Functioning Systems: Food Assimilation

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Questions and Answers

What is the primary function of the digestive system?

To break down food into molecules for absorption (correct)

To mechanically break down food into smaller pieces

To absorb nutrients into the blood

To eliminate wastes from the body

Which process begins the digestion of food?

Mastication in the mouth (correct)

Peristalsis in the esophagus

Segmentation in the colon

Chemical digestion in the stomach

What is the role of bile in the digestive process?

To emulsify lipids in the small intestine (correct)

To absorb carbohydrates

To initiate chemical digestion in the mouth

To break down proteins in the stomach

Which of the following accurately describes peristalsis?

Contraction of circular muscles to move food through the digestive tract Signup and view all the answers

Which digestive juice is primarily responsible for breaking down proteins?

Gastric juice containing pepsinogen Signup and view all the answers

What enzyme is responsible for carbohydrate digestion in the mouth?

Salivary amylase Signup and view all the answers

Which substance is absorbed into the blood through secondary active transport?

Glucose Signup and view all the answers

Which of the following is a catabolic process for glucose?

Glycolysis Signup and view all the answers

What is the primary function of the urinary system?

Regulation of blood composition and volume Signup and view all the answers

What is the process by which urine is formed that involves filtering blood?

Filtration Signup and view all the answers

Which nutrient is metabolically processed through deamination?

Amino acids Signup and view all the answers

Which of the following substances is NOT considered a metabolic waste product disposed of by the kidneys?

Glucose Signup and view all the answers

Which nutrient is absorbed into the lymphatic system by simple diffusion?

Fatty acids Signup and view all the answers

What is the approximate blood pH that must be maintained for acid-base balance?

7.4 Signup and view all the answers

Where are the kidneys located in relation to the diaphragm?

Below Signup and view all the answers

What is the typical storage capacity of a healthy adult bladder?

600 ml Signup and view all the answers

Which part of the nephron is responsible for filtration?

Glomerular capsule Signup and view all the answers

What is the primary function of the ureters?

To transport urine from kidneys to bladder Signup and view all the answers

What structure comprises the renal corpuscle in a nephron?

Glomerular capsule and glomerulus Signup and view all the answers

How much filtrate does the kidneys produce per minute as part of the Glomerular Filtration Rate (GFR)?

1000-1200 ml Signup and view all the answers

What occurs during the reabsorption stage of urine formation?

Water and essential molecules are returned to the blood Signup and view all the answers

What is the Glomerular filtration rate (GFR) in liters per day?

180 liters/day Signup and view all the answers

How much of the filtrate produced daily is reabsorbed by the kidneys?

99% Signup and view all the answers

What is the Glomerular capillary hydrostatic pressure (GHP)?

+55 mmHg Signup and view all the answers

Which of the following substances is primarily involved in the obligatory reabsorption in the PCT?

Glucose Signup and view all the answers

What is the effect of blood osmotic (colloidal) pressure on filtration?

Reduces filtration by holding water Signup and view all the answers

What happens if blood glucose levels rise above 180 mg/dl?

Some glucose remains in urine (glucosuria) Signup and view all the answers

What movement primarily occurs in the descending loop of Henle?

Water moves out of the tubules Signup and view all the answers

How does sodium reabsorption affect chloride movement in the PCT?

Chloride follows sodium by simple diffusion Signup and view all the answers

What role does the loop of Henle play in the kidney function?

It increases the concentration of urine. Signup and view all the answers

Which statement is true regarding the ascending loop of Henle?

It has many sodium pumps. Signup and view all the answers

What triggers the release of ADH (anti-diuretic hormone)?

Reduction in blood pressure. Signup and view all the answers

What effect does ADH have on urine concentration?

It decreases urine volume and increases concentration. Signup and view all the answers

What is the function of the distal convoluted tubule (DCT) and collecting tubule (CT)?

They have tight junctions that limit permeability. Signup and view all the answers

What is a symptom of a lack of ADH?

Increased thirst. Signup and view all the answers

How does the nephron adaptation serve desert animals?

They have longer loops for more water reabsorption. Signup and view all the answers

What does secretion in the kidneys involve?

Selectively transporting molecules from blood into renal tubules. Signup and view all the answers

What is the primary function of the kidneys in urine formation?

To eliminate waste products and maintain homeostasis Signup and view all the answers

What does ADH (antidiuretic hormone) do in relation to urine production?

Prevents excess water loss from the kidneys Signup and view all the answers

What is considered oligourea in terms of daily urine production?

Less than 500 ml Signup and view all the answers

Which of the following substances increases the rate of salt and water loss from the kidneys?

Caffeine Signup and view all the answers

What is the main process by which dialysis removes waste from the blood?

Passive diffusion across a membrane Signup and view all the answers

How does alcohol affect urine production?

Inhibits secretion of ADH and increases urine volume Signup and view all the answers

What is a common treatment option for kidney failure?

Hemodialysis Signup and view all the answers

What happens to essential minerals and amino acids during dialysis?

They move from the dialysate to the blood Signup and view all the answers

Study Notes

Functioning Systems

The presentation is on Functioning Systems, specifically Food Assimilation, by Prof. Dr. Eman Salah Abdel-Rehim.
The presentation covers the digestive system, digestion, types of digestion (mechanical and chemical), expressions related to mechanical digestion, the process of chemical digestion, absorption, metabolism, and the urinary system.

Learning Objectives (Food Assimilation)

Students will understand the general function of the Digestive System.
Students will know about Mechanical and Chemical Digestion.
Students will understand the simplest forms of nutrients and their absorption.
Students will learn simple outlines about Metabolism.

Functions of Digestive System

The digestive system breaks down food into smaller molecules.
The absorbed molecules are transported throughout the body.
Wastes are eliminated from the body.

How the Body Gets Energy from Food

Digestion is the process where the body breaks down food into small nutrient molecules.
It begins in the digestive system, starting in the mouth.

Types of Digestion

Mechanical Digestion: Physically breaking down food.
- Begins when taking the first bite of food.
- Cutting by teeth is the first stage.
Chemical Digestion: The body breaks foods into smaller chemical building blocks, using chemicals.
- Begins in the mouth.

Mechanical Digestion Expressions

Mastication: Chewing and enzymatic breakdown by saliva.
Deglutition: Swallowing, voluntary in the mouth, and involuntary in the esophagus.
Churning: In the stomach, forming chyme.
Peristalsis: Contraction of circular muscle.
Segmentation: Contraction of longitudinal muscle (backward and forward movement) to the colon.

Chemical Digestion Digestive Juices

Saliva: From parotid, sublingual, and submandibular glands.
Gastric Juice: Chief cells make pepsinogen, and parietal cells make HCl.
Pancreatic Juice: Exocrine cells of the pancreas.
Bile: Produced by the liver, stored in the gall bladder, and secreted into the small intestine aiding lipid digestion.
Intestinal Juice: Secreted by the mucosa of the small and large intestine.

Chemical Digestion (Enzymes)

Mouth: Carbohydrates—salivary amylase
Stomach: Proteins—pepsin
Small Intestine: Lipids
Trypsin, chymotrypsin, amylase and lipase (from pancreas)
Maltase, sucrase, lactase and peptidases (from intestinal villi)

Absorption

After digestion, the simplest forms of food (glucose, amino acids, fatty acids) are absorbed.
Absorption occurs through the intestinal mucosa into the blood.
- Amino acids and glucose are transported through secondary active transport.
- Fatty acids go into lymph via simple diffusion.

Metabolism

Catabolism:
- Hydrolysis—breaks down polymers into monomers
- Cellular respiration—oxidation of monomers to yield energy
Anabolism:
- Cell maintenance and repair
- Growth
- Formation of secretions
- Nutrient reserves

Metabolism Processes

Glucose
- Catabolism: glycolysis, Krebs' cycle, electron transport chain.
- Anabolism: glycogenesis, gluconeogenesis.
Fatty Acids
- Catabolism: Beta-oxidation, Krebs' cycle, and electron transport chain.
- Anabolism: lipogenesis
Amino Acids
- Catabolism: deamination, Krebs' cycle and electron transport chain.
- Anabolism: synthesis of nonessential amino acids.

Urinary System

The presentation also introduces the urinary system.
Learning objectives for the Urinary System include: functions of the urinary system, anatomy of the urinary system, nephron structure, urine formation (filtration, reabsorption, secretion), urine composition.
Factors affecting kidney function are also discussed.
Renal dialysis and transplantation as treatments for kidney diseases, as well as the date of the first human transplantation are mentioned.

Functions of the Urinary System

Regulate blood composition and volume to maintain homeostasis.
Disposing of metabolic wastes (urea, creatinine, ammonium, uric acid).
Maintaining water-salt and electrolyte balance (sodium, potassium, bicarbonate).
Maintaining acid-base balance (blood pH ≈ 7.4).

Urinary System Structure & Anatomy

Kidneys
Ureters
Bladder
Urethra

Kidney Anatomy

Protected by fibrous tissue, fat, muscle, and ribs.
Consists of renal cortex, medulla, and pelvis (including minor and major calyxes)

Nephron

The structural and functional unit of the kidney.
Composed of glomerular capsule, capillary network (glomerulus), renal tubules (proximal convoluted tubule, loop of Henle, distal convoluted tubule)

Steps in Urine Formation

Filtration: removes water and small molecules from blood, in the renal capsule.
Reabsorption: water and essential molecules are returned to the blood from the renal tubules.
Secretion: wastes and excess salts are added from body fluids into the tubule fluid (urine) in the renal tubules.

Glomerular Filtration Rate (GFR)

Amount of filtrate produced per minute by the kidneys.
About 20% of total blood plasma—enters the kidneys every minute (approx 1000-1200ml/min).
625 ml plasma only pass as filtrate.
Approximately 125-130ml of this filtrate passes through the renal tubules.

Glomerular Filtration Rate Formula:

Calculation for GFR in liters per day.
Kidneys can filter about 150-200 liters of plasma per day.

Forces Affecting Filtration

Glomerular capillary hydrostatic pressure (GHP): +55 mmHg
Blood osmotic (colloidal) pressure (BOP): -30 mmHg
Capsular hydrostatic pressure(CHP): -15 mmHg
Net filtration pressure: ≈+10mmHg

Reabsorption

Reabsorption of water, nutrients, and electrolytes via different transport mechanisms through the renal tubules, primarily in the PCT, Loop of Henle , and DCT.

PCT Reabsorption — "Obligatory Reabsorption"

Glucose and amino acids are pumped out of the tubules and also reabsorbed into the blood.
The transporters are limited and can become saturated if glucose concentrations rise above 180 mg/dl. (Glucosuria)

PCT Reabsorption

70% of sodium and water are reabsorbed.
Chloride follows sodium by simple diffusion.
Positively charged ions draw chloride out of the filtrate.
Some compounds present in high concentration in the filtrate go into the blood by diffusion.

Loop of Henle — Reabsorption

Descending loop: permeable to water, water moves out of the tubule due to the osmotic gradient.
Ascending loop: thick epithelium, impermeable to water, pumps out sodium.

So, why is the Loop of Henle useful?

The longer the loop, the deeper it travels into the hyperosmotic medulla. This allows for more reabsorption and concentrated tubular fluid.

DCT and CT - Reabsorption “Facultative-Reabsorption"

Reabsorption depends on the body's needs.
DCT and CT walls have tight junctions, impermeable to water.
Cells have ADH (antidiuretic hormone) and Aldosterone receptors that modify water/ion permeability according to needs

Regulation of ADH Secretion

ADH increases water retention reducing urine volume and prevents dehydration.
Affected by decreased blood volume and blood pressure by Baroreceptors and increased salt concentration by Osmoreceptors.

DCT and CT Reabsorption (Urine Concentration)

Late distal tubule is impermeable to water, with low ADH.
When ADH is released from the posterior pituitary, aquaporin channels open. More water is thus absorbed.

Secretion and Excretion

Secretion: Selective transport of molecules from blood in peritubular capillaries into filtered fluid in the tubular lumen.
Waste products like urea, excess metabolites, K+, H+, and Ca++
Excretion: The body removes urine (molecules dumped outside the tubules).

Urine Formation Summary

Key stages and direction of urine formation, as well as proportion of amount in different stages.

Urine Composition

95-96% water
Urea, uric acid, amino acids, electrolytes

Daily Urine Production

Average urine production (600ml-2500ml/day)

Factors Affecting Kidney Function

ADH: prevents excess water loss.
Alcohol: inhibits ADH secretion, more urine volume, and diluted.
Aldosterone: prevents sodium and water loss.
Caffeine: increases the rate of salt and water loss.
Increased blood pressure: increases the rate of water loss.

Kidney Diseases

Affect structure and function through stages, which can lead to failure.
Kidney failure is fatal, but it can be treated by dialysis or transplantation.
Kidney is the first successfully transplanted organ in humans (1954).

Hemodialysis

A treatment for people with kidney failure.
The kidneys filter the blood, removing wastes and toxins.
Dialysis works by using a dialyzer with a thin membrane to separate the patient's blood from a dialysis solution.
Waste products move from the blood into the dialysis solution by diffusion due to the concentration gradient.
Essential minerals and amino acids move from the dialysis solution into the blood.

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Description

This quiz explores the functioning systems involved in food assimilation as presented by Prof. Dr. Eman Salah Abdel-Rehim. Delve into the intricacies of the digestive system, including mechanical and chemical digestion, nutrient absorption, metabolism, and the urinary system. Enhance your understanding of how the body processes food and extracts energy.