Circulatory system, Respiratory system and excretory system Flashcards
Homeostasis
homeostasis is the state of steady internal, physical, and chemical conditions maintained by living systems.
The simple animals lacking specialized system for the transport and distribution are
Cnidarians, Flat worms and nematodes
In these animals materials exchange through direct diffusion through the body surface
Substances that are transported in the body include
respiratory gases (oxygen, carbon
dioxide), nutrients (glucose, amino acids, fatty acids, vitamins, etc.), waste products of
metabolism (urea, ammonia, etc), hormones and antibodies.
Interstitial fluid
Fluid found in the spaces around cells. It comes from substances that leak out of blood capillaries
open circulatory system
There is no distinction between the circulatory fluid and the interstitial fluid surrounding cells.
Heamolymph pumped from the heart bathes the body tissues directly. Back flow of heamolymph takes place via the pore (ostia.)
The open circulatory system has evolved in some invertebrate phyla such as
Arthropoda and Mollusca (some mollusc groups)
Back flow of the hemolymph takes place via
the pores (ostia)
The closed circulatory system has evolved in
vertebrates and invertebrates such as Annelids
Single circulation
During single circulation, in a complete circulation through the entire body, blood passes through the heart only once
In animals that demonstrate single circulation, posses two chambers in the heart. They are atrium and ventricle.
e.g.: Bony fishes, Cartilaginous fishes such as rays and sharks.
Double circulation
During double circulation, in a complete circulation through the entire body, blood passes through the heart twice.
e.g. Amphibians, Reptiles, Aves, Mammals
What is meant by incomplete double circulation
Amphibians contains a 3 chambered heart with 2 atria and 1 ventricle.
Some reptiles contains a 3 chambered heart with an partally separated ventricle.
In these animals O2 rich blood and O2 poor blood are mixed in the heart and hence it is known as incomplete double circulation.
3 layers of veins and arteries
Inner layer tunica intima containing simple squamous cells
Middle layer tunica media consisting of collagen fibres, elastic fibres and smooth muscles.
Outer layer tunica externa consisting mostly of collagen fibres.
Blood capillaries forms a network over all the tissues in the body except
Cornea and cartilage
Flow rate of blood and lymph
blood - 80 cm3s-1
lymph - 100 cm3h-1
Blood volume and mass in a human
5 dm3
5 kg
Exceptions of the general functions of veins and arteries
Arteries usually carry O2 rich blood however pulmonary arteries and umbilical artery transport O2 poor blood.
Usually veins carry O2 poor blood but pulmonary veins and umbilical veins transport O2 rich blood.
Largest artery and vein
Largest artery is the aorta while the largest vein is the inferior vena cava.
Differences between arteries and veins
Arteries have thick walls with muscle tissue. Veins have thinner walls and use valves to keep your blood flowing
The conducting system of the heart consists of
• SA node (Sinoatrial node)
• AV node (Atrioventricular node)
• Atrioventricular bundle (bundle of His), bundle branches and Purkinje fibres
Heart beat responds to a number of circulating factors including
Autonomic nervous system, hormones such as adrenaline and thyroxine and temperature.
SA node / Sinoatrial node
SA node is a small mass of specialized cells. It lies in the myocardium of the right atrium near the opening of the superior vena cava. The stimulus for contraction of the heart originates in the ‘SA node’. The SA node initiates the heart beat and sets the rhythm of the heart beat so it is called the pace maker.
SA node and AV node contains which type of cells
Neuromuscular
AV node
It is situated between wall of the left and right atria. The AV node transmits the electrical signals from the atria into the
ventricles.
Atrioventricular bundle (bundle of His), bundle branches and Purkinje fibres
The AV bundle branches and the Purkinje fibers transmit electrical impulse from the AV node to the apex of the myocardium. As a result of this impulse, wave of ventricular contractions begin. Then the contraction sweeps upwards and outwards pumping blood simultaneously into the pulmonary artery and the aorta.