Circulatory systems 1 Flashcards
Simply put, what is a circulatory system?
Simply a transport system
Moves fluid throughout the body
The circulatory system provides cells with __ & _________
and
Removes wastes such as _________ ______ & ___
A. 02 & Nutrients
B. Nitrogenous wastes & CO2
Who needs a circulatory system?
(small animals vs large animals)
Small animals and single celled organisms rely on simple or facilitated diffusion of substances or active transport of substances.
-
In large animals diffusion of substances becomes inefficient over distances greater than 1mm
Types of circulatory systems
What is external circulation and give an example of an animals that uses external circulation
- Simple animals such as sponges & coelentates
- No control over the nature of the environment
- Tiny pores (ostia) in their outer walls through which water is drawn.
- Cells in the sponge walls filter food from the water as the water is pumped through the body. and the osculum (“little mouth”).
- The flow of water through the sponge is in one direction only, driven by the beating of flagella which line the surface of chambers connected by a series of canals.
- Sponge cells perform a wide range of bodily functions and appear to be more independent of each other than are the cells of other animals.
Types of circulatory systems
What is Coelomic circulation?
Can control the internal environment but very little control of its circulation
- A fluid filled space in the body called the coelem
- Fluid circulated around within the body by contracting muscles in the body wall
- lSoshes the fluid around to try and reduce any regional gradience in terms of 02, nutrience and waste products
Blood + Coelomic Fluid =
Haemolymph
Describe the open circulatory system of an arthropod
- Hemolymph instead of blood.
- This “hemolymph” performs the functions of blood, lymph, and intestinal fluid. (highly specialized fluids in animals with closed circulatory systems)
Instead of a complex and closed system of veins and arteries, organisms with open circulatory systems have a “hemocoel.”
This is a central body cavity found inside most invertebrate animals where both digestive and circulatory functions are performed.
This hemocoel may have “arteries” through which the blood can reach tissues – but these arteries are not closed and do not circulate blood as quickly as closed, muscle-assisted arteries.
Descrie a closed circulatory system?
- Vertebrates have a closed circulatory system
- Blood remains within blood vessels and does not directly interact with body tissues.
- In birds and mammals, the primary organ of the cardiovascular system is a four-chambered heart, with its associated blood vessels. In other vertebrates, the heart can have either two or three chambers.
- “Blood can be sent anywhere its needed, muscles demand more blood during exercise and they can get it because of the bodys ability to send blood to muscles that need it”*
What happens during anaphylactic shock?
- An opening up of all of the blood vessels
- Blood pressure drops so low no blood going to the brain
- You die.
Describe a complex circulatory system and its three main components
- Pump (heart)
- Piping (blood vessels)
- Valve (unidirectional flow)
- Muscular pumps with multiple chambers and valves
- Regular cycle of contraction (systole) and relaxation (diastole)
- Heart rate controlled by cardiac pace maker
- Hearts are reciprocating pumps
What is a Neurogenic heart?
A heartrate set by pacemakers cells in the central nervous system (arthropods)
What is a Myogenic heart?
Heart rate set by pacemakers cells in the cardiac muscles (all vertebrates)
The heart is a _________ type of pump where the heart has to _____ and _____ in order to refill.
A. Recipricating
B. Pump
C. Relax
Cardiac muscle is spontaneously active, explain why.
- Because it has an unstable resting membrane potential
- 70mv is resting membrane potential but ions are constantly leeking towards threshold potential (-55mv)
Once threshold crossed, volted gates sodium channels open and cell fires action potential which returns it to resting membrane potential of -70mv and the process repeats
(Cardiac muscle does not tetanise because of long refractory period)
“once action potential fired, absolute refractory period very long, which gives muscle time to relax before it fires again”
The rate of depolarisation can be altered to either fast aka __________ or slow aka ___________.
A. Tachycardia (fast)
B. Bradycardia (slow)
The pacemaker potential is conveyed thoughout the heart via ________ fibres.
Delay of the signal as it passes through the __________ node allows the _____ to contract before the ventricles.
Transmission from cell to cell is by electrical ________.
A. Purkinje
B. Atrioventricular node allows the Atria
C. Synapses
