Review Questions and Answers

Chapter 3 – Human Physiological Systems

1) What is meant by the term homeostasis? Describe the roles of insulin and glucagon in maintaining this.

Homeostasis can be described as the overall process by which the human body maintains a relatively constant internal environment whilst facing challenges such as injury, disease, illness and environmental stress.

Both insulin and glucagons are crucial in maintaining a relatively constant concentration of glucose in the blood.

Insulin: In response to an increase in blood glucose concentration insulin is released from the beta cells of the islets of langerhans within the pancreas. It is secreted into the hepatic portal vein reaching the liver directly. It lowers blood glucose levels by facilitating glucose uptake by muscles and inhibiting hepatic glucose output.

Glucagon: Also secreted by the pancreas but from the alpha cells of the islets of langerhans. Glucagon is antagonistic to insulin causing the breakdown of glycogen in the liver, a process known as glycogenolysis. This process increases blood glucose concentration.

2) Make a route map of the divisions and sub-divisions of the nervous system.

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3) Make a list of five hormones and their metabolic effects.

Hormones and their effects could include any of the below

HORMONE EFFECT
Growth Hormone Stimulates growth.
Thyrotropin Stimulates production and release of thyroxine from thyroid gland.
Corticotrophin Stimulates production and release of cortisol, aldosterone and adrenal hormones.
Endorphins Block pain
Insulin Decreases blood glucose.
Glucagon Increases blood glucose.
Aldosterone Promotes retention of sodium, potassium and water by kidney.
Parathormone Raises blood calcium, lowers blood phosphate.
Testosterone Controls muscle size, decreases body fat.
Estrogen Controls menstrual cycle.

4) Explain the route that blood makes through the body making reference to systemic and pulmonary circulations.

The heart has four chambers, two atria and two ventricles allowing a double circulation to occur. This allows the oxygen rich blood on the left side of the heart to be handled separately from the oxygen-depleted blood on the right. At each heartbeat the atria contract to fill the ventricles, with the ventricles then contracting to eject the blood on one of two circulations. Blood on the left side of the heart is sent around the body on the systemic circulation via the aorta. Blood on the right hand side goes on the pulmonary circulation to the lungs via the pulmonary artery. Blood then returns from the systemic circulation oxygen depleted and enters the right side of the heart via the vena cava, with blood on the pulmonary circulation entering the heart from the lungs via the pulmonary vein.

5) Compare and contrast the adaptive (specific) components and the less specific components of the immune system.

a) Non-specific and less specific:

Can be divided into two types –

• First line: skin secretions, mucous membranes and tears.
• Second line: described as innate immunity including chemical, cellular, biochemical and inflammatory responses.

b) Specific or adaptive:

Dependant on lymphocyte cells is essentially the third line of defence.

There are two types of response:

• Antibody mediated: B Lymphocytes mature in bone marrow.
• Cell mediated: T lymphocyte production to attack foreign cells directly.

These differing responses are stimulated by different antigens and surface molecules.

6) Explain the lung volumes and capacities that can be measured in respiratory physiology.

• Total Lung Capacity: total capacity of lungs
• Inspiratory Capacity: maximum volume inspired following tidal expiration
• Functional Residual Capacity: volume in lungs after tidal expiration
• Vital Capacity: maximum volume expired after maximal inspiration
• Inspiratory Reserve Volume: maximum inspiration at the end of tidal inspiration
• Expiratory Reserve Volume: maximum expiration at the end of tidal expiration
• Tidal Volume: volume inspired or expired per breath
• Residual Volume: volume in lungs after maximum expiration
  
  

7) What are the functions of the liver and biliary system?

The liver and biliary system has a number of functions:

• Produces bile for digestive system.
• Processes and stores nutrients such as glycogen and vitamins.
• Synthesises new molecules such as cholesterol and plasma proteins.
• Metabolises ingested compounds such as alcohol.
• Detoxifies harmful chemicals.
  
  

8) Name a hormone produced by the kidney and a hormone that acts on the kidney, explain their roles.

Erythropoietin: Polypeptide hormone of the peritubular interstitial cells produced by the kidney. It attaches to receptors on the surface of erythrocyte precursors and is stimulated by tissue hypoxia, which can be brought about by exposure to high altitude. This essentially improves the ability of the blood system to carry and transport oxygen.

Antidiuretic hormone: acts on the kidney to facilitate water reabsorption.

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