Reflex action:- reflex action is a involuntary mechanism, spontaneous, automatic, rapid and mechanical response to the external stimuli on specific receptor without the will of an organism. eg. beating of heart, blinking of eyes, upward and downward movement of diaphragm during respiration.
Walking:- walking is a voluntary mechanism, slower than involuntary mechanism, occurs with the will of an organism. It requires brain involvement which sends the electrical signals to various body parts for the movement.
Synapse is a point of connection where two neurons gets connected or communicated, where one neuron sends information to another target nerve cell. Synapses are electrical or chemical. Electrical is where flow or exchange if ions occurs and in chemical synapse, they communicate using chemical messengers called hormones, or neurotransmitters.
Sensory nerves carry nerve impulses to the axon terminal which releases chemical messengers called neurotransmitters, then they goes through the synapse to reach the dendrite part of another neuron. And, finally these neurotransmitters goes to muscles, glands etc. to carry forward their actions.
Hind- brain parts cerebellum (back of the brain), maintains the posture and equillibrium of body. hind- brain consists of pons, cerebellum and medulla- which controls most of the involuntary actions (saliva secretion, vomiting, blood pressure, pupil contraction and relaxation etc.)
When we lighted an incense stick, then its fragnance diffuses and reaches our nose. which is detected by olfactory receptors. Then, through the sensory neurons these receptors goes in the special part of the brain, i.e, fore- brain :- detect the smell (where it is already stored as a memory), and converts in the form of electrical signals.
Reflex action is a rapid or quick response to stimulus (involuntary mechanism) because of lower number of synapses. so, the organism don't have enough time to think. The path of an impulse to travel only in one direction (reflex arc) as afferent to efferent neurons and this information also reaches the brain, where the brain records this event and stores it as a memory.
These are organic compounds which is synthesized by cells and tissues of plants called plant hormones/ phytohormones. They actively promote, or inhibit some factors and developmental processes of plants. five major groups of plants hormones are present:-
1. Auxin:- it stimulates cell elongation in stems by the protein expansin, which has low pH, 4.5. The amount of xylem and phloem ratio are regulated by auxin.
2. Gibbererllin:- It promotes the internodal elongation of plants. It also helps in seed germination by activating vegetative growth of embryo in plants.
3.Cytokinin:- It involves the cell division in which formation, maintainance and growth of root apical meristem and shoot apical meristem by cytokinin's both positive regulators in shoot apical meristem and negative regulators in root apical merisrtem. Also helps in chloroplast maturation.
4. Abscisic acid:- It is also known as stress hormone which acts in the stress condition of a plant (eg. closing of stomata in extremely drought conditon). It also promotes the root and shoot growth with seed dormancy and germination, also includes wilting of leaves.
5. Ethylene:- It is a gaseous hormone, present in almost every plant because it is responsible for may factors like flowering, fruit ripening, rooting and also for senescence (depends on its concentration).
The movement of leaves of the sensitive plants shows the bending or drooping of leaves when they being touched by someone and they doesn't show any growth pattern in them.
On the other hand, the movement of shoot towards light shows the process of phototropism which is unidirectional & shows the growth pattern.
Auxin is a plant hormone produced in stem tips that helps in cell elongation or expansion. Auxin also helps in the process of phototropism by binding, which helps the plant to grow towards light direction.
Also shows more physiological effects like cell differentiation (shows relative amount of xylem and phloem), inhibits root elongation etc.
Auxin promotes the cell elongation and inhibits the growth of lateral buds (shows apical dominance) cause it is produced in the stems tips.
Tendrils are sensitive to touch. When tendrils found any support, auxin stimulates on the faster rate of the cell on the opposite side and tendril then forms a circle around their support.
Hydrotropism is a part of tropism process that shows in plants. The growth and movement of plant roots towards or away from moisture is hydrotropism.
Chemical coordination takes place in animals by the chemical messengers called hormones, which are secreted by the endocrine glands or occurs by the nervous system.
Hypothalamus is the important part in intergrating the nervous and endocrine system.
When endocrine glands secrete hormones, neurosecretory cells are present in the brain which secrets the neurotransmitters. And these chemical messengers get converted into electrical signals and goes into muscles or glands for the movement or for the growth and development of an animal.
Iodized salt contains potassium iodate, dextrose etc. which is neccessory for our body for secretion of thyroxine hormone by thyroid gland. Deficiency of iodized salt cause goitre. which results into the swelling of neck.
Adrenaline is a hormone also called epinephrine, produced by adrenal gland. It increases the heart rate, increase blood pressure, redistribute the blood to muscles. The breathing rate increases during the diaphragm contraction and the muscles contraction, also if blood pressure increases it allows more glucose level to get into the bloodstream when adrenaline hormone is secreted into the blood.
Insulin is a hormone produced in pancreas and that helps to control high glucose level. It converts the food which we are taking into the form of energy in the bloodstream.
Diabetes occurs when too much sugar is taken in food or found in blood (high blood glucose level). If any patient is suffering from diabetes, doctors give that patient a insulin injection and it cannot be taken as a pill because it is made up of protein or secreted in pancreas that if taken through mouth, then it is denatured by the digestive process.
(d) Cytokinin
Cytokinin is a plant growth hormone also called phytohormones that promotes cell division (in shoot apical meristem or root apical meristem), morphogenesis (shoot & root initiation), chloroplast maturation and apical dominance (where main stem of the plant is dominant over side stem).
Involuntary actions are very quick which is performed by animal without its will or without thinking of the actions but controlled by parts of brain, eg. Heart beating, hand pulling when we touch an hot object.
On the other hand, reflex actions are automatic, result of sudden impulse without any stimulus and it is not controlled by brain .famous eg. - knee jerk (slow strike below the knee cap while sitting with freely hanging legs that kicks the legs forward), yawning, blinking of eyes, sneezing etc.
Nervous system:- It is consist of neurons, bundles of nerve fibres, neuroglia cells and have neurosecretory cells. Human nervous system is consist of two main parts:- CNS (central nervous system)- lies along the main axis of the body, consists of upper large brain in head or narrow spinal cord in neck or trunk.
PNS (peripheral nervous system)- It is associated with the CNS defined by afferent nerve fibre that transmit impulses from receptors present in organs to CNS) and efferent nerve fibre which transmit regulatory impulses from CNS to peripheral organs.
It is divided into two parts:
1. Somatic nervous system relays voluntary impulses from CNS to skeletal muscles.
2. Autonomic nervous system relays impulses from CNS to involuntary parts of the body.
On the other hand, hormonal mechanism is slower than nervous mechanism. Hormones are the chemical messengers which brings control, secreted by endocrine glands and released into the blood stream from axon ending. Various hormonal secretion is done by hypothalamus and are under control of secretion of neurosecretory cells.
sensitive plants- they are sensitive to touch, mostly their leaves like a plant chui mui (shows quick fold inward or droop when we touch their leaves). And they do not have special proteins for the movement they show only growth pattern.
Movement in our legs:- this is a voluntary action which depends on our willingness. They have special protein and muscles to contract by which they are able to walk or run. The nerve impulses sends to the brain and the brain sends signals the various body parts for the voluntary or as well as involuntary actions.
(b) Synapse
Synapse is a point of connections of two neurons. When a chemical reactions occurs in our body, it creates an electrical impulses from dendrite to the axon end. Then, it releases some chemicals and these chemicals goes in synapse and generate similar electrical impulses in dendrite of next neuron to muscle cells or glands.
(d) All of the above
Fore- brain is responsible for thinking, Medulla is responsible for the involuntary actions like breathing, heart rate, heart beat etc. And the voluntary actions like maintaining and balancing our body, comes under the part of hind- brain.
Receptors are transducers which exhibits sensitivity in various body parts. When our body receives any external or internal stimuli, it converts stimuli into nerve impulses (action potential) and send these impulses to other neurons, muscle fibres or glands.
If the receptors get damaged they will not detect the stimulus, as well our brain also will not detect the signals which will be harmful for our body (Eg. When we touch an cold or hot object or to getting burnt etc.)
Nervous system controls and coordinates the activities, bevahiour of animals, also maintains the homeostasis (internal body temperature) & is composed of two principal cells:-
Neurons (nerve cells)
Neuroglia or glial cells
Neurons:- These are the basic structural & functional unit of nervous system. They are specialized to respond to stimulus (any change in envirionment ,i.e, strong enough to initiate an nerve impulses) can be physical or chemical, conduct nerve impulses and release chemicals called neurotransmitters.
Nerve impulses travels at the speed ranges from 0.5 to 130 meters per second along plasma membrane of a neuron.
Neroglia cells or glial cells (glia-glue) :- These cells nourishes, protects and support the neurons.
Phototropism is the process of growth of an organism in response to light reaction or stimulus. It is mostly seen in plants, but can also observed on other organisms. There are two types of phototropism:-
Positive phototropism:- Growth of plant towards the direction of light is positive phototropism.
Negative phototropism:- When growth of a plant is away from light is negative phototropism.
Several signalling molecules helps the plants to determine the light stimulus, activates genes & change the hormones for the growth of plant (i.e, auxine). This hormone helps the plants to have elongated cells on the farthest side from the light stimulus.
In spinal cord injury, the receptor signal and the nerve signal will get disrupted that is conducted by the brain. And both these signals meets at one point ,i.e, spinal cord where the signals get disrupted.
Plants do not have nervous or muscular system for movement or responsiveness like animals have. Plants only shows the growth (by growth hormones like phytohormones) with the attached substratum by giving them appropriate soil moisture, favourable environmental or physiological conditions. Various plant hormones are present for the plant growth like auxin, gibberellin, cytokinin, ethylene or abscisic acid.
Auxin is responsible for the growth of the stem, gibberellins are those growth hormones which enhances the long growth of stem according to the plant in the presence of meristematic cells, cytokinin acts on the cell division part of the plant, ethylene is a gas present in atmosphere and mainly responsible for fruit growth or ripening with root initiation ,And abscisic acid is responsible for seed development, stomatal closing, bud dormancy etc.
Control and coordination is important for the survival of living organisms. Control comes under endocrine system by sending chemical messengers called hormones and nervous system composed of neurons which controls our body by sending electrical signals called nerve impulses.
Coordination is working together of various parts of body of multicellular living organisms in a sequence to inhance the functions of each other. Control and coordination is important in organisms so that they can do voluntary, involuntary actions in their biological rhythm cycle (24 hour cycle or sleep-awake cycle).
a) Sensory neuron
b) Spinal cord
c) Motor neuron
d) Muscles
a) Elongation of cells:- Auxin
b) Growth of stem:- Gibberellins
c) Promotion of cell division:- Cytokinin
d) Falling of senescent leaves:- Abscisic acid
Auxin, Gibberellins, Cytokinin, Abscisic acid all are the plant growth hormones which influences the specific physiological role or processes. Auxin promotes cell elongation, apical dominance, prevention of abscission layer and regulates the plant growth movement like phototropism and geotropism. Gibberellins enhance the longitudinal growth of stem when applied to intact plants; stimulate the pollen germination and growth of pollen tubes in some species. Cytokinin main function is to promote the cell division and also show some other physiological effects like cell enlargement, provides resistance to plant under high temperature, cold or diseases. And, Abscisic acid inhibits gibberellins stimulated growth and promotes senescence in leaves by causing the loss of chlorophyll pigment, decreasing rate of photosynthesis and change the metabolism of proteins and nucleic acid.
Endocrine glands:
a) Pineal gland
b) Pituitary gland
c) Thyroid gland
d) Thymus gland
Pineal gland secretes a hormone called melatonin. It causes the high and low concentration of pigment granules in the melanocyte, which makes the skin colour darker or lighter in certain animals.
Pituitary gland secretes various types of hormones and each hormone has its specific role like antidiuretic or vasopressin hormone decreases the loss of water in the urine by increasing the reabsorption of water in distal convoluted tubule, collecting tubule and collecting ducts.
Thyroid gland secretes three hormones and these hormones control the general metabolism by regulating the rate of oxidation and production of energy.
Thymus gland secretes peptide hormones called thymosins. They accelerate cell division, stimulate the development or differentiation of T- lymphocytes and increase the resistance to infection. Thus provides humoral and cell- mediated immunity.
Figure (a) is more accurate because the roots are growing towards the right direction according to the gravitational force hence shows positive geotropism and shoots upward i.e, opposite to the gravitational force hence shows negative geotropism.
Environment triggers various factors like gravity, light or water which changes the direction of growth of the plant. These directions show the tropic movements which can be towards the stimulus or can be away from it and shows positive or negative plant tropism respectively.
a) Dendrites (receiving or input portion of neurons)
b) Cell body (contains nucleus and surrounds by cytoplasm which includes cellular organelles)
c) Axon (cytoplasm of an axon called axoplasm and is surrounded by plasma membrane known as axolemma or myelin sheath)
d) Axonal terminal (axon and its collaterals end by dividing into many processes called axon terminals or telodendria).
Match the terms of Column (A) with those of Column (B)
| Column (A) | Column (B) |
|---|---|
|
(a) Olfactory receptors |
(i) Tongue (ii) Eye (iii) Nose (iv) Skin |
| Column (A) | Column (B) |
|---|---|
|
(a) Olfactory receptors |
(iii) Nose (iv) Skin (i) Tongue (ii) Eye |
Direction of growth of a plant due to environmental factors or external stimuli is known as tropic movement. The directional movements can be either towards the stimulus or can be away from it. Example:- The roots are growing towards the right direction according to the gravitational force hence shows positive geotropism and shoots upward i.e, opposite to the gravitational force hence shows negative geotropism.
Iodine is very essential for the synthesis of thyroxine hormone. Iodized salt contains potassium iodate, dextrose etc. which is necessary for our body. If the amount of iodine is less than the requirement, it may cause swelling up the neck.
Due to the deficiency of iodized salt, it may cause goitre disease and causes the enlargement of thyroid gland also known as hypothyroidism.
Synapse is a point of connection where two neurons get connected or communicated, where one neuron sends information to another target nerve cell. Synapses are electrical or chemical. Electrical is where flow or exchange if ions occurs and in chemical synapse, they communicate using chemical messengers called hormones, or neurotransmitters.
Sensory nerves carry nerve impulses in the form of electrical impulses to the axon terminal which releases chemical messengers called neurotransmitters, then they go through the synapse to reach the dendrite part of another neuron. And, finally these neurotransmitters go to muscles, glands etc. to carry forward their actions.
a) Oestrogen or Estrogen is responsible for the changes noticed in females at the stage of puberty. Women attain puberty at the age of 13. Estrogen is secreted by the ovarian follicle cells in the ovaries. This hormone leads to the growth and maturation of reproductive tract; and development of accessory sex characters.
b) Dwarfism results due to deficiency of Somatotrophic or Growth hormone which is secreted by anterior lobe of pituitary gland. Dwarfism shows the stoppage of growth of long bones of the body.
c) Blood sugar level rises due to deficiency of Insulin hormone. Insulin is secreted by the beta cells of islets of Langerhans by the rise in blood- sugar level. Deficiency of insulin causes diabetes mellitus.
d) Iodine is necessary for the synthesis of Thyroxine hormone. Due to deficiency of iodine can cause the swelling up of neck and goitre disease and causes the enlargement of thyroid gland.
a) Pituitary gland is associated with the brain. Anterior lobe of the pituitary and the posterior lobe of the pituitary are connected with the hypothalamus by the hypothalamo- hypophyseal portal system and by the axons of hypothalamic neurons respectively.
b) Pancreas secretes digestive enzymes like pancreatic juices as well as hormones (insulin, glucagon, somatostatin and pancreatic polypeptide).
c) Adrenals are the paired glands placed on the top of the kidneys. Adrenal gland secretes three types of steroid hormones:- Mineralocorticoids, Glucocorticoides, Sexcorticoids.
d) Testes are present in males but not in females. Testes secrete the testosterone hormone which leads to formation of sperms.
The nervous system consists of two types of cells:- Neurons and Neuroglia. Neurons are the basic structural and functional unit of the nervous system. They respond to the specific physical or chemical stimuli and conduct nerve impulses and release neurotransmitters. Whereas neuroglial cells are the glial cells which support, nourish and protect the neurons.
Neurons possess the ability to respond to a stimulus and convert it into the action potential. An action potential is an electrical signal that travels along the plasma membrane of a neuron and these nerve impulses travel at the speed ranging from 0.5 to 130 meters per second. On the basis of structure and functions neurons are classified into various types.
Structural:- Multipolar contains many dendrites and one axon; Bipolar contains dendrite and axon with a cell body; Unipolar possess extension of cell body which divides into two branches.
Functional:- afferent or sensory neurons carry nerve impulses from peripheral sensory receptors to the CNS; efferent or motor neurons transmit nerve impulses from the CNS to effector organs; and Interneurons are located within the CNS in which they form connection between afferent or efferent neuron.
Neurons are consisted of cell body, dendrites, axon, myelin sheath and their functions are as follows:-
1. Cell body:- also known as perikaryon and contains a nucleus which is surrounded by cytoplasm. cytoplasm contains cell organelles like lysosome, mitochondria etc. it contains free ribosomes and the cell body in the peripheral nervous system usually occurs in the cluster form known as Nissl bodies.
2. Dendrites:- Dendrites are the receiving or input portion of the neurons. They are short, hair- like or tightly branched.
3. Axon:- it is a long, thin, cylindrical projection which joins the cell body to the cone shaped structure called axon hillock. Axon propagates nerve impulses towards other neurons and then muscles or gland cells.
4. Myelin sheath:- axons are covered by a protective myelin sheath and this sheath is interrupted by gaps called Nodes of Ranvier. Myelin sheath serves as an excellent insulator.
Diagram:
The brain can be grouped into various parts based on anatomical distinctions and functional specialization. The brain is divided into three major regions:-
1. Forebrain (prosencephalon):- Largest part of the brain. It includes cerebrum and diencephalon. The diencephalon further consists of two main parts- thalamus and hypothalamus.
2. Midbrain (mesencephalon):- it includes tectum and tegmentum.
3. Hindbrain (rhombencephalon):- it includes pons, cerebellum and medulla.
Diagram:
Nervous system coordinates and controls the activities of the animals. Endocrine and nervous system together helps to maintain the homeostasis and also responsible for the behaviour, memories and controls all voluntary actions. There are two main subdivisions- central nervous system (includes brain and spinal cord) and Peripheral nervous system (consists of many nerve fibres including cranial nerves, spinal nerves, ganglia and sensory receptors etc.).
Diagram:
Brain is covered by cranial meninges. The outermost meninx is the dura mater which is composed of dense and irregular tissues, middle meninx is arachnoid mater and the innermost meninx is pia mater which contains cerebrospinal fluid provides cushion against the mechanical shock. Brain is enclosed in the skull which provides protection. Spinal cord is located within the vertebrate cavity of the vertebral column and spinal meninges surround the spinal cord which provides protection.
a) Thyroxin:- Thyroid gland secretes thyroxin hormone and control the general metabolism by regulating the rate of oxidation and production of energy. Iodine is necessary for the synthesis of Thyroxin hormone. Due to deficiency of iodine can cause the swelling up of neck and goitre disease. They promote the growth of the body tissues and stimulate tissue differentiation. Thyroxin also controls the working of kidneys and its deficiency results in the less amount of urine production.
b) Insulin:- Insulin is secreted by the beta cells of islets of Langerhans by the rise in blood- sugar level. Deficiency of insulin causes diabetes mellitus. It enables the liver and muscles to store glucose as glycogen and enables the tissues to take up and uses the glucose as the source of energy; thus lowers the blood- glucose level.
c) Adrenaline:- Adrenal has dual origin and are paired glands present on the top of the kidneys. It contains two regions:- adrenal cortex and adrenal medulla. Adrenal cortex secretes three hormones:- Mineralocorticoids, Glucocorticoides, Sexcorticoids. Each one of them has its own functions like Mineralocorticoids regulate minerals metabolism and controls the sodium and potassium ratio in the intra or extracellular fluids. Or, Adrenal medulla secretes two hormones:- epinephrine and norepinephrine.
d) Growth hormone:- Growth hormones are secreted by the anterior lobe of pituitary gland, also called Somatotropin which stimulates the growth and development of all tissues by triggered the protein production and cell division.
Deficiency and excessive release of growth hormone causes various diseases like Dwarfism, Gigantism, acromegaly etc.
e) Testosterone:- Testosterone is secreted by testes and stimulates the male reproductive system to grow to full size and formation of sperms. It also stimulates the development of accessory sex characters like hair on face, deepening of voice etc. at the age of puberty and increases the fertility in males.
Plant hormones are organic compounds which are synthesized by cells and tissues of plants called plant hormones/ phytohormones. They actively promote, or inhibit some factors and developmental processes of plants. Five major groups of plants hormones are present:-
1. Auxin:- it stimulates cell elongation in stems by the protein expansion, which has low pH, 4.5. The amount of xylem and phloem ratio is regulated by Auxin.
2. Gibberellins:- It promotes the internodal elongation of plants. It also helps in seed germination by activating vegetative growth of embryos in plants.
3. Cytokinin:- It involves the cell division in which formation, maintenance and growth of root apical meristem and shoot apical meristem by cytokinin’s both positive regulators in shoot apical meristem and negative regulators in root apical meristem. Also helps in chloroplast maturation.
4. Abscisic acid: It is also known as stress hormone which acts in the stress condition of a plant (example:- closing of stomata in extremely drought conditions). It also promotes the root and shoots growth with seed dormancy and germination, also includes wilting of leaves.
5. Ethylene: It is a gaseous hormone, present in almost every plant because it is responsible for many factors like flowering, fruit ripening, rooting and also for senescence (depends on its concentration).
Reflex action is a rapid or quick response to stimulus (involuntary mechanism) because of lower number of synapses. So, the organisms don’t have enough time to think. Or, it is also defined as the spontaneous, automatic and mechanical response to external stimuli which acts on the specific receptor.
Examples:- beating of heart, blinking of eyes, knee jerk reflex action, upward and downward movement of diaphragm during respiration. In knee- jerk reflex, a gentle strike below the knee cap, while sitting with free hanging legs then it shows the movement i.e it kicks the leg forward.
Reflex arc:- The path travelled by an electric impulse in a reflex action is called reflex arc. It consists of five parts:
1. A specific receptor:- It receives a stimulus and sets up a sensory impulse.
2. An afferent nerve:- it brings the sensory impulse from the receptors to the central nervous system.
3. Brain or spinal cord, are the portion of CNS which analyse and interpret the sensory impulse and set up an appropriate motor impulse.
4. An efferent nerve:- it carries the motor impulse from CNS to specific modulator and results in specific response to stimuli for the immediate action.
The endocrine system and nervous system are structurally, chemically and functionally related to each other. Endocrine glands are directly connected with the brain. And nervous system contains neurosecretory cells which are present in the brain i.e hypothalamus secretes many hormones. Hypothalamus receives information about any environmental changes and availability of mate occurrence through the nerves and then it releases some hormones required according to the requirement.
Nervous system and endocrine system affect each other’s output. This statement is justified by the following example:- the release of milk by nursing mother, is controlled by various nervous and hormonal signals. When the infant sucks the nipples of the mother, then suckling stimulates sensory cells in nipples, and the nervous signals to hypothalamus which causes the release of hormone oxytocin. And, oxytocin then stimulates the mammary glands to secrete milk. Hypothalamus plays important role in integrating the nervous and endocrine system in the vertebrates.
Chemical coordination takes place in animals by the chemical messengers called hormones, which are secreted by the endocrine glands or occurs by the nervous system. When endocrine glands secrete hormones, neurosecretory cells are present in the brain which secrets the neurotransmitters which are released into the blood stream to reach the target site. And, these chemical messengers get converted into electrical signals and goes into muscles or glands for the movement or for the growth and development of an animal.
Like in adrenal medulla, it secretes two hormones epinephrine and Norepinephrine which prepare the animal to face special condition created by physical stress such as fall in blood pressure or blood sugar etc. all these conditions require more energy provided by increasing heart beat, blood pressure, respiratory rate etc. Heart speeds up the pumping action so that more blood could be supplied to the body parts and shows various activities. These both hormones role also called fight or flight reaction which prepares us to meet the stress.
One neuron sends information to another target nerve cell in the form of electrical or chemical signals. Electrical is where flow or exchange if ions occurs and in chemical synapse, they communicate using chemical messengers called hormones, or neurotransmitters. Sensory nerves carry nerve impulses to the axon terminal which releases chemical messengers called neurotransmitters, and then they passed through the synaptic cleft to reach the dendrite part of another neuron. And, finally these neurotransmitters goes to muscles, glands etc. to carry forward their actions.
A nerve impulse can flow only in one direction in a reflex arc (afferent to efferent neuron) because the nerve impulse can cross the synapse only in the one way or direction. Stimulation of an effector cannot produce a reflex arc response in the receptor. Thus the flow of signals in a synapse will be from axonal end of one neuron to another neuron.
