Biology Homeostasis and Hormonal Control PDF - Tanjong Katong Girls' School

Tanjong Katong Girls’ School Biology (Syllabus 6093) Homeostasis and Hormonal Control Chapter 9  synthesis (chemical reactions on...

Tanjong Katong Girls’ School Biology (Syllabus 6093) Homeostasis and Hormonal Control Chapter 9  synthesis (chemical reactions on cells - ↳ control of these activities : enzymes - photosynthes is lower activation : energy - ↓ Lelse , too high Cells Learning Outcomes specifictemp , PH -homeostasis : maintainance of constant internal environment for cells to remain functional. & maintaining Up : prevent bursting crenation of cells Define homeostasis as the maintenance of a constant internal ↓  can not drink water pure (remineralisation) environment  Explain the basic principles of homeostasis in terms of stimulus resulting from a change in the internal environment, a corrective mechanism and negative feedback  Describe the maintenance of a constant body temperature in humans in terms of the role of:  temperature receptors in the skin detecting changes in temperature  sweating  shivering  altering blood flow through blood vessels near the skin surface  the co-ordinating role of the hypothalamus Learning Outcomes  Define a hormone as a chemical substance, produced by a gland, carried by the blood, which alters the activity of one or more specific target organs  Explain what is meant by an endocrine gland, with reference to the islets of Langerhans in the pancreas  Explain how blood glucose concentration is regulated by insulin and glucagon as a homeostatic mechanism  Describe type 2 diabetes mellitus in terms of a persistently higher than normal blood glucose concentration due to the body's resistance to insulin or insufficient production of insulin  Identify the risk factors of (e.g. unhealthy diet and sedentary lifestyle) and ways to manage type 2 diabetes mellitus  Outline the role of anti-diuretic hormone (ADH) in osmoregulation (covered in Chapter 8 notes) What is Homeostasis?  Homeostasis is the maintenance of a constant internal environment.  It ensures that the internal environment, such as the blood and tissue fluids, is kept within narrow limits  Maintain body temperature  Maintain water potential  Maintain blood glucose concentrations  Allows an organism to be independent from changes in the external environment. Homeostasis involves Negative Feedback  When there are changes detected in the (internal and external) environment, the body carries out a series of corrective mechanisms in response to a stimulus to bring about the reverse effect of the stimulus, which on restoring the normal conditions, causes a feedback to the receptor to stop the corrective mechanism. *  This process is known as negative feedback. the feedback encouraged to do Feedback : something discourages doing something & ↳ keep doing more of it ~ stimulus eg. ↑BC concentration > pancreas - insulin Scorrective - eg. contractions (shorter intervals) mechanism : reduces stimulus · igircose-grycogent livers ↳ opposite = encourage child birth ↳ BS4-feedback , slows down lactation I normarectivemechanism throngthe · ↳ encourage Stimulus production of milk (suckling * sequence to describe for homeostasis (applies to all Change in normal level or the onset of a stimulus *state the change from normal (stimulus Detection by a receptor cell iron - RB( Body undergoes a sequence of events cannothave Vitamin set (corrective mechanisms) > - explain ↳ moderation The sequence of events will counteract the change (brings about the reverse effect of the stimulus) Until the normal level is restored Upon restoration of the normal level, a feedback is sent to the receptor to stop the chain of events (stop the corrective mechanism)  * key words determines response lowering to release insulin it 1 I State receptor ↑ cell permeability negative - leg. Islets of langerhans feedback reduces stimulus * - state normal crhat it is I for different conditions Negative Feedback ↳ most likely to come out key concept Homeostatic Control: How does Your Body Regulate Temperature? -redder/pink The Skin not day-sweat cold-contract ~ hair rises goosebumps & relatecomma m , I pale * waterproofacy /pee(diluted sweat : water a salt - (from sweat pore) blood diffusion plasma in epidermis dermis - rein ↓ (nutrients hav blood to hair plucking - damages (fats hair papillia (wound scarring infections , : , rough skin When your body temperature increases above the normal level water needs energy to change from 1--a ↳ water evaporating -> removing Sweat Glands sweating :  energy  More active, produces more sweat  Sweat is sent to the sweat pore via the sweat duct and secreted to the skin surface  When water in sweat evaporates, latent heat is lost from the body reduce size of lumen , Skin Arterioles -> contract  - ↓ blood flow -controlblood toaa ne body exercise : musclecells relax elephants ears &SA : V many Vasodilation of skin arterioles - ,  - blood capillaries -> lose heat easier  More blood sent to the blood capillaries under the skin /direct contact between 2 mediums ~ transfer heat tomngmedium  More heat is lost from the skin by conduction, convection - ↳movement of medium to transfer and radiation ↑ ↑ blood carries heat-mostly water causes diff colour of neat Lin frared radiation skin heat faster , (no mediums blood near skin-loses us blood& core-harder to losen at not , How closer to Skin When your body temperature increases above the normal level - hair stands barrier is too fine narr  Hair Erector Muscles (not very effective in humans) clothes , Strap ai > - jacket , keeps heat us warm  Hair erector muscles relax, hair lies closer to the skin surface  Traps a thinner layer of air above skin  More heat is able to be lost (by conduction, convection and radiation) aerobic  Metabolic rate of the body ↑ controlaeration.  Decrease in metabolic rate, decrease in heat release (co + H20 , energy crelease resp ↑ aerobic. produced ↑ heat When your body temperature decreases below the normal level  Sweat Glands  Less active, produces less sweat  Less evaporation of water in sweat, less latent heat is lost from the body  Skin Arterioles  Vasoconstriction of skin arterioles  Less blood sent to the blood capillaries under the skin  Less heat is lost from the skin by conduction, convection and radiation When your body temperature decreases below the normal level  Hair Erector Muscles (not very effective in humans)  Hair erector muscles contract, hair becomes erected  Traps a thicker layer of air above skin  Less heat is able to be lost (by conduction, convection and radiation)  Metabolic rate of the body  Increase in metabolic rate, increase in heat release  Shivering > - rapid movement of muscles ↳ aerobic respiration heat produced. energy - -  Spasmodic contraction of skeletal muscles  Increase in rate of respiration, increase in heat energy released Vasodilation & Vasoconstriction  > Chemicala Homeostatic Control with Hormones  Regulation of blood glucose concentration  When blood glucose concentration increases above norm → Insulin  When blood glucose concentration decreases below norm → Glucagon  Regulation of water potential in the blood  When water potential in the blood increases above norm → Less ADH Canti-diuretic hormone) diuretic peemore  When water potential in the blood decreases below norm → More ADH What is a Hormone? imbalance normonal ↳ problems : leg) growth (too tall /too short) Dendocrine duct-tube  Definition: glands secrete ② + exocrine  Chemical substance produced in minute quantities by an endocrine gland. It is released into the blood and transported by the blood to target organ(s), where it will exert its effect(s). After exerting the effect(s), it is destroyed in the liver and excreted by the kidneys.  Chemical messengers that are able to influence growth and development of an organism. What is an Endocrine Gland? Type of Exocrine Endocrine Gland Structure Consists of a duct into Ductless: releases its secretion which secretions will be directly into the bloodstream released through it Examples Salivary gland → saliva Islets of Langerhans of Pancreas → pancreatic pancreas → insulin, glucagon juice (through Pituitary gland of pancreatic duct) hypothalamus → ADH (both exogendo. Ovaries → oestrogen, Ovidutegy progesterone not normones Testes → testosterone duct sperm + Sperm ↓ transport Homeostatic Control – Insulin when blood glucose level rises above norm Homeostatic Control – Glucagon when blood glucose level decreases below norm What is Diabetes Mellitus?  A medical condition in which the body of a person experiences a persistently higher than normal blood glucose concentration.  Type 1  Develop at any age (used to be called juvenile or insulin-dependent diabetes)  Isletsof Langerhans of pancreas unable to produce and secrete sufficient insulin  Type 2  Late-onset diabetes  Target cells (liver and muscle cells) do not respond well to insulin Risk Factors of Diabetes Mellitus  Obesity  Age  The risk is higher as one grows older  Family history  Higher risk if family members are affected  Blood lipids level  Higher risk if one has higher levels of low-density cholesterol level in the blood  Lifestyle  Higher risk if one is less active Treatment of Diabetes Mellitus  Constant monitoring of blood glucose level and urine  Constant monitoring of diet  Regular medication  Leading a healthy lifestyle  Exercise  Diet  Weight management  Insulin injections (for Type 1)