Chapter 3

Question 1

what are gonads?

Answer 1

Testes and ovaries, whose hormones are required for reproduction. The testes secrete testosterone, which is responsible for the appearance of secondary sexual characteristics of males, for example beards and coarseness of voice. Ovaries produce oestrogen, which are responsible for secondary sexual characteristics of women.

Question 2

What is feedback mechanism?

Answer 2

The secretion of hormones is regulated through a feedback mechanism. The regulation of a process by the output of the process is called feedback. It has two types, negative and positive.

Question 3

what is negative feedback?

Answer 3

output which inhibits processes. it maintains homeostasis as it returns conditions to normal. Common in living organisms.

Example, blood glucose level is the output of the process that inhibits further glucose secretion.

Question 4

What is insulin and why is it important?

Answer 4

Insulin is a hormone that helps the body to absorb and store glucose as glycogen in the liver and skeletal muscles, which returns blood glucose level back to normal once it is detected to decrease.

It facilitates the movement of glucose across cell membranes and enhances the conversion of glucose into glycogen.

Question 5

What is positive feedback?

Answer 5

Output of the process that further enhances the process. Non homeostatic as it diverts conditions from normal and is less common in living organisms.

suckling actions by infants stimulates milk production through hormonal secretion. More suckling will result in more milk production.

Question 6

How many types of nervous disorders are there?

Answer 6

Two, vascular nervous disorders like paralysis and functional nervous disorders like epilepsy.

Question 7

What is paralysis?

Answer 7

Partial of complete loss of motion, especially in voluntary muscles. Can be on one end or both.

Causes include attacks like strokes that cause some part of the brain to stop functioning. Haemorrhaging or the clotting of blood vessels can also cause severe becomes damage as a result of viral toxins like polio.

teated by physiotherapy and rehabilitation. Is incurable in severe cases.

Question 8

what is epilepsy?

Answer 8

Epilepsy is the abnormal and excessive discharge or nerve impulses in the brain.

Symptoms include an unstable state of brain impulses that cause seizures.

Causes include deformity in brain structure, genetic defects, infectious diseases, strokes, tumors, head injuries, or metabolic changes.

Anti-seizure drugs are used to treat.

Question 9

What are hormones or what is the endocrine system?

Answer 9

The endocrine system is a complex network of glands and organs. It uses hormones to control and coordinate your body.

Hormones are chemicals produced by ductless glands that can quicken, slow down, or alter organs functions. The organ on which these act upon are called target organs.

Hormones are chemical messengers which regulate or control a number of activities in the body. They are slow and regulates processes that occur over days or even months.

Question 10

Why is it beneficial for an animal to have two different coordinating activities.

Answer 10

To react to two different types og stimuli, those needing immediate action and those that depend on long-term response.

Question 11

What endocrine glands are present in man?

Answer 11

Pituitary galnd, thyroid gland, parathyroid gland, pancreas, andrenal gland, gonads.

Question 12

What is a pituitary gland?

Answer 12

attached with the hypothalamus, and is about the side of a pea, consisting of two distinct lobes: the anterior and the posterior lobe. AKA master gland because it controls all other glands.

Question 13

What is the anterior lobe?

Answer 13

affects, maintains, and regulates the development and functions of the endocrine glands. Larger than the posterior lobe and secretes many hormones. Thyroid stimulating hormones control maintenance of thyroid gland and hormone.

Question 14

What is the posterior lobe?

Answer 14

secretes oxytocin and antidiuretic hormone.

Oxytocin causes contractions during birth, and the ejection of milk.

Antidiuretic hormone causes water reabsorption from nephrons. Under secretion results in large quantities of urine, this is a disease known as diabetes insipidus.

Question 15

What is the thyroid gland

Answer 15

located in the neck, fits closely around the sides of trachea just below the larynx. Has two lobes. Produces thyroxin and calcitonin.

Thyroxin regulates basic metabolism and process of growth both skeletal and mental in children. Deficiency of iodine in diet causes the disease goitre, which is the enlargement of the gland itself.

Calcitonin encourages the deposition of extra calcium in bone. secreted when high calcium is in blood.

Question 16

Parathyroid gland

Answer 16

Located in two pairs on the thyroid gland as very small structures. secrete parathormone, which functions as an opposite of calcitonin, as it balances calcium and phosphates in the body.

Question 17

Pancrease

Answer 17

Located in the abdominal cavity, is an exocrine and endocrine gland. has cells called islet of langerhans, which contain alpha and beta cells. alpha cells secrete glucagon and beta cells secrete insulin.

Glucagon increases glucose concentrations by stimulating the conversion of glycogen into glucose by the liver.

Question 18

How is diabetes caused?

Answer 18

diabetes is high blood sugar, which is caused when beta cells dont produce enough insulin. This causes glucose to accumulate in blood and exit the body with urine. treated with regular insulin shots.

Question 19

what are adrenal gland

Answer 19

two rest on the kidney, each having further two parts, the adrenal cortex and adrenal medulla. adrenal cortex secretes several hormones collectively called corticosteroids.

adrenal medulla produces hormones called adrenaline and nor-adrenaline. Adrenaline is produced in emergency fight or flight situations, and during anxiety and fear. adrenaline increases heart rate and intensity of heart beat, blood pressure and blood flow to the limbs. prepares the body to face severe situations.

Noradrenaline raises blood pressure and is responsible for the constriction of blood vessels.

Question 20

What is an exocrine gland?

Answer 20

secretes substances through ducts, secretion is either inside the boyd or outside the body, example includes sweat glands Pancreas is also an exocrine gland

Question 21

Why is the pancreas both endo and exocrine

Answer 21

because it has dual roles - it is an organ of the digestive system and of the endocrine system. The exocrine pancreas produces enzymes that help to digest food, particularly protein. The endocrine pancreas makes the hormone insulin, which helps to control blood sugar levels.

Question 22

why are the following scientists famous? Ibne al haitham and al ibn isa.

Answer 22

Ibne al haitham was the first person to accurately describe the various parts of the eye and give scientific explanations of the process of vision. He also attempted to explain binocular vision, and is referred to as the father of optics due to his work on lenses, mirrors, refraction, and reflection. Explained and proved the modern theory of vision.

Al ibne Isa described 130 eye diseases and 143 drugs to teat them.

Question 23

What is the ear?

Answer 23

organ of hearing, contains receptor cells for sound vibrations. Divided into three points

external ear, consists of an outer funnel-like structure called the planna, external or auditory canal and the eardrum.

middle ear includes auditory ossicles malleus, incus, and stapes. these bones form a bridge connect the ear drum to the inner ear, which transmits vibrations. The stappes attached to an oval windwo also lead to the inner ear. eustachian tube connects the middle. ear to the throat which maintains air pressure on both sides of the ear drum necessary for hearing.

inner ear has the snail like structure of the cochlea, and three semi circular canals which connect to the vestibule. A round window connect the inner ear to the middle ear.

Question 24

how do we hear?

Answer 24

the pina of the ear collects sound waves traveling through he air then directs them to the auditory canal. The waves vibrate the eardrum to produce sound.

from the eardrum, the waves pass the malleus, incus, and stapes in the middle ear, which amplify the sound before transmitting them to the oval window, rom where they strike the cochlea, which sends impulses to the brain through the auditory nerve.

Question 25

How does ear maintain balance in the body?

Answer 25

three semicircular canals detect rotational acceleration and the ear vestibule detects changes in body movement and positioning.

Question 26

what is coordination? what is stimulus?

Answer 26

working of different parts of cells to produce appropriate responses.

irritation and sensitivity are characteristics of living organisms, change in the environment is stimulus, which is received by a receptor. structure that gives responses is called an effector.

in animals, coordination is produced by the nervous system and the endocrine glands aka chemical coordination.

Question 27

What is the nervous system?

Answer 27

Comprises of a central and peripheral system interconnected with three functions, input, integration, and motor output. The central system consists of the brain and spinal column. peripheral nerves from the brain and the spinal column. Structural and functional unit is a neuron.

sensory is triggered by stimuli like light of touch. Sensory input is the conduction of these signals from receptors to processing centers in the nervous system. Integration is its interpretation, and motor output is the conduction of signals from the processing center to the effector cells.

Info passes from the processing center to effector cells, while impulses from nerves travel along pathways of neurons.

Question 28

What is a neuron? (with diagram)

Answer 28

Long thin and delicate cells that are the structural and functional center of the nervous system. Bundles of neurons are called nerves, its body contains a nucleus and cytoplasm> Long connecting body is the axon, which trasmits pulses away from the cell body. The other end is a branched part called dendrite.

IMPULSES MOVE TOWARD THE CELL BODY FROM THE DENDRITE AND THEN TO THE AXON.

Question 29

Structure of the neuron

Answer 29

long neuron fibres are covered by a fatty myeline sheath. Cells of meyline sheath are called schwann cells, small distances in between which are called nodes of ranvier. Both are important for the speed of impulses.

Myelin sheath is an insulator so the membrane coated with this sheath does not conduct nerve impulses. in such a neuron, the impulse jumps over from node to node. These jumping impulses increase the speed of nerve impulses.

Question 30

Describe the types of neurons (with disagrams)

Answer 30

Differ in structure and direction towards which impulse is carried.

Sensory neurons carry sensory information to from receptors to the brain and spinal cord. It has one dendrite and one axon.

Motor neurons carry impulses from the brain and spinal cord to the effectors. Many dendrites and one axon.

Interneurons are found in the brain and spine, have many dendrites and axons. carry impulses from sensory neuron to motor neurons.

Question 31

moving your head fast and stopping suddenly makes you dizzy, why?

Answer 31

Inside the inner ear is a series of canals filled with fluid. These canals are oriented at different angles. When the head is moved, the rolling of the fluid inside these canals tells the brain exactly how far, how fast and in what direction the head is moving. When this fluid moves in a certain way, your brain receives signals from the inner ear that don’t match what your eyes and sensory nerves are receiving. this results in dizziness as your brain works to sort out the confusion.

Question 32

how is the spinal cord protected

Answer 32

Bones, discs, ligaments and muscles all work to protect the spinal cord. The spine is made of 33 bones called vertebrae, which have holes (spinal canals) through which the spinal cord passes. Between each vertebra, discs act as cushions; absorbing shock to the spine.

Question 33

relationship between iodine and goitre

Answer 33

Iodine deficiency is the most common cause of goiter, a condition where the thyroid gland becomes enlarged. When there isn’t enough iodine in the diet, the thyroid gland works harder to capture as much iodine as possible to make the right amount of thyroid hormone. This causes the thyroid to swell.

Question 34

why plants have slow response to stimuli

Answer 34

The plants respond to various stimuli very slowly by growing due to lack of nervous system. So, in most of the cases, the response of a plant to a stimulus cannot be observed immediately. It usually takes a considerable time to observe the effect of a stimulus on a plant.