SNS - Biology - Circulatory Systems and Immunology Flashcards
Transport Systems In Plants
Translocation
Circulation in plants
Transport Systems In Plants
Fibrovascular Bundle
Found at the centre of the stem. Contains xylem, phloem and cambium cells
Transport Systems In Plants
Xylem
- Thick walled, often hollow cells found on the inside of the vascular bundle
- Carry water and minerals up the plant and give the plant its rigid support
- Two types of xylem cell – vessel cells and tracheids
Transport Systems In Plants
Sapwood
Outer, living layer of the xylem
Transport Systems In Plants
Mechanism of Movements Via Xylem
- Capillary action – any liquid in a thin tube will rise due to surface tension between the liquid and tube walls
- Transpiration pull – as water evaporates from plant leaves, vacuum is created that pulls water up the stem
- Root pressure – water entering root hairs exerts a pressure that pushes water up the stem
Transport Systems In Plants
Phloem
- Thin walled cells found on the outside of the vascular bundle
- Transport nutrients (especially carbohydrates produced in the leaves) down the stem
- Living cells
- Include Sieve tube and companion cells
Transport Systems In Plants
Cambium
- Two layers thick, found between the xylem and phloem cell layers
- Are the actively dividing, undifferentiated cells
- Give rise to xylem and phloem
- As they divide, cells near the phloem differentiate into phloem cells and vice versa
Transport Systems In Plants
Stem Structure
Layers – Outside to Inside
- Epidermis – outer bark
- Cortex
- Phloem
- Cambium
- Xylem
- Pith – tissue involved in storage of nutrients and plant support
Transport Systems In Plants
Root
- Anchor the plant and absorb materials via root hairs
- Some provide energy reserves – carrots, turnips
Transport Systems In Plants
Root Hairs
Specialised cells of the root epidermis with thin-walled projections
Increase surface area for absorption of water and minerals from the soil
Transport Systems In Plants
Root Structure
Layers – Outer to Inner
- Epidermis – containing root hair cells
- Cortex
- Phloem
- Xylem
- Cambium
Circulation In Invertebrates
Protozoans
Simple diffusion within the cell
Circulation In Invertebrates
Cnidarians
- Hydra and other cnidarians have body walls that are two cells thick.
- All cells are in direct contact with either external medium or internal environment, so no need for specialised circulatory systems
Circulation In Invertebrates
Arthropods
- Have open circulatory systems in which blood (interstitial fluid) is in direct contact with the body tissues.
- The blood is circulated primarily by body movements
- Blood flows via a dorsal vessel and into spaces called sinuses where exchange occurs
Circulation In Invertebrates
Annelids
- Earthworm
- Uses a close circulatory system to deliver material to cells not in contact with external environment
- Blood is confined to blood vessels
- Moves towards the head in the dorsal vessel which functions as the main heart by coordinated contractions
- Five pairs of vessels – aortic loops – connect dorsal vessel to ventral vessel and function as additional pumps
- Lack RBCs but instead have a haemoglobin-like pigment dissolved in an aqueous medium
Circulation In Humans
Bicarbonate Buffering System
CO2 combines with water to generate carbonic acid. This can dissociate into bicarbonate ions (weak base) and H+ (acidic). Therefore, small shifts in the chemical equilibrium of this system via respiration in the lungs or cells can accommodate pH imbalances in the body
CO2 + H2O ⇔ H2CO3 ⇔ H+ + HCO3-
Foetal Circulation
- Bypasses the lungs
- Foramen Ovale connects right and left atria, shunting blood away from the right ventricle
- Ductus arteriosus connects the aorta and pulmonary artery, preventing any blood in the right ventricle from entering the circulation of the developing lumgs
- Ductus venosus moves blood from the umbilical vein to the inferior vena cava of the foetus allowing oxygenated blood to bypass the liver and travel more directly to the developing foetal brain
Blood
Volume In Average Human
4-6 litres
Blood
- % Liquid components
- % Cellular components
- 55%
- 45%
Blood
Liquid Components
- Plasma
- Aqueous mixture of nutrients, salts, respiratory gases, wastes, hormones and blood proteins – imunoglobulins, albumin, fibrinogen
Blood
Cellular Components
- Erythrocytes
- Leukocytes
- Platelets
Blood
RBCs
Molecule Haemoglobin per Cell
~250 million
Blood
RBCs
Lifespan
- Produced in bone marrow
- Circulate in the blood for ~120 days
- Phagocytosed by specialised cells in the spleen and liver
Blood
Clot Formation
- Platelets (cell fragments lacking nuclei) come into contact with exposed collagen of damaged vessel wall
- Release chemical causing neighbouring platelets to adhere together, forming a platelet plug
- Both platelets and damaged tissue release clotting factor thromboplastin
- With aid of cofactors vitamin K and calcium, converts inactive prothrombin into thrombin
- Thrombin converts fibrinogen into fibrin
- Fibrin threads coat the damaged area, trapping blood cells to form a clot
Non-Specific Immunological Defence
- Skin
- Mucous and ciliated epithelia
- Macrophages
- Inflammatory response
- Interferons
Blood Typing
ABO Group
- A blood has A antigen present
- B blood had B antigen
- AB has both – universal recipient
- O has neither – universal donor
Blood Typing
Rh factor
- Antigen that can be present on RBC surface
- Rh+ - carry
- Rh- don’t carry
- Important during pregnancy – Rh- woman can be sensitised by an Rh+ foetus if foetal RBCs enter the maternal circulation during birth. If the woman subsequently carries another Rh+ foetus, anti-Rh antibodies she produced may cross the placenta and destroy foetal RBCs resulting in erythroblastosis (severe anaemia). Anti-A or –B antibodies can’t cross the placenta however
