W6 PASS

BOONEZ

W6 PASS

BOONEZ

W3 PASS

DIFFUSION + TONICITY

W6 PASS

BOONEZ

W3 PASS

DIFFUSION + TONICITY

W6 PASS

BOONEZ

TODAY’S SESSION

TODAY’S SESSION

KAHOOT

Multi choice quiz :)

SAQs

• Table Groups

CONGRATS MID SEM!

Mid sem antics

Mid sem antics

1 week off ➡️ 5 weeks of content

Two main options!

Reset fully!

Take whole days off + catch up and come back refreshed!

Small consistent efforts - BALANCED with time off daily

Mid sem antics

JAS’ tips

• whatever works for you
• The point is to ENJOY your time off above all else without causing future consequences

5 more weeks to get through after this break (decently intense)

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Try hit balance of the two

• Hardcore mornings + rest of day off
• Study cut off
• Big assessments (outputting)
• Do study you ACTUALLY feel like doing (DOPAMINE HIT>>)

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PLAN. PLAN. PLAN.

WIN OF THY WEEK

Formula collisions w week 3

WIN OF THY WEEK

GAIT

STANCE

SWING

60%

40%

WIN OF THY WEEK

BONE + cells

WIN OF THY WEEK

BONE + cells (2 minutes)

WIN OF THY WEEK

Topic collision!

WIN OF THY WEEK

BONE + cells

• More surface area = more space for osteoblasts, osteoclasts, and remodeling activity.�

WIN OF THY WEEK

MEMORY HACK

Osteoporosis is caused by an imbalance between bone resorption and bone formation, where osteoclast activity > osteoblast activity

WIN OF THY WEEK

MEMORY HACK

Osteoporosis is caused by an imbalance between bone resorption and bone formation, where osteoclast activity > osteoblast activity

KAHOOT time

Young’s modulus is a material property — it depends only on the material itself, not on the size or shape of the object. That’s what makes it useful for comparing how “stiff” different materials are.

The rhythmic alternative of the upper + lower extremities in order to create forward progression

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SAQ1 More aneurysms!

A section of a cerebral artery (E=1.2 × 10⁶ Pa) has developed a localized bulge — an aneurysm. This aneurysm can be approximated as a thin-walled cylindrical vessel with an initial length of 1.0 cm and cross-sectional area of 2.0 × 10⁻⁶ m². The maximum tensile force that the arterial tissue can withstand before rupture is 0.48 N.

Blood is flowing through the vessel at a velocity of 0.5 m/s, and the pressure inside the aneurysm is initially 13.3 kPa (100 mmHg). As the aneurysm begins to expand, the velocity of blood flow decreases due to the larger cross-sectional area at the site, and the pressure increases accordingly due to Bernoulli’s principle.

1. At what length of the aneurysm will the stress on the arterial wall exceed the material limit, causing it to rupture?

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• Explain how the slowing of blood inside the aneurysm could further promote rupture. What role does increasing pressure play once the wall is already stretched?

BONUS Q: As the aneurysm expands and blood slows at the bulge, use Bernoulli’s equation to calculate the new pressure if the blood velocity decreases to 0.2 m/s inside the aneurysm. Assume the blood density is 1060 kg/m³, and external pressure is constant.

“Length of vessel” longitudinal span of the swollen/ballooned area. It might be a few mm-cm long, and we could measure how much it expands along the artery over time under pressure.

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SAQ1 More aneurysms!

• At what length of the aneurysm will the stress on the arterial wall exceed the material limit, causing it to rupture?

SAQ1 More aneurysms!

• Explain how the slowing of blood inside the aneurysm could further promote rupture. What role does increasing pressure play once the wall is already stretched?

BONUS Q: As the aneurysm expands and blood slows at the bulge, use Bernoulli’s equation to calculate the new pressure if the blood velocity decreases to 0.2 m/s inside the aneurysm. Assume the blood density is 1060 kg/m³, and external pressure is constant. =13411.2 Pa // 13.4 kPa

if velocity decreases, then the pressure must increase (especially in a region of slower flow like an aneurysm. This added pressure:

• Increases wall stress, especially in the already weakened and thinned vessel wall,�
• Promotes further expansion of the aneurysm,�
• Which leads to greater strain and greater wall tension (via Laplace’s Law),�
• And increases the risk of rupture if the tensile limits of the arterial wall are exceeded.�

SAQ2 Easter bunny

The easter bunny is investigating whether a drug changes bone density in a randomised control trial. Assume the bone can withstand a max stress of 150,000 N/m² before fracturing.

1. If the cross-sectional area is 0.004 m², calculate the max force the bone can sustain.

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1. After 3 months of medication, the max stress the bone can handle decreases by 5%. How much force can the bone take? (1 mark)

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1. Based on your answer in part b, does Young’s Modulus increase or decrease? (1 mark)

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1. Analysis on 500 participants shows that this effect was not statistically significant (p = 0.10). Is this drug harmful to the participants? (1 mark)

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SAQ2 Easter bunny

The easter bunny is investigating whether a drug changes bone density in a randomised control trial. Assume the bone can withstand a max stress of 150,000 N/m² before fracturing.

• If the cross-sectional area is 0.004 m², calculate the max force the bone can sustain.

Stress = F / A

F = Stress x A = 150,000 N/m² x 0.004 m² = 600 N

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• After 3 months of medication, the max stress the bone can handle decreases by 5%. How much force can the bone take?

F = 0.95 * 150,000 N/m² x 0.004 m² = 570 N

F prop stress

600 N x 0.95 = 570 N

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• Based on your answer in part b, does Young’s Modulus increase or decrease? (1 mark)

Young’s modulus = stress / strain

Young’s modulus is proportional to stress, therefore decreased stress => decreased YM

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• Analysis on 500 participants shows that this effect was not statistically significant (p = 0.10). Is this drug harmful to the participants? (1 mark)

There is no evidence to say that this drug is harmful to the participants.

SAQ3 ACL

The anterior cruciate ligament (ACL) of the knee has a length of 40mm. Its cross-sectional area is 78mm^2.

1. Calculate the force required to elongate it by 0.1% to 1 dp. Assume Young’s Modulus for the ACL is = 1 x 10⁸ N/m^2 (3 marks)

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SAQ 2 ACL

The anterior cruciate ligament (ACL) of the knee has a length of 40mm. Its cross-sectional area is 78mm^2.

• Calculate the force required to elongate it by 0.1% to 1 dp. Assume Young’s Modulus for the ACL is = 1 x 10⁸ N/m^2 (3 marks)

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Young’s modulus = stress / strain

Strain = del_L / L_0 = 0.1% = (0.001 * 40mm) / 40mm = 0.001 (dimensionless)

Stress = Young’s modulus * strain = 1 x 10⁸ N/m^2 * 0.001 = 100,000 N/m^2

Force = Stress * area = 100,000 N/m^2 * (78 * 10^-3)² m² = 7.8N

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SAQ4 100 kg volleyball man

BOBBY is a 100kg man who plays volleyball!

He supports 40kg of his mass on his lower leg including 25kg on his tibia. Assuming his the bones in his lower leg are both 30cm and his fibula has a radius of 1cm, find the change in length of his fibula.

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Bobby isn’t completely focused on the game, instead concentrating on remembering the differences between cortical and trabecular bone. As he is thinking about this, the ball comes his way and he is taken in a crunching tackle that leaves him with a wrist fracture.

What are the differences between trabecular and cortical bone?

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What is the difference between stiffness and strength of a bone?

Young’s modulus (fibula)

=9 x 10^8 N/m^2

SAQ4 100 kg volleyball man

Young’s modulus (fibula)

=9 x 10^8 N/m^2

ENJOY YOUR

MID SEM BREAK

I WILL SEE YOU FOR WEEK 8 revision for muscles and work, friction, energy!!!

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