Chapter 1 - Guyton

Question 1

Primary constituents of intracellular fluid.

Answer 1

potassium, magnesium, phosphate

Question 2

All of the blood in circulation passes through entire circulatory circuit in how long?

Answer 2

1 minute at rest, 6 times a minute when extremely active

Question 3

How does the baroreceptor system work to control arterial blood pressure?

Answer 3

• baroreceptors (in the walls of the bifurcation region of the carotid arteries + arch of the aorta in the thorax) are stimulated by the stretch of the arterial wall
• send impulses to the medulla to inhibit the vasomotor center
• resulting in diminished pumping activity and dilation of peripheral blood vessels

Question 4

Most control systems of the body act through which mechanism?

Answer 4

negative feedback

Question 5

Examples of negative feedback?

Answer 5

• Carbon dioxide regulation - High CO2 in ECF increases pulmonary ventilation > decreased CO2 concentration (i.e. result is negative to initial stimulus)
• Arterial-pressure regulating mechanisms - High pressure > reactions promote reduced pressure)

Question 6

What is “gain” of a control system?

Answer 6

the degree of effectiveness with which a control system maintains constant conditions (Gain = correction/error)

Question 7

What is positive feedback and why does it lead to instability?

Answer 7

Initiating stimulus causes more of the same
E.g. Blood loss–>arterial pressure falls–>flows to heart through coronary vessels diminishes–>more weakness of heart–>death

Question 8

Examples of healthy positive feedback.

Answer 8

Blood clotting, uterine contractions, nerve signals (action potentials)

Question 9

What is feed-forward control in muscle contraction?

Answer 9

Sensory nerve signals from the moving parts –> brain –> assess whether the movement is performed correctly –> if not, corrects the next movement (adaptive control)

Question 10

Primary constituents of extracellular fluid

Answer 10

• Sodium, chloride, and bicarbonate ions
• Nutrients - oxygen, glucose, fatty acids, and amino acids
• Carbon dioxide being transported from cells > lungs
• Other cellular waste > kidneys for excretion

Question 11

What is homeostasis

Answer 11

maintenance of nearly constant conditions in the internal environment

Question 12

What are the two stages extracellular fluid is transported through the body?

Answer 12

1. Movement of blood through the body in the blood vessels.
2. Movement of fluid between the blood capillaries and the intercellular spaces between the tissue cells

Question 13

Where do nutrients originate from (and via which systems) in the ECF

Answer 13

• Respiratory system - oxygen diffuses via molecular motion through the alveolar membrane
• GI Tract - carbohydrates, fatty acids and amino acids absorbed from food
• Liver (adipocytes, GI mucosa, Kidneys, endocrine glands) - help modify absorbed substances and store them
• MSK - mobility to obtain nutrient

Question 14

Mechanisms for removal of metabolic end products

Answer 14

• Lungs - remove CO2 (most abundant metabolic product)
• Kidney - removes products of cellular metabolism (urea, uric acid, excess water + ions)
• GIT - undigested material + some metabolic waste
• Liver - detoxification of drugs/chemicals (often secreted into bile)

Question 15

What are two main systems which regulate body function

Answer 15

• Nervous system (sensory input, CNS or integrative portion, motor output)
• Hormone systems (endocrine glands)

Question 16

Systems for protection of the body

Answer 16

• Immune system
• Integumentary system (skin comprises 12-15% BW)