Transport in Humans Study Guide

Competency: The learner appreciates the mechanisms of transport of substances in the blood, and the immune system’s role in protecting the human body by analyzing the processes and their role in the maintenance of human health, to prevent diseases in everyday life.

Fig. 5: Diagram of heart cut open (left side)
- Aorta: Blood flows from the left ventricle to the body.
- Vena Cava: Brings deoxygenated blood from the head and body into the right atrium.
- Pulmonary Artery: Carries deoxygenated blood from the right ventricle to the lungs.
- Pulmonary Veins: Bring oxygenated blood back from the lungs to the left atrium.
- Semilunar Valve: Valves at the base of arteries; prevent backflow.
- Tricuspid Valve: Valves between the right atrium and right ventricle.
- Bicuspid Valve: Valves between the left atrium and left ventricle.
- Supportive Structures: Tendons support the valves (heartstrings).

The heart has different wall thicknesses for its chambers.
- Oxygenated blood has a thicker wall in the left ventricle to pump blood throughout the body, while deoxygenated blood from the right side faces lower pressures and thinner walls.

Key Components
- Anterior and Posterior Vena Cava: Drains blood into the right atrium.
- Sinoatrial Node: The heart's pacemaker located in the right atrium.
- Atrioventricular Node: Transfers signal from atria to ventricles.
- Papillary Muscles: Prevent the inversion of the heart valves.
- Septum: Divides left and right side of the heart.

Heart tissue has a high demand for oxygen and nutrients, supplied by coronary arteries.
Blockage of coronary arteries can lead to a heart attack.

The heart is enclosed by the pericardium, a double-layered sac that contains fluid to lubricate heart movements.
Function: Prevent overexpansion, especially under high demand.

The cardiac cycle consists of a.
- Atrial Diastole: Atria relax, blood enters from veins.
- Atrial Systole: Atria contract, pushing blood into ventricles.
- Ventricular Systole: Ventricles contract, pushing blood into arteries.
- Ventricular Diastole: Ventricles relax and fill with blood.

Normal heart beats approximately 72 times per minute, meaning each cardiac cycle lasts about $\frac{60 ext{ seconds}}{72} ext{ minutes} = 0.83 ext{ seconds}$ .

Valves
- Prevent backflow.
- Tricuspid Valve: Between right atrium and right ventricle.
- Bicuspid Valve: Between left atrium and left ventricle.
- Semilunar Valves: In aorta and pulmonary artery.
Blood Flow Process
- Deoxygenated blood travels from body -> right atrium -> right ventricle -> lungs.
- Oxygenated blood travels from lungs -> left atrium -> left ventricle -> body.

Heart Sounds: "Lub" corresponds to closure of atrioventricular valves during ventricular systole, and "Dub" to closure of semilunar valves during ventricular diastole.

Blood pressure changes during the cardiac cycle: rises during ventricular contraction, falls during diastole. Typical values: systolic around 120 mmHg, diastolic around 80 mmHg.
Blood pressure is regulated by the nervous and hormonal systems. Sensors in arteries alert the brain of pressure changes.

blood is made up of approximately 55% plasma and 45% cells, including erythrocytes, leukocytes, and thrombocytes (platelets).

Function: Carry oxygen through haemoglobin.
Haemoglobin: A conjugated protein that binds oxygen. Each molecule has four iron-containing hemes.

Immunity Definition: Ability of the body to resist diseases, involving innate and adaptive immunity.
Innate Immunity: Non-specific, immediate response, including physical barriers (skin, mucous) and immune cells (phagocytes).
Adaptive Immunity: Specific, involves B and T lymphocytes.

Vaccines prompt primary immune response, leading to the formation of memory cells for quicker reaction to pathogens upon re-exposure.