraction
• Cross-bridge cycling: myosin heads binding to actin filaments
• Contraction: when sarcomeres shorten and overall muscle contracts
• Relaxation: Ca++ taken back into sarcoplasmic reticulum and muscle relaxes

Muscle Twitch and Fused Tetanus

• Muscle twitch has three phases: latent period, contraction, and relaxation.
• Increased frequency of stimulation → summed contractions → incomplete / complete tetanus.

Muscle Force Output

• Length-tension relationship = tension is maximal when muscle is at its resting length
• Fiber diameter = larger fibers are able to produce more force.
• Load vs shortening velocity = inverse relationship = more load less velocity, and less load, faster velocity.

Muscle Fatigue

• Peripheral fatigue: muscle fatigue at the site of contraction due to metabolites accumulating and impairing muscle function
• Central fatigue: caused by neural signals & CNS

Skeletal Muscle Phenotypes

• Type I fibers (slow oxidative): high oxidative capacity, low glycolytic capacity, slow contraction speed, high resistance to fatigue
• Type IIa fibers (fast oxidative-glycolytic): intermediate oxidative and glycolytic capacity, intermediate contraction speed, moderate resistance to fatigue
• Type IIx fibers (fast glycolytic): high glycolytic capacity, low oxidative capacity, fast contraction speed, low resistance to fatigue

Energy Systems for Muscle Contraction

• Creatine phosphate: immediate source of energy for short-term, high-intensity activities
• Glycolysis: anaerobic pathway for energy production
• Oxidative phosphorylation: aerobic pathway for energy production in the mitochondria, high output

Metabolic Rate

• Direct calorimetry: measures heat production in a person to calculate output
• Indirect calorimetry: measures oxygen consumption and carbon dioxide production to measure metabolic rate

Questo quiz explora conceptos fundamentales in physiologia, como le output cardiac, minute ventilation, e le curve de saturazione de O2. Supera le questionas pro testar tu comprehension sobre le interactiones complex del sistema nervose e muscular contraction. Examina le effectos de bradycardia e le significato de EPOC all'interno de le contextos clinicos.