Unit 6 Human Homeostasis

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Unit 6

Human Homeostasis

That homeostasis describes how the human body regulates a number of key functions to maintain an ideal internal environment.

That the excretory system controls urea, salt and water levels in the body.

That the functional tissue of the kidney is the nephron.

The role of the nephron in controlling urea, salt and water levels in the body.

The role of ADH in controlling water reabsorption by the nephron.

That the skin is the largest organ having several important functions.

How the anatomy of the skin is related to its function.

The role of the skin in helping to control core body temperature.

The consequences of hypo or hyperthermia in humans.

Homeostasis, Control, Regulate, Internal, Environment, Excretory, System, Urea, Water, Salt, Kidney, Nephron, Anti diuretic hormone, Skin, Temperature, Regulation, Sweating & Vasodilation & Vasoconstriction. Unit 6: Human Homeostasis web: www.science-interactive.co.uk email: sales@science-interactive.co.uk Science Interactive LTD PO BOX 50764 LONDON NW6 9AT Click mouse to begin Science Interactive LTD Copyright 2005 Understand: Keywords:

Human homeostasis Your internal bodily e___________ needs to remain constant so that all bodily functions can proceed normally. Your body and its organs controls blood pH, water levels, blood sugar and body temperature within narrow limits. Furthermore, your body needs to rid chemicals like urea, which is made in the l______ from protein breakdown, before they begin to poison you. Your brain constantly monitors all these factors. This constant control of our internal environment is called homeostasis. Think of three other factors that need to be controlled inside the human body ? Controlling your internal environment: Science Interactive LTD Copyright 2005 Word bank: environment liver Urea is very toxic and needs to be removed as it is produced by the liver. If your core body temperature goes above 41 o C or below 28 o C you’re dead Insulin and glucagon control our blood sugar. 1 in 20 adults are diabetic. Too much water increases our blood pressure. Too little leads to dehydration. Notes __________________________________________________? Body temperature __________________________________________________? Blood glucose has to be kept constant at 90mg/100ml. Our water levels are controlled by our excretory system. Set point Diagram Factor Water Blood sugar Urea

The excretory system one Like other organ systems, the excretory system is a collection of c_____, tissues and organs. Its main function is to control water and salt levels in the b_______ and bodily tissues and excrete urea from the breakdown of excess dietary protein by the liver. If urea is allowed to remain inside the body, it can prove fatal. The kidneys remove waste c_________ like urea from the blood by filtration. These waste substances are removed from the body as urine. The excretory system: Science Interactive LTD Copyright 2005 Word bank: cells blood chemicals The kidney is a collection of tissues which rid the body of urea, excess salt and water forming urine, which is then excreted as liquid waste. Inside the kidney there are thousands of tiny nephrons which function together to clean the blood. They act as a filter removing unwanted substances like urea. Notes Diagram Overview of the excretory system

Waste chemicals like u____ are carried to your kidneys by the r______ arteries, which branches many times in the kidney cortex. The kidneys remove urea completely and control w_____ and salt levels in your blood. Excess p______ from the diet are broken down by the liver to form urea. This needs to be removed from your body, otherwise it would poison us. The cleaned blood is taken from the kidneys by the r______ vein back to the h_____ and the bodies’ circulatory system. The excretory system: Complete the table The excretory system two Science Interactive LTD Copyright 2005 Word bank: urea renal water proteins renal heart kidney urine body kidneys Carries cleaned blood from the k__________. Renal vein Carries unclean blood to the k_________. Renal artery Takes urine from b_______ to outside. Urethra Controls when urination occurs, without this muscle urine would leak form your urethra. Sphincter muscle Stores u______. Bladder Takes urine from k_______ to bladder. Ureter Removes u____ form the blood. Controls water and salt levels. Kidneys Function Organ/tissue

Inside the kidneys The kidneys are the key organ of the excretory system. The kidney has two distinct areas: The dark cortex and the lighter medulla . Waste chemicals like u______ are carried to your kidneys in the blood by the renal artery. The kidneys take these chemicals out of the blood as it flows through them. These waste chemicals are excreted as urine. Cleaned blood is returned to the heart and the rest of the body by the renal vein. The main functional tissue of the kidney is called the nephron. There are millions of nephrons found in the kidney cortex and medulla. The kidney : Complete the table Science Interactive LTD Copyright 2005 Word bank: urea kidneys Maintains the kidney’s shape. Capsule Takes urine from k_______ to bladder. Ureter Collects urine into the ureter. Pelvis Carries cleaned blood from the k________. Renal vein Carries unclean blood to the k________. Renal artery Contains rich blood supply. Cortex Contains kidneys neprhons and collecting ducts which forms the urine. Medulla Function Tissue

The nephron Inside the kidney there are thousands of tiny tubes called nephrons. The nephrons are found in the dark cortex and the light medulla of the kidney. Thousands of nephrons filter your blood to remove u_______. The nephron tissue also controls the amount of salt and water in your blood plasma. The waste chemicals removed from the blood are then taken through the collecting duct, forming urine which is then stored in the b________. The nephron is incredibly complex and each part has a specific function during the process of cleaning the blood. The nephron: Complete the table Science Interactive LTD Copyright 2005 Word bank: urea bladder ______________________________________________________ ? Can reabsorbs salt and water back into the blood stream. This depends on their existing levels in the blood stream. ______________________________________________________ ? High blood pressure forces filtrate from blood vessels into the Bowman’s capsule. Function Collecting duct Loop of Henle The proximal and distal tubules The glomerulus and Bowman’s capsule Part

Understanding the nephron one Blood is brought to the kidney by the renal artery which branches many times in the kidney c______. Each branch ends in a knot of vessels which creates high pressure and causes small molecules including u____, salt and water to be forced into the bowman’s capsule of the neprhon. It is here, that the process of cleaning the blood begins. Salt and water molecules can be reabsorbed back into the blood supply from the proximal tubule and the loop of henle . This depends on a person’s dietary salt and water intake. Urea, excess salt and water are taken via the collecting duct to the bladder forming urine. The nephron in detail: Science Interactive LTD Copyright 2005 Word bank: cortex urea The loop of henle along with the distal tubule is sensitive to a hormone called ADH. This area reabsorbs the necessary water to keep the body fully hydrated. Loop of henle The collecting duct takes urine containing urea, excess salt, water and other waste materials from the kidney via the ureter to the bladder, where it is stored. The proximal tubule begins to reabsorb very useful substances like glucose, some salts and water. Urea is not reabsorbed at any point along the nephron. The bowman’s capsule collects the blood filtrate forced through blood vessels at high pressure and contains urea, salt and water. Glomerelus Proximal tubule Collecting duct

Understanding the nephron two When unclean blood passes through the glomerulus or capillary knot, waste substance like urea, excess s_____ and water are forced through and collected by the bowman’s capsule. Useful substances like amino acids and g_______ also pass through the capillary wall. These useful substances are reabsorbed from the proximal tubule back into the renal vein. Excess salt, water and urea, all pass through the nephron to the bladder via the collecting duct. By what process is the blood cleaned; diffusion, filtration or distillation ? How the nephron works: Urea Salt Water Amino Acids Glucose Salt Water Amino Acids Glucose Salt Water Urea from renal artery to nephron from nephron to renal vein Science Interactive LTD Copyright 2005 Word bank: salt glucose There are many thousands of specialised nephron tissues found in the human kidney. Their job is to clean the blood. The proximal tubule begins to reabsorb useful substances like amino acids and glucose. Urea is not reabsorbed at any point along the nephron. The loop of henle along with the distal tubule is sensitive to a hormone called ADH. Both become more permeable to water in the presence of ADH, therefore ensuring correct water levels in bodily fluids and tissues. The collecting duct takes urine containing urea, excess salt and water the kidney to the bladder where it is stored. Diagram How the nephron works

Understanding the nephron three Comparing the amount of urea, glucose, salt, amino acids and protein found in the renal artery carrying unclean blood, the nephron, the renal vein carrying clean blood and urine, gives us an idea of how the k________ nephron tissue is able to reabsorb useful chemicals like glucose and excrete toxic chemicals like urea. The table below shows the content of 5 substances (urea, glucose, amino acids, salts, & protein) in renal artery, v_____, nephron and urine. (All values are in mg/dm 3 ) Understanding the kidney: Science Interactive LTD Copyright 2005 Word bank: kidney vein Complete the table and answer the following questions: 1. Which substances pass from the blood to the nephron. 2. How do these substances pass from the blood to the nephron. 3. Which substances are reabsorbed back into the blood and why. Explain the figures for protein. 4. Why is urea not reabsorbed by the blood and why is it more concentrated in the urine. __ ? 0.0 ___ ? 82 Protein __ ? 8.0 3.0 8.0 Salts 0.0 0.8 0.8 0.8 Amino acids 0.0 8.9 mg/dm 3 Urine 1.5 1.5 1.5 Glucose ___ ? __ ? 0.4 Urea mg/dm 3 mg/dm 3 mg/dm 3 Unit Nephron Renal vein Renal artery Substance

Kidney dialysis As you know, your kidneys are your body’s filter, removing toxic urea and excess salt and water from the blood. If your kidneys fail through d_________ or other injury, it can be fatal. You have two choices: receive another person’s kidney or undergo kidney dialysis using a dialysis m________. These machines work just like a human kidney, removing the toxic urea, using highly specialised dialysis membranes. A patient may dialyse their blood 3 to 4 times a week to keep it clean. Kidney dialysis: Unclean blood Clean blood Vein Artery Dialysis fluid in Dialysis fluid out urea excess salt Other chemicals Science Interactive LTD Copyright 2005 Word bank: disease machine Inside the kidney dialysis machine, the blood is pumped over the dialysis membrane. Urea and other chemicals diffuse across the membrane and are removed from the blood. The dialysis fluid contains amino acids and glucose to prevent your sugars and amino acids leaving the blood. The cleaned blood is then pumped back into the body. Notes Diagram Overview of kidney dialysis

ADH controlling body water one The amount of water in your body and circulatory system and the quantity you excrete in u_________ is controlled by the actions of a hormone called anti diuretic hormone ( ADH ). ADH is made by your pituitary gland found in your brain, in response to low blood volume or pressure. The ADH hormone travels in the blood from the brain, to the kidney. It then acts on the nephron’s loop of henle to increase the amount of water reabsorbed back into the renal vein. What is the difference between the urine you excrete on a hot summer’s day and a cold winter’s day ? Water gains and losses: Science Interactive LTD Copyright 2005 Word bank: urine Water losses include: 1:Water in exhaled air (12%) 2:Faeces (3%) 3: Sweat (25%) 4: Urine (60%) Water gains include: 1:Cellular respiration (10%) 2:Drinking fluids (70%) 3:Food (20%) Notes Diagram Water gains Water losses

ADH controlling body water two The amount of water in your body and blood vessels and the quantity you excrete as u_________ is controlled by the actions of a hormone called anti diuretic hormone ( ADH ) on your kidney. This feedback mechanism allows the body to finely control fluid levels in the blood and other tissues like the brain. Without feedback, our body would not be able to keep us correctly hydrated. Correct hydration is important to allow the right blood volume and pressure. What happens to blood pressure if blood volume falls ? Overview of ADH in the body: Science Interactive LTD Copyright 2005 Word bank: urine _______________________________ ? _____________________________ ? ___________________________ ? ___________________________ ? Too little water The loop of henle and distal tubule stops absorbing water. The nephron Collecting duct takes large volumes of dilute urine to the bladder. No ADH hormone carried to the kidney via renal a_______. The brain stops producing ADH from the pituitary. Too much water Diagram Brain Blood supply Urine volume

Hormones like insulin, thyroxine and ADH help keep conditions in the body like sugar levels, metabolism rates and water levels constant. The control of bodily water levels relies on feedback . The brain (pituitary) monitors the levels of w_______ in the blood. When these levels begin to fall, ADH is released, which begins to act on the target tissue and restore the body’s water levels. At this point the brain ceases to make and release any more ADH . Keeping conditions stable inside the body is called homeostasis and h__________ help with this. Anti diuretic hormone in action: Increasing ADH Reduced ADH Normal Low blood water High blood water ADH controlling body water three Science Interactive LTD Copyright 2005 Word bank: water hormones The amount of water in your blood is controlled by the actions of a hormone called anti diuretic hormone (ADH) on your kidney. On a hot summers day for example, you lose water through your skin as sweat. If you fail to replace lost fluids by drinking, your blood volume begins to drop. This triggers the pituitary to produce ADH. ADH then travels and targets the kidney. Water is then reabsorbed from the kidneys back to the renal vein, therefore reducing water loss. Your urine is low in volume and very concentrated. Notes Diagram Effect of ADH around the body’s tissues Water levels

The skin and its roles one Your skin has many important functions. It is also the largest organ of the human body. A key role of the skin is to help maintain c______ body temperature at 37 o C. The skin also has many other functions. It helps protects your body against physical injury. The skin also prevents disease and microbial infection, by acting as a physical barrier. It also secretes an antiseptic oil to keep it supple and help prevent bacterial cells breeding on its surface. The skin also prevents water loss, it is i____________ to water. What role does the layer of fat found underneath the skin play ? Functions of the skin: Science Interactive LTD Copyright 2005 Word bank: core impermeable The skin is a tough barrier against water loss. The skin cells form an impermeable barrier to water. Why is this so important to our survival ? Water loss Skin prevents bacterial and many fungal infections. It is a physical barrier as well as being able to produce an antiseptic oil which prevents bacterial growth on the skin. Skin is able to increase heat loss by sweating and insulate us against the cold. It help keeps the internal core temperature constant at 37 o C. Notes Diagram Temperature Disease

The skin and its roles two In addition to controlling your body temperature, helping to reduce disease and preventing water loss, the skin also has several other important roles. It lets you sense the external environment allowing you to feel pain, touch, pressure and t___________. It also protects you against UV light from our s______. Skin cells are constantly replaced so any cells that are damaged by UV radiation or chemicals in the air are lost and simply replaced . The skin also stores long term energy in the form of fat. How does this fat layer help to protect us against physical injury ? Functions of the skin: Temperature Pain Touch Pressure Science Interactive LTD Copyright 2005 Word bank: temperature sun Skin cells damaged by U.V light and cancer causing chemicals in the air are lost on a daily basis. Dust in the air is about 80% skin cells. Protecting against U.V The skin together with the blood clotting response forms a scab during wound healing. This prevents microbes from entering the wound. Information like touch, pressure and temperature is sent to the brain from the skin. This gives us a sense of our surroundings. Notes Diagram Sensing information Preventing infection

Skin its anatomy The skin is the largest o________ in the body and contains mainly specialised cells and tissues that have specific functions to help maintain our core body temperature, protect us against disease and sense our environment. The skin’s outer cells are in fact dead and are called the epidermis . These cells are constantly being replaced from living tissue called the dermis . Underneath the dermis, is a f____ layer which helps keep us warm and acts as a energy store. Anatomy of the skin: Complete the table Science Interactive LTD Copyright 2005 Word bank: organ fat ______________________________ ? Blood vessels ______________________________ ? Fat layer ______________________________ ? Hair muscle ______________________________ ? Sweat gland ______________________________ ? Receptors ______________________________ ? Dermis ______________________________ ? Epidermis ______________________________ ? Oil layer To trap an insulating layer of air. Hair Function Tissue (label)

Skin sensing information one Your skin is also home to thousands of r_________ that help our nervous system monitor our internal environment and external surroundings. When you get an itch on your scalp, for example, a chain of events follows, leading to you scratching the itch. All this information is collected, sent and processed by your nervous system. How is this response different to the blink reflex that protects your eye from dust or dirt ? Sensors in the skin: Science Interactive LTD Copyright 2005 Word bank: receptors Effector Coordinator Response Receptors located in your skin detect an itch on your scalp. This begins the process. You have many other types of receptors in your skin. The receptor cells send an electrical message along a sensory neurone through the spinal cord to your brain. The brain receives the message that you have an itch and decides on the right response. The message is sent to your muscles in your arm, elbow and hand from the brain by motor neurones. It tells your elbow and hand to scratch the itch The response in this case is to relieve the itch or irritation and scratch the itchy scalp. The cycle is complete. Notes Diagram Stimulus Receptor

Skin sensing information two Detecting touch and pressure is essential to protect our skin, muscles, joints and bones from serious crippling injury. During a long film, you may start to feel uncomfortable, due to the pressure of sitting on your behind for long periods. Your body will automatically shift your weight, avoiding excess p_________ on your joints and muscles. You do this even when your are asleep, to avoid developing bed sores. Also sensing t_______ is important to connect us with our environment, the things we move and the people close to us. Try mapping out the number and location of touch receptors located on your hand. Where do you find the greatest concentration ? Detecting touch and pressure: Temperature Pain Touch Pressure Science Interactive LTD Copyright 2005 Word bank: pressure touch Your skin and other areas of your body can detect the lightest touch or intense pressure. This helps us communicate with other humans and sense objects in our own environment. Found in the dermal layers of the skin are temperature, pain, touch and pressure sensors which all convey information to your brain. Notes Diagram Human skin Touch Pain

The skin is the largest organ in the body. One of its main functions is to act as a ‘physical barrier’ to the entry of microbes. If cut, you are at risk of infection caused by the entry and subsequent multiplication of m_________ in the circulatory system. Once cut, the skin rapidly heals to prevent further blood loss and the entry of microbes into the blood stream. Healing and scab formation is helped by the clotting response. This is where platelets and fibrinogen, both carried in the blood, form a tightly knitted s_____ that closes the wound. What role do plasters play in helping us avoid infection from microbes ? Forming a scab: Skin preventing infection Science Interactive LTD Copyright 2005 Word bank: microbes scab Stage two Stage three When you cut healthy skin, a three stage response occurs before scab formation takes place. One: The skin is cut, bleeding occurs. Two: Platelets are pumped to the injury site. Three: Platelets and fibrinogen form a scab which prevents further bleeding and closes the wound. White blood cells are also rushed to the injury site to destroy what ? A key role of the skin is to help maintain core body temperature at 37 o C. The skin also has many other roles. It protects your body against disease and bacterial infection by acting as a physical barrier Notes Diagram Human skin Stage one

Skin Temperature control in the body one All warm blooded animals need to control their core body temperature so they can avoid hyper or hypothermia . The skin’s main role is either to increase or r_________ heat loss to our surroundings. It has a number of strategies to carry out this important function. Our core body temperature needs to be maintained at 37 o C, so that all our enzymes can function properly. Even small changes in core temperature can have serious effects on how we function. The body’s response to cold: Hair (stands up) Science Interactive LTD Copyright 2005 Word bank: reduce Blood flow to the skin and extremities is slowed by vasoconstriction of the blood capillaries, therefore reducing heat loss by radiation to the environment. Blood flow All sweating stops, with the skin remaining dry. Less of the body’s heat is taken away by water evaporating from the skin’s surface to the environment. Hairs stand upright and traps air to provide an insulating layer or still air that reduces heat loss from the skin to the environment. This is known as goose bumps !

Behavioural changes include:

Seek shelter

Put on clothes

Huddle

Increased appetite

Too cold Diagram Behaviour Hair Sweating

Skin Temperature control in the body two Even small increases in the core temperature can lead to coma and death. During hyperthermia, where core body temperature rises by only 2 to 3 o C, digestive enzymes and those enzymes that carry out c_________ respiration can begin to denature and cease to function. If the core temperature is not reduced by sweating or increased blood flow to the skin it can be fatal. Why are the young and old at particular risk of hypo or hyperthermia ? The body’s response to heat: Hair (lays flat) Science Interactive LTD Copyright 2005 Word bank: cellular Blood flow to the skin is increased by vasodilation of the blood capillaries. increasing heat loss by radiation to the environment. Blood flow Sweating increases with body heat taken away by the evaporating water. During exercise up to two litres per hour can be lost by sweating. Hairs lays flat allowing increased air flow . This reduces the amount of insulation, therefore increasing heat loss from the skin to the environment.

Behavioural changes include:

Seek shade

Increase water intake

Take off clothes

Reduced appetite

Too Hot Diagram Behaviour Hair Sweating

Skin Its responses Your skin responds to the external environment, your w______ intake, the clothes that you are wearing and any exercise that you may be doing. Look at the two pictures below and consider what is happening to the skin’s blood vessels, sweat glands and blood supply in response to the cold and heat. Use the table to give your answers. Skin and its responses: Science Interactive LTD Copyright 2005 Word bank: water Shivering Skin hairs Blood supply Sweating ____________________________________________ ? ______________________________________________ ? ___________________________________________ ? ________________________________________ ? Summer (hot day) ____________________________________________ ? ______________________________________________ ? ___________________________________________ ? ________________________________________ ? Winter (Cold day) Cold winters day Diagram Hot summer day

37 o C Reducing core temp Increasing core temp Bodily response to changes in core temperature The human body using the skin, metabolism, skeletal muscle system must maintain a constant internal core body temperature. If it cannot control and maintain your core temperature at 37 o C, a series of events leading to hyperthermia or hypothermia will result. Hypothermia and hypothermia: Normal core temp o C 42 o C 41 o C 40 o C 39 o C 38 o C 35 o C 33 o C 31 o C 27 o C 25 o C Science Interactive LTD Copyright 2005 Word bank: sweating vasoconstriction stops urine increases Deep coma, death follows. Coma. Slowed responses, now hypothermic. Shivering begins.

Vasoc__________ ?

Sweating s_______?

Dilute u_________ ?

Seeking warmth

Metabolism i________ ?

Shivering

Metabolism increases. No response: normal core temperature. No response: normal core temperature. Moderate s________ and increases in blood flow. High fever, heart rate increases. Very high fever, nausea feeling unwell. Coma. Deep coma, enzymes denature, Death follows.

Sweating

Drinking

Seeking shade

Metabolism slows

Vasodilatation

Hairs lay flat

Hyperthermia Temperature Hypothermia

1: Define the following terms: Homeostasis, Internal-environment, Nephron, Anti diuretic hormone, Sweating, Vasodilation & Vasoconstriction. 2: Look at the diagram below. Complete the table. 3: Answer the following: a) The human body produces two main waste substances that it needs to get rid of. Name these two substances and for each say which process inside the human body produces them and which organ excretes them. b) Which of the following organs are homeostatic organs helping to remove waste products: Liver, Stomach, Lungs, Bladder, Brain, Kidney, Heart and Appendix. c) Name three internal conditions that the body controls within narrow limits. d) Name the specific hormone that controls the amount of water reabsorbed by the kidney nephron. e) What is the process whereby urea, salts, water and other harmful substances are removed from the renal artery into the Bowman’s Capsule. f) The second convoluted tubule and the collecting duct is responsible for the reabsorption of water. How might these parts of the nephron differ in the camel and a fish. g) Describe the differences in the volume of urine, concentration of urea and its colour on a hot summer’s day and a cold winter’s day. Extension questions and homework Science Interactive LTD Copyright 2005 7 Loop of henle 6 5 Proximal convoluted tubule 4 Carries unclean blood towards the glomerulus Function in the kidney 3 2 1 Name Number 1 2 3 4 5 6 7

4: Look at the information in the table below. Draw a line graph of volume of sweat and urine produced over a number of temperatures: Is there a relationship between the two. At what time are the two volumes the same and how do changes in air temperature, affect the volume of urine and sweat produced. Explain the last answers: 5: a) Give five different function of the skin. b) Give a role for the following tissues of the skin. Epidermis, Hair, Oil-gland, Touch receptor and Sweat-pore. c) Describe the several stages that happen after the skin is cut and forms a scab. Why is the quick formation of a scab very important. d) Humans are warm blood animals producing heat as a by product of digestion, respiration and movement. What systems control our core bodily temperature. e) The part of the brain that monitors core temperature is called the thermoregulatory centre. If this is damaged, how might this affect the body’s ability to regulate core body temperature. f) If the core temperature rises above 37 o C what two behavioural traits could reduce body temperature. What two measures could the skin use to reduce body temperature. g) If the core temperature falls below 37 o C what two behavioural traits could increase body temperature. What two measures could the skin use to increase body temperature. 6: Complete the following: Maintaining the conditions inside the body is called _______________. During the day our water gain and loss may differ. The _______________ and the nephron tissue ensure that we are correctly hydrated. Internet: Go to google.co.uk and find about kidney dialysis and kidney transplants. Science Interactive LTD Copyright 2005 12 23 35 42 54 68 82 91 102 Urine produced (cm 3 /hr) 204 189 114 73 44 29 13 9 7 Sweat produced (cm 3 /hr) 40 35 30 25 20 15 10 5 0 Air temp o C