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Body Logistics ILO's > Session 1 ILOs - Homeostasis & Examining tissues > Flashcards

Session 1 ILOs - Homeostasis & Examining tissues Flashcards

1
Q

Define the term ‘homeostasis’ with respect to water, temperature and pH balance (Break down the term ‘homeostasis)

A

Homeostatis is ‘homeo’ meaning sameness and ‘stasis’ meaning standing still - this applies to water, temperature and pH balance

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2
Q

Give a thorough definition of homeostasis

A
  • The ability or tendency of a living organism, cell, or tissue to keep the conditions inside it the same despite any changes in the conditions around it

OR:

  • Maintaining a state of internal balance/dynamic equilibrium
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3
Q

Explain concepts behind positive and negative feedback loops:

What do positive and negative feedback loops do?

A
  • Positive and negative feedback loops act to maintain homeostasis
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4
Q

Explain concepts behind positive and negative feedback loops:

What do positive and negative feedback loops consist of? (4)

A
  • Feedback loops consist of:
  • A stimulus
  • A sensor
  • A control centre
  • An effector
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5
Q

Explain concepts behind positive and negative feedback loops:

What classifies positive feedback?

A
  • Strengthens or reinforces a change in one if the body’s controlled conditions
  • The output enhances or exaggerates the original stimulus
  • Stops when the initiator/stimulus ceases
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6
Q

Explain concepts behind positive and negative feedback loops:

What classifies negative feedback? (2)

A
  • Reverses a change in a controlled condition
  • Stops when the effector ceases
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7
Q

In terms of temperature control, and negative feedback state the:

a) Stimulus
b) Sensor
c) Control Centre
d) Effector

A
  • A stimulus (e.g. high or low temp)
  • A sensor (e.g. skin, hypothalamus)
  • A control centre (e.g. hypothalamus)
  • An effector ( e.g. muscles, blood vessels, hair on skin, fat, sweat glands)
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8
Q

Explain concepts behind positive and negative feedback loops:

Give 2 examples of positive feedback

A
  • Regulation of blood clotting
  • The Ferguson reflex during child birth
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9
Q

Explain concepts behind positive and negative feedback loops:

Give 3 examples of negative feedback

A
  • Temperature control
  • pH control
  • Blood glucose levels
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10
Q

Describe the Ferguson Reflex

A

1) The positive feedback stops when the original stimulus ceases.

The original stimulus is the baby pushing against the cervix.

When the original stimulus stops, that is when positive feedback ceases. The process stops when the baby stops pushing against the cervix as the baby is out of the mother

2) The output enhances or exaggerates the original stimulus/positive feedback enhances or exaggerates a change in one of the body’s controlled conditions

The output is release of oxytocin to cause the uterus to contract.

This causes the baby to push against the cervix, which is the original stimulus getting exaggerated

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11
Q

Recall the percentage of water and in a ‘standard’ 70kg male

A

60%

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12
Q

Recall the volume of blood in a ‘standard’ 70kg male

A

5 Litres:
- 3 Litres Plasma
- 2 Litres red cells

  • We know there are 3 litres of plasma and we know that the volume of red cells in blood is 40% total blood volume.

60% = 3 litres
1% = 0.05 litres
100% = 5 Litres

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13
Q

State the body compartments where fluids accumulate

A

• A standard 70kg male has 60% of his body weight being water = 42L or 42Kg of total body water

• Intracellular Fluid Volume is 2/3 of total body water = 2/3 x 42L = 28 Litres

• Extracellular Fluid Volume is 1/3 of total body water = 1/3 x 42L = 14 Litres

• Interstitial Fluid Volume (fluid found in the spaces around cells) is 75% of ECF volume = (75/100%) x 14L = 10.5 Litres

• Plasma volume is 25% of ECF volume = (25/100%) x 14L = 3.5 Litres (0.5L of water in the transmembrane space (space occupied by plasma membranes) and then the actual amount of water in plasma is 3.0 litres.

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14
Q

Compare and contrast water balance in males and females (and in very young and very old)

A
  • When it comes to adults, the higher the percentage of body fat, the lower the percentage of TBW

% water = greater in males compared to females ( this is because females have a higher proportion of body fat which displaces water)

AGE:
Infants/very young = around 70% of body mass is water
Elderly = 50% of body mass is water

WEIGHT:
Underweight = 10% higher, around 70% for 70kg male
Overweight = 10% Lower, around 50% for 70kg male (LEARN TABLE)

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15
Q

Outline the physiological differences between dehydration
and water toxicity

Describe dehydration

A
  • Dehydration is a lack of total body water,
  • with an accompanying disruption of metabolic processes.
  • It occurs when free water loss exceeds free water intake,
  • usually due to exercise, disease, or high environmental temperature.
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16
Q

Outline the physiological differences between dehydration
and water toxicity

Describe water intoxication

A
  • Water toxicity is a potentially fatal disturbance in brain functions
  • That results when the normal balance of electrolytes in the body is pushed outside safe limits
  • by excessive water intake
  • the increase in water volume dilutes the fluid surrounding the cell.
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17
Q

Outline the physiological differences between dehydration
and water toxicity

State some physiological features of dehydration

A
  • Increased thirst
  • Dry mouth
  • Dry skin
  • Light-headedness
  • Fatigue
  • Impaired mental focus
  • Low, dark urine output volume
  • Inability to produce tears
  • Sunken eyes

(9)

This can lead to:
- Weight loss
- Dizziness
- Confusion
- Fever
- Blood clots
- Tachycardia
- Muscle cramps

(7)

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18
Q

Outline the physiological differences between dehydration
and water toxicity

State some physiological features of water toxicity

A
  • Seizures
  • Brain damage
  • Coma
  • Death
  • Cerebral Oedema due to hyponatraemia (low blood sodium)
  • Nausea and vomiting
  • Headache
  • Dizziness

(8)

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19
Q

What is osmolality?

A

The concentration of a solution expressed as the total number of solute particles per kilogram.

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20
Q

Outline the effects of dehydration and water toxicity on osmolality

A

Dehydration increases osmolality so water leaves the cell down the osmotic gradient = cell shrinkage (osmolality becomes more negative)

Water toxicity leads to a decreased osmolality (less negative) and water moves into cell by osmosis = cell bursts

21
Q

What effect does osmolality have on blood volume and thus the person’s ability to move that blood around their body?

A

Increased osmolality in the blood will stimulate secretion of antidiuretic hormone (ADH). This will result in increased water reabsorption, more concentrated urine thereby minimizing further loss of blood volume and decreasing the osmolarity of the plasma back toward normal. - finish off

22
Q

State the ‘normal range’ for pH in tissues including blood

A

pH range: 7.35 - 7.45

23
Q

Explain the importance of acid-base balance for normal human physiology

A
  • If acid-base balance is not maintained i.e. too acidic (7-7.35) can cause (Metabolic or respiratory) acidosis and too alkaline (7.45-7.8) can cause (Metabolic or respiratory) alkalosis.
  • Outside the normal range, it can cause inflammation of organs
  • If the pH of blood falls below 6.8 or increases above pH 8.0 for a significant period of time, then death is likely.
24
Q

State the ‘normal range’ for core body temperature

A

Core body temp: 36.5 - 37.5 degrees

25
Q

Recall the mechanisms (in broad terms) that regulate pH and core body temperature

A

pH:
- Phosphate buffer system
- Carbonic acid-bicarbonate buffer system
- Protein buffer system (incl. amino acid buffers, haemoglobin buffer system and plasma protein buffers)

Core body temp:
1. Shivering/sweating
2. Vasconstriction/vasodilation
3. Piloerection/pilorelaxation
4. Curling up/stretching out

26
Q

Describe the process of oedema

A

Oedema (fluid retention) in the interstitial space of cells ( space outside the cell) occurs when hydrostatic pressure is greater than oncotic pressure which leads to water being forced out of the capillary and into the interstitial space

27
Q

What is oncotic pressure?

A

A form of osmotic pressure induced by the proteins, notably albumin, in a blood vessel’s plasma that causes a pull on fluid back into the capillary.

28
Q

What is hydrostatic pressure?

A

Hydrostatic pressure is the pressure exerted from the blood onto the blood vessel walls.

29
Q

State the meaning of the term ‘tissue’

A

Tissues are groups of cells that have a similar structure and act together to perform a specific function. Defined as cells woven together (latin word woven)

30
Q

What are the 4 types of tissue?

A
  1. Epithelial tissue
  2. Connective tissue
  3. Muscle tissue
  4. Nerve tissue
31
Q

Provide an example of each of the 4 types of tissue

A
  1. Epithelial tissue - keratinised squamous epithelial cells (of the skin)
  2. Connective tissue - tendon (of the calcanea Achilles tendon)
  3. Muscle tissue - cardiomyocyte of the heart
  4. Nerve tissue - oligodendrocyte of the CNS
32
Q

State the relationship between milli-, micro- and nano-metres

A

1 Millimeter = 1000 micrometres
1 Micrometre = 1000 nanometres

33
Q

Define the term, “limit of resolution”

A

Minimum distance that 2 objects can be apart that you are able to distinguish between the two

34
Q

Explain why electron microscopes are capable of finer resolution than light microscopes

A

Wavelength of an electron can is much shorter than that of visible light photons, so electron microscopes have a higher resolving power (much greater magnification) than light microscopes

35
Q

Describe common biopsy techniques (e.g. Curettage, needle, transvascular, etc.) giving examples of tissues which can be sampled by each method

A
  1. Endometrial biopsy/cutterage - effectively scratching off cells using a small scoop EXAMPLE endometrial tissue
  2. Pipelle - removes a small section of tissue EXAMPLE endometrial tissue
  3. Hysterectomy - removal of most or all of the organ EXAMPLE entire uterus
  4. Venepuncture - process of obtaining intravenous access for the purpose of venous blood sampling
  5. Aspiration (mainly bone marrow) - Jamshidi needle is inserted into the bone marrow to obtain a biopsy

(check notability notes for diagrams and further explanations)

36
Q

Explain why tissue needs to be fixed and state which fixatives are commonly used

A
  • Once removed from the body, tissues and cells are no longer protected by the body’d immune system so can be digested by microbes or destroyed by decay, so fixation prevents this (preserves tissue as close ti their natural state as possible.
  • It also removes water from the tissue, thus stiffening the biopsy

Formalin solution (10% buffered neutral) most commonly used

37
Q

Describe how tissue processing can lead to the formation of shrinkage and other artefacts

A

After fixation, tissues need to be dehydrated by alcohol and this can cause shrinkage. Artefacts can form at any point in tissue processing (ie due to dehydration)

38
Q

Discuss the value of histological staining and state the components of tissue stained by routine stains, such as Haematoxylin and Eosin (H&E) and specialist methods, such as immunohistochemistry and immunofluorescence

A

Staining is used to highlight important features of the tissue as well as to enhance the tissue contrast

Haemotoxylin = stains/binds to acidic structures e.g. nucelus

Eosin (an acidic dye) = stains/binds to basic structures e.g. intracellular and extracellular proteins (cytoplasm, extracellular matrix, collagen and elastic fibres)

39
Q

Discuss the value of histological staining state the components of tissue stained by specialist methods, such as
immunohistochemistry and immunofluorescence

A
  • Both utilise labelled antibodies to localise specific cell and tissue targets.

(READ WORKBOOK PAGE 19- 20 FOR UNDERSTANDING)

 These targets (antigens) usually are a 5 to 7 amino acid antibody sequence within a target protein or polypeptide chain (although antibodies to other macromolecules have also been produced).
 These targets (antigens) are complementary to the shape of the antibodies. Because of the exquisite specificity of the antibodies for their antigens, these are amongst the most sensitive and specific of histochemical techniques.
Antibodies directed labelled with fluorescent dyes allow the structure to be visualised directly (immunofluorescence) often with the incident light being from a
19
UV light source, as in confocal microscopy. The use of enzyme activated secondary antibody complexes that precipitate a coloured product at the site of interaction allows for an even more sensitive technique (indirect immunohistochemistry), where as little as 100 antigens can be detected per cell.
 The enzymes routinely used are the peroxidases (horse-radish peroxidase because it is absent from human tissue), which when combined with 3,3’- diaminobenzidine and peroxide produced a brown precipitate at the reaction site
 The acid phosphatases, which when combined with glycerophosphate and lead nitrate produces a colourless precipitate.
 If the tissue is then immersed in ammonium sulphide, a black precipitate of lead sulphide is produced at the site of enzyme activity.
These techniques can be used to identify organelles that contain acid phosphatase (e.g. lysosomes).

40
Q

Outline the advantages conferred by phase contrast, dark field, fluorescence, and confocal light microscopy

Phase contrast

A
  • Allows manipulation of the cells e.g. work out function of some drugs
  • Ability to combine it with other techniques
  • Living cells can be examined in their natural state without previously been killed, fixed and stained
  • Can generate image contrast from materials that don’t absorb light. This allows identification of cellular structures and sub-cellular components such h as nucleus and organelles with different densities
41
Q

Outline the advantages conferred by phase contrast, dark field, fluorescence, and confocal light microscopy

Dark field advantages

A
  • Allows you to view objects that are unstained, transparent and absorb little or no light
  • Dark background offers a degree of contrast, making it easy to see samples on difficult backgrounds
42
Q

Outline the advantages conferred by phase contrast, dark field, fluorescence, and confocal light microscopy

Fluorescence advantages

A
  • High sensitivity and specifity i.e. only binds to specific target protein
  • Live-cell ops is possible so they can be studied in situ without the need for toxic and time-consuming staining processes
  • Offers a magnified and clear image of the cellular molecules in specimen, compared with traditional optical microscope
43
Q

Outline the advantages conferred by phase contrast, dark field, fluorescence, and confocal light microscopy

Confocal light advantages

A
  • elimination or reduction of background information away from the focal plane
  • sharp images (as only one part of the light reaches detector)
  • the entire depth of the cell/tissue can be examined (motorisation allows full section scanning)
  • can be viewed in all 3 directions (z stack)
44
Q

State how a cell functions by describing the structure and function of the major cell components and organelles

A

Nucleus - contains genetic information/material

Mitochondria - generates most of the chemical energy (ATP)

Plasma membrane - selective membrane that separates the interior of the cell from the outside environment

Ribosomes - site of protein synthesis

Lysosomes - contains digestive enzymes which break down excess or worn-out cell parts and may be used to destroy invading viruses and bacteria

Golgi apparatus - responsible for packaging proteins into vesicles prior to secretion

Rough ER - takes polypeptides and amino acids from the cytosol and continues protein assembly

Smooth ER - role in detoxifying some organic chemicals converting them to safer water-soluble products

45
Q

The clinical table for temperatures that you must know

A
46
Q

What kind of solutions are patients given intravenously e.g?

A
  • Isotonic
  • IV drips need physiological saline concentrations (0.9%)
47
Q

Explain the value of histology in diagnosis

A

Enables us to explore cells and tissues in greater detail to find out if there are abnormalities

48
Q

From a simplified diagram of a cell, clearly label those ultrastructural components common to eukaryotic/animal cells

A

Body Logistics ILO's (10 decks)

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