turgor pressure

(noun)

pushes the plasma membrane against the cell wall of plant; caused by the osmotic flow of water from outside of the cell into the cell's vacuole

Examples of turgor pressure in the following topics:

  • Osmoregulation

    • This inflow of water produces turgor pressure, which stiffens the cell walls of the plant.
    • In nonwoody plants, turgor pressure supports the plant.
    • Plants lose turgor pressure in this condition and wilt .
    • Without adequate water, the plant on the left has lost turgor pressure, visible in its wilting; the turgor pressure is restored by watering it (right).
    • The turgor pressure within a plant cell depends on the tonicity of the solution in which it is bathed.
  • Pressure, Gravity, and Matric Potential

    • Pressure potential is also called turgor potential or turgor pressure and is represented by Ψp.
    • Positive pressure inside cells is contained by the cell wall, producing turgor pressure in a plant.
    • Turgor pressure ensures that a plant can maintain its shape.
    • A plant's leaves wilt when the turgor pressure decreases and revive when the plant has been watered .
    • When (b) the total water potential is higher outside the plant cells than inside, water moves into the cells, resulting in turgor pressure (Ψp), keeping the plant erect.
  • Gas Pressure and Respiration

    • Gas pressures in the atmosphere and body determine gas exchange: both O2 and CO2 will flow from areas of high to low pressure.
    • Each gas component of that mixture exerts a pressure.
    • The pressure for an individual gas in the mixture is the partial pressure of that gas.
    • The pressure of the water vapor in the lung does not change the pressure of the air, but it must be included in the partial pressure equation.
    • For this calculation, the water pressure (47 mm Hg) is subtracted from the atmospheric pressure: 760 mm Hg 47 mm Hg = 713 mm Hg, and the partial pressure of oxygen is: (760 mm Hg 47 mm Hg) 0.21 = 150 mm Hg.
  • Blood Pressure

    • Blood pressure is the pressure of blood against the blood vessel walls during the cardiac cycle; it is influenced by a variety of factors.
    • Blood pressure is the pressure of the fluid (blood) against the walls of the blood vessels.
    • Fluid will move from areas of high to low hydrostatic pressures.
    • The systolic pressure is defined as the peak pressure in the arteries during the cardiac cycle; the diastolic pressure is the lowest pressure at the resting phase of the cardiac cycle.
    • The blood pressure of the systole phase and the diastole phase gives the two readings for blood pressure .
  • Basic Principles of Gas Exchange

    • Partial pressure (Px) is the pressure of a single type of gas in a mixture of gases.
    • For example, in the atmosphere, oxygen exerts a partial pressure, and nitrogen exerts another partial pressure, independent of the partial pressure of oxygen (Figure 1).
    • Total pressure is the sum of all the partial pressures of a gaseous mixture.
    • A gas will move from an area where its partial pressure is higher to an area where its partial pressure is lower.
    • The sum of the partial pressures of all the gases in a mixture equals the total pressure.
  • The Mechanics of Human Breathing

    • The relationship between gas pressure and volume helps to explain the mechanics of breathing.
    • As volume decreases, pressure increases and vice versa .
    • Due to this increase in volume, the pressure is decreased, based on the principles of Boyle's Law.
    • This decrease of pressure in the thoracic cavity relative to the environment makes the cavity pressure less than the atmospheric pressure .
    • This increases the pressure within the thoracic cavity relative to the environment.
  • Other Hormonal Controls for Osmoregulation

    • The renin-angiotensin-aldosterone system (RAAS) stabilizes blood pressure and volume via the kidneys, liver, and adrenal cortex.
    • Defective renin production can cause a continued decrease in blood pressure and cardiac output.
    • Thus, via the RAAS, the kidneys control blood pressure and volume directly.
    • Medically, blood pressure can be controlled by drugs that inhibit ACE (called ACE inhibitors).
    • The renin-angiotensin-aldosterone system increases blood pressure and volume.
  • Gas Exchange across the Alveoli

    • Since this pressure gradient exists, oxygen can diffuse down its pressure gradient, moving out of the alveoli and entering the blood of the capillaries where O2 binds to hemoglobin.
    • Oxygen and carbon dioxide move independently of each other; they diffuse down their own pressure gradients.
    • This pressure gradient drives the diffusion of oxygen out of the capillaries and into the tissue cells.
    • The pressure gradient drives CO2 out of tissue cells and into the capillaries.
    • The partial pressures of oxygen and carbon dioxide change as blood moves through the body.
  • Hormonal Regulation of the Excretory System

    • The reabsorption of Na+ also results in the osmotic reabsorption of water, which alters blood volume and blood pressure.
    • Aldosterone production can be stimulated by low blood pressure, which triggers a sequence of chemical release .
    • When blood pressure drops, the renin-angiotensin-aldosterone system (RAAS) is activated.
    • ADH and aldosterone increase blood pressure and volume.
    • This increases water retention and blood pressure.
  • Somatosensory Receptors

    • They contain mechanically-gated ion channels whose gates open or close in response to pressure, touch, stretching, and sound.
    • Light touch, also known as discriminative touch, is a light pressure that allows the location of a stimulus to be pinpointed.
    • They respond to fine touch and pressure, but they also respond to low-frequency vibration or flutter.
    • Pacinian receptors detect pressure and vibration by being compressed which stimulates their internal dendrites.
    • Pacinian corpuscles detect transient pressure and high-frequency vibration.
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