Task 4 Homeostatic Mechanisms and the Maintenance of an

Internal Environment.

Homeostasis and how the body responds to exercise (P5, M2, D2) To secure knowledge by explaining the concept of homeostasis

To further develop knowledge by discussing the probable homeostatic responses to changes in the internal environment during exercise

To show excellence by evaluating the importance of homeostasis in maintaining the healthy functioning of the body.

Task ref. Evidence submitted Page numbers ordescription

P5 explain the concept of homeostasis

M2 discuss the probablehomeostatic responsesto changes in the internalenvironment during exercise

D2 evaluate the importance ofhomeostasis in maintainingthe healthy functioning of the body.

Additional comments to the Assessor:

Homeostatic Mechanisms and the Maintenance of an Internal Environment.

Homeostasis is the process of maintaining a constant internal environment despite external changes.For this task you need to;(a) Describe the homeostatic mechanisms that regulate;• heart rate• breathing rate • body temperature • blood glucose levels.Include annotated diagrams with supporting descriptions.(b) Explain how these homeostatic responses change in the internal environment during exercise. Use the scenario given and show how the body works to maintain homeostasis.(c ) Explain the importance of homeostasis in maintaining the healthy functioning of the body. What would happen if homeostasis did not occur? How would the body cope?

Range of Content:3 Understand how homeostatic mechanisms operate in the maintenance of an internal environment• Homeostasis: definition of homeostasis, internal environment, concept of negative

feedback as a regulatory mechanism• Homeostatic mechanisms for regulation of: heart rate: roles of internal receptors,

autonomic nervous system-sympathetic and parasympathetic nerve supply, cardiac centre, sinoatrial node; effects of increased body temperature and adrenaline on

• heart rate breathing rate: roles of internal receptors, autonomic nervous system – sympathetic and parasympathetic nerve supply, respiratory centre, diaphragm and intercostal muscles body temperature: production of heat by the body, e.g. through metabolic processes; loss of heat by the body – radiation, conduction, convection, evaporation; roles of hypothalamus, autonomic nervous system – sympathetic and parasympathetic, skin – role of arterioles and sweat glands; effects of shivering; implications of surface area to volume ratios, e.g. in the care of babies; fever blood glucose levels: roles of pancreas, liver, insulin, glucagon

a)Homeostasis is…..the process of maintaining a constant internal environment despite external changes.• Heart rate • Role of internal receptors• Role of autonomic nervous system• Effects of body temperature • Effects of adrenaline• Breathing rate• Role of internal receptors • Role of autonomic nervous system • Role of diaphragm and intercostal

muscles• Effects of adrenaline

• Body temperature • Effect of metabolic processes• Role of the skin• How heat is lost• Role of autonomic nervous system• Blood glucose • Role of pancreas• Role of liver• Effects of insulin• Effects of glucagonWatch the following video http://

study.com/academy/lesson/what-is-homeostasis-definition-examples-quiz.html

Heart rate Explain how each of the following is involved within homeostasis

• Role of internal receptors• What are they? How do they

work?

• https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/introduction-to-human-anatomy-and-physiology-1/homeostasis-32/homeostatic-control-284-3141/

• http://www.ncbi.nlm.nih.gov/pubmed/15255616

• http://www.nursingtimes.net/clinical-subjects/respiratory/homeostasis-part-1-anatomy-and-physiology/203292.fullarticle

Heart rate• Role of autonomic nervous

system• What is it?• http

://www.s-cool.co.uk/gcse/pe/how-the-body-is-controlled/revise-it/the-autonomic-nervous-system

Heart Rate explain how the heart rate affects each.• Effects of body temperatureBlood PressureThe human body uses homeostasis to regulate itself internally, despite whatever activity the person is engaged in or environmental issues he is encountering. Blood pressure regulation is part of homeostasis. A normal blood pressure should be approximately 120 over 80, according to Creighton University Medical Center. Depending on the outside temperature, blood vessels will either dilate or contract. A dilation of the blood vessels will cause a drop in blood pressure, and this lowers body temperature. Contracting vessels increase blood pressure, resulting in increasing core temperature.• http://www.livestrong.com/article/228784-the-effe

cts-of-body-temperature-on-heart-rate/

• Effects of adrenalineAdrenaline, also called epinephrine, is a hormone secreted by your adrenal glands, which sit on top of each of your kidneys. Once released by these glands, adrenaline produces a variety of effects on your body, including increases in your heart rate. These effects are triggered through interactions with certain portals on the surfaces of your cells called adrenergic receptors.• http://www.livestrong.com/article/3556

72-why-adrenaline-speeds-up-heart-rate/

Breathing rate

Explain each of the following;• Role of internal receptors • Role of autonomic nervous

system • Role of diaphragm and

intercostal muscles• Effects of adrenaline

What is happening in this image?

http://www.livestrong.com/article/30209-breathing-regulated/

Body temperature http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/homeostasis/bodytemprev1.shtml

• Effect of metabolic processes• Role of the skin• How heat is lost• Role of autonomic nervous system

• The human body is designed to function most efficiently at 37ºC. This is controlled to maintain the temperature at which the body’s enzymes work best.

• If you become too hot or too cold, there are ways in which your body temperature can be controlled. Too hotWhen we get too hot:• Sweat glands in the skin release more sweat. The sweat evaporates, removing heat energy from the skin. • Blood vessels leading to the skin capillaries become wider - they dilate - allowing more blood to flow through the skin, and more heat to be lost. Too coldWhen we get too cold:• Muscles contract rapidly - we shiver. These contractions need energy from respiration, and some of this is released as heat. • Blood vessels leading to the skin capillaries become narrower - they constrict - letting less blood flow through the skin and conserving heat in the

body. • The skin • The hairs on the skin also help to control body temperature. They lie flat when we are warm, and rise when we are cold. The hairs trap a layer of

air above the skin, which helps to insulate the skin against heat loss.• The hypothalamus is the part of the brain which monitors the body's temperature. It receives information from temperature-sensitive receptors

in the skin and circulatory system. • The hypothalamus responds to this information by sending nerve impulses to effectors to maintain body temperature.

Watch the video• http://

study.com/academy/lesson/homeostasis-and-temperature-regulation-in-humans.html

For example, if we become too cold, the hair erector muscles contract. This raises the skin hairs and traps a layer of air next to the skin.

Skin hairs lie flat when we are hot and stand upright when we are cold

Negative feedback mechanisms control body temperature. They include the amount of:•shivering (rapid muscle contractions release heat) •sweating (evaporation of water in sweat causes cooling) •blood flowing in the skin capillaries

Too cold Too hotProcess Vasoconstriction VasodilationArterioles Get narrower Get widerBlood flow in skin capillaries Decreases IncreasesHeat loss from skin Decreases Increases

Vasoconstriction and vasodilationThe amount of blood flowing through the skin capillaries is altered by vasoconstriction and vasodilation.

Blood glucose• Glucose is needed by cells for

respiration. It is important that the concentration of glucose in the blood is maintained at a constant level. Insulin is a hormone - produced by the pancreas - that regulates glucose levels in the blood.

• Blood sugar level• This is controlled to provide cells

with a constant supply of glucose for respiration. It is controlled by the release and storage of glucose, which is in turn controlled by insulin.

Low glucose High glucoseEffect on pancreas Insulin not secreted into the blood Insulin secreted into the blood

Effect on liver Does not convert glucose into glycogen Converts glucose into glycogen

Effect on blood glucose level Increases Decreases

Action of insulin

http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/responses_to_environment/homeostasisrev6.shtml find out more!

DiabetesDiabetes is a condition in which the blood glucose levels remain too high. It can be treated by injecting insulin. The extra insulin causes the liver to convert glucose into glycogen, which reduces the blood glucose level. There are two types of diabetes - Type 1 and Type 2.Type 1 diabetesType 1 diabetes is caused by a lack of insulin. It can be controlled by:•monitoring the diet •injecting insulinPeople with Type 1 diabetes have to monitor their blood sugar levels throughout the day. Their levels of physical activity and their diet affect the amount of insulin needed.They can help to control their blood glucose level by being careful with their diet (eating foods that will not cause big spikes in their blood sugar level) and by exercising (which can lower blood glucose levels due to increased respiration in the muscles).

Type 2 diabetesType 2 diabetes is caused by a person’s body becoming resistant to insulin. It can be controlled by diet and exercise. There is a link between rising levels of obesity and increasing levels of Type 2 diabetes.

Changes in obesity and Type 2 diabetes

Watch the video http://study.com/academy/lesson/homeostasis-glucose-levels-and-osmolarity-hormonal-control.html

Water content

• This is controlled to protect cells by stopping too much water from entering or leaving them. Water content is controlled by water loss from:

• the lungs - when we exhale • the skin - by sweating • the body - in urine produced by

the kidneys

• http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/homeostasis/waterbalrev1.shtml

• Explain what is happening in each organ.

Negative feedbackHomeostatic control is achieved using negative feedback mechanisms:•if the level of something rises, control systems reduce it again •if the level of something falls, control systems raise it again

Additional Resources• http://

www.bbc.co.uk/education/guides/z4khvcw/revision

• http://www.s-cool.co.uk/gcse/biology/homeostasis/revise-it/what-is-homeostasis

• http://www.abpischools.org.uk/page/modules/homeostasis_kidneys/index.cfm?coSiteNavigation_allTopic=1

• http://www.bbc.co.uk/bitesize/higher/biology/control_regulation/homeostatic_control/revision/1/

• https://www.youtube.com/watch?v=vB7tSHqR1eY

b)How and why do homeostatic responses change in the internal environment during exercise. Use the scenario given and show how the body works to maintain homeostasis.• When you sweat, breathe heavily and feel

your heart pounding, it doesn’t just mean you are having a good workout. These physiological factors are also vital to your body maintaining a state of homeostasis. Homeostasis is defined as a constant, steady environment despite external changes, such as exercise. Exercise affects your body temperature, blood oxygen levels, sugar levels and hydration – all properties necessary for your survival. Your body uses an automatic feedback system to preserve normal temperature and water levels, so you can keep exercising. Eat properly and drink plenty of fluids to help your body maintain homeostasis.

Find out more at http://www.livestrong.com/article/369714-how-does-the-body-maintain-homeostasis-in-response-to-exercise/

c) Explain the importance of homeostasis in maintaining the healthy functioning of the body. What would happen if homeostasis did not occur? How would the body cope?Body system How does Homeostasis

help maintain the system?

What would happen if homeostasis did not occur? What would go wrong?

How would the body cope? What changes would occur?

Cardiovascular

Respiratory

Digestive

Renal

Nervous

Muscular-skeletal

Immune/Lymph/Endocrine Reproductive