3.2 Flashcards
Why do multicellular animals need transport system?
They are big
Have a low surface area to volume ratio
Higher metabolic rate (speed at which chemical reactions take place in the body)
What is a single circulatory system
Blood only passes through the heart once for each complete circuit of the body
E.g fish heart ➡️gills➡️body
What is a double circulatory system
Bloody passes thru heart twice for each complete circuit of body
E.g mammals, heart is divided down middle Right➡️lungs➡️left➡️body
What is an open circulatory system
Blood isn’t enclosed in bloody vessels all the time instead it flows freely through the body cavity
E.g Insects heart segmented
Closed circulatory system
Blood enclosed inside blood vessels e.g all vertebrates (fish and mammals)
Structure + function or artery
Out➡️in Elastic tissue wall Thick muscle layer Folded endothelium Lumen
- blood heart ➡️ rest of body
- high pressure
- oxygenated (except pulmonary)
Arteriole
Arteries branch into arterioles and arterioles beach into capillaries
•smooth muscle
•elastic tissue
Capillaries
Endothelium
1 cell thick➡️Adapted for efficient diffusion
Connect to venules
Veins
Out➡️in
Thin muscle wall
Endothelium
Large lumen
- Blood➡️back to heart
- Low pressure
- Valves to stop blood flowing backwards
- deoxygenated except pulmonary veins
Venules
Connected from capillaries
Thin walls
Join together to form veins
Formation of tissue fluid from plasma
- at end of capillary blood at high hydrostatic pressure
- pressure pushes blood fluid out of capillary wall
- tissue fluid consists of plasma with dissolved nutrients and oxygen
- surrounds body cells so diffusion can happen
Oncotic pressure
Pressure created by the osmotic effects of the solutes
Hydrostatic pressure
The pressure that a fluid exerts when pushing against the sides of a vessel or container
Blood
The fluid used to transport materials around the body
Lymph
The fluid held in the lymphatic system
Define cardiac cycle
The sequence of events in one full beat of the heart
What is cardiac cycle
Ventricles relax
atria contract➡️decreases volume increases pressure ➡️ pushes blood 2 ventricles pressure ⬆️
Ventricles contract atria relax
Ventricles contract➡️decrease volume increase pressure ➡️ pressure higher than in atria so atrioventricular valves shut to prevent back flow➡️high pressure in ventricles open semi-lunar valves ➡️blood forced out of pulmonary artery + aorta
Ventricles relax atria relax
Semi lunar valves close as higher pressure in pulmonary artery and aorta. Prevents back flow. Atria fill with blood ⬆️pressure (higher pressure in vena cava and pulmonary vein). Ventricles relax pressure⬇️pressure in aria. Atrioventricular valves open blood flows passively.
How heart action is initiated and coordinated
SAN=pacemaker
Sends waves of electrical activity
Causes right+left atria to contact at same time
Collagen tissue prevents waves passing 2 ventricles instead it goes 2 AVN which passes it on 2 bundle of His. Slight delay makes sure ventricles contract after atria emptied. Purkyne tissue carried waves into muscular walls of right&left ventricles➡️contract simultaneously from bottom up
SAN
Sino-atrial node
AVN
Atrio-ventricular node
Purkyne tissue
Consists of specially adapted muscle fibres that conduct the wave of excitation from the AVN down the septum to the ventricles
Myogenic muscle
Muscle that can initiate its own contraction
Tachycardia
A rapid heart rhythm
Bradycardia
A slow heart rhythm
