Biological Science 101

Transport Systems

Introduction to Transport

Vascular Plants
- transport water and minerals in xylem
- transport food (sugars) in phloem
- see xylem and phloem cells
Animals transport in a circulatory system
- Closed system [circulating blood within blood vessels]
  - Blood is pumped by heart
  - Blood vessels [arteries, arterioles, capillaries and veins]
  - Smallest blood vessels (capillaries) leak fluid from blood [lymph]
  - Lymph is collected and returned to blood by lymphatic system
  - Found in Vertebrates
- Open Circulatory System
  - Circulating fluid (hemolymph) not separated into blood and lymph
  - Hemolymph not confined to blood vessels
  - Found in Arthropods and most molluscs

Blood is the circulating fluid composed of plasma + formed elements

In hematocrit, blood separates into plasma, buffy layer and erythrocytes.
Plasma is water + solutes [nutrients, waste, electrolytes, gases, buffers, proteins]
Formed elements of the blood [erythrocytes, leucocytes, platelets] * see illustration
- See a quick view of micrographs of all blood cell types.
- For a greater histology lesson check out more micrographs of blood cell types.
Erythrocytes make up about 45% of blood
- Erythropoiesis forms erythrocytes in red bone marrow
- Cells are biconcave discs lacking nuclei.
- Almost entire weight is hemoglobin.
- About 98% of O₂ and 8% of CO₂ are transported on hemoglobin .
Leucocytes function in body defense and immunity
- Granulocytes are leucocytes the with cytoplasmic granuals.
  - Three types [neutrophils, eosinophils & basophils]
  - LMC histology lab slide [Neutrophil]
  - Neutrophils are phagocytic
- Agranulocytes are leucocytes without cytoplasmic granuals
  - [lymphocytes and monocytes]
  - Lymphocytes [T-cells & B-cells] function in immune process
  - LMC histology lab slides [Lymphocyte] [Monocyte]
Platelets (Thrombocytes) function in hemostasis
- Start the production of blood clotting
- Hemostasis prevents blood loss.

Heart is muscular, parallel pumps. a right and left [Online Exploration of Heart]

Heart animation
Four Heart Chambers
- R & L. atria receive venous blood
  - R atrium receives deoxygenated blood from body
  - L atrium receives oxygenated blood from lungs
- R. & L. ventricles pump blood into arteries
  - R ventricle sends deoxygenated blood to lungs
  - L ventricle sends oxygenated blood inot aorta for body organs
Right & Left chambers are seperated by a septum [interatrial] [interventricular]
Heart valves regulate blood flow. Close to prevent blood back flow.
Heart Valves closing produce heart beat [lubb dubb]
- "dubb" is semilunar valves closing [aortic & pulmonary]
- "lubb" is atrioventricular valves closing [tricuspid & bicuspid]
Circulatory Routes through heart
- Pulmonary Circulation to lungs
- Systemic Circulation to all body organs except lungs and heart
Cardiac Cycle has two main stages;
1. Systole = contraction of ventricles [AV Valves close]
2. Diastole = relaxation of ventricles [Semilunar Valves close]

Blood Vessels * See Tubular Circulation and major blood vessels on lab model

Blood Pressure [Systoic and diastolic]
Arteries carry blood from heart to organs
- Arteries have thick walls and high blood pressure
- Blood is oxygenated (red) (pulmonary is exception)
Arterioles control volumn of blood flow into organs
- Walls posses muscles for dilation and constriction
Capillaries join arterial blood flow to venous blood flow.
- Function in molecular exchange with tissues
- Lymph formed at capillaries from blood
Veins carry blood from organs to atria of heart.
- Veins have thin wall and low blood pressure
- Blood is oxygen depleted (blue)
- Large viens have one-way valves

Fluid lost from the blood at the capillaries is returned to the blood by the lymphatic system.
Lymph is fluid within the lymphatic system
Lymphatic Vessels start as lymph capillaries
Lymph is returned to blood in large veins at neck.
Lymph nodes are specialized swellings along lymph vessels
Lymphoid organs [thymus] [tonsils] [spleen ]
Lymphocytes are organized in lymphoid tissue and function in immunity.

Lymphocytes are immunity cells and monocytes are phagocytic.
Lymphocytes produce protein molecules that recognize antigens and bind to them.
When stimulated by antigen lymphocytes produce clones of immunity cells and memory cells.
Antigens are proteins foreign to the body.
Two classes of lymphocytes [B-cells & T-cells] provide a dual immunity.
- Table comparing B & T lymphocyte action
- Animation of B & T lymphocyte action
B-lymphocytes
- Stimulated by antigen to forms clones of plasma cells and memory cells
- Plasma cells secret antigen specific antibodies.
- Responsible for humoral immunity.
- if antigen returns, memory cells can form plasma cells in hours
T-lymphocytes
- Produce antigen specific receptors on its cell surface.
- Responsible for cell-mediated immunity.
- Have subclasses of cells
  - Helper T-cells stimulate B-cells and Killer T-cells
  - Killer T-cells destroy tumor cells and virus infected cells.
  - Memory T-cells