HUBS 191 FINAL EXAM ACTUAL QUESTIONS AND CORRECT ANSWERS WITH COMPLETE SOLUTION. 2024/2025
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HUBS 191
HUBS 191 FINAL EXAM ACTUAL QUESTIONS AND CORRECT ANSWERS WITH COMPLETE SOLUTION. 2024/2025
Name the four basic types of tissue
Connective tissue, epithelial tissue, muscle tissue and nervous tissue.
Why do the four types of tissues have different structures and function?
They are made up of d...
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HUBS 191 FINAL EXAM ACTUAL QUESTIONS AND
CORRECT ANSWERS WITH COMPLETE SOLUTION.
2024/2025
Name the four basic types of tissue
Connective tissue, epithelial tissue, muscle tissue and nervous tissue.
Why do the four types of tissues have different structures and function?
They are made up of different kinds of cells. They have different things that make up the
extracellular matrix. They have varying amounts of extracellular matrix.
Types of connective tissue
Connective tissue proper
- Loose connective tissue which keeps organs and epithelia in place.
- Dense connective tissue forms ligaments and tendons.
- Adipose tissue (fat) and reticular connective tissue (support lymph organs like the
lymph nodes)
Specialised connective tissue
- Blood, bone and cartilage
Main role of connective tissue
- Transport substances
- Provide support and structure
Features of epithelial tissue
- Tightly packed cells
- Little extracellular matrix
- Forms skin and lines internal cavities
- Many glands are made of epithelial tissue
Features of muscle tissue
- Cells are stretched or fibre-like
- Main role is contraction
- Allows body and its organs to move
- Cardiac muscle, skeletal muscle, smooth muscle.
Nervous Tissue
- Made up of neurons (conduct messages) and glia (support and protect nervous
system)
- Main role is to transmit electrical signals allowing for communication and coordination.
Cells only survive if the following conditions are meet
- Enough nutrients
- Correct temprature
- Correct pH
- Can only tolerate smal amounts of toxic substance and waste.
This is why maintaining a constant internal environment (homeostasis) is so important,
along with exchange of nutrients and wast across the cell membrane.
Total body fluid numbers to memorise
,2/3 of total body fluid is intracellular fluid (ICF)
1/3 of total body fluid is extracellular fluid (ECF)
4/5 or 80% of extracellular fluid is interstitial fluid (between cells).
1/5 or 20% of extracellular fluid is plasma (50% of total blood volume).
What are transcellular fluids?
ECF also includes various 'transcellular fluids' contained within epithelial lined spaces
e.g. synovial fluid in joints, ocular fluid in the eye, cerebrospinal fluid
What does a unicellular organism depend on its immediate environment to
provide?
Nutrients
Solute concentration
Temperature
pH
Toxins (including own wastes)
Lack of Predators
This limits the environment a unicellular organism is able to survive.
What is 'milieu interieur'
Claude Bernard (1813 - 1878) recognised the importance of the body's internal
environment or extracellular fluid. The constancy of the internal environment is the
condition for a free and independent life.
How did Walter Bradford Cannon (1871-1945) define homeostasis?
The maintenance of relatively constant conditions in the internal environment (ECF) in
the face of external (or internal) change.
1. In our bodies there are mechanisms that act to maintain constancy.
2. Any tendency toward change automatically meets with factors that resist change.
3. There are co-operating mechanisms which act simultaneously or successively to
maintain homeostasis
4. Homeostasis does not occur by chance, but is the result of organised self-
government.
Normal concentration of sodium (Na+) in the ECF and why it needs to be
controlled.
Normal concentration in ECF is about 135 - 145 mmol/L.
Main extracellular cation. Largely determines extracellular fluid volume so also
influences blood pressure (BP). Important in action potential generation in nerve and
muscle tissue.
Normal concentration of calcium (Ca+) in the ECF and why it needs to be
controlled.
Normal total plasma conc. is about 2.2 - 2.6 mmol/L.
Important structural component of bone and teeth. Involved in neurotransmission and
muscle contraction. Essential for blood clotting. Regulates enzyme function.
,Normal concentration of potassium (K+) in the ECF and why it needs to be
controlled.
Normal concentration in ECF is about 3.5 - 5 mmol/L.
Most abundant intracellular cation. Main determinant of the resting membrane potential
(RMP). Particularly important in excitable tissue i.e. nerve and muscle.
Normal concentration of glucose in the ECF and why it needs to be controlled.
Normal fasHng glucose concentration ≈ 3.5 - 6 mmol/L. Non fasting (random) ≈ 3.5 - 8
mmol/L
Used by cells (especially neurons) to produce adenosine triphosphate (ATP). Neurons
particularly affected by low glucose levels. High blood glucose causes other problems
both acute and chronic.
Normal pH range and conditions that result in pH being outside of the normal
range.
Normal pH range is 7.35 - 7.45.
Acidosis is when pH is too low (acidic), decreased neuronal function and decreased
level of consciousness.
Alkalosis is when pH is too high (basic), over excitability of nerve and muscle tissue.
Goes from 'pins and needles' → muscle spasms → convulsions.
Typical core body temperature
'Core' Body Temperature is generally maintained between 36 to 37.5 C which allows for
optimal
metabolic and physiological functioning. Oral and axillary temperatures are usually
about 0.5 C less
than rectal (core). 'Peripheral temperature' is more variable.
Core Body Temperature - Why is it so important?
At higher temperatures proteins start to denature. At lower temperatures, chemical
reactions slow down, preventing normal cell function. As cells of the nervous system
become compromised, the ability to thermoregulate is lost. Rapid worsening of the initial
condition and accelerated movement of temperature away from normal leading toward
death. This is an example of a viscous cycle and a detrimental positive feedback loop.
Diffusion
Diffusion results from the random movement of individual molecules as a consequence
of their thermal energy. Distance travelled is proportional to the square root of time - It
takes four times as long to diffuse twice as far OR, quarter of the time to diffuse half the
distance. Diffusion is therefore very rapid over the short distances within cells and
between cells and capillaries.
What substances are able to diffuse directly through the lipid bilayer of our cells
from regions of high to low concentration (down their concentration gradient)?
Oxygen
Carbon dioxide
Steroid hormones
Anaesthetic agents
, Such diffusion is passive because the net direction of movement is 'downhill' and so
requires no energy input from the body.
Many other substances (because of their size or physiochemical properties) are
not able to 'dissolve' in the lipid bilayer. How do they cross?
Water diffuses through protein channels known as aquaporins. There are specific
channels for many ions e.g. K+, Na+ and Ca++
Types of membrane channels used in simple diffusion
Channels are usually specific and may be open/close spontaneously (leak channels) or
in response to various stimuli e.g. chemicals (ligand gated), change in membrane
potential (voltage gated).
Carrier Mediated Passive Transport is also known as facilitated diffusion, what is
this process?
Substance binds to carrier on one side of the membrane which induces the carrier to
change shape and release of substance to the other side. ("Downhill" i.e. down conc.
gradient).
For example, glucose entry into cells when insulin is present.
Passive vs Active transport
Passive transport moves molecules down their concentration gradient and requires no
energy whereas active transport moves molecules against their concentration gradient
and requirers energy.
Primary Active Transport description, example and function.
Energy from the hydrolysis of ATP used to
move substances against their concentration gradient.
e.g. The sodium-potassium pump which moves 3 Na+ out of the cell in exchange for 2
K+.
- maintains ionic gradients
- helps regulate cell volume
Exocytosis and Endocytosis
Substances transported out of (or into) the
cell in membranous (bilayer) vesicles.
Physiological examples:
- Secretion of insulin by β cells of pancreas (exocytosis)
- Phagocytosis of microbes by neutrophils (endocytosis)
What is osmosis?
Osmosis is the net movement of water across a membrane down its own concentration
gradient (or toward the region of higher solute concentration).
Differences in solute concentration across cell membranes can cause fluid shifts and
create pressure that can damage cells.
What is osmolarity and normal osmolarity in ECF and ICF.
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