Respiration and Breathing Cycle

Respiration

• Respiration refers to the movement of air between the lungs and atmosphere.
• Types of respiration include external and internal respiration.
• External respiration involves the interchange of oxygen and carbon dioxide between the alveoli of the lungs and the pulmonary blood. 
• Internal respiration involves the interchange of these gases between the circulating blood and the cells of body tissues.

Breathing Cycle

• Breathing cycle includes inspiration (inhalation) and expiration (exhalation).
• A full breathing cycle takes 5 seconds, inspiration takes 2 seconds, and expiration takes 3 seconds.
• Average respiratory rate is 12 breaths per minute.

Inspiration Mechanism

• Firstly inspiratory muscles, including the external intercostal muscles and the diaphragm, contract increasing the chest volume.
• As a result, the pressure in the lungs decreases.
• Atmospheric pressure becomes greater than lung pressure, causing air to move from the atmosphere into the lungs.

Expiration Mechanism

• Expiration is a passive process achieved by relaxation of the inspiratory muscles of the lung and chest.
• Lungs pressure increases.
• Pressure in the lungs becomes greater than atmospheric pressure, which moves air from the lungs to the atmosphere.

Blood Pressure Basics

• Blood pressure is the force exerted by blood against blood vessel walls.
• The pumping action of the heart generates blood flow.
• Blood pressure arises as blood flow meets resistance from vessel walls.
• Formula: BP = BF + R.

Methods of Measuring Blood Pressure

• Direct Method: Involves intra-arterial cannula
• Indirect Methods: Include palpatory and auscultatory methods

Blood Pressure Graph Components

• Systolic pressure
• Dicrotic notch
• Diastole pressure
• Pulse pressure
• Mean arterial pressure

Systolic Pressure

• Systolic pressure is the maximum pressure exerted by the blood against the artery wall.
• It's a result of ventricular systole or contraction and is normally about 120 mmHg on average.
• Range is between 100 - 140 mmHg.

Dicrotic Notch

• The dicrotic notch represents interruption of smooth flow due to a brief backflow of blood.
• This backflow closes the aortic semilunar valve when the ventricles relax.

Diastole Pressure

• Diastole pressure is the lowest pressure in the artery.
• It results from ventricular diastole or relaxation and it is normally about 80 mmHg
• Range is 60 – 90 mmHg.

Pulse Pressure

• Pulse pressure is the difference between systolic and diastole pressure.
• Pulse pressure is calculated by subtracting diastole pressure from systole pressure.
• Example, 120 mmHg - 80 mmHg.

Mean Arterial Pressure (MAP)

• Mean arterial pressure calculates the "average" pressure in arteries.
• MAP is calculated by adding diastole pressure to one-third of the pulse pressure.
• Example, 93 mmHg = 80 mmHg + 40/3

Auscultatory Method

• Measuring blood pressure by using a sphygmomanometer and stethoscope

Palpatory Method

• Measuring blood pressure using a mercury monometer until the pulse reappears.
• Systolic pressure = A + B / 2

Overview of respiration, including external and internal respiration, outlining the interchange of oxygen and carbon dioxide. The breathing cycle includes inspiration and expiration. Inspiration involves muscle contraction and pressure changes in the lungs.