- Movements in Plants
- Hormones in Animals
- Control and Coordination in Animals
- Human Nervous System
- Coordination in Plants
Plants do not show the type of movements that animals exhibit. Plants are anchored to a place, remain stationary and perform their duties.However, plants also show certain movements of their body or body parts in response to changes in the environment. Most of these movements are hard to see. The movements that plants exhibit come under two categories viz Growth movements and Turgor movements.
Growth movements are brought about by the unequal growth in different places of the same plant organ.
- Nutation: Shoot growth occurs at a faster rate alternately on the right and left sides of the axis, resulting in a zig-zag axis. Examples: the inflorescence axis of wheat and barley.
- Circumnutation: The weak stems of climbers and twiners as they coil around a support, exhibits a movement called Circumnutation. This spiral movement of stems is due to unequal growth on the two sides of the stem.
- Hyponasty: The differential growth of young leaves, buds and floral parts resulting in the curving upwards of these organs, are movements coming under the category of Hyponasty. This is because of a higher level of growth of the lower surface of the organ as a result of which the budgets enclosed. The circinate coiling of fern leaves is an example of such movements.
- Autonomic Growth Movement: When the leaves mature and grow in size and the flower buds open, more rapid growth occurs on the upper surface. This results in unfolding of coiled leaves and the opening of the flowers. This type of movement is called autonomic growth movement.
Movement in plants :
Plant shows two types of movements- one dependent on growth and the other independent of growth.
Tropic Movements: Movements due to growth
- A growth movement of a plant part in response to an external stimulus in which the direction of a stimulus determines the direction of response s called tropism. Thus tropism is a directional movement of the part of a plant caused due to its growth.
- The tropic movements can be either towards the stimulus or away from it e.g. the shoot of a growing plant bends towards the light, while roots of a plant move away from light
Types of tropism:
1. The movement of a plant part in response to light is called phototropism.
2. The movement of a plant part in response to gravity is called geotropism.
3. The movement of a plant part in response to chemicals is called chemotropism.
4. The movement of a plant part in response to water is called hydrotropism
5. The directional growth movement of a plant part in response to the touch of an object is called Thigmotropism.
Nastic Movements: Independent of growth.
- In nastic movements, the movement of plant part is neither towards the stimulus nor away from the stimulus. This movement is not a directional movement of the plant part with respect to the stimulus. In nastic movements, growth may or may not take place.
Types of nastic movements:
(1) Seismonastic Movements These movements are brought about by mechanical stimuli such as contact with a foreign body, fast wind and raindrops etc.
(2) Photonastic Movements These movements are induced by fluctuations in the intensity of light
(3) Thermonastic Movements Such movements are brought about by changes in temperature.
(4) Nyctinastic Movements. These movements are induced by the alternation of day and night.
Hormones in animals conduct a variety of functions like growth, sexual development, vegetative development, cellular respiration, metabolism, thermal production etc. While the nervous system coordinates activities of animals like movement, hormones integrate the coordination. Larger complex animals like vertebrates have endocrine glands to produce hormones.
The well-known animal hormones are insulin, estrogen, testosterone.
- Hormones play an important role in control and coordination in humans along with nervous system.
- Glands are known to secrete hormones and enzymes.
- There are two types of glands viz. endocrine and exocrine.
- Endocrine glands lack the ducts and hence, release the hormones directly into the blood. Blood carries the hormones from the site of secretion to the site of action.
- Exocrine glands contain ducts and hence, the site of synthesis of glands is same as their site of action i.e. the enzymes produced by the exocrine glands are not dependent on blood to carry them to their respective site of action.
Pituitary gland (master gland) (single):
- Present in the Hypothalamus of the brain
- It controls growth.
- Controls secretion of other glands.
Pineal gland (single):
- Present in the brain.
- Responds to light exposure.
Thyroid gland (paired):
- Present in the neck region.
- Produces thyroxin (contains iodine).
- Responsible for metabolic rate,healthy hair & skin.
- Lack of iodinespan id="Mathax-Element-1-Frame" class="MathJax" style="display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 16px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;" tabindex="0" data-mathml="">→→ Deficiency of Thyroxinespan id="MathJax-Element2-Frame" class="MathJax" style="display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 16px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;" tabindex="0" data-mathml="">→→ Goitre
Parathyroid gland (paired):
- Present above the thyroid gland.
- It is a Para hormone.
- Controls and regulates the level of calcium and phosphorus in blood.
- Lack of this hormonespan id="MathJax-Elment-3-Frame" class="MathJax" style="display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 16px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;" tabindex="0" data-mathml="">→→ Brittle bones,
Pancreas (Islets of Langerhans):
- It is present behind the stomach.
- Produces insulin.
- Regulates blood sugar level.
- Deficiency of insulin causes diabetes.
Testes, ovaries (paired):
The body of all living organisms is made up of cells. These cells aggregate and differentiate to form tissues and assembly of different tissues form different organs. The various organs perform their functions at the right time so that they can work together efficiently. Therefore, some form of control is needed to coordinate their functions.
In case of animals, including man, the chemicals produced by ductless (endocrine) glands also bring about coordination. This coordination by chemicals is brought about by the endocrine system. On the other hand, the nervous system consists of a series of nerve cells throughout the body. Signals from one part of the body are transmitted to another part through these nerve cells
Control and Coordination in Animals:
- A system of control and coordination is essential in living organism to maintain homeostasis as well as to respond to various stimuli.
- The working together of various organs in an organism, to produce a proper response to a stimulus is called coordination.
- In animals, control and coordination is done by the nervous system and endocrine system.
- Nervous system is an organ system containing network of specialized cells called neurons.
Important terms
- Receptors: Specialized structures at the ends of the nerve fibres, that collect the information to be conducted by the nerves, and are located in the sense organs.
- Synapse: A specialized junction between two neurons, across which nerve impulse passes.
- Neuromuscular junction: A junction between a nerve fiber and muscle cell.
- Nerve impulse: An electrochemical signal that travels through a neuron in response to a stimulus.
- Effectors: A muscle, gland, or organ capable of responding to a stimulus, especially a nerve impulse.
- Sensory neuron: A neuron that conducts impulses from a receptor organ to the central nervous system.
- Motor neuron: A neuron that conducts impulses from the central nervous system to muscle or gland.
- Relay neuron: A neuron which connects sensory neurons with motor neurons in neural pathways.
- Reflex action: An automatic, rapid, involuntary and immediate reaction to a stimulus.
- Reflex arc: The neural pathway that mediates a reflex action.
Neuron
- A neuron is a cell that carries electrical impulses.Neurons are the basic units of the nervous system and its most important part is the brain.
- Every neuron is made of a cell body (also called a soma), dendrites and an axon.
- Dendrites and axons are nerve fibres.
- Neurons are connected to one another and tissues.
- They do not touch and instead form tiny gaps called synapses.
- These gaps can be chemical or electrical synapses and pass the signal from one neuron to the next.
- Males span i="MathJax-Element-4-Frame" class="MathJax" style="display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 16px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;" tabindex="0" data-mathml="">→→ Present outside the pelvic region and produces testosterone.
- Females span id=MathJax-Element-5-Frame" class="MathJax" style="display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 16px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;" tabindex="0" data-mathml="">→→ Present inside the pelvic region and produces oestrogen.
- Responsible for Secondary sexual characters, puberty, sperm production (males), Egg production (females)
- Lack of secretion of these hormones would result in infertility & delay in onset of puberty.
Adrenal gland:
- It is present above the kidney.
- Produces adrenaline (fight or flight hormone).
- Functions include span id="MathJax-Eement-6-Frame" class="MathJax" style="display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 16px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;" tabindex="0" data-mathml="">→→ increases heartbeat, supplies more oxygen to muscles, increases breathing rate, lowers blood supply to the digestive organs and increases supply to the skeletal system.
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4. Human Nervous System
There are billions and billions of neurons in your brain (about 85 billion), and they’re all sending electrical signals throughout your body right now! They tell your eyes to move across this page, how to interpret the words that you read, how to maintain your posture, your heart rate, and your breathing…all of it in a fraction of a second. In this section, we’ll explore the nature of this vast, complex system, from the cellular level to how it operates at a sensory level. A common misconception is that we only have 5 senses (see, smell, taste, hear, and feel), but we have many more that are nuanced but equally important. Here, we will learn more about how our bodies are designed to interact with the world.
- Unlike, plants that lack nervous system, animals have an elaborate nervous system.
- In humans, nervous system is divided into three categories viz. central nervous system (CNS), autonomous nervous system (ANS) and peripheral nervous system (PNS).
- CNS consists of brain and spinal cord. Brain in turn is divided in fore brain, mid brain and hind brain.
- All the different parts of the brain together control voluntary and involuntary actions. It is responsible for controlling thinking, reasoning and intelligence. In contrast, spinal cord controls reflex action and is the centre part of reflex arc.
- Cerebrum is the most complex and specialised part of fore brain. The thought process, control of voluntary actions, memory and hunger are the main functions performed by fore brain.
- Mid brain consists of hypothalamus and pituitary gland that serves pivotal role in chemical coordination and secretion of hormones respectively.
- Hind brain is divided into three parts viz. cerebellum (controls posture and balance, precision of voluntary actions), medulla (controls involuntary actions viz. vomiting, salivation and blood pressure) and PONS (controls involuntary action, and role in regulation of respiration).
- ANS consists of two types of nerves viz. sympathetic and parasympathetic which perform antagonistic functions with respect to each other.
- PNS consists of twelve pairs of cranial nerves and thirty one pairs of spinal nerves.
5. Coordination in PlantsAlthough plants lack nerves and muscles, they too have well-coordinated and controlled movements, Movements are the basic features of any living being. Plants may seem less interactive than animals, yet they actually have many ways of responding to their environment, changing their growth or physiology to make the best use of available resources. In this section, you will learn more about plants and their response to environmental cues.
- Phytohormones are the plant hormones that are responsible for control and coordination in plants.
- They are naturally occurring chemical substances which control one or other aspect of growth.
- Auxins are phytohormones responsible for cell enlargement and differentiation.
- Gibberellins are phytohormones responsible for cell enlargement and differentiation They can perform this function only in the presence of auxins.
- Cytokinins are phytohormones that promote cell division, and opening of stomata.
- Abscisic acid is a phytohormone responsible for closing of stomata, wilting and falling of leaves. Abscisic acid owes its name to its role in the abscission of plant leaves.
