control and coordination

Stimulus

Any change in the environment that produces a response in an organism

Receptors

They are cells or groups of cells present in sensory organs that detect stimuli and then convert them into nerve impulses

Photoreceptors

Location - eye

Function: detect light and help in vision

Phonoreceptors

Located in inner ear

Detect sound vibrations and help in hearing

Thermo receptors

Located in our skin

Detect temperature changes

Olafactory receptors

Located in the nose

They detect smell

Gustatory receptors

They are located in the tongue

and they detect taste

Response

The reaction of the organism to a stimulus

Effectors

Parts of the body that respond to impulses sent by the nervous system and convert them into actions

Ex- muscles

Neurons

Basics structural functional units of nervous system

Specialised cells that transmit information in the form of electrical impulses

Functions of neurons

Receive signals from sensory organs

Process and interpret those signals

Send responses to effectors for action

Synapse

It is the gap between the nerve ending of €1 and the dendrite of the next neuron

Signals move through the Synapse in chemical form

It is the site of conversion of electric impulse into chemical signal

Nerve impulse

An electrochemical signal that travels along the neuron

Working of neurons

Stimulus is detected by receptors

Chemical reaction at dendrite and electrical impulse is generated

This electrical impulse it travels through the neuron

At axon terminal neurotransmitters are released

And now the signal is transported in the form of chemicals to the next cell

Neuromuscular junction

The point where an nerve ending meets a muscle so that the nerves message can make the muscle contract

Neurotransmitters

Chemical messengers that are released by axon terminals they help in transmitting the nerve impulse across the Synapse

Sensory neurons

Carry messages from sense organs to brain of spinal cord

Motor neurons

Carry messages from brain or spinal cord to effectors

Relay neurons/inter neurons

Connect sensory and motor neurons within brain and spinal cord

Myelin Sheath

Fatty layer around the axon of some neurons

Act as insulating layer and speeds up transmission of nerve impulse

Voluntary actions

They are controlled by our own will

Thinking is involved

Brain is involved

Examples include walking, writing, dancing

Involuntary actions

Cannot be controlled by our own will

Thinking is not involved

Brain is involved

Examples include pumping of blood and peristaltic movements

Reflex action

A sudden automatic and involuntary response to a simulus without conscious thinking

It cannot be controlled by our own will as thinking is not involved

Spinal cord is involved

Brain is indirectly involved as message is sent to brain

Importance of reflex action

Provides immediate and automatic response to harmful similar

Protects body from injury

Saves time by avoiding delay of thinking in brain

Helps in Survival and safety by giving quick reactions in emergencies

Reflex arc

It is the pathway for reflex actions connecting sensory nerve to motor nerve

Fore brain

It is responsible for higher level function such as thinking perceiving and mainly controlling voluntary actions

it has three parts cerebrum, thalamus and hypothalamus

Cerebrum

Controls:

intelligence

memory

learning

emotions

voluntary movement

Thalamus

Act as relay station it directs sensory signals to cerebrum

Hypothalamus (thermos)

Regulates hunger, thirst, sleep, body temperature and emotions

Controls pituitary gland

Mid brain

It is the middle part of the brain and is located between the fore brain and hind brain

Functions:

Connects fore brain and Hind brain

Controls certain involuntary actions

Helps in processing sensory information and keeps body alert

Hind brain

It is the lower part of the brain and is located at the back of the skull

it connects the brain to spinal cord

It has three parts cerebellum, pons and medulla

Cerebellum (balance)

It controls balance posture and coordination of body movements

Pons (ponds)

Relay signals between different parts of the brain

It controls breathing

It controls sleep cycle

Medulla (medicine)

Controls involuntary actions like heartbeat, breathing, blood pressure and vomiting

Protection of brain and spinal cord

Both are covered by membranes called meninges

Cerebrospinal fluid surrounds them and acts as a shock absorber to protect from injury and damage

Difference:

Spinal cord is protected by vertebral column

Brain is protected by cranium

Glands

Glands are special organs in our body that make and release substances like hormones or enzymes

There are mainly two types of glands:

exocrine glands and endocrine glands

Exocrine glands

They have ducts

Secret substances like enzyme, sweat, saliva etc

They act locally

Examples are salivary glands, sweat glands,tear glands

Endocrine glands

Ductless glands - release hormones directly into blood

Secrete hormones only

Act on distant organs or tissues through blood

Examples:

Pituitary gland, thyroid gland, etc

Hormones

Chemical messengers

are secreted by endocrine glands

transported by blood

Pituitary gland

Located below the hypothalamus in the brain

Secrets many hormones but mainly growth hormone

Growth hormone regulates growth and development of bones and muscles

This gland is controlled by hypothylamus

Deficiency of growth hormone during childhood causes dwarfism

Excess of growth hormone leads to gigantism

Thyroid gland

Attached to windpipe in body

Producers thyroxine which contains iodine

Thyroxine controls the rate of metabolism of carbs, fats and proteins

Lack of iodine meaning lack of thyroxine can cause greater which is swelling of the neck due to enlarged thyroid gland

Parathyroid gland

Small glands embedded in the thyroid gland

They secret parat hormone with regulates calcium and phosphate levels in blood

Thymus gland

Located in lower part of neck and upper chest

Secrets thymus hormone which is responsible for development of bodies immune system

It is large in young children but shrinks after puberty

Pancreas

It is a mixed gland

Exocrine function includes secreting pancreatic juice

Endocrine function:

It's a creates insulin which lowers the blood sugar level and controls sugar metabolism

Deficiency of insulin causes diabetes characterised by high sugar level

It also secrets glucagon which raises blood sugar level

Adrenal glands

Also known as glands of emergency

They are two glands located on top of kidney

The secret address in hormone

Adrenaline regulates heart rate breathing rate blood pressure and carbohydrate metabolism

Secreted in small amount normally but large amounts during fear or excitement

Prepare the body for flight or fight response

How does Adrenaline help our body during emergency situations

It increases the heartbeat causing more oxygen to reach muscles

It increases the breathing rate causing more oxygen intake

It diverts the blood from the skin and digestive system to the skeletal muscles

Prepare the body for fight or flight response

Testes

Present only in males

Produce the male sex hormone testosterone

Also produce male gametes

Testosterone controls the development of male sex organs and secondary sexual characters

Changes caused by testosterone usually occur during puberty

Ovaries

Present only in female

It produces estrogen and progesterone

Estrogen controls the development of female sex organs and secondary sexual characters

progesterone - pregnancy

Hormonal imbalance

Excess or deficiency of hormones harms the body

Feedback mechanism

It controls the hormone release timing and amount of hormones released

For example if blood sugar is increased then pancreas secrete more insulin as the blood sugar level fault to normal insulin secretion automatically decreases

Control and coordination in plants

Plants have no specialised tissues for conduction of information

The movement happens due to the change in amount of water in cells

Phototropism

Movement of part of plant in response to sunlight

The plants stem shows positive phototropism

Plants root show negative phototropism

Geotropism

It is movement in response to gravity

Roots tend to show positive geotropism

Stem tends to show negative geotropism

Chemotropism

Movement in response to chemical stimulus

For example Pollen tube growing towards ovules

Hydrotropism

Movement in response to water

Roots show positive hydrotropism

Thigmotropism

Movement in response to touch

Example of thygmotropism is tendrils

Thigmonasty

Non directional movement in response to touch

Shown by Mimosa pudica

Photonasty

Non directional movement in response to light

Dandeline and tulips open in light

Moon flower open when it is dark

Tropic movement

It is directional movement

Growth occurs

It is more or less permanent

It takes longer

Nastic movement

Non directional response to stimulus

Movement is independent of growth

It is temporary and reversible

Immediate action occurs

Auxin

It promotes cell longation

It controls photo and geotropism

It helps in fruit development

Why do stem of plants bend towards light

When the light falls on one side auxin moves to the shady side and their the cells grow longer there for the stem bands towards the light

Gibberellins

Help in seed germination

Promote fruit development and flowering

Cytokinins

It Pramod cell division

It is found in high concentration in fruits and C

Abscisic acid

Inhibits growth

Causes welding of leaves and induces dormancy in seats

It helps the plant respond to droughts by closing the stomata during water stress to prevent water loss

Ethylene

Mainly responsible for writing a fruits

Also promote leaf fall and aging