Lecture 1 & 2 - Homeostasis & Cells Flashcards
At what temperature would patients with sever hypothermia (<32) start to wake up?
And how are they treated?
- 32 C
- Full functioning not restored until: 35.5 C
- Treated with external warming and introduction to warm oxygen + internal fluids
What is the endpoint clinical complication of hypothermia?
- Cardiac arrest. Low body temp can cause the heart to stop beating.
- Coma is complication of hyperthermia.
What is normal pH of venous and arterial blood?
- Venous: pH 7.35, Arterial: 7.45
70kg man lost 500ml of blood. What percentage of his normal circulating volume of blood has he lost?
- 70kg: 5L of blood
- 500/5000= 10%
Which histological technique is most likely to be used to identify the presence or absence of a tumor?
- H&E staining: Can identify type of cell well
- SEM, TEM & Confocal microscopy are too ex and produce too much detail for routine investigation
- Immunohistochemistry: used for prognosis (likely course) of disease one the tumour is indentified
State steps for preparing H&E slides
FECSM
- Fixation using formaldehyde
- Embedding using paraffin wax
- Cutting using microtome
- Staining
- Mounting
Which histological procedure uses ultrathin sections of embedded tissue that are cut with glass or diamond?
TEM
Which technique should be used to identify and localise a specific protein in the cell nucleus?
- Immunohistochemistry: antibody would be specific to the target protein
- SEM, TEM, Freeze Fracture X: Used for general detection for cellular ultrastructure
- Routine H&E: Non-specific + detects most cellular structures
State temperature range & symptoms for fever (1), heat stroke (2) and heat exhaustion (3).
- > 38.5C: pale sweaty skin, cramps in arms and legs
- 40- 46: Flushed dry skin, hot to touch, strong bounding pulse
- > 46: Unconsciousness, seizures, confused, dizzy, coma
State temperature range & symptoms for mild hypothermia (1), severe hypothermia (2) and no vital signs (3).
*Not dead until WARM & DEAD
- 32–35C: Shivering, fatigue, slurred speech, confusion
- <28: Shivering stops, muscles become rigid, very slow and weak pulse, drowsiness, reduction in response levels
- Same range?: Unconsciousness, dilated pupils, pulse undetectable
What is normal pH?
- pH 7.35- 7.45
What are the pH limits to human tissue survival?
- pH 6.8-7.8
- When pH = 7.3, [H+] = 50, so if pH =7.0, [H+] = 100
- pH change either doubles of halves [H+]
State some buffering systems in the body.
- Bicarbonate (erythrocytes as intermediary)
- Sodium phosphate
Drugs:
- AI(OH)3 mildly alkaline, insoluble: good acid neutraliser (control heartburn)
Body Fluid Compartments for 70kg male
- 70kg: 40% solids, 60% liquids Liquid: 1. 70 x 0.6 = 42 kg 2. 2/3 intracellular, 1/3 extra 3. Of the 1/3 extra: 0.75 is interstitial fluid, 0.25 is plasma
Who has the highest total body water?
- Infants have the highest percentage of TBW, followed by adult male then female
- The higher % of body fat the lower the TBW
*the older you get, the less TBW
What happens when there’s not enough H2O?
- Cells and tissues initially absorb water from interstitial space
- Then each other –> organs –> brain, liver, kidney, heart
Define osmolality
- Conc of solute particles per kg in sol.
- For glucose/urea, osmotic pressure is no. of mmol present= 1mOsmol
- For ions, NaCI= 2mOsmol
What causes oedema? Symptoms of oedema.
- Oedema is fluid retention. Swollen ankles.
- Hydrostatic pressure > Osmotic pressure
- More H20 driven out to I.S
What are the disadvantages and advantages of formalin fixation?
A: - Can be preserved for very long peroid
- Produce many slides
D: - Long prep. time
- Unable to see lipid-containing structures
What are the advantages and disadvantages of frozen section?
A:- Short prep time (20 mins)
- Preserve lipid-containing structures
D: - Not clear. Presence of ice crystals produce blurry images
What is the definition of homeostasis? What needs to be maintained in human body?
- Maintenance of a relatively constant internal enviro.
- Conc. of O2,CO2, pH, Temp, BG
- Use of (+)/(–) feedback loops
What occurs when body temp ⬆️ and when body temp ⬇️?
- Thermoreceptors in hypothalamus detect change,
When ⬆️,
- Vasodilation: Increase heat loss from capillaries near surface of skin
- Sweating: Reduce body temp
- Pilorelaxation: Hairs flatten
- Stretching out: Larger SA
When ⬇️,
- Vasconstriction: Less heat loss from skin surface
- Shivering: Rapid contraction of skeletal muscles
- Piloerection: Hairs contract, trap layer of air
- Curling up: Reduce SA
Why is Al(OH)3 a good antacid?
- Midly alkaline
- Insol. = good acid neutraliser, increase pH
- Can control heartburn
What happens when there is X enough water?
- Cells and tissues initially absorb water from interstitial space –> each other –> organs –> brain, liver, kidney, heart
What happens if there is too much water? How to prevent this in IVF of patient?
- Osmotic pressure ⬆️–> cells absorb water and swell –> enzymes & proteins X work –> cell burst
- To prevent use isotonic solutions, 0.9% saline (NaCI)
Define tissue and state its 4 types
- Group of cells that have similar structure and function together as a unit.
- Epithelial, Muscle, Connective, Nervous
What are the advantages of using SEM and TEM?
- SEM: Visualise surface of cell
- TEM: Examine intracellular structure and organelles
What are some common biopsy techniques?
- Curettage (endometrium tissue)
- Venepuncture
Stain diff. type of stains and what they stain
- Haematoxylin: acidic stuff, DNA & RNA [blue]
- Eosin: alkaline, protein [red]
- Masson’s trichome: Red (keratine, muscle fibres), Blue/green (collagen, bone), Pink (cytoplasm)
- Periodic Acid-Schiff stain: sugar
Desc. immunohistochemistry. What is antigen retrival?
- Enzyme activated secondary antibody complexes = indirect immunohistochemistry
(peroxidase- brown, acid phosphatase- colourless) - Antigen retrieval: partial digestion of ‘fixed’ proteins by heating tissue w weak acids (done bcs some targeted antigens structure change after fixation)
What is dark field? What is it use on and how?
- Used w living cells
- Illuminate sample w light –> dark appearance w bright objects on it
- Used w electron microscopy
What are some treatments that utilise hypothermia or hyperthermia?
- Hypo: Used on patients after cardiac arrest/stroke –> divert blood to vital organs
- Hyper: Damage/Kill cancer cells w little/X harm to other cells (increase temp. of tumour, ⬆️blood flow & oxygenation = more sensitive to radiation)
Why is an undescended testis a problem?
- Core body temp too high for sperm production–> infertility
- Cancer risk –> testicular (seminoma)
[temp ⬆️, cells replicate faster] - Testicular torsion: testis twists around each other –> cut off blood supply –> necrosis
To treat fever a patient is given paracetamol, is that a good idea?
- Paracetamol reduces fever by affecting chem. messenger in hypo. that regulate temp
- Good: Reduces fever & help pain relief
- Bad: Immune system work harder, infection longer
Define pyrexia. Why does it occur?
- Body temp ≥38.5C
- Increase immune system efficacy by increasing temp to denature enzymes in bac.
- Upon infection, IL6/IL1 increases temp. setpoint
What is rigor? When does it occur and why?
- Sudden feeling of chill/shivering due to ⬆️temp
- Common in fever, psychological response to increase setpoint
What is a febrile seizure and how does it differ to rigor?
- Fits when child has a fever, unknown cause
- Febrile convulsions caused by rapid changes in temp (not fever), rarely harmful
Symptoms of adult, baby and elderly being dehydrated are…
- Adult: dry mouth, dizzy, drowsy
- Baby: Dry lips, sunken eyes, dry skin
- Elderly: Dry lips, dry skin, drowsy
What happens when you drink too much water. Symptoms?
- If drink too quickly, cells take up too quickly and swell–> oedema
- Brain cells swell –> convulsions –> coma/death
- Symptoms: seizure, confusion, nausea, headaches
