Human Physiology: Calcium Regulation & Respiratory Gas Exchange Principles

What hormone is secreted in response to low calcium levels?

Parathyroid hormone (PTH)

What are the effects of parathyroid hormone on calcium levels?

Increases calcium uptake from the bone, decreases calcium resorption, and activates vitamin D for greater calcium absorption in the gut.

What hormone is secreted when calcium levels are high?

Calcitonin

What does calcitonin do in the body?

It stops calcium reabsorption from the bone, decreases the conversion to active vitamin D, reduces gut intake of calcium, and increases calcium excretion in urine.

How does the body manage calcium levels in the bones?

The bone acts as a reservoir, releasing calcium when supplies are low and storing it when supplies are high.

What is the primary function of the respiratory system?

To take in necessary gases and expel gases produced by metabolism.

What are the primary gases that make up Earth's atmosphere?

Approximately 21% oxygen, 79% nitrogen, 1% argon, and 0.04% carbon dioxide.

What happens to the percentage of gases in a closed cylinder filled with pure oxygen?

The percentage of oxygen jumps to 100%.

What is the relationship between gas percentages and partial pressures?

The total of all partial pressures in a given environment will always equal one atmosphere.

What is the partial pressure of oxygen at sea level?

Approximately 0.2095 atmospheres.

What happens to the partial pressure of oxygen at high altitudes?

The partial pressure of oxygen decreases.

What is the significance of the total partial pressures in any environment?

They will always sum to one atmosphere.

What is the partial pressure of carbon dioxide in the atmosphere?

Approximately 0.004 atmospheres.

What occurs to gas percentages when moving to different altitudes or depths?

Gas percentages remain constant, but partial pressures change due to atmospheric pressure variations.

What is the role of vitamin D in calcium regulation?

It enhances calcium absorption in the gut and reabsorption in the kidneys.

How does the body respond when calcium levels are adequate?

It reduces the secretion of parathyroid hormone and increases calcitonin to prevent excess calcium release from bones.

What is the effect of high calcium levels on vitamin D conversion?

High calcium levels inhibit the conversion of vitamin D to its active form.

What is the primary gas that humans inhale during respiration?

Oxygen

What is the process of gas exchange in the respiratory system?

Taking in oxygen and expelling carbon dioxide as a waste product.

What happens to the body's calcium levels when there is a deficiency?

The body will mobilize calcium from the bones to maintain necessary levels.

What is the primary function of the kidneys in calcium regulation?

To reabsorb calcium from urine back into the bloodstream.

What happens to calcium levels during excessive exercise or metabolic activity?

Calcium may be mobilized from bones to meet physiological demands.

What is the relationship between atmospheric pressure and gas behavior in the body?

Gas behavior follows physical laws, meaning total partial pressures must equal atmospheric pressure.

What is the significance of understanding gas percentages and partial pressures in physiology?

It is crucial for understanding how gases interact with the body under different environmental conditions.

What happens to partial pressures of gases as a diver descends?

The partial pressures of oxygen decrease as the diver goes deeper.

What is a major risk when a diver ascends too quickly?

Bubbles can form in the body, potentially leading to serious conditions like stroke.

Why is it important for divers to acclimatize to their environment?

Acclimatization helps the body adjust to changes in pressure and gas concentrations.

What happens to turtle eggs when a storm covers them with water?

The eggs experience reduced oxygen transfer due to underwater conditions, leading to high mortality rates.

How does the concentration of oxygen change as a diver goes deeper?

The concentration of oxygen decreases as depth increases, despite the partial pressure remaining constant.

What adaptation do water beetles use to breathe underwater?

Water beetles create a bubble that maintains a lower partial pressure of oxygen.

What is the concentration of oxygen that a water beetle needs to survive?

4.3 millimoles per liter.

How does the water beetle manage to obtain enough oxygen in low concentration environments?

By maintaining a bubble at a partial pressure of 0.1 atmospheres, allowing it to extract oxygen from the surrounding water.

What principle governs gas movement in relation to partial pressures?

Gas moves from areas of higher partial pressure to areas of lower partial pressure.

What happens to the concentration of gases as a diver ascends?

The concentration of gases decreases as the diver ascends.

Why is the concept of partial pressure important in scuba diving?

It has real-world implications for how gases behave under pressure and affects diver safety.

What is the effect of rapid ascent on a diver's body?

It can lead to decompression sickness due to the formation of nitrogen bubbles.

How does the water beetle's bubble affect its oxygen intake?

The bubble allows the beetle to maintain a higher effective concentration of oxygen despite lower ambient levels.

What is the significance of maintaining equilibrium with the environment?

It is crucial for survival as it allows organisms to adapt to changing conditions.

How does the partial pressure of oxygen in water compare to that in the atmosphere?

The partial pressure remains the same at 0.21 atmospheres, but the concentration can vary with depth.

What is the concentration of oxygen at a depth where the water beetle operates?

0.3 millimoles per liter.

What happens to the oxygen concentration as a diver goes deeper?

The concentration of oxygen decreases even though the partial pressure remains constant.

What is the primary gas that divers breathe in?

Oxygen, which constitutes about 21% of the air.

What is the role of nitrogen in the air divers breathe?

Nitrogen is present but not used by the body, and can form bubbles during rapid ascent.

What is the relationship between gas concentration and partial pressure?

Gas concentration can decrease while partial pressure remains constant, affecting gas availability.

What is the partial pressure of oxygen underwater for the beetle?

0

How does oxygen flow in relation to partial pressure?

Oxygen flows from higher partial pressure to lower partial pressure.

What drives respiration across all animals?

The movement of gases from higher partial pressure to lower partial pressure.

How does a water beetle maintain oxygen concentration in its bubble?

By maintaining the bubble at 10% oxygen concentration.

What are the three types of lungs mentioned?

Invaginated lungs, external gills, and internal gills.

What effect does temperature have on the ability of water to dissolve oxygen?

As temperature increases, the ability to dissolve oxygen decreases.

What happens to dissolved gases when salt concentration in a liquid increases?

The ability of the liquid to hold dissolved gases decreases.

What is unidirectional airflow?

Air flows in one direction through a tube, such as from the nose to the trachea.

What is tidal flow in respiration?

Air flows in and out, mixing in the lungs rather than moving in one direction.

What are the two principles that govern air movement in the body?

Convection (movement in the same phase) and diffusion (movement across phases).

Why do we care about how much gas can be held in solution?

It determines how air dissolves in blood, allowing normal physiological processes.

What is the relationship between temperature and the ability to dissolve gases?

Higher temperatures reduce the ability to dissolve gases.

What happens to dissolved gases when boiling water?

Bubbles form as dissolved air is released due to increased temperature.

How does the concentration of salt affect dissolved gases in liquids?

Higher salt concentrations decrease the ability of liquids to hold dissolved gases.

What is the significance of maintaining oxygen levels for aquatic animals?

It is crucial for their survival and physiological functions.

How does gas exchange occur in the lungs?

Gas moves through convection in the same phase and diffusion across phases.

What is the role of mitochondria in respiration?

Mitochondria require oxygen to produce energy for the cell.

What happens to gas exchange when the body is underwater?

Gas exchange continues as long as partial pressures allow for diffusion.

How does the body know where to deliver oxygen?

Oxygen travels from the lungs to cells and then to mitochondria.

What is the effect of increased temperature on dissolved gases in the ocean?

It reduces the levels of dissolved gases available for aquatic life.

What is the relationship between atmospheric pressure and gas exchange?

Gas exchange is influenced by the difference in partial pressures between the atmosphere and the organism.

What is the importance of maintaining a concentration gradient for gases?

It drives the movement of gases necessary for respiration.

What happens to gas levels in saltwater compared to freshwater?

Saltwater has lower levels of dissolved gases due to higher salt concentration.

What is the role of convection in gas exchange?

Convection allows for rapid movement of air over long distances within the same phase.

What is diffusion in the context of respiration?

Diffusion is the movement of gases across cell membranes from areas of higher concentration to lower concentration.

What are the two principles that allow air movement in the body?

Convection and diffusion.

What is the primary function of convection in gas exchange?

To allow movement of air over long distances within the same phase.

What is the primary function of diffusion in gas exchange?

To allow movement of air across different phases, but only over short distances.

What surfaces in the body act as gas exchange membranes?

Skin, lungs, cells on the lungs, alveoli, gills in fish.

How does oxygen move from the alveoli to the blood?

Oxygen diffuses from the alveoli into the blood vessels.

What role does the circulatory system play in gas exchange?

It pumps oxygenated blood throughout the body.

What happens to deoxygenated blood in the body?

It returns to the lungs where carbon dioxide is released.

How does carbon dioxide move from cells back to the lungs?

It diffuses into the blood and is then transported back to the lungs via convection.

What is the significance of partial pressure in gas exchange?

Gas transfer direction is determined by differences in partial pressures, not concentrations.

What is the partial pressure of oxygen in ambient air?

Approximately 0.2 atm.

What must happen to the partial pressure of oxygen for it to move from the air to the alveoli?

The partial pressure in the alveoli must be lower than in the ambient air.

What happens to the partial pressure of oxygen as it moves from the alveoli to arterial blood?

It decreases from about 0.14 to lower values, allowing diffusion into the blood.

What is the process of gas exchange in the lungs called?

Diffusion across the alveolar membrane.

What happens to oxygen once it enters the bloodstream?

It is transported to cells where it is used by mitochondria.

What is the role of mitochondria in gas exchange?

They utilize oxygen for metabolic processes within cells.

What is the process of moving gases through the circulatory system called?

Convection, as it involves movement through the same liquid phase.

What occurs when there is an impingement on the gas exchange membrane?

It can disrupt the normal drop in partial pressure, affecting gas exchange.

How does the body ensure efficient gas exchange?

By maintaining lower partial pressures in the areas where gas needs to diffuse.

What happens to carbon dioxide produced in the body?

It is transported back to the lungs for exhalation.

What happens to oxygen during the process of gas exchange?

It is inhaled, diffuses into the blood, and is delivered to cells.

What is the role of the heart in gas exchange?

It pumps oxygenated blood throughout the body and returns deoxygenated blood to the lungs.

What is the term for the movement of gases across cell membranes?

Diffusion.

How does the body differentiate between gases during respiration?

The body does not differentiate; it takes in all gases present in the air.

What is the significance of the alveoli in the lungs?

They are the sites where gas exchange occurs between air and blood.

What is the process called when oxygen moves from the blood to the cells?

Diffusion, as it crosses the cell membrane.

What is the primary mechanism by which oxygen moves from blood to tissues?

Oxygen moves from areas of higher partial pressure to areas of lower partial pressure.

What happens to the partial pressure of oxygen as it moves from arterial blood to systemic capillary blood?

The partial pressure of oxygen drops significantly, from about 0.2 atmosphere to as low as 0.01 atmosphere.

How does the body prioritize oxygen delivery to tissues?

The body directs oxygen to tissues with lower partial pressures of oxygen, indicating higher demand.

What is the role of partial pressures in gas exchange?

Partial pressures, rather than concentrations, drive the movement of gases between blood and tissues.

What happens to carbon dioxide levels during metabolic activity?

Metabolic activity increases carbon dioxide levels in tissues, prompting its movement back into the blood.

What is the significance of nitrogen's partial pressure in the body?

Nitrogen has a high partial pressure and does not participate in gas exchange; it remains at equilibrium.