🤾🏻‍♂️Human Physiology Engineering Unit 1 – Human Physiology Fundamentals

Key Concepts and Terminology

• Anatomy studies the structure of living organisms including their physical form, chemical processes, and development
• Physiology examines how anatomical structures, organs, and systems function within a living organism
• Homeostasis maintains stable internal conditions necessary for survival (temperature, pH, blood pressure)
• Negative feedback loops correct deviations from the set point to maintain homeostasis (thermoregulation, blood glucose regulation)
• Positive feedback loops amplify changes in a system moving it away from equilibrium (blood clotting, childbirth)
• Metabolism encompasses all chemical reactions involved in maintaining the living state of cells and organisms
  • Catabolism breaks down complex molecules to release energy (cellular respiration)
  • Anabolism constructs complex molecules from simpler ones requiring energy input (protein synthesis)
• Anatomical terminology describes locations and directions within the body
  • Proximal refers to a position closer to the trunk or root of a structure (proximal end of the humerus)
  • Distal indicates a position further from the trunk or root of a structure (distal phalanges of the fingers)

Anatomical Structures and Systems

• Cells are the basic structural and functional units of life serving as building blocks for tissues, organs, and systems
• Tissues consist of cells with similar structure and function working together (epithelial, connective, muscle, nervous)
• Organs are composed of multiple tissue types performing specific functions (heart, lungs, liver)
• Systems are groups of organs that work together to carry out a particular function (circulatory, respiratory, digestive)
• The skeletal system provides structural support, protects internal organs, and enables movement
  • Bones are living tissues that undergo constant remodeling in response to physical stress and calcium homeostasis
  • Joints are points of articulation between bones allowing for various degrees of movement (synovial, fibrous, cartilaginous)
• The muscular system generates force and motion through contraction of muscle fibers
  • Skeletal muscle is voluntarily controlled attaching to bones via tendons to produce movement (biceps brachii)
  • Smooth muscle is involuntarily controlled found in walls of hollow organs and blood vessels (intestines, arteries)
  • Cardiac muscle is specialized muscle tissue found only in the heart exhibiting autorhythmicity

Physiological Processes and Functions

• Respiration is the process of gas exchange between an organism and its environment
  • External respiration involves the exchange of oxygen and carbon dioxide between the lungs and the bloodstream
  • Internal respiration refers to the exchange of gases between the bloodstream and tissues at the cellular level
• Circulation transports oxygen, nutrients, hormones, and waste products throughout the body
  • The heart pumps blood through a closed system of blood vessels (arteries, capillaries, veins)
  • Blood consists of plasma, red blood cells, white blood cells, and platelets each serving specific functions
• Digestion breaks down food into smaller components that can be absorbed and utilized by the body
  • Mechanical digestion physically breaks down food through chewing and peristalsis
  • Chemical digestion uses enzymes to break down macromolecules into absorbable units (carbohydrates, proteins, lipids)
• Excretion removes metabolic waste products and maintains fluid and electrolyte balance
  • The kidneys filter blood, reabsorb essential nutrients, and produce urine to eliminate waste (urea, excess ions)
  • The liver detoxifies harmful substances, produces bile, and regulates blood glucose levels
• Endocrine system secretes hormones that regulate various physiological processes
  • Hormones are chemical messengers released into the bloodstream that act on target cells (insulin, thyroid hormone)
  • Negative feedback loops regulate hormone secretion to maintain homeostasis (hypothalamus-pituitary-target organ axes)

Homeostasis and Regulation

• Thermoregulation maintains a stable internal body temperature despite changes in environmental conditions
  • Hypothalamus acts as the body's thermostat detecting changes in blood temperature
  • Mechanisms for heat loss include vasodilation, sweating, and behavioral adaptations (seeking shade)
  • Mechanisms for heat generation include vasoconstriction, shivering, and increased metabolic activity (thermogenesis)
• Osmoregulation maintains proper water and electrolyte balance within the body
  • Antidiuretic hormone (ADH) regulates water reabsorption in the kidneys in response to changes in blood osmolarity
  • Aldosterone regulates sodium reabsorption and potassium excretion in the kidneys affecting blood volume and pressure
• Blood glucose regulation maintains stable blood sugar levels essential for proper brain function and energy metabolism
  • Insulin lowers blood glucose by promoting uptake into cells and storage as glycogen in the liver and muscles
  • Glucagon increases blood glucose by stimulating the breakdown of glycogen and promoting gluconeogenesis in the liver
• Acid-base balance maintains a stable pH in the body's fluids essential for proper enzyme function and cellular processes
  • Respiratory system regulates blood pH by adjusting the rate and depth of breathing affecting carbon dioxide levels
  • Renal system regulates blood pH by excreting or reabsorbing hydrogen ions and bicarbonate in the urine
• Immune system protects the body against pathogens and foreign substances
  • Innate immunity provides non-specific defense mechanisms (skin barrier, inflammatory response, phagocytosis)
  • Adaptive immunity develops specific responses to pathogens through the action of lymphocytes (B cells, T cells)

Measurement and Diagnostic Techniques

• Vital signs provide essential information about a patient's physiological status
  • Body temperature is measured using thermometers placed in the mouth, ear, or rectum
  • Pulse rate is assessed by palpating arteries or using an electronic pulse oximeter
  • Blood pressure is measured using a sphygmomanometer and stethoscope or an automated blood pressure cuff
  • Respiratory rate is determined by counting breaths per minute through observation or auscultation
• Blood tests analyze various components of the blood to assess health status and diagnose disorders
  • Complete blood count (CBC) measures red blood cells, white blood cells, platelets, and hemoglobin levels
  • Metabolic panels evaluate electrolyte balance, kidney function, and liver function (BUN, creatinine, ALT, AST)
  • Lipid panels assess cardiovascular risk by measuring cholesterol and triglyceride levels (total cholesterol, LDL, HDL)
• Imaging techniques allow for visualization of internal structures and assessment of organ function
  • X-rays use ionizing radiation to create two-dimensional images of dense structures like bones and teeth
  • Computed tomography (CT) scans combine multiple X-ray images to generate detailed cross-sectional views
  • Magnetic resonance imaging (MRI) uses strong magnetic fields and radio waves to produce high-resolution images of soft tissues
  • Ultrasound uses high-frequency sound waves to visualize soft tissues and monitor blood flow (echocardiography)
• Electrocardiography (ECG) records the electrical activity of the heart to assess rhythm and detect abnormalities
  • Electrodes placed on the skin detect the heart's electrical impulses generating a waveform (P wave, QRS complex, T wave)
  • ECG can diagnose arrhythmias, myocardial infarction, and conduction disorders (atrial fibrillation, heart block)
• Pulmonary function tests evaluate lung volumes, capacities, and gas exchange efficiency
  • Spirometry measures the volume and flow of air during inhalation and exhalation (FEV1, FVC)
  • Peak expiratory flow rate (PEFR) assesses the maximum speed of exhalation indicating airway obstruction (asthma)

Clinical Applications and Case Studies

• Coronary artery disease (CAD) is characterized by the buildup of atherosclerotic plaques in the coronary arteries
  • Risk factors include hypertension, hyperlipidemia, smoking, diabetes, and family history
  • Symptoms may include chest pain (angina), shortness of breath, and fatigue
  • Treatment options include lifestyle modifications, medications (statins, beta-blockers), and surgical interventions (angioplasty, bypass surgery)
• Type 2 diabetes mellitus is a metabolic disorder characterized by insulin resistance and impaired glucose regulation
  • Risk factors include obesity, sedentary lifestyle, family history, and certain ethnic backgrounds
  • Complications can affect multiple organ systems (cardiovascular disease, nephropathy, neuropathy, retinopathy)
  • Management involves lifestyle changes (diet, exercise), medications (metformin, insulin), and regular monitoring of blood glucose levels
• Asthma is a chronic inflammatory disorder of the airways characterized by reversible airflow obstruction
  • Triggers include allergens, respiratory infections, exercise, and stress
  • Symptoms include wheezing, coughing, chest tightness, and shortness of breath
  • Treatment involves a combination of long-term control medications (inhaled corticosteroids) and quick-relief medications (short-acting beta-agonists)
• Parkinson's disease is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra
  • Clinical features include tremor, rigidity, bradykinesia, and postural instability
  • Non-motor symptoms may include cognitive impairment, depression, and sleep disturbances
  • Treatment involves dopamine replacement therapy (levodopa), dopamine agonists, and surgical interventions (deep brain stimulation)
• Osteoporosis is a metabolic bone disorder characterized by reduced bone mass and increased fracture risk
  • Risk factors include advanced age, female sex, low body weight, smoking, and prolonged corticosteroid use
  • Diagnosis is based on bone mineral density (BMD) measurements using dual-energy X-ray absorptiometry (DXA)
  • Prevention and treatment strategies include calcium and vitamin D supplementation, weight-bearing exercise, and medications (bisphosphonates, denosumab)

Emerging Research and Technologies

• Stem cell therapy involves the use of undifferentiated cells to regenerate or repair damaged tissues
  • Embryonic stem cells are pluripotent capable of differentiating into any cell type
  • Adult stem cells are multipotent found in various tissues (bone marrow, adipose tissue) with limited differentiation potential
  • Potential applications include treatment of neurodegenerative disorders, spinal cord injuries, and cardiovascular diseases
• Gene editing techniques like CRISPR-Cas9 allow for precise modification of DNA sequences
  • Guide RNA directs the Cas9 endonuclease to a specific location in the genome where it creates a double-strand break
  • DNA repair mechanisms can be harnessed to introduce desired genetic changes (gene knockout, gene correction)
  • Applications include studying gene function, developing disease models, and potential gene therapy approaches
• Tissue engineering combines principles of biology, materials science, and engineering to create functional tissue substitutes
  • Scaffolds provide a three-dimensional structure for cell attachment, proliferation, and differentiation
  • Cells can be derived from the patient (autologous) or donors (allogeneic) and expanded in vitro
  • Potential applications include replacement of damaged or diseased organs (skin, cartilage, blood vessels)
• Wearable technology allows for continuous monitoring of physiological parameters in real-time
  • Smartwatches and fitness trackers can measure heart rate, physical activity, and sleep patterns
  • Biosensors can detect changes in biochemical markers (glucose, lactate, electrolytes) in sweat or interstitial fluid
  • Data collected can be used for personalized health monitoring, early disease detection, and treatment optimization
• Artificial intelligence (AI) and machine learning algorithms can analyze large datasets to identify patterns and make predictions
  • AI can assist in medical image analysis for early detection of diseases (cancer, retinopathy)
  • Machine learning models can predict patient outcomes, guide treatment decisions, and identify high-risk individuals
  • Integration of AI in healthcare can improve diagnostic accuracy, optimize resource allocation, and personalize patient care

Review Questions and Practice Problems

1. Describe the main components of a negative feedback loop and provide an example of how it maintains homeostasis.
2. Explain the difference between external and internal respiration, and discuss the role of the circulatory system in gas exchange.
3. Compare and contrast the functions of the sympathetic and parasympathetic divisions of the autonomic nervous system.
4. Outline the steps involved in the process of blood clotting, and explain how it serves as an example of a positive feedback loop.
5. Discuss the role of the hypothalamus in regulating body temperature, and describe the mechanisms of heat loss and heat generation.
6. Explain the concept of osmosis, and describe how the kidneys regulate water balance through the action of antidiuretic hormone (ADH).
7. Compare and contrast the actions of insulin and glucagon in regulating blood glucose levels, and discuss the consequences of insulin resistance in type 2 diabetes.
8. Describe the main components of a complete blood count (CBC), and explain how each parameter can provide information about a patient's health status.
9. Discuss the principles behind magnetic resonance imaging (MRI), and explain how it differs from other imaging techniques like X-rays and CT scans.
10. Explain the concept of stem cell therapy, and discuss the potential applications and ethical considerations associated with the use of embryonic and adult stem cells.