Plant Movements and Tropisms

• Complexity in organisms increases the distance between cells and organs.
• A system for different parts of organisms to function as a single unit is required.
• Coordination between different parts is essential to perform functions.
• Picking up an object requires coordination among eyes, hands, legs, and the vertebral column.
• Actions need to be coordinated in a specific sequence for completion.
• Internal body functions also necessitate similar coordination.
• Organisms respond and react to changes in the environment, these changes are called stimuli.
• Response to a stimulus usually involves movement of a body part.
• Both plants and animals respond to stimuli.
• Homeostasis is maintaining constant internal body conditions.
• 'Homeo' means same and 'stasis' means standing still.
• The physiology of the organism controls internal conditions to maintain a constant state.
• Plants, like animals, need to control and coordinate various functions.

Coordination in Plants

• Plants lack a nervous system.
• Plants use plant hormones or phytohormones for control and coordination.
• Plant hormones regulate various aspects of plant growth.
• Plant growth is divided into three stages: cell division, cell enlargement, and cell differentiation.
• Plant hormones control these three stages of plant growth.
• Plant hormones are responsible for promotion and breaking of dormancy, control of stomata, fruit growth, leaf fall, and plant aging.
• Four major types of plant hormones include Auxins, Gibberellins, Cytokinins, Abscisic acid, and Ethylene gas.
• Abscisic acid inhibits growth, while Auxins, gibberellins, and cytokinins encourage growth.

Plant Hormones

• Auxins promote cell enlargement, cell differentiation, and fruit growth.
• Auxins are responsible for phototropic and geotropic movements in plants.
• Auxins are produced at the tips of stems and roots.
• Auxin moves away from light and toward gravity, affecting stem and root growth.
• In stems, growth is sped up, but in roots, growth is slowed down.
• Synthetic auxins like indole -3- acetic acid, 2,4 – D are used in agriculture and horticulture.
• Gibberellins promote cell enlargement and differentiation in the presence of auxins.
• They aid stem elongation, breaking dormancy, and promoting germination.
• They also promote fruit growth.
• Gibberellic acid (GA3) is sprayed on grape vines to induce parthenocarpy, or the development of seedless grapes.
• Cytokinins promote cell division, break dormancy in seeds and buds, and delay leaf aging.
• Cytokinins promote the opening of stomata and fruit growth.
• Abscisic acid mainly functions as a growth inhibitor, promoting dormancy in seeds and buds.
• It helps in closing stomata and encourages wilting and leaf fall.
• ABA causes the detachment of flowers and fruits from plants.
• Ethylene gas stimulates fruit ripening; ripe fruits release ethylene gas to ripen raw fruits nearby.
• Calcium carbide meets water and produces acetylene gas.
• Acetylene gas, like ethylene gas, ripens fruits quickly, used by fruit vendors.

Plant Movements

• Plant movements are divided into tropic movement and nastic movement.
• Geotropic movement is growth in response to gravity.
• Roots usually show positive geotropic movement, and stems usually show negative geotropic movement.
• Phototropic movement is growth in response to light.
• Stems usually show positive phototropic movement, roots usually show negative phototropic movement.
• When a plant is shielded from sunlight except for a hole, the stem grows toward the sunlight due to higher cell division rates away from sunlight.
• Hydrotropic movement occurs when roots grow toward the nearest water source, which is a positive hydrotropic movement.
• Thigmotropic movement is growth in response to touch, found in tendrils of climbers.
• Tendrils coil around a support due to differential cell division caused by auxin.
• Chemotropic movement is the movement in response to a chemical stimulus.
• Positive chemotropism is movement toward the chemical, negative chemotropism is movement away.
• Pollen tube growth toward the ovule is an example of positive chemotropism.
• The pollen tube grows toward a sugary substance secreted by the carpel in the flower.
• Nastic movement does not depend on the direction of the stimulus.
• Seismonastic movements are caused by mechanical stimuli like touch, wind, or raindrops.
• Touching leaves of Mimosa pudica causes them to droop, independent of the direction of touch.
• Photonastic movements are induced by light intensity changes.
• Flowers of several plants open with increasing light and close with decreasing light.
• Thermonastic movements are brought about by changes in temperature.
• Mirabilis jalapa starts blooming in the late afternoon and closes by mid-morning in response to temperature.
• Nyctinastic movements, or "sleeping movements", are induced by alternating day and night.
• Leaves of plants like clover droop and close toward evening, not rising until the next morning.

Control and Coordination in Animals

• The nervous and hormonal (endocrine) systems are responsible for control and coordination.

The Nervous System

• The nervous system is composed of nervous tissue, which is made of nerve cells or neurons.
• The nervous system is responsible for control and coordination in complex animals.

Receptors

• Receptors include specialized nerve fiber tips that collect information to be conducted by the nerves.
• Receptors are in the sense organs.
• Phono-receptors: inner ear, hearing and body balance.
• Photo-receptors: eye, visual stimulus.
• Thermo-receptors: skin, pain/touch/heat stimuli.
• Olfactory-receptors: nose, smell.
• Gustatory-receptors: tongue, taste detection.
• Receptors in sense organs receive stimuli and send messages as electrical impulses to spinal cord and brain through sensory nerves.
• An effector is a body part that responds to a stimulus based on instructions from the nervous system.
• Effectors are mainly muscles and glands.

Human Nervous System

• The structural and functional unit of the nervous system is the neuron.
• Each neuron has three main parts: dendrites, cyton/soma/cell body, and axon.
• Dendrites receive impulses from neurons.
• Cyton/soma processes impulses.
• Axons transmit impulses to another neuron or to muscles/glands.
• Axons may be myelinated or non-myelinated.
• Impulse transmission is faster in myelinated neurons.
• Schwann cells and the myelin sheath provide myelin insulation to axons, increasing impulse speed in the peripheral nervous system.
• Nodes of Ranvier are gaps between myelin sheath cells along axons.
• Types of Neuron; Sensory neurons receive signals from a sense organ.
• Motor neurons send signals to a muscle or gland.
• Association or relay neurons relay signals between sensory and motor neurons.
• A synapse is the point of contact between the terminal branches of axon of one neuron with the dendrite of another neuron.
• The neuromuscular junction (NMJ) is where a muscle fiber meets a motor neuron carrying nerve impulse from the central nervous system.
• The transmission of nerve impulses from one neuron to the next: Dendrites to cell body to axon to nerve endings at the tip of the axon to synapse to dendrite of next neuron.
• Chemicals are released from axon tip of one neuron cross the synapse or neuromuscular junction to the next cell.
• Acetylcholine is one of these neurotransmitters.

Organs of the Human Nervous System

• The central nervous system (CNS) consists of the brain and spinal cord.
• The brain controls all bodily functions.
• The spinal cord relays signals between the brain and the peripheral nervous system.
• The peripheral nervous system consists of cranial nerves and spinal nerves.
• There are 12 pairs of cranial nerves extend from the brain to organs in the head region.
• There are 31 pairs of spinal nerves extend from the spinal cord to organs below the head.
• Visceral nerves connect internal organs to the spinal cord and some directly to the brain.
• The autonomous nervous system is composed of a chain of nerve ganglion running along the spinal cord.
• It controls all involuntary actions. -It is divided into the sympathetic and parasympathetic nervous systems.
• The sympathetic nervous system (SNS) controls the 'fight or flight' response.
• In threatening situations, the SNS prepares to fight or flee.
• It directs energy from non-essential functions to essential functions.
• The hormone adrenaline is released from the adrenal gland, causing physiological changes.
• During the SNS response, heart rate and blood pressure increase - boosting oxygenated blood flow.
• Bronchial tubes dilate, and extra oxygen improves alertness.
• Pupils dilate for better vision.
• Responses occur rapidly and involuntarily.
• Adrenaline released; heart rate increases; high blood pressure; bronchial tubes dilate are effects of the SNS.
• The parasympathetic nervous system slows down organ activity, creating a calming effect and facilitating the conservation of energy.
• It maintains steady heart rate and blood pressure while stimulating digestion and sexual function.
• This includes saliva production, tears, urination, digestion, defecation, and sexual arousal.
• Key effects of the parasympathetic System; increased production of saliva, increased production of mucus, higher motility of large and small intestines, higher activity in stomach,increased urine, constricted bronchial muscles, constricted pupils and decreased heart rate,.

Human Brain

• The brain is a complex organ composed of nervous tissue.
• Tissues are folded to maximize surface area within a small space.
• The brain is covered by three layers of membranes called meninges.
• Cerebrospinal fluid between the meninges cushions the brain against mechanical shocks.
• Parts of the human brain: forebrain, Midbrain, and Hindbrain.
• The forebrain consists of the olfactory lobes, cerebrum, and diencephalon.
• The midbrain consists of the hypothalamus.
• The hindbrain consists of the cerebellum, pons, and medulla oblongata.

Some main structures

• Olfactory lobes deal with the sense of smell.
• The cerebrum is the brain's largest part, divided into two hemispheres connected by the corpus callosum.
• The corpus callosum transmits messages between hemispheres.
• Each hemisphere controls the opposite side of the body.
• Cerebral hemispheres are hollow with an outer cortex of grey matter and an inner medulla of white matter.
• Each hemisphere consists of 4 lobes: Frontal responsible for the reasoning, emotion, and speech
• Parietal responsible movement - Occipital responsible visual processing - Temporal responsible for memory.
• The cerebrum controls voluntary motor actions, is responsible for sensory perceptions (tactile and auditory), seat of learning and memory.
• The diencephalon lies between the cerebrum and midbrain, linking the nervous and endocrine systems.
• It receives and interprets nerve signals, signaling the pituitary gland.
• It consists of the thalamus and hypothalamus.
• The thalamus relays center for pressure and pain.
• The hypothalamus lies at the base of the cerebrum, controlling the circadian rhythm, controls the urges for eating and drinking, pituitary gland, body temperature and blood pressure.
• The midbrain connects the forebrain with the hindbrain and integrates sensory information to enable fine motor adjustments.
• The hindbrain consists of the pons, medulla oblongata, and cerebellum, governing autonomic body systems.
• The pons relays impulses and regulates respiration.
• The medulla forms the brain stem and controls heart rate and blood pressure.
• Medulla controls involuntary actions such as vomiting,.
• The cerebellum coordinates motor functions - controlling posture, balance, and precision of voluntary actions.
• The spinal cord is part of the central nervous system and is connected to the brain.
• The spinal cord contains a collection of nerve fibers within the vertebral column.
• Cross-sections of spinal cord displays grey matter shaped like a butterfly surrounded by a white matter.
• The gray matter of the spinal cord contains the central canal, filled with cerebrospinal fluid (CSF).
• The white matter of the spinal cord consists of axons, facilitating communication.
• The spinal cord links between the brain and the peripheral nervous system, provides skeletal support and body's posture, facilitates flexible movements, allows the myelin insulates and electrical conduction.
• The spinal cord communicates messages and coordinates reflexes for sensory to send for processing.
• Reflex Action: body part immediately pulled away from danger for its own safety.
• Reflex Arc involves the nerves that signals follow in a reflex action. -Receptor to sensory neuron to relay neuron to motor neuron to effector muscle.
• The receptor in the danger zone, sensory neurons pick signals from the receptor, the relay neuron is in the spinal cord for signals via the motor neuron.
• The reflex arc passes at the spinal cord level, signals involved do not travel up to the brain, allowing an ultimately action, the reflex action is mainly controlled at the level of spinal cord.
• Brain protection involves a fluid-filled balloon shock absorber and enclosure in the cranium.
• The spinal cord is enclosed in the vertebral column.
• Special filaments such as actin and myosin in muscle tissues allows muscular Movements and Nervous Control. A series of triggered events occurs.
• When a muscle receives a nerve signal, calcium ions will enter the muscle for actin and myosin filaments sliding towards each contracting a muscle.
• Contraction in a muscle brings movement.

Endocrine System

• The endocrine system is composed of several ductless glands that are called endocrine which hormones are produced in.
• These hormones directly go to bloodstream; controlling many body functions, involving reproductive processes.
• Hormones assist the nervous system, and are required for the control and coordination. Hormonal control is slow; requiring the release of chemical messengers by specialized tissues.
• They act on target tissues/organs away from their source on the specific protein molecule.
• Around 20 hormones are released in animals to the bloodstream.
• Several factors such as minerals, stress, infection for hormone levels in the body.
• Gland: A cell, a tissue or an organ which secretes useful chemical compounds.
• Endocrine Glands that secrete hormones such as; Pituitary, Thyroid, Adrenal, Parathyroid etc.
• Exocrine Glands that secrete either directly such as; salivary glands, Tear, sweat, gastric gland, and liver etc.
• Heterocrine Glands that have both endocrine and exocrine glands such as; Alpha cells that secrete glucagon, beta cells secrete insulin.
• The islets of Langerhans in the pancreas have both Alpha and beta cells.
• The testes and ovaries in the gonads produce gametes and secrete hormones.
• The hypothalamus is a minute region that is present a center of the brain.
• Following the functions where the hypothalamus is maintaining the body's internal balance.
• The hypothalamus connects both for releasing of releases 8 Hormones.
• For activities like regulating the body temperature, body weight, heart rate and maintaining homeostasis where the hypothalamus controls the rhythm.
• Pituitary gland that is a pea-sized gland at the base of the brain for all endocrine glands.
• Growth Hormone that is for dwarfism/Gigantism and Thyroid is Luteinizing where other hormones are secretes glands.
• Thyroid gland that is a butterfly for regulating metabolism of the body and playing in growth.
• In case of iodine where there could be undersetion of the thyroid in the body.
• Cause enlargement of the thyroid gland leads to swollen neck in children.
• There is stoppage of the hormones and growth of child,.
• Parathyroid Releases parathormone for calcium in bones.
• Pineal The produce that produce that regulate sleep patterns.
• Pancreas A leak like the stomach has functions such as the endocrine and is known for glucagon .
• The endocrine glands produce hormones for diabetes is produced.
• Adrenal that secretes the adrenaline where paired each kidney helps adrenaline response.
• The hormone is rapidly increases the breathing rate etc.
• Norepinephrine This hormone also works to mobilze stress.
• Thymus Between the the Brest bone plays role in immune system .
• Gonads are a produce where male hormones occurs .

Feedback Mechanism in Harmones

• These should be precise in both access and deficiency for a harmful in how much should be secreted.
• With levels in our sugar, more insulin is secreted with our pancreas.
• To maintain our glucose and the breakdown our sugar for the better in maintain.

Explore plant movements like phototropism, thigmotropism, and nastic movements. Understand the role of auxin in plant responses to light and touch. Learn about stimuli for nyctinastic movements and the causes for drooping of mimosa leaves.