do all organisms have circulatory systems?
no. since their body structures are different and live in different environments.
environmental problem. circulatory system transports stuff around body since environment does not do that naturally (only by diffusion)
need oxygen and glucose (simple sugars which is a carbohydrate)
what problems does circulatory system solve?
functions of the system
- transport: oxygen and nutrients to tissues, carbon dioxide and other wastes from tissues
- regulation: blood pH and body temperature (blood chemistry) which is response
- protection: from blood loss through clotting and against infection by pathogens (a disease causing organism)
main components of c-s
- blood: medium to carry substances
- blood vessels: pathway to transport
- heart: pump to move medium along pathway
- motor that converts energy to movement: respiration, process where nutrients turn to food
- highway analogy
blood goes from…
heart to arteries to capillaries to venules to veins to heart
- blood leaves heart through arteries (away from heart. arteries=away)
* arteries carry high pressure blood away from the heart. only the arteries not going to lungs carry high oxygen blood. the ones going to lungs carry low oxygen blood.
smaller diameter. carries lower pressure blood away from heart. delivers blood to different body parts. can strech to accomodate more blood.
- capillaries (allow exchange by diffusion with the tissues takes in cell deposits oxygen and glucose to parts and cell takes in waste . some capillaries are 1 cell diameter and 1 cell thick so diffusion is super fast!)
- venules take blood to heart (goes back). less thick, larger lumen
- veins carry low pressure blood back to the heart. blood is low oxygen as well. largest lumen.
arteries vs veins
- arteries have thicker walls (to carry high pressure blood) than veins
- smaller lumen than veins
inner layer of capillaries are only made of a single layer of epithelial cells. this layer is called the endothelium (inside, epithelial).
second innermost layer
next thickness: connective tissue. secretes a protein called elastic collagen. this stretches the vessel to allow blood. it goes back to its original position. Tunica interna: single layer of epithelial cells and connective tissue. There are ridges to strech during systole
thickest part of wall. this is a layer of smooth muscle. stretches to accommodate passing blood. restricts blood by contracting
produces more elastic collagen. when they stretch, they spring back to original shape; these are known as tunica intermedia (smooth muscle plus more connective tissue with elastic collagen). this is thicker in arteries
a layer of connective tissue that produces elastic collagen and rigid collagen fibres. this layer will stretch to a limit. this is called the turnica externa. this tougher layer prevents walls from ballooning when pressure is high. thicker in arteries.
each system needs 3 things
a network of pathways, a motor that converts energy, a medium to carry goods
there is a complete double loop system in which one side of the heart pumps blood only to the lungs.
complete double loop system in which one side of the heart pumps blood to all of body
a network of capillaries that supplies a particular tissue