Topic 5b - Circulatory systems Flashcards
Circulatory systems functions…
transport of gases & nutrient transport of wastes distributions of hormones reg. of body temp wound healing protection from disease
Heartbeat is …?
myogenic
Where is cardiac cycle initiated?
right atrium (SA node) ‘pacemaker’ -> cells of atrium contract then signal -> ventricles
What allows synchronous contraction of ventricles?
extensive nerve fibres (Purkinje fibres) beginning at apex of heart
Components of blood…?
plasma
erythrocytes
white blood cells
platelets
Plasma properties…?
90% water
dissolved proteins, nutrients, gases, wastes, hormones etc
What are erythrocytes?
RBCs contain haemoglobin (carry oxygen)
How many RBCs formed per second?
25 million
T or F - RBCs level is tightly controlled
true
How are RBC levels tightly controlled?
mediated by erythropoietin
If RBC low…? high…?
increased erythropoietin production -> ++ RBC prod.
decreased erythropoietin production -> decreased RBC prod.
O2 deficiency…?
stimulates erythropoietin production by kidneys -> stimulates RBC prod. in bone marrow -> restored O2 level -> inhibits erythropoietin production by kidneys
Different types of white blood cells…?
neutrophils basophils lymphocyte eosinophil monocyte
What is a platelet?
pieces of large cells produced by megakaryocytes
Blood clotting occurs…?
upon exposure to air
How many cascades in clotting?
12 enzymatic reactions
- each step proceeds only after previous one is finished
- highly regulated cos of potentially disastrous results
What does the final step in clotting involve?
thrombin (enzyme)
Blood vessels damaged -> …?
- vessel constricts reducing flow
- exposes collagen -> activates platelets which stick & form plug
- damaged cells & activated platelets release chemicals convert prothrombin -> thrombin
- thrombin converts fibrinogen -> fibrin (insoluble fibres)
- fibrin forms meshwork & seals cut vessel
Layers that make up blood vessels…? outer to inner?
connective tissue
smooth muscle
endothelium
lumen
Properties of capillaries…?
Thin & permeable to:
- gases
- nutrients
- cellular wastes
When calf muscle is relaxed, vein valves are…? When muscle contracts…?
closed
bottom are closed & top open
Properties of lymphatic system…?
returns plasma proteins & excess fluid back to blood stream
How do lymph gradients work…?
- Pressure forces fluid from plasma at arteriole end of capillary network
- Extracellular fluid -> lymph vessels at venous ends of capillaries
- Lymph -> larger lymph vessels & back to blood stream
