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★Circulatory and Digestive System★

por Asad Zaara

Healthy Body Systems

Active and passive physical activity

We use more energy during active activity than passive because we and exerting ourselves, rather than having someone move our bodies for us. --> we need physical activity to keep ourselves healthy and well to have improved circulation and muscle ROM.

Exercise is a good way to reduce pain as well -->whilst it will be painful in the beginning, it reduces pain in the big picture by reducing the risk of getting diseases like muscle atrophy which causes bad deformities.

Limbs can start to curl inward towards the body in severe cases when a patient is paralysed, for example. --> muscle tissue starts to decay and joints stiffen. Movement prevents this from happening by lubricating the joints. In these situations, it's likely passive ROM is required.

People who have a limited ROM can also have poor circulation as they are unable to move and circulate the blood around the body. --> exercise is a good way to prevent pools of blood forming in the lower portion of the body, as well as improving heart health by helping it pump blood around the body through movement.

When muscles aren't being used frequently, they become weak or stiff and unable to support the joint. --> using resistance bands is the best way to start muscle movement again after a period of being stationary e.g. after having a knee replacement.

Passive movement is sometimes also used by doctors to test hoe far a. joint can move before deciding whether they require passive or active treatment.

It is much easier for patients who can move independently to gain their full ROM.

Without ROM exercises, our joints and muscles would lock and lose their ability to functions and move properly --> patients who are bed-ridden face the risk of developing muscle atrophy if they don't do passive physical activity.

Range of motion (ROM) is how far a joint moves during physical activity.

Passive range of motion means someone is moving the joint for them.

Active range of motion refers to someone physically moving the joint and subsequent parts of the body on their own.

Maintenance of blood pressure

Neurotransmitter called catecholamine activates the fight-or-flght response and responds when blood pressure falls.

Renin is produced in the kidney's that causes vasoconstriction

When our bodies have higher blood flow in one area of the body, blood vessels will widen in another area to balance flow and blood pressure.

Kidney's are the primary organ responsible for maintaining healthy blood pressure. --> chemical signals trigger the kidneys to increase urine productions when blood pressure is too high, and decrease urine production when blood pressure is too low. The ratio of blood to fluids to water is controlled in the kidney's.

If our bodies suddenly lose a lot of blood, the sudden drop in blood pressure will signal hormones (renin) to be released which tell the kidney's to retain salt and fluids to maintain blood density.

Our bodies adjust quickly to changes in physical activity --> pressure senses in blood vessels detect an increase in blood pressure e.g. when we start exercising sends a message to the brain via the nervous system telling the heart to decrease the number of contractions and relax blood vessels (vasodilation) to decrease blood pressure.

Cardiovascular centre, located in the brain stem, detects changes in pH and blood pressure. Affects these changes by sending nerve impulses to the heart, and regulates stroke rate (amount of blood pumped). --> both of these changes maintain the heart's cardiac output. BPM x stroke volume = cardiac output

Fluid, electrolyte and pH balance

Exhaling CO2 rids the body of some acids --> breathing too fast (hyperventilating) causes too much acid to be release, creating an alkaline environment which isn't compatible with consciousness, causing us to faint. The same happens when we hold our breathe for too long as our bodies become too acidic.

Carbonic acid and bicarbonate are the two pH stabilising chemicals is the body. --> carbonic acid neutralises excess bases and bicarbonate neutralises excess acids.

We lose water through breathing in the form of water vapour. How much water is lost through breathing is dependent on how humid the air is. It's estimated we lose ~400mL of water per day by breathing.

When the body is dehydrated, we draw water from the blood, to maintain both blood concentration and water levels.

Water is mostly lost through urine, but also through faeces and the respiratory tract.

Water intake is balanced by water loss. This means, when the body is losing water, the kidney's will produce small amounts of concentrated urine to conserve water. Kidney's will produce larger amounts of urine when there is too much water as well. Everything is balanced.

Kidney's maintain electrolyte levels by filtering waste products out of the blood and converting it to urine. --> the kidney's main role is to monitor the bodies consumption and excretion of water and electrolytes.

Blood electrolytes include potassium, chloride sodium and bicarbonate. --> they help to regulate nerve and muscle function, maintain pH levels and water levels.

Role of the urinary and respiratory systems.

Protection from infection

We develop our immunity naturally, from vaccinations and from our mothers. --> naturally being being exposed means we get sick and develop our antibodies that way. Vaccinations help to develop antibodies before we get sick (usually with more serious illnesses). After birth, we get some of our immunity from our mum if she has been vaccinated during birth, during the first 6 months.

Antibodies are essential proteins that are formed when new germs enter the body --> they're produced by B-leukocytes and attach onto antigens that cause diseases, whilst other cells work to destroy the cells, so it then remembers that germ. Once the antibody has been produced it then remains in the body to protect us from that infection if it returns in the future. We may still show symptoms, but our bodies will be able to fight the infection quicker. Different antibodies fight different infections.

Having healthy bone marrow cells is essential because our blood cells don't live for long in our body and have to constantly be re-produced --> without red blood cells, we couldn't transport oxygen around the body. Without white blood cells we couldn't fights infection and without platelets we'd all be haemophiliacs.

Lymphatic system transports B and T leukocytes into the bones where blood cells are made --> bone marrow is where the formation of red and white bloods cells and platelets takes place

Lymph nodes are an essential part of the immune system -->filter foreign particles and cancer cells from the body. Located in the neck, armpits, groin and behind the knees.

Leukocytes (white blood cells) both B and T are the main cells that are make up the immune system --> travel through the body looking for any disease- causing germs and destroy them

When germs do get into the body, the immune system then takes over to destroy them

The skin and mucous membranes are the body's first line of defence --> main role is to protect the bodies internal tissues and organs from infection

Immune system and blood cells

Elimination of waste

Sweat is not only produced to cool us down, but it eliminates waste as well. --> waste products like extra salt and sugars, urea and ammonia are excreted when we sweat.

Our noses and ears have small hairs that help prevent dirt and germs from building up in our mucous membranes.

Earwax is another way we eliminate waste. --> sticky substance called cerumen is made up of germs and dirt, but also protects our ears by keeping them moist and prevents infection. The dirt and germs that get stuck in the cerumen forms the earwax and leaves the body when the earwax falls out.

The respiratory system is also responsible for eliminating waste. --> our lungs breathe in air filled with a combination of oxygen, CO2 and nitrogen. We only have need to keep the oxygen in our bodies, which is passed into the blood in the lungs via small sacks called arioli. CO2 from the air and from within our bodies (produced by cells as a waste product of converting food to energy) is exhaled back into the air as it causes our bodies to become too acidic and our cells would die.

We also excrete waste through faeces. --> the food we eat is broken down by digestive enzymes in both our saliva and in our gut. Once this food has been broken down into a liquid, it travels into the small intestine where nutrients is absorbs by villi that lines the wall of the intestine. The nutrients we need is absorbed into the blood, and any left over material passes through into the large intestine and bowel where it is kept until we go to the bathroom.

Kidney's remove toxins from the blood, which then travels down the uterers as the form of urine and stored in our bladder's until we go to the bathroom.

Our excretory systems prevent salt and urea from building up in our bodies.

Homeostasis

When we are cold, our muscle contractions are reduced by carbohydrates being relocated and our muscles produce lactic acid. Our nervous system also slows down when we're cold to conserve energy. --> NS slowing down and the production of lactic acid acts like a chemical signal telling our bodies to slow down to retain heat.

STIMULUS-> RECEPTOR-> CONTROL CENTRE-> RESPONSE e.g. when our hand touches a hot stove, receptor cells in our fingers recognise that it is hot and a message is sent to the control centre, or brain, saying that we have touched a hot surface. a reflex response is carried out to remove our hand from the hot surface --> reflex responses are vital to ensuring we don't cause serious injury to ourselves.

The nervous system and the endocrine system work together to maintain maturation and homeostasis.

Our body's will slowly stop sending chemical signals to parts of the body as the set point is reached again.

The dermis layer of the skin is where our body's water is stored --> this water, plus salt, are brought to the surface of the skin when we are hot to form sweat. It's purpose is to cool on top of the skin due to evaporation to reduce the body's temperature.

37 degrees is the optimal temperature at which our bodies function normally. --> cells don't function properly when our core temperature is changed too drastically.

Our blood vessels constrict when our bodies are too hot, and expand when our bodies are too cold

Hypothalamus is the part of the brain and endocrine system that is responsible for thermoregulation. --> sends chemical signals to muscles, glands, organs and nervous system.