Biology Nerves, Hormones and Excretion in Animals

Differences of the nervous and endocrine systym?

• The nervous system’s communication is via impulses that travel down neurones - The endocrine system’s communication is via hormones that travel in the blood

• The nervous system’s response is instant - The endocrine system’s response takes a long time to happen

• The nervous system’s response is short lived - The endocrine system’s response can last for a long time

What is the central nervous system made up of?

The central nervous system is made up of the brain, the spinal cord and linked to effector cells by neurones

How does the central nervous system work?

A stimulus is detected by a receptor cells, which sends an electrical impulse to a sensory neurone. The sensory neurone sends the electrical impulse through the central nervous system and to a relay neurone, which connects sensory neurones with motor neurones. The motor neurone carries the impulse from the central nervous system to the effector cells, where a response takes place

What is the role of neurotransmitters at synapses?

Neurones don’t touch one another, so where the dendrites of two neurones meet, a synaptic cleft is formed. This is where the presynaptic membrane of the presynaptic neurone fuses with vesicles filled with neurotransmitters. This turns the electrical signal to a chemical signal and then the neurotransmitters diffuse across the synaptic cleft, and bind to the receptor cells of the post-synaptic neurone, converting the chemical signal back into an electrical signal, carrying on the electrical impulse

What is the structure of a reflex arc?

Reflex arcs consist of a stimulus, receptor, coordinator, effector and a response

What is the function of a reflex arc when a finger touches something hot?

The temperature receptors detect the stimulus of a hot object. Sensory neurone relays the electrical impulse to the spinal cord where it is passed to a relay neurone, which synapses with a motor neurone. Motor neurone carries the impulse to the finger muscles(effector), where the muscle will contract and pull finger away

What is the function of the cornea?

The function of the cornea is to refract light as it enters the eye

What is the function of the iris?

The function of the iris is to control how much light enters the pupil

What is the function of the lens?

The function of the lens is to change shape to focus light onto the retina

What is the function of the retina?

The function of the retina is to use rods to detect light intensity, and cones to detect colour

What is the function of the optic nerve?

The function of the optic nerve is to carry impulses between the eye and the brain

What is the function of the pupil?

The function of the pupil is to allow light to enter the eye

What happens to the eye when entering a dark room?

The radical muscles contract,the circular muscles relax and the pupil dilates to let as much light in as possible

What happens to the eye when entering a light room?

The radical muscles relax, the circular muscles contract and the pupil constricts

What happens to the eye when focusing on a distant object?

The ciliary muscles relax, the suspensory ligaments tighten and lens is pulled thin

What happens to the eye when focusing on a close object?

The ciliary muscles contract, the suspensory ligaments loosen and lens becomes circular

What does the skin do when it is too cold?

Vasoconstriction occurs where hair muscles pull hair on end to trap hot air, and blood flow in capillaries decreases to minimise the loss of heat to the environment

What does the skin do when it is too hot?

Vasodilation occurs where hair muscles relax so the hair lies flat and heat can escape. Swear secreted by sweat glands cools skin by evaporation, and blood flow in capillaries increases so heat is loss to the environment

Source, role and effect of insulin?

Insulin is made in the pancreas, and its role is to control the blood sugar level. The effect is that it stimulates glucose to be stored as glycogen in the liver

Source, role and effect of adrenaline?

Adrenaline is produced in the adrenal gland. Its role is to prepare the body for action. The effect is that it increase heart and breathing rate to allow more oxygen to get to the cells to respire

Source, role and effect of testosterone?

Testosterone is produced in the testes. Its role is to be a male sex hormone. The effect is that it promotes male secondary sexual characteristics.

Source, role and effect of oestrogen?

Oestrogen is produced in the ovaries. Its role is to be a female sex hormone. The effect is that it promotes female secondary sexual characteristics .

Source, role and effect of progesterone?

Progesterone is produced in the ovaries. Its role is to control the menstrual cycle an support pregnancy. The effect is it maintains the uterus lining

Source, role and effect of FSH?

FSH is produced in the pituitary gland. Its role is to be a female sex hormone. Its effect is causing an egg to mature and for the ovaries to produce oestrogen

Source, role and effect of LH?

LH is produced in the Pituitary gland. Its role is to be a female sex hormone. Its role is to cause ovulation

What is the effect of testosterone explained?

The increase of testosterone causes the growth of body and facial hair, growth of penis and testes start to produce sperm

What is the effect of oestrogen explained?

The increase of oestrogen causes the growth of the breasts, growth of body hair and menstrual cycle begins