Nervous System Overview

Nervous System

• CAD Diagnosis: Physical exam (listening to carotid artery for a bruit), carotid ultrasound (non-invasive sound waves), MRI/CT/CT angiogram, carotid angiography (contrast dye).

• Neurons: Fundamental unit of the nervous system responsible for receiving, processing, and transmitting information throughout the body by electrochemical signals.

• Basic Structure:

  • Soma (cell body): Contains the nucleus and organelles.
  • Dendrites: Fingerlike branched extensions receiving signals from other neurons.
  • Axon: Carries nerve impulses away from the soma to other neurons, muscles, and glands. Action potentials begin at the axon hillock. Terminal branches at the end form synapses.
  • Multipolar Neuron: Most common neuron type; has sensory neurons (transmit to CNS), interneurons (decision-making), and motor neurons (transmit to effector organ).

• Motor Neurons: Transmit impulses from the CNS (brain and spinal cord) to effector organs (muscles and glands) via the efferent pathway. Their primary function is initiating and controlling movements.

Upper and Lower Motor Neurons

• Upper Motor Neurons: Control fine motor movements, modify spinal reflex arcs and circuits. Dysfunction can lead to initial paralysis followed by partial recovery.

• Lower Motor Neurons: Direct influence on muscles, with axons extending into the peripheral nervous system (PNS). Dysfunction results in permanent paralysis.

Cerebellum

• Function: Maintains balance and posture, coordinates conscious and unconscious muscle synergy. Lesions cause loss of equilibrium, balance, and motor coordination on the same side of the body.

Occipital Lobe

• Functions:
  • Maps the visual world.
  • Determines characteristics of visual objects (color).
  • Assesses distance, size, and depth.
  • Identifies visual stimuli.
  • Transmits visual information to other brain regions.

Frontal Lobe

• Functions:
  • Coordinates voluntary movements.
  • Assesses future consequences of current actions.
  • Forms and retains long-term memories.
  • Processes language.
  • Manages emotional expression.
  • Is involved in personality development.

Meninges

• Function: Protective membranes surrounding the brain and spinal cord. Composed of:
  • Dura mater: Tough, outermost layer attached to the skull.
  • Arachnoid mater: Thin, impermeable layer beneath the dura.
  • Pia mater: Thin, vascular layer closely adhering to the brain and spinal cord.

Subdural Space

• Location: Between the dura and arachnoid mater.
• Contents: Clear, colorless fluid similar to blood plasma.

Afferent Pathway

• Function: Carries information toward the CNS (ascending). Sensory information from peripheral receptors to the spinal cord via sensory neurons.

Efferent Pathway

• Function: Carries information away from the CNS to the muscles and glands (descending), innervating effector organs. Impulses are transmitted to effector organs via motor neurons.

Stroke Risk Factors

• Age (over 55).
• Family history.
• Race (African American, Hispanic, Native American).
• Sex.
• Hypertension.
• High cholesterol.
• Heart disease.
• Diabetes (DM).
• Smoking.
• Obesity.
• Poor diet.
• Sleep apnea.
• Drug usage.

Stimulation of Nervous Systems

• Sympathetic Nervous System: Decreases peristalsis, increases blood pressure, body temperature & tone. "Fight or flight response."
• Parasympathetic Nervous System: Promotes rest and tranquility, reduces heart rate, strengthens digestive functions. "Rest and digest response."

Dermatome

• Definition: Area of skin on the body that receives sensory input from a specific spinal nerve.

Dementia

• Pathophysiology: Progressive failure of cognitive function causing impairment. Many factors contribute, but age is the greatest risk factor.
• Symptoms: Progressive dementia that produces nerve cell degeneration and brain atrophy, leading to impairment of intellectual function (memory, language) and behavioral alterations.

Musculoskeletal System

• Articular Cartilage: Hyaline cartilage covering the end of bones to reduce friction and distribute weight-bearing forces.

• Pennate Muscles: Broad, flat, fan-shaped muscles.

• Fusiform Muscles: Elongated, strap-shaped muscles; run from one joint to another.

• Sensory Receptors: Mechanoreceptors (e.g., spindles) detect muscle stretching and send signals to the CNS, responsible for maintaining muscle tone.

• Oxygen Debt: The amount of oxygen required to convert lactic acid into glucose and replenish ATP energy stores.

• Effects of Aging on Bones:

  • Loss of bone tissue.
  • Brittleness, decreased strength.
  • Lengthened bone remodeling cycle.
  • Evidence of osteoporosis.
  • Increased bone resorption

• Effects of Aging on Muscles:

  • Apoptosis of cells.
  • Reduced muscle strength.
  • Loss of muscle mass (sarcopenia).
  • Reduced oxygen intake.

• Effects of Aging on Joints:

  • Cartilage changes (stiff, fragile more susceptible to fraying).
  • Decreased range of motion.

• Amphiarthrosis: Slightly movable joints, such as intervertebral disks, ribs, and pubic symphysis.

• Comminuted Fracture: Bone fracture with more than two fragments.

Musculoskeletal Healing

• Phases of healing in a fracture:
  • Inflammatory phase: Inflammation response. lasting 3-4 days
  • Repair phase: Bone healing and tissue regeneration. lasting several days

Gout

• Definition: A metabolic disorder causing high levels of uric acid in the blood, potentially leading to crystal deposition and inflammation.

Myoblasts

• Definition: Cells responsible for muscle growth and regeneration. (also called satellite cells).

Osteoarthritis

• Definition: A common age-related disorder of synovial joints, involving cartilage erosion.

Inflammatory Joint Disease

• Symptoms: Pain, stiffness, enlargement of joints, tenderness, and reduced mobility. Joint effusion (exudate or blood in the joint space), and deformity may also occur.

Compact Bone

• Definition: Dense, solid bone, comprising 85% of the skeleton. Composed of a haversian system with concentric tubes and cell bodies.

Long Bones

• Diaphysis: Long shaft of the long bone, with the medullary cavity containing "yellow marrow."
• Metaphysis: Connection between the diaphysis and epiphysis.
• Epiphysis: End of the long bone.
• Medullary Cavity: Contains bone marrow (red/yellow).
• Epiphyseal Plate: Growth plate in children that eventually calcifies to become the epiphyseal line.

Renal/Urinary System

• Acute Kidney Injury (AKI): Sudden decline in kidney function characterized by decreased glomerular filtration rate and an accumulation of waste products in the blood.

• Chronic Kidney Disease (CKD): Progressive loss of kidney function, often associated with various system diseases.

Alterations in Renal Function

• Tubular Obstruction: blockages in kidney tubules,
• Backleak: fluid leaks from glomeruli into tubules.
• Hypertension, glomerular, and tubulointerstitial: damage to the filtering components of the kidneys (glomeruli) and the tubules.

Test your knowledge on the nervous system, including the structure and function of neurons, CAD diagnosis methods, and the role of motor neurons. This quiz covers essential aspects of the nervous system and its components, providing a comprehensive review for students. Get ready to explore the fascinating world of neural communication!