Biology SL

Chapters

553

Notes

Theme A - Unity & Diversity

Theme B - Form & Function

Theme C - Interaction & Interdependence

Theme D - Continuity & Change

Biology SL

Theme B - Form & Function

Explore Vein Adaptations Heartward Blood Journey!

418 words

3 mins read

Last edited on 14th Jun 2024

Role: Collect and transport blood from body organs back to the heart.
Fun fact!: Blood drains constantly from capillaries into veins, and there’s no pulse in the veins.

Elastic Fibers: Veins have fewer of these than arteries.
Smooth Muscle Cells: Also fewer in veins. Why? Because veins aren’t traffic cops! They don't adjust blood flow to different body parts.
Wall Thickness: Veins have thinner walls than arteries because blood in veins is chill, under low pressure. Think of arteries as the high-pressure water hoses, and veins as calm streams!

Problem: Low pressure could cause:
- Blood backflow (imagine water flowing backward in a stream).
- Not enough blood getting back to the heart. Not cool!❤️🔙
Solution: Pocket Valves!
- Structure: Three cup-shaped tissue flaps, looking like mini umbrellas in the vein.
- Function:
  - If blood goes rogue and flows backward? It's trapped in the pocket valve! Flaps fill up, close the valve, and block the vein.
  - When blood is a good citizen and flows towards the heart? It gently pushes the flaps aside, and voila, the valve opens! Blood flows with style.

Dive deeper and gain exclusive access to premium files of Biology SL. Subscribe now and get closer to that 45 🌟

Biology SL

418 words

3 mins read

Last edited on 14th Jun 2024

Role: Collect and transport blood from body organs back to the heart.
Fun fact!: Blood drains constantly from capillaries into veins, and there’s no pulse in the veins.

Elastic Fibers: Veins have fewer of these than arteries.
Smooth Muscle Cells: Also fewer in veins. Why? Because veins aren’t traffic cops! They don't adjust blood flow to different body parts.
Wall Thickness: Veins have thinner walls than arteries because blood in veins is chill, under low pressure. Think of arteries as the high-pressure water hoses, and veins as calm streams!

Problem: Low pressure could cause:
- Blood backflow (imagine water flowing backward in a stream).
- Not enough blood getting back to the heart. Not cool!❤️🔙
Solution: Pocket Valves!
- Structure: Three cup-shaped tissue flaps, looking like mini umbrellas in the vein.
- Function:
  - If blood goes rogue and flows backward? It's trapped in the pocket valve! Flaps fill up, close the valve, and block the vein.
  - When blood is a good citizen and flows towards the heart? It gently pushes the flaps aside, and voila, the valve opens! Blood flows with style.

Dive deeper and gain exclusive access to premium files of Biology SL. Subscribe now and get closer to that 45 🌟