Cardiovascular System

• Characteristics of blood vessels:

  • Function
  • Pressure
  • Lumen diameter
  • Wall thickness
  • Wall layers
  • Connective tissue
  • Valves
• Layers of blood vessels:

  • INNER: tunica intima (endothelium)
  • MIDDLE: tunica media
  • OUTER: tunica adventitia
• Blood flow, pressure and resistance:

  • Stiffening of arteries leads to increased resistance, higher pressure, reduced flow, and increased workload
• Prevalence of Cardiovascular Diseases (CVDs) includes:

  • Ischemic heart disease
  • Stroke
  • Peripheral vascular disease
  • Heart failure
  • Other CVDs such as congenital heart disease and cardiomyopathy
• Atherosclerosis:

  • Build-up of fatty deposits in artery walls
  • Fueled by an inflammatory response
  • LDL cholesterol accumulation stimulates the body's defense system
  • May narrow arteries and reduce blood flow
• Problems with Blood Vessels:

  • Atherosclerosis
  • Blood clots (thrombus, embolus)
  • Treated with blood thinning or blood dissolving drugs
  • Aneurysm
• Ischemic Heart Disease:

  • Fatty deposits in coronary arteries
  • Angina pectoris as a warning sign
  • Imbalance between myocardial blood supply and demand
  • Symptoms include chest pain, shortness of breath, fatigue, sweating, weakness, discomfort in various body parts, nausea, and stomach pain
• Gender Bias and CVD:

  • Unique effects on the heart due to estrogens, menopause, and pregnancy
• Traditional Risk Factors for CVD:

  • Cigarette smoking
  • Cholesterol (Total cholesterol, LDL cholesterol)
  • Hypertension
  • Age
  • Sex
  • Type 2 Diabetes
  • Overweight or Obesity
• Genetic Factors:

  • Familial hypercholesterolemia (FH) caused by inherited changes in LDLR, APOB, and PCSK9 genes
  • Risk Enhancers include family history of early atherosclerotic cardiovascular disease, history of early menopause, metabolic syndrome, chronic kidney disease, chronic inflammatory conditions, and high-risk ethnicity
• Who should be screened for high cholesterol:

  • Men ≥40 years of age; Women ≥40 years of age (or post-menopausal)
  • Consider earlier screening for ethnic groups at increased risk
  • All patients with certain conditions regardless of age
• Detecting ischemic heart disease:

  • Coronary angiogram
  • Coronary CT
• Treating ischemic heart disease:

  • Medications
  • Surgery such as coronary bypass graft surgery
• Treatment with Cholesterol Drugs:

  • Consideration of total cholesterol and LDL levels, history of cardiovascular events, and other risk factors for CVD
  • Statins are common cholesterol-lowering drugs that disrupt cholesterol production by blocking an enzyme in the liver cells
• Rehabilitation after a Cardiac Event:

  • Programs to help individuals take charge of their medical condition, improve risk factors for CVD, maintain an exercise program, make healthy food choices, manage psychosocial risks for CVD
• Central Nervous System (CNS):

  • Integrates and coordinates all voluntary and involuntary nervous functions
  • Structures include the brain and spinal cord
• Peripheral Nervous System (PNS):

  • Consists of nerves that carry messages to and from the CNS
  • Some cell bodies are grouped in clusters called ganglia
  • Maintains continuous connection with almost every part of the body
  • Can be further divided
• Autonomic Nervous System:

  • Governs involuntary, subconscious movements for proper body functioning
  • Has two parts with opposite effects on muscles and glands:
  • Sympathetic nervous system: active during stressful or emergency situations
  • Parasympathetic nervous system: conserves energy during non-stressful times
• Somatic Nervous System:

  • Consists of nerves for sensations and voluntary movement
• Protection of the Central Nervous System:

  • The Meninges: 3 protective connective tissue coverings of the brain and spinal cord
  • Dura mater: tough and leathery outermost layer
  • Arachnoid: anchored to the next-lower layer by thin, threadlike extensions
  • Pia mater: innermost layer molded around the brain
  • Cerebrospinal Fluid:
  • Fills space between meninges and brain cavities
  • Functions include shock absorption, support, nourishment, and waste removal
  • Blood-Brain Barrier:
  • Selects substances permitted to enter cerebrospinal fluid from the blood
• • Formed by tight junctions between capillary walls
• • Hypothalamus: responsible for homeostasis and vital physiological processes
  • Cerebellum: responsible for sensory-motor coordination and equilibrium
  • Brain Stem: consists of medulla oblongata, pons, and midbrain
  • Limbic System: produces emotions and memory
• Brain:

  • Cerebrum: largest part of the brain, divided into two hemispheres
  • Cerebral Cortex: thin outer layer with billions of cells and gray matter
  • Cerebral White Matter: consists of myelinated axons for communication
  • Corpus Callosum: connects cerebral hemispheres
  • Lobes: frontal, parietal, temporal, and occipital
  • Sensory Areas:
  • Primary somatosensory area: processes sensory information
  • Premotor cortex: coordinates learned motor skills
  • Association Areas: analyze and act on sensory input
  • Thalamus: gateway to the cerebral cortex, sorts sensory information
• Reticular Activating System:

  • Extensive network of neurons that filters sensory input
  • Keeps the cerebral cortex alert and awake
  • Inhibited during sleep
• Spinal Cord:

  • Transmits messages to and from the brain
  • Serves as a reflex center
  • Reflex arc: automatic response circuit of neurons
• Peripheral Nervous System (PNS):

  • Consists of 31 pairs of spinal nerves and 12 pairs of cranial nerves
  • Carries both sensory and motor fibers
  • Ventral and dorsal roots join to form spinal nerves
• Autonomic Nervous System:

  • Automatically adjusts body organ functioning to maintain internal conditions
  • Divided into sympathetic and parasympathetic systems with opposite effects
  • Sympathetic neurons release norepinephrine, parasympathetic neurons release acetylcholine
• Disorders of the Nervous System:

  • Headaches: tension headaches caused by stress, migraine headaches with throbbing pain
  • Strokes: interruption of blood flow causing nerve cell death
  • Coma: caused by damage to systems keeping the cerebrum awake
  • Spinal Cord Injury: impairs sensation and motor control