4. Fuel for life Flashcards
Digestion
= the mechanical and chemical breakdown of food to absorb nutrients and functioning
- essential for energy, growth and maintenance of our bodies
- glucose is an essential source of energy release from varied food sources by enzymes and hormone insulin
- in healthy body water, monosaccharides, aa, fatty acids and glycerol, vitamins and minerals absorbed within an appropriate range
Digestive system anatomy in order
- Oral cavity
- salivary glands
- saliva
- oesophagus/ esophagus
- stomach
- small intestine
- Accessory organ secretion - liver and pancreas
- large intestine
Oral cavity
= lips cheeks, teeth and tounge
mechanical - biting and chewing mechanics chops food into small pieces to swallow
Salivary glands
= 3 pairs - parotid, submandibular and sublingutar glands
- produce saliva through ducts into mouth
- Salivary amylase enzymes converts polysaccharides to disaccharides
Saliva
= mixture of serous and mucus fluids
serous (watery) component
- moistens food for swallowing
- dissolves food for tasting
- contains enzymes amylase - carbohydrates for state of
chemical digestion
mucous component
- lubricates food
- enzyme lysosym is antibacterial
Oesophagus
= muscular contractions in oesophagus occur in peristaltic waves to push food down tract
Stomach
= huge muscular sac that is a J shaped enlargement of GI tract (4 functions) - food churned (mechanical breakdown)
- Mixes saliva, food, gastric juice to form chyme (chemical breakdown)
- Serves as a resviour for food before release into small intestine
- Secretes gastric juice, which contains
- HCL - kills bacteria dn denatures proteins
- pepsin - begins the digestion of proteins
- intrinsic factor - aids absorption of vitamin B12
- gastric lipase - aids digestion of triglycerides - secretes gastrin into blood
Small intestine
= digestion and absorption
- three parts - Duodenum, jejunum and ileum
Modification increase surface area
- circular folds: mucosa and submucosa
- Cilli: finger like projection from mucosa
- microvilli
- food entering the small intestine is only particularly digested
- secrets digestive enzymes
Accessory organ secretion
Liver = produces bile to aid digestion
- stored in galbladder
- bile allows secretion
Pancreas
- bicarbonate to neutralise acidic chyme
- enzymes
Large intestine
4 main functions
- reabsorption of water and mineral ions
- formation and temporary storage of faeces
- maintain residence pop of over 500 species of bacteria
- assist vitamin production
- defecation (empty rectum)
Colon = mucosal lining with tubular glands which contains mucous producing goblet cells
Rectum = straight muscular tube
Anal canal = waste on the way out
Anatomy of the GI tract
4 layers of tissue called tunics:
- Tunica Serosa - protection/ covering
- Tunic muscularis - longitudinal and circular which work together to propel food/ chyme through digestive tract
- Tunic submucosa - loose tissue containing blood and lymphatic vessels, provide nervous control to mucosa
- Tunica mucosa - inner layer - secretion, absorption and hormone
What does the stomach absorb
=water , alcohol, aspirin
Pancreas
- gland that lies in the posterior of the stomach
- produces enzymes that digest carbohydrates, proteins, fats, nucleic acids
- produces bicarbonate
- empties contents into duodenum
Endocrine and exocrine function in pancreas?
Endocrine = organs release hormones
- insulin and glucagon
Exocrine = relate to releasing a substance through a duct
- release enzymes that aid digestion
- pancreatic lipase
- amylase
Pancreatic juice
= helps to protect and prevent erosion of the intestinal mucosa
- digestive enzymes which breakdown
Bile
= bile acids are critical for digestion and absorption of fats in small intestine
- contains waste products which are eliminated from the body via secretion into bile e.g. bilirubin
- stored in gallbladder
What is cirrhosis
- liver damage from alcohol abuse leading to many issues with liver
- no storage site for carbohydrates
Metabolism
= refers to all chemical processes occurring within a cell or organism that are necessary for the maintenance of life
- nutrients are broken down in GI tract, absorbed into the blood an then transported to the cells
- in the cells these molecules are either catabolised or anabolism
What is Catabolism
= the process by which metabolic pathways break down molecules into smaller units and release energy
Large molecules are broken down into digestible units
- polysaccharides - monosaccharides
- lipids - fatty acids
- proteins - aa
What is Anabolism
= set of metabolic pathways that construct molecules from smaller units
e.g. production of protein from aa
The kidney
= remover of wastes, maintainers of balance
- maintain extracellular fluid composition and volume
- filtration and reabsorption
- secretion of some waste products
- produce some hormones
- contains nephrons
Three process that occur in the nephron
= filters blood in kidney
THREE PROCESSES:
- Filtration (USWAG
- urea
- Salts
- Water
- AA
- Glucose
- Reabsorption (USWAG)
- urea - 0%
- Salts - Vary
- Water - Vary
- AA - 100%
- Glucose - 100%
- Secretion - this is the process where the body actively transports substances from the blood into the nephron - active transport
LEARN PICTURE
Nephron structure
- Glomerulus
- bowman capsule
- proximal tubule
- loop of Henele - descending and ascending
- distal tubule
- collecting duct
The liver
= filters blood - detoxifies chemicals and metabolises drugs
- maintains blood glucose levels
- produces ketone bodies, aa and nutrients
- produces transport proteins
- removes waste products
- makes bile
Hepatic
= pertaining to the liver
Blood supply to the liver
LEARN PICTURE
Oxygenated blood from hepatic artery + Nutrient rich deoxygenated blood from Haptic portal vein
- Hepatic sinusoids
- central vein
- hepatic vein
- inferior vena cava
- right atrium of the heart
Glucose homeostasis
Two important hormones - glucagon/ insulin
- glucagon causes liver to release glucose
- insulin causes the liver to store glucose as glycogen
Endocrine system
= collection of glands that produce hormones that regulate metabolism, growth, development, tissue function, sexual function, reproduction, sleep, mood etc
- nervous system and endocrine system work together to coordinate all systems if the body
- maintains homeostasis via the release of hormones from endocrine glands directly into blood
- most hormones circulate blood and bind to receptors on ‘target cells’
Exocrine Glands
- secrete products into ducts
- not hormones
Hormones
= produced by endocrine gland specific to the hormone produced
Hypothalamus and pituitary gland
- work together to control other endocrine glands connected by infundibulum
anterior lobe - secretes 7 hormones
posterior lobe - releases 2 hormones oxytocin and vasopressin ( anti diuretic hormone )
Negative feedback
Tropic hormones
- produced in one endocrine gland and regulates the secretion in another
- TSH stimulates thyroid to produce thyroid hormone (T3 and T4)
- ACTH stimulates adrenal cortex to produce cortisol
- FSH - sex hormones
Non tropic of anterior pituitary
- growth hormones - stimulates growth, promotes protein synthese and fat metabolism and increase BGL
Define deglutition and explain the process?
= action and process of swallowing
- oral cavity
- oesophagus
- into stomach
