Eye and Hormonal coordination

Question 1

Response due to changes in light intensity

Answer 1

Reflex action carried out to protect the retina from bright light and protect us from not seeing objects in dim light

Question 2

High light intensity reaction

Answer 2

Circular muscles contract
Radial muscles relax
Pupil size constricts
This is done to prevent entry of more light in the eye to protect rod and cone cells

Question 3

Low light intensity reaction

Answer 3

Circular muscles relax
Radial muscles contracts
Pupil dilates
Done to allow more light into the eye

Question 4

Forming an image

Answer 4

Light rays travel in a straight line
70% refraction of light in cornea
Light enters through pupil
Further refraction in lens
Crossing of light rays in vitreous humour
Upside down image formed in fovea
Image on the retina is inverted and the brain interprets the image the right way up

Question 5

Accomodation

Answer 5

Viewing near and distant objects
The way lens brings about fine focusing is called accomodation
Lens is elastic and its shape can be changed when suspensory ligaments attached to it become tight or loose
The changes are brought about by the contraction and relaxation of the ciliary muscles

Question 6

Accomodation of distant object

Answer 6

Ciliary muscles relax
Suspensory ligaments stretch thin
This allows lens to become thinner
Light is refracted less

Question 7

Accomodation of close objects

Answer 7

Ciliary muscles contract
Suspensory ligaments stretch thin
This allows lens to become fatter
Light is refracted more

Question 8

Hormone

Answer 8

It is a chemical substance produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
Glands that produce hormones in animals are known as the endocrine system

Question 9

Why do endocrine glands have good blood supply

Answer 9

As when they make hormones, they need it to get it into the bloodstream as fast as possible to transport hormones as fast as possible to target organs to bring about a response

Question 10

What happens to a hormone after its used

Answer 10

It is destroyed by the liver

Question 11

Adrenaline

Answer 11

Made in Adrenal gland
Readies the body for a flight or fight response
It increases heart and breathing rate and increases blood flow to muscles

Question 12

Insulin

Answer 12

Made in Pancreas
Lowers blood glucose levels
Causes excess glucose in the blood to be taken up by the muscles and liver and converted into glycogen for storage

Question 13

Testosterone

Answer 13

Made in the testes
Main sex hormone in males
Development of secondary sexual characteristics in males

Question 14

Progesterone

Answer 14

Made in ovaries
Maintains pregnancy
Maintains uterus lining to cushion the egg and allow it to develop

Question 15

Oestrogen

Answer 15

Made in ovaries
Main sex hormone in females
Development of secondary sexual characteristics in females and controls menstrual cycle

Question 16

Adrenaline specify

Answer 16

Flight or fight hormone
Breathing rate becomes deeper, taking more oxygen into the body
Heart beats faster, sending more blood to the muscles so that they receive more glucose and oxygen for respiration
Blood is diverted away from the intestine and into the muscle
In liver, stored carbohydrate is changed into glucose and sent into blood. Muscle cells absorb more glucose and use it for respiration
Pupil dilates, increasing visual sensitivity to movement
Body hair stands upright, making animal look larger to a enemy
Mental awareness increases, so reaction is faster

Question 17

Insulin specify

Answer 17

Concentration of blood glucose level increases after a meal
Sugar carried to liver from hepatic portal vein
In liver glucose is converted to glycogen so blood leaving the liver has a lower concentration of glucose