Digestive and Reproductive Systems

Alimentary Canal

The path food takes from the mouth to the anus (Oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum)

What are the four layers of the digestive tract?

1. Mucosa

2. Sub-mucosa

3. Muscularis Externa

4. Serosa (visceral peritoneum)

Mucosa

The inner-most layer made of stratified squamous or simple columnar epithelium.

What are the folds in the mucosa called?

Plicae Circularis

Submucosa

The second most inner layer made of connective tissue and containing blood vessels, nerves, and lymphatics.

Muscularis Externa

The 3rd deepest layer made of smooth muscle and nerves.

What is the role of the muscularis externa?

Peristalsis and mixing of contents

Serosa

The outermost layer that anchors the digestive system.

How much saliva is produced each day?

1-1.5 L

What percentage of saliva is water?

99.4%

Deglutition

Swallowing

Swallowing is a voluntary process

Kinda true, it is started voluntarily but then proceeds automatically

Oral phase of deglutition (buccal)

Bolus of food enters the pharynx under voluntary control.

Pharyngeal Phase of swallowing

The larynx elevates, the epiglottis folds, and bolus moves into the esophagus

Esophageal Phase of swallowing

Peristaltic contractions move the bolus into the stomach

What do the inner walls of the stomach contain?

Gastric pits and gastric glands

Parietal Cells

Secrete HCl and absorb B12

Chief Cells

Turn pepsinogen into pepsin

Gastric Juice

HCl + pepsinogen

What is the food called once it enters the stomach and has been mixed with gastric juice?

Chyme

Amylase

An enzyme secreted by the salivary glands that helps to break down sugars.

Pepsin

Breaks down proteins into peptides and polypeptides.

Digestion occurs in the stomach

False

Small intestine

Where digestion is completed and most of the absorption takes place.

Duodenum

Receives chyme from the stomach and mixes it with pancreatic, liver, and gallbladder secretions.

Jejunum

The second portion of the small intestine, a lot of surface area

Ileum

The third portion of the small intestine that absorbs B12

Gastrin

A hormone that increases acid production to break down proteins

Secretin

A hormone that causes alkaline secretions from pancreas and bile secretion from liver.

Cholecystokinin (CCK)

Pancreatic enzymes, contraction of gallbladder

Gastric Inhibitory Peptide

Insulin release from pancreas, slows gastric secretion/motility

Digestive role of the pancreas?

Produces digestive enzymes and alkaline buffers.

Digestive role of the gallbladder?

Stores, concentrates, and releases bile from the liver

What is bile?

Water, ions, bilirubin, cholesterol, and salts that emulsify lipids.

What is the flow of bile?

1. Collected from hepatocytes by bile canaliculi

2. Bile canaliculi form right and left hepatic ducts

3. Right and left hepatic ducts form common hepatic duct.

4. Common hepatic duct transports bile to common bile duct or cystic duct

Where does the common bile duct lead to?

Duodenum

Where does the cystic duct lead to?

The gallbladder

Where is digestion completed? (specific)

Jejunum

What is the main role of the duodenum?

Mix chyme with pancreatic enzymes and bile.

What breaks down carbohydrates?

Amylases in the saliva and from the pancreas (tri and di saccharides)

What breaks down tri and di saccharides?

Enzymes found on the microvilli of the intestinal wall (monosaccharides)

How are monosaccharides moved from the intestines into the blood?

Moved into epithelial cells via cotransport/facilitated transport, and then diffuse into blood via facilitated diffusion.

Facilitated diffusion

Passive transport

How are proteins broken down?

By mastication and HCl (polypeptides)

How are polypeptides broken down?

Pepsin and pancreases proteases break down the peptide bonds between the amino acids.

How are dipeptides broken down?

When they brush the border enzymes of the intestinal wall

What accounts for the first 20% of fat digestion

Lipases in the mouth and the stomach

What acts on fat to turn it into monoglycerides?

Bile emulsifies it and it’s broken down further by pancreatic lipase.

What happens when monoglycerides interact with bile salts?

Micelles are produced

What happens when micelles diffuse into epithelial cells?

They are assembled into triglycerides

Chylomicrons

Triglycerides coated with proteins that are excreted via exocytosis into interstitial fluid and eventually dumped into the blood stream at the L subclavian vein.

The liver produces what?

Bile

Kupffer Cells

Phagocytic cells in the liver

What organ produces plasma proteins?

The liver

How does the liver receive blood?

Hepatic portal vein and the hepatic artery

Portal Areas

Lobules surrounded by branches of portal vein, hepatic artery, and bile ducts.

How does the blood flow in the liver?

Through sinusoids, past hepatocytes, and to central veins.

Hepatocytes

Cells in the liver that absorb nutrients and secrete plasma proteins.

What is the function of the large intestine?

Absorption of water, bile salts, and vitamins.

How many sperm are produced per day?

1-2 billion

What tissue of the penis extends to form the glans?

The corpus spongiosum

Cremaster and Dartos muscles

Contract or relax to control temperature in the testes.

Tunica Albuginea

A dense layer of connective tissue that surrounds the testes

Role of interstitial cells in the male reproductive system?

Produce testosterone

Nurse Cells (sustentacular, Sertoli)

Provide the proper environment in seminiferous tubules

Seminiferous tubules

Produce sperm

Spermatogenesis

The process of sperm production

Where does spermatogenesis begin?

The very outermost layer of the seminiferous tubules.

How many spermatozoa result from one Primary spermatocyte?

4 after 2 rounds of meiosis

Are Primary spermatocytes diploid or haploid?

Neither, they are tetrad

Secondary spermatocytes are haploid

False, they are diploid

Spermiogenesis

The last step of spermatogenesis resulting in sperm (spermatozoa) (spermatozoon)

Acrosomal Cap

Located at the tip of the head of sperm

What part of the sperm contains the mitochondria?

The middle peice

How do sperm get nutrients?

From the fructose in seminal fluid

What is the pathway of sperm during ejaculation?

Testis, epididymis, ductus deferens, ejaculatory duct, urethra.

What are the three sections of the male urethra?

1. Prostatic

2. Membranous

3. Spongy

What is the function of accessory male reproductive organs?

Secrete fluid into ejaculatory duct and urethra

Seminal Glands

Discharge fluid containing fructose into the ejaculatory duct

Semen is slightly acidic

False, it is slightly alkaline to neutralize the environment of the vagina.

What percent of semen is spermatozoa?

1 %

FSH

Stimulates nurse cells to start spermatogenesis and spermiogenesis

LH

Stimulates interstitial cells to produce testosterone

How often is an oocyte produced?

Once a month

What are the stages of oogenesis?

1. Oogonium

2. Primary Oocyte

3. Secondary oocyte

4. Ovum

Meiosis 1

Begins before birth and is completed after puberty resulting in a haploid secondary oocyte and a polar body.

Meiosis 2

Began in tertiary follicle and finished if fertilization occurs.

How many polar bodies can be produced during meiosis 1 and 2?

2-3

An ovum is haploid

True

Oogonium

Undergo mitosis to form primary oocytes

What stimulates primordial follicles to start developing?

FSH

What hormone do follicular cells secrete?

Estrogen

What type of oocyte does a tertiary follicle contain?

Secondary oocyte

What causes a primary oocyte to complete meiosis 1?

LH

Atresia

The degeneration of primordial follicles (2 mill at birth, 200-440k at puberty, and 400 ovulated)

The cytoplasm of a primary oocyte divide unevenly during meiosis 1

True, creates a secondary oocyte and a polar body.

Ovulation

Release of secondary oocyte and some follicular cells from the tertiary follicle.

Corona Radiata

Some follicular cells that surround the secondary oocyte when it is ovulated.

Corpus Luteum

What results from the tertiary follicle after ovulation.