TUTTEE ACADEMY LOGO
broken image
  • Home
  • About Us
  • Subjects 
    • CHEMISTRY
    • BIOLOGY
    • PHYSICS
    • MATHEMATICS
    • PSYCHOLOGY
    • ECONOMICS
    • BUSINESS
    • COMPUTER SCIENCE
    • CHINESE
    • ENGLISH
    • SPANISH
    • IBDP IA / EE
    • IBDP TOK
    • ONLINE TUTORIAL
  • Exam Boards 
    • IBDP
    • IBMYP
    • IGCSE & GCSE
    • HKDSE
    • GCE A-LEVELS
  • Courses 
    • IBDP Tuition
    • GCE A-Level Tuition
    • IBMYP Tuition
    • I/GCSE Tuition
    • HKDSE Tuition
  • Admission Test Prep 
    • PREDICTED GRADE
    • SAT / SSAT
    • UKISET (UK)
    • BMAT
    • UKCAT / UCAT
    • LNAT
    • TMUA (Cambridge)
  • Student Results 
    • IBDP STUDENT RESULTS
    • IGCSE & GCSE MATHEMATICS
    • A-LEVEL STUDENT RESULTS
    • IGCSE STUDENT RESULTS
    • GCSE STUDENT RESULTS (UK)
    • HKDSE STUDENT RESULTS
    • OUR STORIES
  • Question Bank
  • Resources
SCHEDULE A LESSON NOW

IBDP Biology: Circulatory System - Part 2

Circulatory System

· biology,IB biology,IBDP BIOLOGY,Circulatory system

In this topic of IBDP Biology, we will learn about circulatory system.

Blood vessels

  •     Three layers surrounding a central blood carrying canal (the lumen).
  •     The outer layer.
  •      Composed mainly of collagen – tough.
  •     Smooth muscle cells may be present, particularly in veins.
  •     Often the most prominent layer in the walls of veins.
  •     The middle layer.
  •     Composed mainly of smooth muscle.
  •     Reinforced by layers of elastic tissue.
  •     Inner lining:
  •     A lining layer of flattened epithelial cells termed endothelium.
  •     Sits on a basement membrane.
  •     The only layer that is present in all blood vessels
broken image
  • Arteries:
    • When it comes to IBDP Biology, arteries carry blood away from the heart
    • Relatively high pressure.
    • Vary in diameter.
    • Thick muscle to maintain high blood pressure.
    • Elastic to even out the blood pressure.
    • Endothelium is very smooth to recue resistance.
  • Arterioles:
    • Less than 0.3mm thick
    • Small arteries.
    • Less elastic tissue.
    • Middle layer consists almost entirely of smooth muscle:
      • Constricts to reduce blood flow by narrowing lumen.
      • Dilates to increase blood flow by enlarging lumen.
  • Veins:
    • Small veins = venules.
    • Carry blood back to the heart.
    • Very little elastic and muscle tissue.
    • Wider lumen than arteries.
    • Relatively low pressure.
    • Contraction of skeletal muscle squeeszes veins, enabling movement of blood
    • Contain valves:
      • Delicate projections of the endothelium.
      • Mainly in limbs.
      • Ensure blood flows towards the heart.

Tissue fluid & Capillaries

  • When it comes to IBDP Biology, capillaries provide the link between the arterial and venous blood vessels.
  • Diameter approx 7micrometers.
    • This enables them to fit between cells in tissues.
    • It also ensures that red blood cells need to squeeze through:
      • This increases their surface areas in contact with the endothelium.
  • They are highly branched.
  • Wall of single layer of flattened endothelial cells.
  • Quite loose fitting with fenestrations (pores).
  • Held together by basement membrane.
  • Water and small solutes can pass through creating tissue fluid.
  • Capillaries allow efficient exchange between blood and tissue fluid.
  • Its composition remains fairly constant because it is constantly formed and removed.
  • All cells must be bathed in fluid to survive
  • Proteins remain in blood
  • Tissue fluid provides respiring cells with:
    • Water
    • Oxygen
    • Glucose
    • Amino acids
    • Fatty acids
    • Hormones
    • Salts
    • Vitamins
  • Tissue fluid enables various substances to move back into the blood:
    • Water
    • Carbon dioxide
    • Urea
    • Lactic acid

Exchange of materials at the capillary bed

Arteriole end

  • As the blood enters the capillary, it is under high hydrostatic pressure
  • There is opposed by the osmotic effect of the plasma proteins and the hydrostatic pressure of the tissue fluid
  • Capillary hydrostatic pressure is much greater.
  • There is a net outwards force
  • This forces water and solutes out of the capillaries

Venule end

  • When it comes to IBDP Biology, as blood passes through the capillary the hydrostatic pressure drops.
  • Hydrostatic pressure of tissue fluid increases.
  • Fluid returns into the capillaries due to this pressure gradient.
  • Concentration of plasma proteins increases due to reduction in water content.
  • This creates a water potential gradient from tissue fluid to blood
  • Water is also drawn in by osmosis
broken image

This is the end of this topic.

broken image

CLICK HERE TO LEARN MORE ABOUT OUR IBDP BIOLOGY COURSES

SIGN UP FOR A FREE IBDP BIOLOGY TRIAL
Subscribe
Previous
IBDP Biology: Circulatory System - Part 1
Next
IBDP Physics: Transformers
 Return to site
Profile picture
Cancel
Cookie Use
We use cookies to improve browsing experience, security, and data collection. By accepting, you agree to the use of cookies for advertising and analytics. You can change your cookie settings at any time. Learn More
Accept all
Settings
Decline All
Cookie Settings
Necessary Cookies
These cookies enable core functionality such as security, network management, and accessibility. These cookies can’t be switched off.
Analytics Cookies
These cookies help us better understand how visitors interact with our website and help us discover errors.
Preferences Cookies
These cookies allow the website to remember choices you've made to provide enhanced functionality and personalization.
Save