Human Body Physiology Overview

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Questions and Answers

What percentage of water typically composes most cells?

70 to 85% (correct)

85 to 90%

60 to 70%

50 to 60%

Which type of proteins mainly form the cytoskeleton of cells?

Structural proteins (correct)

Enzymatic proteins

Functional proteins

Membrane proteins

What structural role do carbohydrates primarily serve in cells?

Structural and nutritional support (correct)

Cell membrane formation

Energy storage

Chemical signaling

Which type of lipids is key in forming the cell membrane?

Phospholipids Signup and view all the answers

What is the primary function of integral proteins in cell membranes?

Transporting specific substances Signup and view all the answers

What is the characteristic of the cell membrane thickness?

7.5 to 10 nanometers thick Signup and view all the answers

Which ion is NOT mentioned as being important in cellular functions?

Iron Signup and view all the answers

How does the lipid composition of membranes affect substance movement?

It impedes movement of water and water-soluble substances Signup and view all the answers

What do Baroque systems primarily contain instead of high places?

Oxidizers Signup and view all the answers

What is the primary function of mitochondria in cells?

To oxidize substances and release energy Signup and view all the answers

What is the composition of the mitochondria's membranes?

Two lipid bilayer membranes Signup and view all the answers

Which of the following best describes the role of intermediate filaments?

To act as a cytoskeleton for structural support Signup and view all the answers

How does the number of mitochondria in a cell vary?

According to the energy requirements of the cell Signup and view all the answers

What substance is primarily synthesized as a result of oxidation in the mitochondria?

Adenosine triphosphate (ATP) Signup and view all the answers

What message does the nucleus send to the cell?

To grow, mature, replicate, or die Signup and view all the answers

Which structure is continuous with the nuclear membrane?

Endoplasmic reticulum Signup and view all the answers

What is a characteristic of isotonic solutions regarding cell volume?

It does not cause cells to shrink or swell. Signup and view all the answers

What happens to cells when placed in a hypertonic solution?

Water moves out of the cells, causing them to shrink. Signup and view all the answers

What primarily determines the effectiveness of a saline solution in affecting cell volume?

The concentration of impermeable solids in the solution. Signup and view all the answers

How is osmolarity typically corrected in the body after a change occurs?

It is corrected within seconds to minutes. Signup and view all the answers

Which statement best describes the effect of a hypertonic solution on extracellular volume?

It increases extracellular volume by drawing water out of cells. Signup and view all the answers

What condition can lead to hyponatremia?

Excess water addition diluting sodium levels. Signup and view all the answers

What is the main effect of adding isotonic saline to extracellular fluid?

It increases the extracellular fluid volume without altering cell volume. Signup and view all the answers

If a cell is placed in a solution with less than 0.9% sodium chloride, what is expected?

Water will diffuse into the cell, causing it to swell. Signup and view all the answers

What occurs when the membrane potential rises towards zero?

Potassium channels open and allow diffusion. Signup and view all the answers

Which ion has a higher conductance during the resting state compared to sodium?

Potassium Signup and view all the answers

What initiates the positive feedback cycle during an action potential?

Initial rise in membrane potential from -70mV Signup and view all the answers

What is the role of potassium channels during repolarization?

Restore resting membrane potential by allowing potassium to exit Signup and view all the answers

What effect does the inactivation of sodium channels have after depolarization?

Prevents further sodium entry into the cell. Signup and view all the answers

What occurs to sodium and potassium ions during the action potential?

Sodium enters the cell, while potassium exits the cell. Signup and view all the answers

How is an action potential propagated along a nerve or muscle?

By simultaneous ion flow in all directions Signup and view all the answers

What is the approximate voltage change needed to start the positive feedback loop?

15 to 30mV Signup and view all the answers

What is the primary cause of extracellular edema?

Increased leakage of fluid from plasma Signup and view all the answers

How does heart failure contribute to edema?

By increasing capillary filtration and pressure Signup and view all the answers

What condition can cause a decrease in plasma colloid osmotic pressure?

Nephrotic syndrome Signup and view all the answers

What safety factors typically prevent edema in the body?

Ability of lymph flow to increase significantly Signup and view all the answers

What effect does high sodium chloride concentration in extracellular fluid have?

It leads to leakage into interstitial spaces Signup and view all the answers

In which condition might substantial fluid collect in potential spaces of the body?

Edema in adjacent subcutaneous tissue Signup and view all the answers

What physiological function is affected by hydrogen concentration changes in the body?

Operation of enzyme systems Signup and view all the answers

What can result from blockage of phallic vessels draining potential spaces?

Effusion or fluid accumulation Signup and view all the answers

What functions do the Starling forces serve in fluid movement?

They influence both filtration and reabsorption of fluid. Signup and view all the answers

What is the average capillary pressure at the arterial ends of the capillary?

15 to 25 mm of mercury Signup and view all the answers

How does interstitial fluid pressure typically affect lymph flow?

It increases lymph flow when increased. Signup and view all the answers

What is the fate of most fluid filtered from the capillaries?

It is reabsorbed back into the capillaries. Signup and view all the answers

What role does the lymphatic system serve in fluid regulation?

It drains excess fluid from interstitial spaces back to the blood. Signup and view all the answers

What is the average plasma colloid osmotic pressure?

28 mm of mercury Signup and view all the answers

What initiates fluid filtration across the capillaries?

Positive net filtration pressure Signup and view all the answers

What is the average volume of fluid entering the lymphatic system daily?

2 to 3 liters Signup and view all the answers

Study Notes

Functional Organization of the Human Body

Homeostasis is the maintenance of nearly constant internal conditions.
Disease is often a disruption of homeostasis.
Physiology explains how physiologic processes change in disease and injury.

Extracellular Fluid Transport

Fluid moves through the body in two stages:
- Blood flow through vessels
- Movement from capillaries to interstitial space
Cells are typically within 50 micrometers of a capillary.
Exchange between plasma and interstitial fluid occurs constantly.
Blood picks up oxygen in alveoli during pulmonary circulation.
Gastrointestinal tract absorbs carbohydrates, fatty acids, and amino acids.
Liver processes these substances into usable forms and eliminates waste.
Kidneys filter plasma, reabsorbing needed substances and excreting waste.

Nervous System

Three parts: sensory, central, and motor output
Sensory receptors detect body/environment conditions.
Brain processes sensory input and generates responses.
Motor output transmits signals to regulate body functions (organs and tissues).
Hormones are chemical messengers transported in the extracellular fluid to regulate cellular functions (insulin e.g.).

Immune System

Composed of white blood cells (WBCs), thymus, lymph nodes, and lymph vessels
Distinguishes self cells from foreign invaders, destroying those invaders through phagocytosis or antibodies.
Skin, hair, nails, and glands protect deeper tissues.
Plays role in temperature regulation and waste excretion.

Reproductive System

Contributes to maintaining homeostasis by generating new organisms.

Control Systems

Body has thousands of control systems (genetic, within cells, within organs, throughout body) to regulate homeostasis and conditions (e.g. oxygen, CO2, and blood pressure).
Negative feedback mechanisms are common in the body. Initial disruption triggers a response to return conditions to normal.
Positive feedback mechanisms can result in instability.

Cell Structure and Function

Most cells contain 70-85% water, with many ions and 10-20% proteins (e.g. enzymes).
Lipids are essential for membranes and cellular compartmentalization (e.g. phospholipids and cholesterol).
Carbohydrates provide energy and structure.
Organelles like mitochondria, covered in membrane, produce ATP (cellular energy).
Cytoskeleton provides structure and support to organelles.
Membranes composed of proteins and lipids control substance passage.

Membrane Proteins/Transport

Proteins (integral, peripheral) function as channels/pores for passage of molecules.
Carbohydrates and lipids create glycoproteins/glycolipids.
Receptors on cell surface bind specific substances (hormones, drugs) to transmit signals to the interior of a cell.

Action Potentials/Nerve Signaling

Nerve signals spread in the form of action potentials.
Sodium & potassium move across the membrane with changes in permeability of channels.
Positive feedback loops rapidly drive depolarization.
Negative feedback returns the membrane potential to resting (normal) state.
Myelin sheath speeds up these nerve signals.

Microcirculation and Lymphatic System

Capillaries are small blood vessels, allowing diffusion of substances between blood and interstitial fluid.
Starling forces regulate fluid movement in and out of capillaries.
Lymphatic system is an important route for fluid return to the circulatory system.

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Description

This quiz explores the functional organization of the human body, focusing on homeostasis, fluid transport, and the nervous system. Understand how physiological processes change in disease and the role of various systems in maintaining internal conditions. Test your knowledge of these essential concepts in human physiology.