Topic 6: Human Physiology

Question 1

[6.1.]
Definition of ‘Peristalsis’ //
What is Peristalsis?

Answer 1

Waves of muscle contraction [that pass along the intestine]

Question 2

[6.1]

Features of the muscles in the wall of the gut.

Answer 2

CIRCULAR and LONGITUDINAL
SMOOTH muscle (not striated)
Relatively SHORT cells (not elongated fibres)
Muscles often exert CONTINUOUS MODERATE FORCE, with SHORT PERIODS OF VIGOROUS CONTRACTION. (different from other muscles that usually remain relaxed unless stimulated to contract)

Question 3

[6.1]
Mechanism of Peristalsis //
How the muscles in the gut work to move food along

Answer 3

Contractions controlled by the ENTERIC NERVOUS SYSTEM, UNCONSCIOUSLY.

Contraction of CIRCULAR MUSCLES: BEHIND THE FOOD, CONSTRICTS THE GUT - PREVENTING food from being PUSHED BACK.

Contraction LONGITUDINAL MUSCLE: WHERE FOOD IS LOCATED, MOVES FOOD ALONG.

Occurs in ONE direction ONLY (AWAY from the mouth)

Question 4

[6.1]

What muscles are used when food is returned to the mouth i.e. vomiting?

Answer 4

ABDOMINAL muscles (not the circular/longitudinal muscles in the gut wall)

(Recall: Peristalsis only occurs in one direction)

Question 5

[6.1]

What is the main function of Peristalsis in the intestine?

Answer 5

To CHURN the SEMI-DIGESTED food, mixing it with ENZYMES

Therefore SPEEDing up process of digestion

(Because: In the intestine, unlike the oesophagus, food is moved very slowly - allows time for digestion)

Question 6

[6.1]

How many types of gland tissue does the Pancreas contain? What are these types of gland tissue? //

Answer 6

2: Endocrine & Exocrine tissue.

The pancreas is therefore a HETEROCRINE gland.

Question 7

[6.1]
Which two hormones does the Pancreas secrete? //
Which glands secrete these hormones? //
Where are these hormones secreted to?

Answer 7

Insulin & Glucagon //
The ENDOCRINE glands //
The Blood

Question 8

[6.1]

Function of the Mouth

Answer 8

VOLUNTARY CONTROL of eating and swallowing

MECHANICAL DIGESTION: chewing

Mixes food with SALIVA: lubricates food & contains salivary amylase to begin starch digestion

Question 9

[6.1]

Function of the Oesophagus

Answer 9

Moves food via PERISTALSIS from the mouth –> stomach

Question 10

[6.1]

Function of the Stomach

Answer 10

CHURNS and MIXES food with secreted water and HCl: killing foreign bacteria and pathogens in food

Initial stages of PROTEIN DIGESTION

Question 11

[6.1]

Function of the Small Intestine

Answer 11

Final stages of lipid, carbohydrate, protein and nucleic acid DIGESTION.

NEUTRALISING stomach acid

ABSORPTION of nutrients

Question 12

[6.1]

Function of the Pancreas

Answer 12

SECRETES Lipases, Amylases & Proteases

Question 13

[6.1]

Function of the Liver

Answer 13

Secretion of surfactants in BILE to EMULSIFY lipids (break up lipid droplets).

Question 14

[6.1]
Definition of ‘Surfactant’ //
What is a surfactant?

(Give an example)

Answer 14

A substance which tends to reduce the surface tension of a liquid in which it is dissolved

Example: Surfactants in Bile (secreted by the liver)

Question 15

[6.1]

Function of the Gall bladder

Answer 15

STORE and regulate release of BILE.

Question 16

[6.1]

Function of the Large Intestine

Answer 16

RE-ABSORBS Water

Further DIGESTION especially of carbohydrates by symbiotic bacteria

Formation and storage of FAECES

Question 17

[6.1]

Structure of the wall of the Small Intestine

Answer 17

Serosa: Outer Coat

Muscle Layers: Longitudinal muscle and/with circular muscle inside the longitudinal muscle.

Sub-mucosa: Tissue layer containing blood & lymph vessels

Mucosa: Lining of the Small intestine, with the epithelium that absorbs nutrients on its inner surface

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