Chapter Four : Excretion
The main concepts of chapter (4) Excretion in living organisms 1- Excretion is getting rid of waste products of metabolism through the plasma membrane. 2- The main metabolic wastes are, CO2 water vapour, volatile food substances salts and nitrogenous wastes. 3- Getting rid of nitrogen and defecation are not excretion processes. 4- The main excretory organs in animals are, the skin, the liver, the lungs and the kidneys. 5- The excretory organs in animals can regulate the body content of minerals. 6- The skin consists of the outer epidermis and the inner dermis. 7- The epidermis consists of epithelial cells, the surface cells have keratin and the melanin granules are found at the pigment cells. 8- The dermis has the sweat glands, the hair follicles, nerve endings and blood capillaries. 9- In lower vertebrates kidneys are long, thin extend along the two sides of the vertebral column. 10- Each human kidney is a bean shaped 12 cm long, 7 cm wide, 2.5 cm thick, the outer part is convex while the inner one is concave. 11- The renal artery and renal vein are on the inner side of each kidney. 12- Each kidney consists of thin outer cortex and inner broad medulla. 13- The functional unit of the kidney is the nephron. 14- Each kidney has almost one million nephron. 15- The nephron consists of Bowmman's capsule, first coiled tube , loop of Henel, second coiled tube and the collecting duct which opens in the pelvis from which the ureter emerges. 16- The urinary bladder is closed by a sphincter muscle. 17- Extraction of urine takes place in two main stages: A- Ultra filtration B- Selective reabsorption. 18- The total amount of blood which passes daily through the kidney is about 1600 litres. 19- The blood plasma is examined or filtered about 560 time per day. 20- Excretion in plants does not pose a serious problem Because: a- The rate of catabolism is low. b- green plants re-use their catabolic wastes. c- Plant metabolism depends on carbohydrate which reproduce less toxic wastes. d- some catabolic salts and acids are stored in the form of insoluble crystals. e- excess calcium is accumulated in green leaves then they shed down. f- excess water is removed by transpiration and guttation 21- There are three types of transpiration: a- stomatal (about 90%) b- cuticular (about 5%) c- Lenticular (small quantity) 22- The most important functions of transpiration are: a- decrease the plant temperature b- ascent of water and salts.
Chapter Five : Sensitivity
The main concepts of chapter six: Sensitivity 1- Sensitivity is one of the biological functions of the lliving organism that mentain its life. 2- Senstivity is the coordination between the body and the environment. 3- Forms of sensitivity in plants are: A- Response to touch and darkness. B- Tropisms. [phototropism - Geotropism - Hydrotropism] 4- Mimosa plant and some leguminous plants are hold in a horizontal position, but at night the leaflets hang down ward and fold their upper surfaces upward, i.e undergo sleeping movement. 5- The sleeping movement can be explained due to cell turgidity. 6- At the base of each mimosa leaf there is a swallen structure called pulivinus, when the leaf is touched the water in the lower side of pulvinus escape to the neighboring tissues and after the removal of the stimulus these cell regain their turgidity so pulvini act as joints. 7- The cell walls of the lower half of pulvini are more senstive than those of the upper half. 8- Boysen johnson found that oat coleoptile loses its ability to bend towards light if 1 - 2 cm of its tip is cut off but it regains this ability if the cut part is fixed again to the tip with gelatin. 9- Unequal distribution of light around the plant leads to unequal in the distribution in aucxins which in turn leads to unequal in plant growth that the side away of light has more auxins concentration so it is stimulated to grow more than the other side that leads to be bend towards light which we call the plant stem is positive phototropic. 10- The high concentration of auxins in plant root (in one side) leads to the inhibition (decrease) of its growth. 11- Plant hormones (Auxins) can diffuse through gelatin but not through mica. 12- The plant root is negative phototropic. 13- Herman's exp. Proved that the total amount of auxins in the tip of oat coleoptile does not change but change their position that: A- In vertical position equal amount of auxins move into the two halves of the tip. B- In horizontal postion more auxins diffuse or accumulate into the lower half. So the plant stem is negative geotropic and plant root is positive geotropic. 14- The plant root is positively Hydrotoropic if the water is not equally distributed around its two sides, the side facing water has more concentration of auxins and this inhibits its growth, while the other side grows faster and it has less auxins, so it bends towards water. 15- Sensitivity, coordination and response to a stimulus are called irritability. 16- In animals receptors and effectors are linked together and their action is coordinated by the nervous system. 17- Man can not feel all the stimuli like X- rays. Polarized rays - ultraviolet and infera red because man has no nerve cells which are affected by these stimuli. 18- The animal can not preceive all stimuli picked up by its sense organs, but it can preceive changes in them. 19- The external stimuli that most of the animals respond to are: Heat - gravity - pressure - chemicals - sound - water - light. 20- The nerve cell is the building unit of the nervous system. 21- The nerve cell consists of a cell body or cyton and long axon which is surrounded by two fatty layers [Myelin and schwann] these layers accelerate the speed of nerve impulses that reaches 120 m/sec. 22- The nerve cells are neither divide nor renewed. 23- Myelin and schwann's layer are interrupted at regular intervlas by the nodes of ranvier. 24- According to the function there are three types of nerve cells: A - sensory neurons: which transmit nerve impulses from receptors to the central nervous system. B - Motor neurons: which transmit the motor impulses to the effectors from central nervous system. C- Connector neurons: which carry impulses from one neuron to another. 25- The nerve cord: It is a bundel of axons which is surrounded by a sheath of fatty material [myelin and schwann] in addition to the outer nerve sheath. 26- The nerve: It is a long nerve cord. 27- The nerve impulse is a sequence of electro - chemical changes propagated along a nerve fiber and transmitted across synapses . 28- The nerve fiber is surrounded by a plasma membrane which is semipermeable so positive ions are accumulated at the outer surface while negative ions are accumulated at the inner side i.e the membrane has two poles or polarized; this is at rest. 29- When the nerve fiber is stimulated at a certain point, it loses it selective permeability at this point and becomes fully permeable, as a result of that the positive ions move to the inside and the membrane is said to be depolarized. 30- The time needed for the entry of sodium ions and the exit of potassium ions is from 0.002 to 0.005 seconds. 31- A period of about 0.001 - 0.003 sec. elapses between the end of impulse transmission through a certain point and the beginning of a new impulse this period is the refracotry period. 32- Synapse can be defined by two ways: A: Anatomically it is the site at which the terminal arborization of a neuron axon lie very close to the dendrites of a neighboring neuron. B: Physiologically: It is the functional connection between neurons. 33- The synaptic knob or cleft is formed for transmission of nerve impulses. 34- The synaptic knob contains many transmitting substances like nor-adrenaline- acetyl choline - and sympathin. 35- The nervous system in vertebrates consists of highly developed structures these are: A- Sensory receptors [sense organs] B- Nerve fibers [transmit impulses] C- Nerve centres. [in brain] 36- The nervous system in vertebrates and also in man consists of: A- The central nervous system which includes the brain and the spinal cord. B- The peripheral nervous system which includes 31 pairs of spinal nerves and 12 pairs of cranial nerves. 37- Physiologically the nervous system includes: Somatic nervous system (central and peripheral) : which controls the voluntary actions. B- Autonomic nervous system: which controls the involuntary actions. 38- The human brain weights about 1300 - 1400 grams, protected by the cranium bones, and surrounded by three membranes: A: Dura matter: a strong fibrous tissue adhering to the cranium. B: Pia matter: a transparent one adhering to the brain and contains blood vessels. C: Archnoid membranse: intermediate delicate layer of connective tissue, a transparent fluid passes through it, it contains proteins, glucose, sodium and potassium salts, it is used to feed and protect the brain. 39- Meningitis leads to the inflammation of the three membranes around the brain. 40- The human brain consists of: A: The cerebrum [the two cerebral hemispheres.] B: The cerebellum C- pons varolii D- Medulla oblongata. 41- The two cerebral hemispheres are the ceutre of high mental activities thought - memory - and reasoning. 42- Lab animals, car victims, brain tumor patients are used to make a map for the centres on the cerebral hemispheres that: The thinking and memory centres lie at the anterior part followed by voluntary movements centres, followed by the skin sensation, at the back the centre of vision hearing, smell, and taste lie at the two sides. 43- The nerve centres in the right hemisphere control the left sided organs and vice versa. 44- The nerve centres exist in identical locations in both of the two hemispheres except speech and writing centres. 45- The cerebellum coordinates the different voluntary muscle movements, also maintains the balance and posture of the body. 46- Pons varolii transmits impulses from the hemispheres and cerebellum to the medulla oblongata and vice versa. 47- The medulla oblongata transmits the impulses from the hemispheres to the spinal cord also controls the main involuntary actions. 48- The spinal cord transmits both sensory and motor impulses from the body to the brain and vice versa, it also contains the nerve centres which control the reflex actions. 49- The peripheral nervous system consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves. 50- The ability of nerves to transmit the impulses is affected by the amount of oxygen and decreases by the effect of some chemicals such as alcohol ether and other drugs. 51- The reflex action is the unit of the nervous activity. 52- Reflex actions include, constriction of the iris, blinking of the eyes, secretion of digestive juice and jerking of the leg if it is struck below the knee cap. 53- Reflex action is involuntary rapid response to a stimulus threatening the body with danger without brain involvement. 54- Reflex actions may take place during sleep or mild anesthesia. 55- The intensity of reflex action depends upon the general state of the body, it is affected by durgs. 56- Reflex actions may stop completely under the effect of strong anaesthetic substances; certain reflex actions may decrease the effect of another reflex actions.