Circulation Flashcards
What are the 3 main components of circulatory systems?
- pump or propulsive structures (ie. heart)
- system of tubes, channels, or spaces
- fluid that circulates through system (ie. blood)
What are the 3 types of pumps?
- chambered hearts
- skeletal muscle
- pulsating blood vessels
How do chambered heart pumps work?
- contractile chambers
- blood moves into muscular wall through vein
- muscular wall contracts
- one-way valves ensure unidirectional blood flow out of chamber through artery into circulatory system
How do skeletal muscle (external) pumps work?
- muscle mass contracts, compressing blood in vessel to generate pressure, which forces blood unidirectionally through one-way valve
- no specifically designed chamber
How do pulsating blood vessel pumps work?
- peristalsis: rhythmic contractions of vessel wall (contractile tissue) pumps blood by elevating hydrostatic pressure, which forces blood to move in intended direction of flow
What are the 4 types of fluid?
- blood
- hemolymph
- interstitial fluid
- lymph*
What is blood?
fluid that circulates within vessel of closed circulatory system
What is hemolymph?
fluid that circulates in open circulatory system
What is interstitial fluid?
extracellular fluid (between cells) that directly bathes tissues
- composition similar to plasma
What is lymph?
fluid that circulates in lymphatic system
What is the lymphatic system?
secondary circulatory system of vertebrates that carries fluid (lymph) that filtered out of vessel
- capillaries are not perfectly impermeable
- pressure that drives blood forces some fluid out across membrane into interstitial fluid → lymph ducts → lymph vessels
What is an open circulatory system?
circulatory fluid comes in direct contact with tissues in spaces called sinuses
- circulating fluid mixes with interstitial fluid
- heart pumps hemolymph to one end of animal, fluid enters big open space (hemocoel), and eventually gets drawn back into venous system to return to heart
- no control of how fluid returns to heart – just mixes the contents to make sure nutrients are distributed throughout the body
What is the tracheal system?
- brings air to within 2-3 cells of every cell in the body
- O2 brought into system, CO2 removed
Does the hemocoel play a role in gas exchange?
no – more about nutrients, waste products
What is a closed circulatory system?
circulatory fluid remains within vessels and doesn’t come in direct contact with tissues
- circulating fluid is distinct from interstitial fluid
- efficient way of circulating fluid throughout body, but molecules must diffuse across vessel wall
- heart pumps blood through circulatory system into capillary bed (high surface area) – everything diffuses across membranes, and blood remains in circulatory system
What happens at the capillaries? (3)
diffusion of molecules between blood and interstitial fluid occurs
- gas exchange (O2 in, CO2 out)
- nutrient delivery from blood
- lymph is generated (which then needs to be removed)
Why did the circulatory system first evolve, and how did it change?
- first evolved to transport nutrients to body cells
- very early began to serve respiratory function – get O2 to metabolizing tissues, and CO2 away from tissues
How did closed circulatory systems evolve? What did this do?
evolved independently in jawed vertebrates, cephalopods, and annelids
- increased blood pressure and flow
- and therefore increased control of blood distribution
What did closed circulatory system evolve in combination with?
with specialized oxygen carrier molecules
- high metabolic rates
How does the circulatory system fit into O2 delivery?
O2 cascade – framework for all vertebrate animals
- external convection
- diffusion
- internal convection
- diffusion
- ATP production
Describe the steps of the O2 cascade.
- EXTERNAL CONVECTION moves air into lungs to obtain O2 from external medium
- DIFFUSION of O2 across barrier and into circulatory system – to quickly and fully saturate respiratory pigment with O2
- INTERNAL CONVECTION – circulatory system pumps blood around circuit of tubes to get blood to where and when it is needed
- DIFFUSION to rapidly unload O2 from blood to mitochondria of tissues
- ATP PRODUCTION
What is convection important for?
for getting medium as close as possible to site where it needs to diffuse, which greatly reduces time constraints
All activities (locomotion, digestion, reproduction, etc.) ultimately require O2. What are the two ways of providing it?
- heart pumps more blood per unit time (higher cardiac output) with activity intensity
- tissues extract more O2 from capillaries with activity intensity (CaO2 remains constant, CvO2 decreases)
What is the equation for O2 uptake?
MO2 = Q(CaO2-CvO2)
- CaO2: content of O2 in arterial blood
- CvO2: content of O2 in venous blood