Topic 8 Transport in mammals Flashcards
Features in the circulatory system
- blood vessels
- blood plasma/ tissue fluid
- white blood cells and red blood cells
Function of the Cardiovascular system
- transport of nutrients and oxygen
- disposal of waste materials
- transport of hormones
- circulate white blood cells and red blood cells in the body
Double, closed circulatory system meaning
double: blood passes the heart twice in one complete circuit
closed: blood in contained in blood vessels
Types of blood vessels
- Artery
- Vein
- Capillary
Arteries
Feature:
carry oxygenated blood away from the heart
- well defined oval shape
- thick wall
- thick tunica media
- narrow lumen
- folded endothelium
contain:
- collagen fibres
- elastic fibres
- smooth muscles
Veins
Features:
Return blood to the heart
- irregular/ flattened oval shape
- wide lumen
- thin tunica media
Capillaries
Vessel diameter= ~7um
made of endothelial cells
adaptation:
- One cell thick: short diffusion distance
- has pores: allow exchange of smaller components
- small lumen diameter: lowers blood pressure
- high surface area: form capillary bed
Components of blood
55% blood plasma
1% platelets and white blood cells
44% red blood cells
Formation of tissue fluid
- Due to differences in blood pressure at artiel and venous ends
- blood pressure in artioles is higher than blood pressure in venules
- blood plasma flows out into tissue spaces
- endothelial pores are small: filtration occurs
Composition of tissue fluid
- H2O, gases, glucose, fatty acis, urea, ions
- smaller proteins (eg antibodies)
- some white blood cells
- lower O2 concentration than plasma
- no platelets, large proteins, red blood cells
Phagocyte function
- patrol in blood, tissue, organs
- remove dead cells and pathogen (phagocytosis)
- involved in non-specific defense
Types of phagocytes
Neutrophils
- multi-lobed nucleus
- have receptor protein on its membrane
- released from bone marrow
- short lived (dies after digesting pathogens)
Monocytes
- lobed nucleus
- have receptor protein on its membrane
- monocytes circulate in blood
- mature into macrophages (found in organs)
- love lived cells
Lymphocyte function
- involved in specific immune response
- mature lymphocytes circulate in the blood & lymph
Red blood cell function
- transport oxygen to body tissue
- short lived
- small
- flexible
- biconcave shape
- no nucleus
Bohr effect
- where the affinity of Hb to O2 is affected by pCO2
- high pCO2 decrease affinity of Hb to O2
= increases dissociation of oxyhaemoglobin in actively respiring tissue
Trasnport of carbon dioxide process
- (from respiring cell) CO2 —> RBC
- CO2 + H2O -> H2CO3 (carbonic anhydrase)
- H2CO3 -> HCO3- + H+ (dissociation)
- HCO3- (diffuses to blood plasma)
- H+ + HbO8 -> 4O2 + HHb
What is H2CO3
Carbonic acid
What is HCO3-
Hydrogen carbonate
What is HbO8
Oxyhaemoglobin
What is HHb
haemoglobinic acid
Cardiac cycle
- Atrial systole
both atria contract
atrioventricular (AV) valves open
Semi lunar valves closed - Ventricular Systole
Both ventricles contract
AV valves closed
Semi lunar valves open - Diastole
Atria and ventricl relax
AV valves open
semi lunar valves closed
Control of heart beat
- Sinoatrial node (SAN) sends wave of excitation
- Impulses spread through out Atria
- Atrial systole
- Wave of excitation passed to Atrioventricular Node (AVN)
- Time delay of ~0.1-0.2 in AVN
- AVN sends wave of excitation to ventricles
- Wave of excitation passed to pukyne tissue
- Purkyne tissue stimulates ventricular muscles to contract
- Ventricular systole
- Refractory period
