Chapter 3 Flashcards
what are gonads?
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.
What is feedback mechanism?
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.
what is negative feedback?
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.
What is insulin and why is it important?
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.
What is positive feedback?
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.
How many types of nervous disorders are there?
Two, vascular nervous disorders like paralysis and functional nervous disorders like epilepsy.
What is paralysis?
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.
what is epilepsy?
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.
What are hormones or what is the endocrine system?
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.
Why is it beneficial for an animal to have two different coordinating activities.
To react to two different types og stimuli, those needing immediate action and those that depend on long-term response.
What endocrine glands are present in man?
Pituitary galnd, thyroid gland, parathyroid gland, pancreas, andrenal gland, gonads.
What is a pituitary gland?
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.
What is the anterior lobe?
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.
What is the posterior lobe?
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.
What is the thyroid gland
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.
Parathyroid gland
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.
Pancrease
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.
How is diabetes caused?
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.
what are adrenal gland
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.
What is an exocrine gland?
secretes substances through ducts, secretion is either inside the boyd or outside the body, example includes sweat glands Pancreas is also an exocrine gland
Why is the pancreas both endo and exocrine
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.
why are the following scientists famous? Ibne al haitham and al ibn isa.
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.
What is the ear?
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.
how do we hear?
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.
