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Core Ch 8 Transport in Humans

Created by Eunice

p.4

Formation of tissue fluid — what are the step-by-step events at the arteriole end of a capillary?

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p.4
  1. Blood pressure (BP) in capillaries near the arteriole end is higher than BP of the surrounding tissue fluid. 2) This pressure difference forces plasma (water, nutrients, sugars, ions) out through the capillary wall into the surrounding tissue — red blood cells, plasma proteins and platelets remain because they are too large. 3) The fluid that collects around cells is called tissue fluid.

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p.4

Formation of tissue fluid — what are the step-by-step events at the arteriole end of a capillary?

  1. Blood pressure (BP) in capillaries near the arteriole end is higher than BP of the surrounding tissue fluid. 2) This pressure difference forces plasma (water, nutrients, sugars, ions) out through the capillary wall into the surrounding tissue — red blood cells, plasma proteins and platelets remain because they are too large. 3) The fluid that collects around cells is called tissue fluid.
p.5

How is tissue fluid returned to the blood at the venule end? Give steps.

  1. At the venule end, the water potential of the blood is lower (due to plasma proteins) than that of tissue fluid. 2) Water is drawn back into the capillary by osmosis, so much tissue fluid returns to the blood. 3) Any excess tissue fluid is collected by lymph capillaries.
p.4

Formation of tissue fluid — what are the step-by-step events at the arteriole end of a capillary?

  1. Blood pressure (BP) in capillaries near the arteriole end is higher than BP of the surrounding tissue fluid. 2) This pressure difference forces plasma (water, nutrients, sugars, ions) out through the capillary wall into the surrounding tissue — red blood cells, plasma proteins and platelets remain because they are too large. 3) The fluid that collects around cells is called tissue fluid.
p.5

Describe the stepwise route by which excess tissue fluid is removed and returned to the bloodstream.

  1. Excess tissue fluid drains into lymph capillaries. 2) Lymph flows from small lymph vessels → large lymph vessels. 3) Lymph passes through lymph nodes (filtered; WBCs kill germs). 4) Large lymph vessels carry lymph to the subclavian veins / anterior vena cava, where it re-enters the blood circulation.
p.4

Step-by-step: how do oxygen and nutrients move from blood to body cells across capillaries?

  1. Blood carrying oxygen and dissolved nutrients reaches capillaries. 2) Capillary walls are one-cell thick and differentially permeable, providing a short diffusion distance. 3) Oxygen and small nutrients diffuse down their concentration gradients from blood → tissue fluid → body cells. 4) The branched capillary network and slow blood flow (large total cross-sectional area) increase time and surface area for diffusion.
p.4

Step-by-step: how do waste products (CO2) move from body cells into blood?

  1. CO2 produced by cells diffuses from cells → tissue fluid because its concentration is higher in cells. 2) CO2 then diffuses across the capillary wall into the blood down its concentration gradient. 3) Blood transports CO2 away (to lungs for exhalation). The capillary structure (thin wall, large surface area, slow flow) facilitates this exchange.
p.4

List the capillary adaptations for efficient exchange in step form.

  1. One-cell-thick walls → very short diffusion distance. 2) Numerous branches → large surface area for diffusion. 3) Large total cross-sectional area → slows blood flow, allowing more time for exchange. Together these features maximize diffusion of materials.
p.4

Pulmonary circulation — list the ordered steps blood follows (pulmonary circuit).

  1. Deoxygenated blood enters the right atrium from the vena cavae. 2) It flows to the right ventricle and is pumped into the pulmonary artery. 3) Blood travels to the lungs, where CO2 is released and O2 taken up. 4) Oxygenated blood returns to the left atrium via the pulmonary veins. This completes the pulmonary circuit.
p.4

Systemic circulation — list the ordered steps of the systemic circuit.

  1. Oxygenated blood enters the left atrium. 2) It passes into the left ventricle and is pumped through the aorta to body tissues (except lungs). 3) Blood delivers O2 and nutrients to tissues and collects CO2/waste. 4) Deoxygenated blood returns via veins → vena cavae → right atrium, completing the systemic circuit.
p.3

During the cardiac cycle, what is the sequence of valve actions (tricuspid, bicuspid, semilunar)?

  1. When ventricles contract, the tricuspid (right) and bicuspid/mitral (left) valves close to prevent backflow into atria. 2) Semilunar valves (at base of aorta and pulmonary artery) open during ventricular contraction to allow blood into arteries and close when ventricles relax to prevent arterial backflow. 3) Atria contract earlier in the cycle; semilunar valves also close when atria begin to contract and when both atria and ventricles relax.
p.4

What keeps the bicuspid and tricuspid valves from turning inside out during ventricular contraction?

p.6

Stepwise: how is lymph flow maintained so it moves toward the heart?

  1. Skeletal muscle contraction surrounding lymph vessels squeezes lymph forward. 2) Valves in lymph vessels prevent backflow. 3) Lymph flows from lymph capillaries → small lymph vessels → large lymph vessels → subclavian veins / anterior vena cava, returning to the bloodstream.
p.7

Describe the steps that maintain high velocity of blood flow in leg veins despite low pressure.

  1. Contraction of skeletal muscles adjacent to leg veins compresses veins and forces blood toward the heart. 2) Valves in veins prevent backflow between muscle contractions. 3) The larger lumen of veins reduces resistance, aiding flow. Combined these mechanisms allow relatively high velocity despite low venous pressure.
p.10

Trace the stepwise path of blood from the small intestine to the lungs (hepatic portal flow).

  1. Blood from the small intestine drains into the hepatic portal vein. 2) It flows into the liver (for processing/detoxification). 3) Blood leaves the liver via the hepatic vein to the vena cava. 4) Blood enters the heart, is pumped into the pulmonary artery, and goes to the lungs for gas exchange.
p.9
10

Stepwise comparison: how structural differences between arteries and veins support their different ways of maintaining blood flow?

  1. Arteries have thicker walls and more elastic tissue → withstand high pressure from heart and recoil to help maintain continuous flow. 2) Arterial muscular layer can contract/relax to change lumen diameter, regulating blood distribution. 3) Veins have larger lumens and valves; flow is assisted by skeletal muscle contractions that squeeze veins and valves that prevent backflow. These features match each vessel's pressure and flow demands.
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