Question

Review the following systems and the major organs in each system.
a. Digestive
b. Respiratory
c. circulatory
d. nervous

Answer 1

Not 100% sure what you're looking for in terms of 'review' here but I'll give it a whack all the same: ( Also I'm assuming human systems)

a) The digestive system is involved in the breakdown of food sources and the absorbance of nutrients into the body. Additionally it is involved in the removal of waste materials. The key structures are te stomach, liver, gall bladder, and both intestines. The stomach is a highly acid environment due to the presence of HCl causing the killing of most bacteria and helping the early breakdown of foods. There is also mechanical churning to assist this. From here food is moved into the intestinal tract where it encounters bile salts from the gall bladder and enzmyes created by the liver. This further breaks down food into the component parts. These are absorbed through the intestines via ciliated cells (these provide a large surface area for efficient transfer) and then the molecules are moved into the blood stream or wherever they are needed.
b) Respiratory system is the lungs and surrounding blood supply, the function of the system being to take in oxygen for use in cellular respiration at the same time as removing waste carbon dioxide. Humans have two lungs, split up into several seperate nodes.The trachea leads from the throat to the bronchus which splits in to and then frther splits down to broncioles and finally the alveoli. THese are the site of gas exchange. They have a huge surface area (about the size of a tennis court) and are clightly damp to allow gas transfer between the alveolar space and the blood capillaries which suround them.
c) The circulatory system acts to spread blood around the body to transport gas and nutrients around. The main component of this is the heart, a large muscle which formed of four chamers that pump blood to the lungs and the body. The blood pumped to the lungs is deoxygenated, heading via the pulmonary artery to the lungs to pick up oxygen then heading back to the heart via the pulmonary vein. This is then sent to the rest of the body via the aorta and returns deoxygenated later in the vena cava. The blood vessels are veins, arteries and capillaries. Arteries are strong with a muscaular wall to cope with high pressures, capillaries are thin to allow efficient gas transfer and the veins are thicker but not under pressure so blood moves through valves.
d) The nervous system is meant to transmit signals to the muscles of the body and other organs. There are two regions for this, the Central Nervous System (CNS) and the Peripheral NS (PNS). The CNS is the brain and spinal cord where actions are determined and sent out to the PNS in the muscles or organs where an effect can be taken. Many motor actions are determined in the spinal cord. The PNS can be split into the sympathetic and parasympathetic systems, with the sympathetic under direct control of the brain (muscles movement etc) and the parasympathetic not under concious control (heart rate, organ action)

There you go, sorry d) is poor - I've never really liked neurobiology.

Answer 2

Woah o_o Thank You.. I just needed to know this stuff for a test :D Tyvm

Answer 3

With regard to the nervous system:

The CNS (central nervous system) controls the PNS (peripheral nervous system), both the conscious and unconscious aspects.

The PNS contains the autonomic (unconscious control) and somatic (conscious control) systems. The sympathetic NS and parasympathetic nervous system are both part of the autonomic nervous system, and act against each other to regulate many parts of the body. The sympathetic NS is associated with "fight or flight" and uses primarily epinephrine (a neurotransmitter) to stimulate skeletal/cardiac muscle while inhibiting smooth muscle (the type used for digestion). The parasympathetic NS uses the primarily the neurotransmitter acetylcholine (ACh) to do exactly the opposite, stimulate muscles involved in digestion and inhibit those used for movement.
In a nutshell, the sympathetic NS produces "stress responses", focusing an organism's energy towards organs that it needs to escape a predator or capture prey. On the other hand, the parasympathetic NS redirects energy towards digestion and growth. The two systems act together in a shifting balance depending on the organism's needs.

As far as organs go, the CNS includes the brain (the brain is complex but you can find some good diagrams on wiki and other places) and spine. The PNS is really just made up of nerve cells (neurons). Motor neurons lead directly from the CNS to the muscles they innervate (control) while many other nerves lead to ganglions (masses of nerve cells) which can act as tiny brains, choosing which signal are passed on and which aren't. More nerves then lead from the ganglion to the tissues that those nerves control. It is possible to go much deeper with the nervous system, but i think that should take care of the question here...

kakitchener answered the rest of the question perfectly, hope this helps

Answer 4

Cheers for the added detail in that section, like I said neurology is not one of my favourite subjects by a long way

Answer 5

Also important in the digestive system is the mouth and oesophagus. The mouth is used to masticate food into smaller pieces for easier digestion and saliva helps hydrate material so it is lubricated. Think about if your mouth and throat were completely dry and you tried to swallow a cracker. The pancreas also contributes enzymatic secretions in the same place as the gall bladder, right after chyme enters the duodenum (first part of the small intestine) from the stomach. The gall bladder simply stores secretions produced by the liver, this is why it can be removed without a great loss of quality-of-life. The cells in the small intestine are not cilliated, cillia are motile and are found in places where surface-secretions need to be moved such as in the trachea, where mucus is moved up from the lungs where it is swallowed (fun factoid - tobacco smoke kills the cilia, so mucus builds-up in the lungs leading to the hacking "smoker's cough"). There are many visible folds in the small intestine as well as many many microscopic villi. Villi are covered in cells that themselves have microvilli. These foldings, villi and microvilli increase the surface area of the small intestine by 200 times, leading to a higher rate of nutrient absorbtion.

Arteries are not all muscular. The aorta (first 1m or 3 feet), is elastic but still very strong. This helps smooth out the "pulses" of blood ejected from the heart. As a high pressure bolus of blood is ejected, the arteries expand and absorb some of the energy, as the blood flows distally from the heart, the elastic arteries retract, prolonging the flow of blood.