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what is the vascular system and how does it work? (6 steps)
the vascular system is a closed system of of vessels through which blood flows continuously, with the heart serving as a pump.
- blood pick up materials and delivers as needed
- 1. blood leaves the right side of the heart by way of the pulmonary artery and goes to he lungs
- 2. In the lungs: blood loses CO2 and picks up O2 and returns to the left side of the heart via the pulmonary vein
- 3. In the heart: blood leaves the left side of the heart via the aorta (main artery that launches blood in the body)
- 4. blood may leave the aorta and go to:
- a) the upper body and head
- b) the lower body5. blood may go to:
- a) the digestive tract and liver
- b) the pelvis, kidneys and legs
- 6. blood returns to the right side of the heart
- 7. lymph from most of the body's organs, including the digestive system, enters the bloodstream near the track
what is arteriosclerosis?
- arteriosclerosis develops when areas of the artery walls become thickened with plaque
- plaque = accumulations of fatty deposits , smooth muscle cells and fibrous connective tissue
- arteries = rough, rigid and narrow
- since artery walls are not elastic anymore, that would increase blood pressure
- it can block flow of blood to the heart and can cause a heart attack
- it can cut off blood flow to the brain and cause a stroke
how does the formation of plaque occur in arteriosclerosis?
- the coronary arteries deliver oxygen and nutrients to the heart muscle
- plaque can begin to form in a person as young as 15, thus reducing the blood flow
- when these arteries become blocked by plaque, the part of the muscle that they feed will die
how does the O2- CO2 exchange work?
what is cardiac output?
its the volume of blood pumped by the heart within a specified period of time
what is peripheral resistance?
refers to the resistance to pumped blood by small arterial branches (arterioles) that carry blood to tissues
what are some non-modifiable risk factors?
- age, sex and family history
- men higher risk than women
- men older than 45 years of age
- women older than 55 years of age (after menopause)
- immediate family history of premature heart disease
what are some modifiable risk factors?
- sedentary behaviour
- atherogenic diet (high calories, high saturated fat, high alcohol, low fibre/ high glycemic, low (high) vitamins/minerals)
- obesity - visceral
- high LDL/low HDL
- high triglycerides
- high homocysteine
- chronic inflammation
what is metabolic syndrome?
- abdominal obesity
- men: waist circumference > 40 inches
- women: waist circumference > 35 inches
- triglycerides: ≥150mg/dL
- HDL: <40mg/dL in men, <50mg/dL in women
- blood pressure: ≥130/85 mm Hg
- fasting glucose: ≥ 100 mg/dL
what are some classic GI tract funtions?
- 1. ingestion
- 2. mechanical processing
- 3. digestion
- 4. secretion
- 5. absorption
- 6. excretion
what are some other functions of the GI tract?
- 1. barrier : from toxins and bacterias in environment
- 2. immunological (GALT)
- 3. endocrine
- 4. neural
- 5. gut microbiota
what are the components of the digestive tract?
what do the oral cavity, teeth and tongue do?
- they're in charge of processing, moistening and mixing with salivary secretions
- salivary amylase = enzyme in saliva
what does the pharynx do?
its moves the food into the esophagus suing its muscles
what does the esophagus do?
- its transports the food to the stomach
- has a flexible tube
- peristalsis = muscle contraction that propel the food to go down
how does peristalsis work?
- STEP 1:
- esophagus muscles relax, opening the passageway
- diaphragm muscles relax, opening the passageway
- STEP 2:
- esophagus muscles contract, squeezing on the inside
- diaphragm muscles contract, squeezing on the outside
what does the stomach do?
- breaks down the material b using eacid and enzymes
- there is mechanical processing that occurs through muscular contractions
what does the small intestine do?
how is our metabolism regulated?
by negative feeback
how does negative feedback work?
- 1. food in the stomach causes the cells of the stomach cell wall to start releasing gastrin
- 2. gastrin stimulates stomach glands to release the components of HCl
- 3. stomach pH reaches 1.5 acidity
- 4. acidity in stomach causes the cells of the stomach wall to stop releasing gastrin
what are some GI hormones?