15

Small Intestine continued…

• Digestion of lipids/fats

  • Step 1- large fat droplets are broken down into smaller droplets with bile in a process called emulsification

  • Bile is delivered from the liver to the SI through a duct into the duodenum

  • Step 2- small fat droplets need to be broken down further

  • The enzyme lipase does this

6-Colon / LI- frames the small intestine/wraps around

Functions:

- reabsorption of water from the fecal material into the blood stream

- storage and elimination of solid wastes

- the secretion of mucus to allow for the passage of solids

- The decomposition of organic material w/ the help of bacteria ex. E. Coli

- the production of some vitamins ex. Vitamin K

• LI has 3 parts:

  • part going up (RQ)- ascending colon

  • part that goes across-transverse colon

  • part that goes down (LQ)-descending colon

  • Then the rectum leading to our anus/anal sphincter

Appendix- pouch b/w small and large intestines — food should NOT go through here — food trapped here can cause appendicitis

• humans can function w/ out the appendix

7-Rectum-

• after the descending colon — leading to the anus

8-Anus-

• exit to the outside for the removal of solid wastes/defecation

Digestion — 2 types

Mechanical

• chewing in mouth

• churning in stomach

Chemical

• saliva in mouth (salivary amylase for starch)

• Acid and pepsin (for digestion of proteins)

• Enzymes in SI (various enzymes, ex. lipase)

Accessory Organs in the Abdominal Cavity:

All produce secretions — to help w/ chemical digestion

NO food passes through these organs — though are connected via ducts

Pancreas

• lobular organ

• found in the loop of the duodenum

• connected via duct

• Pancreatic enzymes: pancreatic amylase (starch), lipase (fat), trypsin (proteins)

• Hormones: insulin, glucagon — antagonistic for blood-glucose regulation

Liver

• connected via duct into the duodenum

• production of bile salts

• bile is stored in the gallbladder

• the liver is great for detoxification (ex. alcohol)

  • liver problems: fatty liver/liver cirrhosis

• Stores glucose in the form of glycogen

Gall Bladder

• stores bile

• gallbladder sits beneath the liver

• the bile from the gallbladder is released into the SI via duct

• Issue: gallstones — cholecystitis

  • severe pain

  • can be removed via laser or even surgery

• can live w/ out the gallbladder

BILE — function

• breaks down/emulsified large fat globules into smaller pieces/particles

• smaller particles are then broken down w/ enzymes (lipase)

SUMMARY OF DIGESTION!!

10 organs

Lasts roughly 30-40 hours

4 main components:

1-GI tract — internal surface of 30-40m²

2-Trio of organs (pancreas, gallbladder, liver) — break down food

3-Enzymes, hormones, blood, nervous

4-Mesentery - holding everything in place

Saliva — producing 1.5L per day

• make food into a bolus — also breaking down starch

Peristalsis — muscle contractions

Stomach — churns food, then hormones trigger the release of acids and enzymes

• alerting the organ trio to secrete their juices

Bolus becomes a frothy liquid called CHYME in the stomach

Goes into the SI —

Villi — maximum surface area for molecule absorption

Thoracic cavity and abdominal cavity are separated by the: diaphragm

CIRCULATORY SYSTEM

Closed vs. open circulatory system

Open:

circulating fluid through open-ended tubes, allowing interstitial fluid to flow out among cells

found in molluscs, arthropods

Closed:

circulating fluid is pumped within a closed set of tubes, keeping blood distinct from the interstitial fluid surrounding cells

There is a single circ. system (ex. in fish) and a double circ. system (ex. in us)

Single

Blood is travelling within one loop

Gills to rest of body

Double

• pulmonary circ.

• systemic circ.

• 2 loops!

HUMAN HEART

How many chambers? — 4 chambers

• at top — atria

  • Right atrium, Left atrium

• at bottom — ventricles

  • Right ventricle, Left ventricle

Size of the heart?? — the size of your fist

How many valves?? — 2 major valves

• at entrance to the major blood vessels

Why 2 colors on diagrams?? —

• Red = oxygenated blood

• Blue = deoxygenated blood

Left side —

• Pumps ONLY oxygenated blood

• Low in CO2

Right side —

• Pumps ONLY deoxygenated blood

• High in CO2

Direction of blood through the heart

• Always top to bottom

• Atria —- down to the ventricles

Valves

Prevent backflow of blood in the heart

ARTERIES

Carries blood away from the heart

Largest = aorta

VEINS

Carry blood towards the heart

Pulmonary blood circuit:

Carries blood b/w the heart and the lungs

Rather small loop

R ventricle is much thinner than L ventricle (as it only pushes blood toward the lungs)

Breathing:

Alveoli — balloon-like structure — making up the lungs

Exhale CO2 during gas exchange — while blood picks up O2

Where do we get CO2 — cellular respiration!! — within the mitochondria

Capillary beds

• branches of the arteries = arterioles

• attached at one end and venules at the other

• capillaries make up the middle part

Systemic blood circuit:

Carries blood b/w the heart and the REST of the body

L ventricle is much thicker — because it has to push the blood further (throughout entire body)

Flow of Blood:

R atrium — tricuspid valve — R ventricle — goes into pulmonary trunk — branching off into R and L pulmonary arteries — take deoxygenated blood towards the lungs — blood will then receive O2 and leave CO2 via gas exchange — come back to heart via pulmonary veins R + L — blood is oxygenated and enters L atrium — through bicuspid valve — into L ventricle — then into the aorta — carries oxygenated blood toward the rest of the body via arteries— repeat!!

Arteries branch off from the aorta

• they’re named for the organs that they deliver blood to

• ex. intercostal arteries — deliver blood to thoracic cavity

• renal arteries — towards kidneys

At the level of the organs — there’s also gas exchange

• blood drops off O2 to the organs and takes in CO2

Inferior and Superior Vena Cava

S — carries deoxygenated blood from upper body

I — carries deoxygenated blood from the bottom of the body

BLOOD

A type of connective tissue

• cells

• fibrous

• liquid called: plasma

Have 4-6L in the human body

Cell types in blood

• RBC (erythrocytes)

• WBC (leukocytes)

• Platelets

Plasma makes up 55% of blood

Cellular elements make up 45%