Homeostasis

Fahad Jaffar


 * 9.1 **


 * Homeostasis **

-Homeostasis – The dynamic process where the internal physical and chemical condition are maintained within an optimal range for essential biological process. -The Body has many fluid and conditions that must be maintained and monitored. Examples: -Internal Temp. -Blood Glucose -Blood pH -Hormone Levels

-Homeostasis is not a “constant” condition -Internal Environment – The extracellular fluid that surrounds our cells and tissues. It also makes up the plasma of our blood -When dealing with homeostasis, we always refer to extracellular fluid NOT intracellular Fluid -Homeostasis is involved in all organ systems such as the integumentary system (skin, sweat glands, and hair) and endocrines system

- The Receptor will continue to monitor environment and makes adjustments when necessary -Negative feedback more common than positive
 * Feed Back Mechanisms **

Example: Blood Glucose -Optimal level = .1% glucose -Increase in activity levels cause an increase demand for glucose, and remove it from the blood -The body must compensate -Eating a meal will increase blood glucose as nutrients are absorbed by the digestive system into the blood - The body will compensate Type 1: Negative - Negative Feedback loops are the basis of most homeostasis mechanisms - This is because they return the body to a pre-assigned “normal” value after a change (ex. Body temperature 37OC or Blood Glucose .1%) Type 2: Positive - The Effect of the positive Stimulus is to produce an increase in the intensity of the stimulus is to produce an increase in the intensity of the stimulus. But there must be some upper limit that is eventually reached.

Example: Labour Contraction during Childbirth - Uterine Contraction detects by the pituitary gland that releases oxytocin -The more oxytocin released the more uterine contractions are created, which leads to more oxytocin… etc. until child birth

- Managing heat and cod in the environment - Cellular respiration is continuously producing heat as a by-product of this chemical reaction -Heat is thus produced in the body core all the time, to much heat is called hyperthermia -Engage effector to remove or release body heat response loss of too much heat (Hypothermia) -Engage effector to conserve or preserve body heat
 * Thermoregulation **

CASE 1: If there is too much heat due to increase in activity - Blood is shunted to the body surface (Blood Vessels Dilates) -Usually a high temperature gradient, therefore increasing heat loss to the environment. -In humans perspiration occurs -The high heat of vaporization for water means the water will absorb large amounts of heat Energy when changing from liquid to vapour -behaviour is triggered that minimizes exposures to heat from external sources -Seek shade, low activity

Homework: -Read 9.3 -Pg. 441 #1,2,6,11 -Aquarium assignments due Friday

CASE 2: Response to Cold - Superficial blood vessels constrict -Reducing exposure of warm cold blood to the cold external environment - Shivering -Increase metabolic activity and hence “heat” in muscles - Goosebumps - Create a boundary layer as small hair strands up on body surface

-Osmoregulation is the process of activity regulating the osmotic pressure of body fluid and cells -Osmotic pressure is the pressure that result from water concentration gradient - The greater the gradient, the greater the osmotic pressure difference between the two sides of Selectively permeable membrane - Hypertonic solution has a higher [solute] compared to the other - Hypotonic solution has a lower [solute] compared to the other - Isotonic solution has a same [solute] compared to the other - Water balance in mammals is directly related to urine excretion - When we break down proteins (Amino Acid) this is called deamination - A highly toxic by product is ammonia - As little as .005ml/L can a kill a human - We combine it with HCO3 (found abundantly in blood) to form urea a very soluble and safer waste product - Now we just have to get rid of it in our urine
 * Water Balancing **



MACROSCOPIC ANATOMY OF KIDNEYS - The kidney has two portions: renal cortex and renal medulla - The cortex is the outer part of the kidney containing most nephron - Medulla is the inner part of the kidney - Approximately 99% of the blood flow goes to the cortex and 1% to the medulla - The kidney is unique as it has two capillary beds arranged in a series - The glomerular capillaries which are under high pressure for filtering - The Peritubular capillaries which are situated around the tubules and are at low pressure - This permits large volumes of fluid to be filtered and reabsorbed
 * The Human Excretory System **

MICROSCOPIC ANATOMY OF A KIDNEY - The functional unit in the kidney is known as a nephron - We have approximately a million slender tubules - Each nephron has a glomerulus and tubule - Small branches from renal arteries (Blood away from heart towards kidneys) they are called afferent arterioles - They supply blood to the nephrons - The arteries brand into a capillary bed called the glomerulus - The glomerulus is the site of filtration -The filtered blood will leave the glomerulus by the efferent arterioles that will direct blood to the peritubular capillaries.

FLOWCHART OF BLOOD FLOW
 * Formation of Urine **

NOTE: Blood travelling into the afferent arteriole is at a very high pressure, determined from the pressure from the pumping heart. -Blood from the afferent arterioles enters the glomerulus -The high pressure of the blood forces water and small dissolved molecules (Amino Acid, Glucose, Urea, and Salt) into Bowman’s capsule -Blood cells and proteins are retained in the blood vessels. This process is called glomerular filtration. -The fluid that enters the Bowman’s capsule is called the glomerular filtrate. This fluid has the same concentrate of molecule as the blood plasma.
 * Filtration **

BACKGROUND INFO: -The beginning part of the ascending loop of Henle has proteins channels that allow Na+, K+, and Cl- to passively diffuse out of the LoH -Later it has proteins pumps that use ATP actively, Pump Na+, K+, and Cl- out of the LoH -This makes the medulla very “Salty” aka hypertonic - The descending loop of Henle is only permeable to water

1. The Filtrate enters the proximal convoluted tubule (PCT). This is the first site of reabsorption. -Water, ions, and nutrients (Glucose) are transferred back into the interstitial fluid using passive and active transport -Na+, K+, and Cl- are actively pumped out of the PCT -The Filtrate because hypertonic and water will passively move out of the PCT 2. The Filtrate enters the loop of Henle (LoH) which is located in the renal medulla -As the filtrate enters the descending loop of Henle, the filtrate is hypertonic compared to the medulla (Recall: It is salty) -Therefore; water will diffuse out passively back into the interstitial fluid 3. As the filtrate enter the 1 st half of the ascending LoH, the filtrate just lost a lot of water, so it is slightly hypertonic compared to the medulla. -Therefore the ions will diffuse out passively back into the interstitial fluid 4. As the filtrate enters the 2 nd half of the ascending LoH, the filtrate just lost a bunch of ions so it is now hypotonic. -the ions do not want to diffuse out passively -This is why we need protein pumps to actively pump the ions out! We need to maintain the “salty medulla”. 5. The filtrate now enters the distil convoluted tubule. -last chance to actively pump back any important ions. 6. Now the filtrate has excess ions and water that we do not need, plus tons of Urea 7. The filtrate finally enters the collecting ducts that dips back to the medulla -The collecting duct may or may not be permeable to water -If you are dehydrated, it will be permeable. This will allow water to diffuse out of the filtrate and back into the body. -A Hormone called Antidiuretic Hormones (ADH) is involved
 * Reabsorption **

-The final concentration of urine depends upon the amount of antidiuretic hormone (ADH) secreted by the posterior lobe of the pituitary duct. -If ADH is present the collecting duct because permeable water -Since the collecting duct passes through the medulla (that has a high solute concentration), the water moves out of the duct and more concentrated urine is formed. -In the absence of ADH the collecting duct is minimally permeable to water.
 * Secretion **

-The balance of ions concentration in the body fluid is closely tied to the regulation of water balance, as water follows the movement of ions osmotically -Sodium (Na+) is perhaps the most significant ions in the blood with Hydrogen (H+), Potassium (K+), Chloride (Cl-), Magnesium (Mg2+), Calcium (Ca2+), and Bicarbonate (HCO3-) playing other important roles -Sodium and Potassium ions played central roles in the transmission of nerve impulse. -Calcium ions crucial for muscle contraction -Hydrogen ions dictate the acidity of the body fluid -In order for the body to work correctly, the concentration of the above ions, plus many more, must be kept within narrow bonds.
 * Ion Balance **

HOMEWORK: -Read/ Make Notes on Section 10.1

January 10th, 2014 By: Viththakan Arunthavanthan


 * Chapter 10.2 - The Endocrine Glands **

Overview:

 * This system contains many glands
 * The glands produce, store and secrete hormones into the bloodstream
 * Organs can also produce and secrete hormones (for example, the liver)

//Major Endocrine Glands: // 1) Pituitary 2) Thyroid & parathyroid 3) Adrenal 4) Pineal Others: Ovaries and testes

Lesson:

 * // Special Gland: Hypothalamus //**
 * this endocrine gland is part of the nervous system
 * it is a region of the brain
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">it is a coordinating center!
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">once it receives information about the stimulus, it sends out the decision by secreting special hormones called neurohormones
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">neurohormones control the pituitary gland
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">neurohormones travel along nerve cells, then diffuse into the bloodstream and travel to the pituitary gland

<span style="font-family: Arial,sans-serif; font-size: 10pt;">**Make a summary of the hormones produced from each lobe, the target tissue, and function of that hormone. (Pg. 474)** <span style="font-family: Arial,sans-serif; font-size: 10pt;"> <span style="font-family: Arial,sans-serif; font-size: 10pt;">
 * // Pituitary Gland: //**
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">it produces hormones to control what happens to other glands, thus it is often called MASTER GLAND
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">the pituitary is composed of two main lobes
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Anterior lobe is involved in producing and releasing 8 various peptide hormones
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Posterior lobe releases ADH and oxytocin


 * // Thyroid & Parathyroid Glands: //**
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Thyroid gland is located in front of the throat
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">it secretes thyroxine (T4), triiodothyronine (T3), and calcitonin
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Parathyroid Glands
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">there are 4, 2 on each side of the thyroid gland
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">it secretes parathoid hormone (PTH)
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Calcitonin and PTH are involved in Ca2+ balance
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">thyroxine (T4) and triiodothyronine (T3) regulate body metabolism, growth, and differentiation



<span style="font-family: Arial,sans-serif; font-size: 10pt;">Calcitonin has two targets: <span style="font-family: Arial,sans-serif; font-size: 10pt;">1) it inhibits the bones from releasing Ca2+ <span style="font-family: Arial,sans-serif; font-size: 10pt;">2) It reduces Ca2+ uptake in kidneys (i.e more Ca2+ left in filtrate) <span style="font-family: Arial,sans-serif; font-size: 10pt;">RESPONSE: decrease in [Ca2+] in blood
 * //<span style="font-family: Arial,sans-serif; font-size: 10pt;">What is the function of calcitonin? //**
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">it is involved in negative feedback
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Stimilus; rising [Ca2+] in blood
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Thyroid gland produces calcitonin

<span style="font-family: Arial,sans-serif; font-size: 10pt;">PTH has 3 targets: <span style="font-family: Arial,sans-serif; font-size: 10pt;">1) it stimulates the release of Ca2+ from the bones <span style="font-family: Arial,sans-serif; font-size: 10pt;">2) it increases the Ca2+ uptake in kidneys <span style="font-family: Arial,sans-serif; font-size: 10pt;">3) it increases Ca2+ in intestines <span style="font-family: Arial,sans-serif; font-size: 10pt;">RESPONSE: increase in [Ca2+] in blood
 * //<span style="font-family: Arial,sans-serif; font-size: 10pt;">What is the function of PTH? //**
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Stimulus: falling [Ca2+] in blood
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Parathyroid gland produces PTH

//**<span style="font-family: Arial,sans-serif; font-size: 10pt;">Why is Ca2+ so important? **//
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">it is involved in muscle contraction, blood clotting and conduction of nerve signals
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">because of too little PTH or too much calcitonin, you will have too little Ca2+:
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">muscles twitch and contract uncontrollably, cramps occur in various muscles. In an extreme case, your breathing may be affected and you can die without enough Ca2+ (because diaphragm is a muscle need to breathe!)
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">because of too much PTH, you will have too much Ca2+:
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">causes calcium deposits to form kidney stones
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">this means you lost too much calcium from your bones which leads to a condition called osteoporosis

<span style="font-family: Arial,sans-serif; font-size: 10pt;">Homework:

 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Look into goiters, and how they form
 * <span style="font-family: Arial,sans-serif; font-size: 10pt; line-height: 1.5;">Pg. 480-481, 482 (#3, 5, 6, 7, 8, 11)

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