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Lab Report Homeostasis

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The purpose of Homeostasis is to maintain a constant internal environment regardless of external factors that affect e.g. temperature, Blood Pressure, Glucose, pH, Water levels etc. Homeostatic blood pressure systems require a reference point (which for us humans, generally it’s 120/80), which is the optimum set point for the organism. When the organism deviates away from this set point (e.g. the blood pressure begins to rise or fall) a control system begins to operate to return the system back to the set point. A system requires 3 components for homeostasis: A receptor, a control center and an effector. These components do specific jobs that allow regulation of the internal environment, returning the system back to set point. Firstly, a stressor …show more content…

This change is detected by the receptors, which inlay the message to the control center. The control center receives the message and passes it on to the effector, which is stimulated to initiate corrective control measures to restore the set point.

For example, blood pressure is the measure of force of blood pushing against blood vessel walls and is measured in mmHg. Blood pressure increases and decreases in response to an external stimulus to maintain homeostasis. The external stimuli are known as stressors. For my experiment, running (independent variable) is my stressor and it ranges from 20min (not so extreme stressor) to 60min (and extreme stressor). This stress is picked up by the receptors called the baroreceptors which are nerves attached to the carotid sinus as well as the aortic arch that monitor the dilation and contraction of the blood vessels. So, when there is disruption to the blood pressure, the baroreceptors convey this disruption to the medulla oblongata through nerve impulses to the brain. The specific nerve called Vagus nerve is the nerve …show more content…

The SNS will then stimulate granular cells within the afron-arteriole/efron-arteriole. Around this area, the granular cells (also known as juxtaglomerular cells) will then release renin. Renin is a vital enzyme. The liver constantly produces a pre-hormone known as angiotensinogen. When angiotensinogen is catalyzed by Renin, it’ll convert to angiotensin I. Angiotensin I doesn’t do much but when it’s converted by ACE (Angiotensin converting enzyme – which is predominantly located in the lungs) to Angiotensin II, it’s a serious hormone that increases blood pressure. Angiotensin II has many functions and targets many tissues but whatever it targets will cause an increase in blood pressure. For example, angiotensin II stimulates the adrenal cortex to release aldosterone, aldosterone will increase blood pressure. Angiotensin II will also cause systemic vasoconstriction and therefore increase blood pressure. Angiotensin II will also stimulate the thirst center in the brain causing us to drink which increases plasma volume which therefore increases blood pressure. Angiotensin II also causes cardiovascular hypotrophy which means increase in muscle, increase in contraction which means increase in blood pressure.

When there’s hypertension, whether due to cardiac extension (when there’s stretching in the right atrium), sympathetic stimulation or detection

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