New Recording 44

Blood Vessels Overview

• Function: Blood vessels transport blood throughout the body.

Differences Between Arteries and Veins

• Arteries:

  • Carry blood away from the heart.

  • Generally shown in red in diagrams.

  • Have thicker walls due to a higher muscular and elastic tissue content, enabling them to withstand high pressure.

  • Example: Aorta - the largest artery in the body's systemic circulation.

  • Pulsation can be felt as arteries maintain pressure even when not filled with blood.

• Veins:

  • Carry blood toward the heart.

  • Generally depicted in blue in illustrations.

  • Thinner walls compared to arteries, leading to potential collapse when not filled with blood.

  • Contain valves that help maintain unidirectional blood flow toward the heart.

  • Example: Venules - small veins that collect blood from capillary beds.

Capillaries

• Structure: Small, thin-walled blood vessels that facilitate the exchange of substances between blood and tissues.

• Function: Allow diffusion of oxygen, carbon dioxide, nutrients, and waste products.

Comparison of Walls

• Artery Walls:

  • Thicker due to the presence of smooth muscle and elastic tissue.

  • Capable of sustaining and regulating blood pressure.

• Vein Walls:

  • Thinner, needing assistance from surrounding muscles to aid blood flow.

  • Valves prevent backflow, important in areas where blood must fight gravity.

Blood Flow Mechanics

• Skeletal Muscle Contraction: Aids in pushing blood through veins; stagnant blood can lead to swelling (edema).

Kidney Circulation

• Renal Artery: Carries oxygen-rich blood to the kidneys.

• Renal Vein: Transports oxygen-poor blood away from the kidneys toward the heart.

Unique Case: The Liver

• Blood from the intestines (rich in nutrients) passes through the Hepatic Portal Vein to the liver before reaching general circulation.

• The liver detoxifies blood and stores nutrients, releasing them when needed.

Vascular Diseases

• Arteriosclerosis: Hardening of arteries often due to cholesterol build-up, narrowing the lumen, potentially leading to heart conditions.

  • Particularly dangerous if it develops in coronary arteries.

  • Related symptom: Ischemic pain due to inadequate blood supply.

  • Treatments include angioplasty or bypass surgeries.

• Varicose Veins: Poor functioning veins resulting in blood pooling, causing pain and potential ulcers.

  • Solutions include leg elevation, compression stockings, or surgery.

• Aneurysms: Abnormal bulging in arteries that may require monitoring or surgery if large enough.

Blood Pressure

• Definition: The pressure exerted by circulating blood on the walls of blood vessels.

• Types:

  • Systolic Pressure: Higher pressure during heart contraction.

  • Diastolic Pressure: Lower pressure during heart relaxation.

• Normal Range: Less than 140/90 mm Hg; high blood pressure (>140 systolic or >90 diastolic) is termed hypertension, often asymptomatic but dangerous.

Shock

• Definition: A medical emergency where the circulatory system fails to deliver adequate oxygen to tissues.

• Types of shock include:

  • Septic Shock: Resulting from infections, characterized by a high mortality rate.

  • Cardiogenic Shock: Due to heart failure.

  • Neurogenic Shock: Caused by nervous system failure, affecting blood pressure regulation.

Sensory Receptors

• General vs. Special Senses:

  • General Senses: Include pain, temperature, touch, vibration, and pressure.

  • Special Senses: Include sight, hearing, taste, and smell.

• Receptor Types:

  • Photoreceptors: Sensitive to light (found in the retina).

  • Olfactory Receptors: Detect smells.

  • Taste Receptors: Detect different tastes.

  • Mechanoreceptors: Respond to pressure and vibration; important for proprioception.

  • Pain Receptors: Alert to tissue damage, do not adapt conveniently over time.

Eye Anatomy

• Layers:

  • Sclera: Outer layer, known as the 'white' of the eye.

  • Cornea: Transparent front part of the eye, allowing light to enter.

  • Iris: Colored part of the eye, controlling the size of the pupil.

  • Retina: Innermost layer with photoreceptors that capture light and generate signals for vision.

• Fluid: Aqueous Humor provides nutrients to the lens and cornea.

• Focus Mechanism: The lens adjusts thickness for focusing on objects at various distances.

• Common Visual Disorders:

  • Myopia: Nearsightedness; difficulty seeing far.

  • Hyperopia: Farsightedness; difficulty seeing close.

  • Astigmatism: Distortion in image focus due to uneven lens curvature.