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Anatomy and Physiology 1 > 1. Homeostasis > Flashcards

1. Homeostasis Flashcards

1
Q

What is the basic living unit of the body?

A

The cell

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2
Q

What is the function of red blood cells?

A

Red blood cells transport oxygen.

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3
Q

What do cells react with to release energy

A

Oxygen reacts with carbohydrates, fats, and proteins to release energy.

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4
Q

What do most cells deliver into surrounding fluids?

A

The end products of their chemical reactions.

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5
Q

What can most cells do in terms of reproduction?

A

Most cells can reproduce themselves.

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6
Q

What are the substances that make up the cell collectively called?

A

Protoplasm
- Cytoplasm + Nucleus

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7
Q

What are the five basic substances that make up protoplasm?

A

Water, electrolytes, proteins, lipids, and carbohydrates.

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8
Q

What percentage of most cells is water?

A

70-85%, except in fat cells.

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9
Q

What role does water play in the cell?

A

Many cellular chemicals are dissolved in the water, and chemical reactions take place among these dissolved chemicals.

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10
Q

What is the role of electrolytes/ions in cells?

A

They provide inorganic chemicals for cellular reactions and are necessary for some cellular control mechanisms.

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11
Q

Name some important electrolytes found in cells.

A

Potassium, magnesium, phosphate, bicarbonate, sulfate, sodium, chloride, calcium

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12
Q

What is the second most abundant substance in cells after water?

A

Proteins, which make up 10-20% of the cell mass.

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13
Q

What are the two main types of proteins in cells?

A

Structural proteins (e.g., microtubules) and functional proteins (mainly enzymes).

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14
Q

What percentage of cell mass is made up of lipids like phospholipids and cholesterol?

A

About 2% of the cell.

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15
Q

What role do lipids play in cells?

A

They form cell membranes and intracellular membrane barriers.

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16
Q

What is a significant type of lipid in adipose cells?

A

Triglycerides, which can make up as much as 95% of the cell mass in adipose cells.

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17
Q

What percentage of the cell is made up of carbohydrates?

A

Very small amounts, about 1% of the total mass.

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18
Q

Which cells have more carbohydrates, and why?

A

Muscle and liver cells (3-6%) because they store energy as glycogen.

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19
Q

How do cells use carbohydrates for energy?

A

Glucose dissolved in extracellular fluid (ECF) is transferred into the cell and used for energy.

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20
Q

What structural role do carbohydrates have in cells?

A

A tiny amount of carbohydrates serve a structural function, mainly in glycoproteins.

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21
Q

Label the diagram

A
  1. N/A
  2. Nucleus
  3. N/A
  4. Secretory Vesicles
  5. Granular ER
  6. Golgi apparatus
  7. Micotubules
  8. Agranular ER
  9. Mitochondria
  10. N/A
  11. N/A
  12. Lysosomes
  13. N/A
  14. Cytoplasm
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22
Q

What is cytosol?

A

The clear fluid portion of the cytoplasm containing dissolved proteins, electrolytes, and glucose.

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23
Q

What particles are dispersed in the cytoplasm?

A

Neutral fat globules, glycogen granules, ribosomes, secretory vesicles, and five important organelles: the endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, and peroxisomes.

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24
Q

What are granular endoplasmic reticulum and their function?

A

Granular (rough) endoplasmic reticulum have ribosomes that synthesize new proteins.

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25
Q

What is the function of agranular (smooth) endoplasmic reticulum?

A

Agranular endoplasmic reticulum synthesizes lipid substances.

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26
Q

What is the role of the Golgi apparatus?

A

The Golgi apparatus processes substances from the endoplasmic reticulum to form lysosomes, secretory vesicles, and more.

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27
Q

What is the primary function of lysosomes?

A

Lysosomes function as the intracellular digestive system, digesting damaged structures, ingested particles, and unwanted substances like bacteria.

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28
Q

How do lysosomes respond to cell damage?

A

Lysosomes rupture, releasing hydrolases to digest damaged components, and in severe cases, can digest the entire cell (autolysis).

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29
Q

How are peroxisomes different from lysosomes?

A

Peroxisomes contain oxidases that detoxify compounds, including 50% of alcohol in the liver, and are formed by self-replication or budding off from the agranular ER.

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30
Q

What are secretory vesicles and their function?

A

Secretory vesicles store and release substances formed by the ER-Golgi apparatus system, such as proenzymes in pancreatic acinar cells.

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31
Q

What is the primary function of mitochondria?

A

Mitochondria produce energy in the form of ATP and can self-replicate, with 100 to 1000s of mitochondria per cell.

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32
Q

What is the role of the nucleus in the cell?

A

The nucleus is the control center of the cell and contains DNA (genes).

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33
Q

What is the function of microtubules?

A

Microtubules act as the cytoskeleton of the cell.

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34
Q
A
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35
Q

What are integral proteins?

A

Proteins that penetrate all the way through the lipid layer of the cell membrane.

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36
Q

What function do integral proteins serve regarding channels?

A

They provide structural channels (pores) for water and water-soluble substances to pass through.

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37
Q

How do integral proteins function as carrier proteins?

A

They facilitate active transport of substances across the membrane.

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38
Q

In what ways do integral proteins act as enzymes?

A

They catalyze biochemical reactions on the cell membrane.

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39
Q

What types of chemicals do integral proteins serve as receptors for?

A

Water-soluble chemicals, such as peptide hormones.

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40
Q

What are peripheral proteins?

A

Proteins attached to only one surface of the membrane; they do not pass through.

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41
Q

How are peripheral proteins related to integral proteins?

A

They are often attached to integral proteins.

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42
Q

What is one function of peripheral proteins?

A

They act as enzymes.

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43
Q

How do peripheral proteins control transport?

A

They regulate transport through the pores formed by integral proteins.

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44
Q

How are carbohydrates associated with the cell membrane?

A

Most are in combination with lipids or proteins

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45
Q

What is glycocalyx?

A

A loose carbohydrate coat on the outer surface of cells.

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46
Q

What are the functions of carbohydrates in the cell membrane?

A
  1. Provide a negative charge that repels other negative charges
  2. Help attach cells to one another
  3. Act as receptor substances for binding hormones
  4. Involved in immune reactions
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47
Q

What fluids are cells bathed in and contain?

A

Cells are bathed in extracellular fluid and contain intracellular fluid.

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48
Q

How do cells interact with extracellular and intracellular fluids?

A

Cells pass constituents back and forth between extracellular and intracellular fluids via cell membranes.

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49
Q

What percentage of body weight does total body water (TBW) represent?

A

TBW represents about 60% of body weight

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50
Q

What percentage of body weight is intracellular fluid (ICF)?

A

ICF accounts for 40% of body weight.

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51
Q

What percentage of body weight is extracellular fluid (ECF)?

A

ECF accounts for 20% of body weight.

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52
Q

What percentage of ECF is interstitial fluid (ISF)?

A

ISF accounts for 15% of body weight

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53
Q

What is the intravascular fluid also known as and accounts for how much of body weight?

A

Plasma volume (PV), which accounts for 5% of body weight.

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54
Q

What is transcellular fluid?

A

Fluid in body cavities, variable in amount, and highest in ruminants.

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55
Q

How does body composition affect total body water (TBW) in animals?

A

Very lean cattle can have about 70% TBW, while very fat animals may have only 40% TBW.

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56
Q

What term is preferred over “water” when discussing body fluids?

A

The term “fluid” is preferred to measure the whole space, including solutes.

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57
Q

What are the major ions found in intracellular fluid (ICF)?

A
  1. Potassium
  2. Magnesium
  3. Phosphate
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58
Q

What are the major ions found in extracellular fluid (ECF)?

A
  1. Sodium
  2. Chloride
  3. Bicarbonate
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59
Q

What is this table?

A

Osmolar substances in ECF and ICF

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60
Q

How does a cell interact with its external environment?

A

Through the cell membrane.

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61
Q

What does the cell membrane separate?

A

Extracellular fluid (ECF) and intracellular fluid (ICF).

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62
Q

How can the cell membrane be described?

A

An organ that supervises and operates the transport of substances into and out of cells.

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63
Q

What type of changes accomplish transport through the cell membrane?

A

Electrochemical changes.

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64
Q

What is the purpose of constant bi-directional transfer across the cell membrane?

A

To maintain cell health and prevent cell death.

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65
Q

What does ionic transfer help maintain?

A

The difference in electrical potential between the inner and outer surfaces of the cell.

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66
Q

How does the cell membrane balance metabolic activity?

A

Through hormone receptors on its outer surface.

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67
Q

What are the types of diffusion?

A
  1. Simple diffusion
  2. Facilitated diffusion
  3. Osmosis
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68
Q

What are the types of active transport?

A
  1. Primary active transport
  2. Secondary active transport
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69
Q

What are the types of endocytosis?

A
  1. Pinocytosis (cell drinking)
  2. Phagocytosis (cell eating)
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70
Q

What is diffusion?

A

The random molecular movement of substances, molecule by molecule.

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71
Q

How does diffusion occur through the membrane?

A

Through intermolecular spaces or in combination with carrier proteins.

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72
Q

What causes diffusion?

A

The energy of kinetic energy.

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73
Q

What characterizes simple diffusion?

A

Kinetic movement of molecules or ions through a membrane opening or intermolecular spaces without interaction with carrier proteins.

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74
Q

What factors determine the rate of simple diffusion?

A
  1. Amount of substance available
  2. Velocity or kinetic motion
  3. Number and size of openings in the membrane
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75
Q

Where do molecules pass through in simple diffusion

A
  1. Through the lipid bilayer (if the substance is lipid-soluble, e.g., oxygen, nitrogen, carbon dioxide, alcohol)
  2. Through watery channels (for lipid-insoluble substances)
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76
Q

What are the characteristics of channels in simple diffusion?

A

Often selectively permeable to certain substances.

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77
Q

Describe the sodium channel.

A

Diameter: 0.3 to 0.5 nanometers
Inner surface: strongly negatively charged

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78
Q

Describe the potassium channel.

A

Slightly smaller than sodium channels and not negatively charged.

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79
Q

How are channels open and closed

A

Channels can be opened and closed by gates.

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80
Q

What is voltage gating?

A

Gating that responds to electrical potential across the cell membrane, as seen in action potentials in nerves.

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81
Q

What is chemical (ligand) gating?

A

Gating opened by the binding of a chemical substance, causing conformational changes in the protein, as seen with acetylcholine in nerve signal transmission.

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82
Q

What is facilitated diffusion?

A

Carrier-mediated diffusion that increases with the concentration of the diffusing substance but has a maximum rate (Vmax).

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83
Q

What is the role of carrier proteins in facilitated diffusion?

A

They have a pore large enough to transport specific molecules.

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84
Q

How does binding work in facilitated diffusion?

A

A molecule binds to a receptor inside the carrier protein, causing a conformational change that opens the pore on the opposite side.

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85
Q

Why is the binding force in facilitated diffusion weak?

A

It allows for the release of the attached molecule once it passes through.

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86
Q

What limits the rate of transport in facilitated diffusion?

A

The rate at which carrier protein molecules can undergo changes back and forth.

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87
Q

Which substances are commonly transported via facilitated diffusion?

A

Glucose and amino acids.

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88
Q

How does insulin affect facilitated diffusion?

A

Insulin can increase glucose facilitated diffusion by 10 to 20 fold by increasing the number of carrier proteins.

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89
Q

What is the relationship between net diffusion rate and concentration?

A

Net diffusion rate inward is proportional to the difference in concentration on the outside (Co) minus the concentration on the inside (Ci).
Formula: net diffusion ∝ (Co - Ci)

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90
Q

How do electrical gradients affect diffusion?

A

Electrical gradients across membranes can attract or repel charged ions.

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91
Q

What is the effect of pressure differences across membranes on diffusion?

A

Net diffusion occurs from high to low pressure, as more molecules strike the pore on the high-pressure side than on the low-pressure side.

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92
Q

What generally occurs with water movement across membranes?

A

A: Water crosses membranes in both directions, but the net diffusion is zero.

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93
Q

Under what conditions does net movement of water occur?

A

A concentration difference for water and/or other substances.

94
Q

What is osmosis?

A

The net movement of water across the cell membrane caused by a concentration difference of water.

95
Q

How do selectively permeable membranes function in osmosis?

A

Water passes through more readily than solutes.

96
Q

What is osmotic pressure?

A

The amount of pressure required to stop osmosis.

97
Q

What determines osmotic pressure?

A

The concentration of the solution in terms of the number of particles.

98
Q

How is osmotic pressure related to concentration?

A

1 milliosmole per liter concentration = 19.3 mm Hg osmotic pressure.
300 milliosmoles = 5790 mm Hg (actual value is 5500 mm Hg due to particle interactions).

99
Q

What is osmolarity?

A

Osmolar concentration, measured in osmoles per liter of solution.

100
Q

Why is osmolarity used instead of osmolality in body solutions?

A

It’s easier to measure liters of water than osmoles per kg of water (osmolality) for determining osmotic pressure.

101
Q

What is the difference between osmolarity and osmolality in dilute solutions?

A

The difference is less than 1%.

102
Q

What is isotonic?

A

A solution with the same concentration of impermeant solutes, resulting in no change in cell size.

103
Q

What is hypotonic?

A

A solution with a lower concentration of impermeant solutes, causing the cell to swell.

104
Q

What is hypertonic?

A

A solution with a higher concentration of impermeant solutes, causing the cell to shrink.

105
Q

What is active transport?

A

Movement of molecules against a concentration, electrical, or pressure gradient, requiring energy.

106
Q

What substances are commonly actively transported?

A

Sodium ions
Potassium ions
Calcium ions
Iron ions
Hydrogen ions
Chloride ions
Iodide ions
Urate ions
Several sugars
Amino acids

107
Q

What is primary active transport?

A

Active transport where energy is derived from the breakdown of ATP or another high-energy phosphate compound.

108
Q

What is secondary active transport?

A

Active transport that uses energy in the form of ionic concentration differences, originally created by primary active transport.

109
Q

What do both primary and secondary active transport rely on?

A

Carrier proteins that penetrate the membrane and can impart energy to the transported substance.

110
Q

What is the sodium-potassium pump?

A

A primary active transport mechanism that pumps sodium out of cells and potassium into cells.

111
Q

What is the function of the sodium-potassium pump?

A

It maintains sodium and potassium concentration differences across the cell membrane and establishes a negative electrical voltage inside the cell, essential for nerve function.

112
Q

What percentage of energy do some nerve cells devote to the sodium-potassium pump?

A

60 to 70 percent of the cell’s energy requirement.

113
Q

How can the sodium-potassium pump run in reverse?

A

If the electrochemical gradients for Na⁺ and K⁺ are increased enough, the pump can synthesize ATP from ADP and phosphate.

114
Q

What determines the direction of the sodium-potassium pump reaction?

A

The relative concentrations of ATP, ADP, phosphate, and the electrochemical gradients for Na⁺ and K⁺.

115
Q

How does the sodium-potassium pump maintain cell volume?

A

By pumping three sodium ions out for every two potassium ions in, preventing cell swelling due to osmotic water influx.

116
Q

What makes the sodium-potassium pump electrogenic?

A

It creates an electrical potential across the membrane (negative inside, positive outside), essential for transmitting nerve and muscle signals.

117
Q

What is the average energy usage of the sodium-potassium pump in cells?

A

It accounts for approximately 24% of the energy utilized by cells.

118
Q

What is the function of the calcium pump?

A

It pumps calcium out of cells, maintaining a much lower intracellular concentration than extracellular fluid.

119
Q

Where else can calcium be pumped in muscle cells?

A

Calcium can be pumped into the mitochondria and the sarcoplasmic reticulum.

120
Q

What is the role of the hydrogen pump and where is it found

A

It is found in the stomach’s gastric glands and parietal cells, involved in transporting hydrogen ions.

121
Q

Where is the hydrogen pump located?

A

In the late distal tubules and cortical collecting ducts of the kidneys.

122
Q

What is secondary active transport? - Cotransport

A

Transport mechanism where diffusion energy of one substance pulls another substance with it.

123
Q

What are examples of co-transport in secondary active transport?

A
  1. Sodium-glucose co-transport
  2. Sodium-amino acid co-transport
  3. Co-transport of chloride ions, iodine ions, iron ions, and urate ions
124
Q

How does co-transport work?

A

One substance’s diffusion energy pulls another substance along with it, utilizing the sodium-binding site for transport.

125
Q

What is counter-transport?

A

A transport mechanism that moves a substance in the opposite direction to the primary ion.

126
Q

Describe the mechanism of sodium-calcium counter-transport.

A

Sodium binds outside the carrier protein, while calcium binds inside; sodium’s movement into the cell causes conformational change, allowing calcium to exit

127
Q

Where is counter-transport commonly found?

A

In several cells, especially renal tubules, where primary transport moves more substances.

128
Q

Summary of secondary active transport

A
129
Q

What is the main purpose of endocytosis?

A

To allow large particles to enter cells to obtain nutrients and other substances from surrounding fluids.

130
Q

What is pinocytosis?

A

The ingestion of minute particles that form vesicles of extracellular fluid (ECF) and particulate constituents inside the cell cytoplasm.

131
Q

How do macromolecules enter cells during pinocytosis?

A

They attach to specialized protein receptors on the membrane surface, concentrated in coated pits.

132
Q

What proteins are involved in the process of pinocytosis?

A

Clathrin, actin, and myosin.

133
Q

What happens to the invaginated part of the membrane during pinocytosis?

A

It breaks away to form a vesicle containing the macromolecules and a small amount of ECF

134
Q

What are the energy requirements for pinocytosis?

A

It requires energy in the form of ATP and calcium ions in the extracellular fluid (ECF).

135
Q

Where does pinocytosis occur most rapidly?

A

In macrophages

136
Q

What is phagocytosis?

A

The ingestion of large particles, such as bacteria, whole cells, or portions of degenerating tissue.

137
Q

Which cells primarily perform phagocytosis?

A

Macrophages

138
Q

Describe the steps involved in phagocytosis.

A
  1. Cell membrane receptors attach to surface ligands of the particle.
  2. Membrane edges evaginate outward to surround the particle (forming pseudopodia).
  3. Actin and other contractile fibrils in the cytoplasm surround the phagocytic vesicle and contract, pushing it inward.
  4. The vesicle separates from the cell membrane.
139
Q
A
140
Q

What do lysosomes do in the digestion of pinocytic and phagocytic contents?

A

They attach to vesicles and release acid hydrolases inside to digest contents.

141
Q

What is opsonization

A

intermediation of antibodies

142
Q

What happens to digestive end products in the cytoplasm?

A

Amino acids, glucose, and phosphates diffuse into the cytoplasm.

143
Q

What is a residual body?

A

It is an indigestible remnant removed from the cell by exocytosis.

144
Q

What occurs during exocytosis?

A

Secretory vesicles diffuse to and fuse with the cell membrane to release substances outside.

145
Q

What stimulates exocytosis

A

The entry of calcium ions into the cell.

146
Q

What is the basic mechanism of active transport via cellular sheets?

A

Simple or facilitated diffusion on one side and active transport on the other side.

147
Q

Where is active transport in sheets observed?

A

Intestinal epithelium, renal tubules, exocrine glands, gallbladder, and choroid plexus.

148
Q

What drives water movement in active transport?

A

Water follows sodium ions via osmosis

149
Q

How does total body water (TBW) change with age?

A

TBW decreases with age: 75% in neonates, 57% in adults.

150
Q

How does body fat affect total body water?

A

TBW decreases with increased adiposity since fat is only 10% water.

151
Q

What is the indicator dilution principle/technique?

A

A method to measure fluid volumes by administering a known amount of a marker substance and measuring its volume of distribution.

152
Q

How is the volume of a compartment calculated using the indicator dilution principle?

A

Volume = (dose of marker) / (concentration of marker)

153
Q

What characteristics must the indicator have for accurate measurement?

A
  1. It must disperse evenly in the compartment
  2. not cross into other compartments
  3. not be metabolized or excreted
  4. not be toxic.
154
Q

If you are measuring TBW, the marker must

A

Diffuse into ECF and ICF

155
Q

If you are measuring ECF, the marker must

A

NOT diffuse across cell membrane

156
Q

How is intracellular fluid (ICF) calculated?

A

ICF = TBW - ECF
- not determined by dilution technique

157
Q

How is plasma volume (PV) calculated?

A

Using a dye that immediately combines with plasma proteins
-5%

158
Q

How is interstitial fluid volume calculated?

A

Interstitial fluid volume = ECF - PV.

159
Q

How does blood volume determination stay in the intravascular system?

A
  1. by binding to plasma proteins (such as vital dye or radioactive iodine)
  2. by combining with red blood cells (like 32P, 59Fe, or 51Cr).
160
Q

How is packed cell volume (PCV) or hematocrit determined?

A

By calculating the proportion of red blood cells in the blood.

161
Q

How is blood volume calculated if plasma volume (PV) is known?

A

Blood volume (mL/kg) = PV (mL/kg) × 1.0 / (1.0 - PCV (L/L)).

162
Q

How is blood volume calculated if erythrocyte volume is known?

A

Blood volume (mL/kg) = Erythrocyte volume (mL/kg) × 1.0 / PCV (L/L).

163
Q

What are typical blood volumes for pigs, ruminants, small animals, horses?

A

Pigs: 50 mL/kg
Ruminants: 60 mL/kg
Small animals: 70-80 mL/kg
Horses: 100 mL/kg

164
Q

How are major components of body fluids expressed?

A

In mmol/L or μmoL/L.

165
Q

What is the total osmotic pressure in intracellular fluid (ICF) and interstitial fluid (ISF)?

A

~300 mOsm/L (280 mOsm/L after correction for intermolecular attraction).

166
Q

What is colloid osmotic pressure (COP)?

A

PV and 1.5 mOsm/L; it contributes to total osmotic pressure but plays a key role in reducing osmosis
- A type of osmotic pressure created by plasma proteins, particularly albumin, that pulls fluid back into capillaries.

167
Q

What happens at osmotic equilibrium in body fluids?

A

Osmolality of ICFs equals ECFs.

168
Q

What occurs when a cell is in a hyposmolal solution?

A

Water diffuses into the cell, dilating it; can lead to hemolysis in red blood cells.

169
Q

What occurs when a cell is in a hyperosmolal solution?

A

A: Water is displaced from the cell, causing it to shrink (crenation) and increasing the concentration of ICF.

170
Q

What is dehydration?

A

A serious issue in digestive, respiratory, and urinary disorders, often due to anorexia, excessive evaporation, or diuresis

171
Q

How does dehydration affect extracellular fluid (ECF)?

A

It decreases ECF water, increasing ECF osmolality, which pulls water out of intracellular fluid (ICF) to balance osmolalities.

172
Q

How is the degree of dehydration assessed?

A
  1. By examining skin fold elasticity
  2. depth of sunken eyes
  3. the moisture and temperature of the oral cavity.
173
Q

What are the signs of slight dehydration (5%)?

A

Skin fold returns to normal in 5 seconds.

174
Q

What are the signs of moderate dehydration (7-8%)?

A

Skin fold persists for 5-10 seconds, sunken eyes, and sticky oral mucosa.

175
Q

What are the signs of severe dehydration (10%)?

A

Skin fold lasts more than 10 seconds, very sunken and softened eyes, dry and cold oral mucosa.

176
Q

What causes hypo-osmotic dehydration?

A

Decreased ECF volume and increased ICF volume, often due to excessive sweating, NaCl deficiency, vomiting, or diarrhea.

177
Q

What happens during excessive diarrhea?

A

Gut secretion exceeds gut absorption, leading to excessive loss of anions, cations, and water in feces.

178
Q

What components are involved in extracellular fluid dynamics?

A

Microcirculation, including arterioles, metarterioles, capillaries, muscular venules, and arteriovenular shunts.

179
Q

How many capillaries are in the human body

A

About 10 billion capillaries, with a total surface area of 500-700 square meters.

180
Q

What is the average density of capillaries in tissue?

A

300-1200 capillaries per mm³, with more in metabolically active tissues.

181
Q

What processes occur at capillaries for particle exchange?

A

Diffusion, filtration, and ultrafiltration (in the kidneys).

182
Q

What are the structures that facilitate exchange in capillaries?

A

Pores in capillary membranes, intracellular clefts, or slit pores, typically with a width of 6-7 nanometers.

183
Q

What characterizes continuous capillaries?

A

They are the most common type, with tight gaps between endothelial cells allowing gases, water, and glucose to pass. The blood-brain barrier capillaries have no gaps.

184
Q

What characterizes fenestrated capillaries?y

A

They are leakier with small pores in kidneys and small intestines

185
Q

What are the special characteristics of capillaries pores in the liver?

A

They have wide openings, allowing almost all dissolved substances, including proteins, to pass through.

186
Q

What are the characteristics of capillaries pores in the brain?

A

They have tight junctions that permit only extremely small molecules (like water, oxygen, and carbon dioxide) to pass.

187
Q

What are the characteristics of capillaries pores in the kidneys (glomerular tufts)?

A

They have fenestrae that penetrate through the middle of endothelial cells, allowing a large amount of small particles to pass.

188
Q

What is the function of the glomerular capillary tuft?

A

It filters plasma water and solute to form urine.

189
Q

What is vasomotion?

A

Blood does not flow continuously through capillaries; it has intermittent flow, turning on and off every few seconds or minutes.

190
Q

What causes the intermittent flow of blood in capillaries?

A

It is caused by the intermittent contraction of metarterioles and precapillary sphincters.

191
Q

What are the two mechanisms of blood flow control?

A

Acute control and long-term control.

192
Q

What characterizes acute control of blood flow?

A

Rapid changes in local vasoconstriction and vasodilation, governed by two theories.

193
Q

What is the “oxygen lack theory”?

A

Lack of oxygen (hypoxia) causes the release of nitric oxide (NO), leading to smooth muscle relaxation, sphincter relaxation, and increased blood flow to oxygen-deficient areas.

194
Q

What happens when there is high oxygen availability according to the oxygen lack theory?

A

Precapillary and metarteriole sphincters contract until cells use up the excess oxygen.

195
Q

What is the vasodilator theory?

A

Increased metabolism or reduced oxygen availability leads to the formation and release of vasodilator substances (e.g., adenosine, carbon dioxide, histamine), promoting vasodilation.

196
Q

How do specific tissues control blood flow during acute control?

A
  1. kidneys - macula densa cells - monitor sodium concentration
  2. brain - increased carbon dioxide and hydrogen ions - increased blood flow.
197
Q

What characterizes long-term control of blood flow?

A

Changes in the physical sizes and numbers of blood vessels supplying tissues, determined by maximum blood flow needs.

198
Q

What is collateral circulation?

A

The development of alternate or backup routes for blood flow, which can involve arteries, capillaries, or veins

199
Q

What does the term “humoral” refer to?

A
  • meaning bodily fluids such as blood,
  • hormone release in response to changes in extracellular fluids.
200
Q

What is humoral control?

A

The regulation of hormone release based on changes in blood or ion concentrations in extracellular fluids.

201
Q

What is the role of norepinephrine (NE)?

A

NE is a powerful vasoconstrictor.

202
Q

How does epinephrine (E) affect blood vessels?

A

E is a less powerful vasoconstrictor and can cause vasodilation in some tissues.

203
Q

What is the function of angiotensin II?

A

It is a powerful vasoconstrictor that causes many arterioles to constrict simultaneously, increasing arterial pressure.

204
Q

What is the role of antidiuretic hormone (vasopressin)?

A

It is one of the body’s most potent vasoconstrictors, although its levels are usually too low to have a significant effect.

205
Q

What does bradykinin do?

A

It causes powerful arteriolar dilation and increases capillary permeability, playing a special role in inflamed tissue.

206
Q

What effect does histamine have on blood vessels?

A

Histamine is a powerful vasodilator that increases capillary porosity, contributing to edema in allergic reactions.

207
Q

How does exchange occur between blood plasma and interstitial fluid?

A

Small ions and metabolites pass through small pores, while large molecules (>20,000 daltons) face restricted transport.

208
Q

What is the role of the endothelium in capillary exchange?

A

The endothelium is permeable to small particles but impermeable to large proteins, exerting a colloid osmotic pressure (COP) of about 25 mm Hg.

209
Q

What is the impact of proteins on fluid movement?

A

Proteins tend to move fluid from the extravascular space to the intravascular space due to their osmotic force.

210
Q

How are substances like oxygen and glucose exchanged in capillaries?

A

They move across the capillary wall via diffusion or filtration.

211
Q

How do colloids affect fluid movement?

A

Colloids displace water molecules, creating a deficit that pulls water back into the circulatory system, especially at the venous end of capillaries.

212
Q

What opposing pressure does COP counteract?

A

hydrostatic blood pressure
pushes water and small molecules out of blood into interstitial spaces.

213
Q

What determines the division of extracellular water?

A

The interaction of hydrostatic pressure and colloidal osmotic pressures in blood plasma and interstitial fluid.

214
Q

What are the four pressures involved in water and solute transfer?

A
  1. Pc: Hydrostatic pressure of blood in capillaries
  2. Pint/if: Hydrostatic pressure of interstitial fluid
  3. COPP: COP of plasma proteins
  4. COPint/if: COP of interstitial fluid
215
Q

When does filtration occur?

A

Filtration occurs when hydrostatic pressure (Pc) is greater than colloid osmotic pressure (COPP).

216
Q

When does reabsorption occur?

A

Reabsorption occurs when COPP is greater than hydrostatic pressure (Pc) at the venular end via osmosis.

217
Q

What role do metarterioles play in capillary blood flow?

A

Vasomotion at metarterioles controls the volume of blood in capillaries, determining whether absorption or filtration occurs.

218
Q

What happens when capillaries are open vs closed?

A
  1. Filtration occurs when capillaries are open.
  2. Reabsorption occurs when capillaries are closed.
219
Q

How much of filtered fluid returns to the blood via the lymphatic system?

A

0.4 to 0.8 mL/L of filtered fluid is not reabsorbed and returns to the blood through the lymphatic system.

220
Q

What percentage of plasma proteins leak into interstitial fluid and are reabsorbed via lymphatics?

A

About 30% of plasma proteins leak into the interstitial fluid of the intestines and liver and are reabsorbed through lymphatics.

221
Q

How do large molecules, such as proteins, enter lymphatic vessels?

A

Large molecules enter easily through overlapping edges of endothelial cells that flap inward, forming openings.

222
Q

What is lymph?

A

Lymph is the clear fluid that flows through the lymphatic system, consisting of leukocytes, a few red blood cells, and varying protein content depending on the tissue drained.

223
Q

What is the protein content of lymph in different tissues?

A

Most tissues have about 2 g/dL; the liver can have up to 6 g/dL, and the intestines 3 to 4 g/dL.

224
Q

What is postprandial

A
  • After a meal
  • Route absorption of nutrients especially fats
  • Thoracic duct lymph as much as 1-2% fat
225
Q

What are chylomicrons?

A

Chylomicrons are lipoproteins that carry dietary lipids from the intestines to other tissues and the liver.

226
Q

How is lymph flow generated?

A

Lymph flow is caused by one-way valves, rhythmic myogenic activity of lymph vessels, tissue pressure, arterial pulsation, and pressure changes associated with skeletal muscle contraction and respiration.

227
Q

What happens when a lymphatic vessel becomes stretched?

A

The smooth muscle of the vessel automatically contracts when stretched by fluid.

228
Q

What factors can increase lymph flow?

A

1skeletal muscle contraction, arterial pulsations, external compression of tissues, and exercise, which can increase flow by 10 to 30 fold.

229
Q

What is edema?

A

Edema is an abnormal increase in interstitial fluid volume.

230
Q

What factors can contribute to edema?

A

Contributing factors include high blood pressure, venous obstruction, cardiac insufficiency, excessive vasodilation, decreased colloid osmotic pressure (COPP), dietary deficiencies, liver disease, severe burns, and kidney failure.

231
Q

What can increase capillary permeability and contribute to edema?

A

Increased capillary permeability to proteins and lymphatic blockage can contribute to edema.

232
Q

What are discontinuous capillaries

A

Largest and leakiest in liver, spleen, bone marrow

Anatomy and Physiology 1 (17 decks)

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