Option: Human Phys

Question 1

Define Hormone

Answer 1

Is a chemical messenger that is transported indiscriminately via the bloodstream to act on a distant target cells.

Question 2

Define Steroid Hormones

Answer 2

Are lipophilic hormones that are able to freely diffuse across the plasma membrane of cells.

Question 3

How do steroid hormones work?

Answer 3

They bind to receptors in either the cytoplasm or nucleus of the target cell, for an active receptor-hormone complex.

This activated complex moves into the nucleus and binds directly to DNA, acting as a transcription factor for gene expression.

Question 4

Define Peptide Hormones

Answer 4

They are hormones that are hydrophilic and lipophobic, thus cannot freely cross the plasma membrane.

Question 5

How do Peptide Hormones work?

Answer 5

They bind to receptors on the surface of the cell, which are typically coupled to internally anchored proteins.

The receptors complex activates a series of intercellular molecules called second messengers, which initiates cell activity. This process is called signal transduction.

The use of second messengers enables the amplification of the initial signals as more molecules are activated.

Question 6

Define Hypothalamus

Answer 6

A section of the brain that links the nervous and endocrine systems in order to maintain homeostasis.

Question 7

Define Growth Hormones

Answer 7

Is an anabolic peptide hormone that stimulates growth.

Question 8

Define Lactation

Answer 8

The production and secretion of milk by maternal mammary glands following birth.

Question 9

Define Autocrine

Answer 9

Occurs when chemicals released by a cell stimulate the cell itself (self-signalling).

Question 10

Define Paracrine

Answer 10

Occurs when chemicals released stimulate a neighbouring cell.

Question 11

Define Endocrine

Answer 11

Occurs when chemicals released travel in the bloodstream to activate distant cells.

Question 12

Define constitutive secretion

Answer 12

Hormones are released as they are produced [vesicles fuse directly with cell membrane].

Question 13

Define regulated secretion

Answer 13

Hormones are stored in vesicles and only released following an external signal.

Question 14

Define Negative Feedback

Answer 14

Involves a response that is the reverse of the change detected.

Question 15

Define Positive Feedback

Answer 15

Involves a response that reinforces the change detected.

Question 16

Nutrients

Answer 16

A chemical substance found in foods that is used in the human body.

Question 17

Define Essential Nutrients

Answer 17

Nutrients that cannot be synthesised by the body and must be ingested as part of the diet.

Question 18

Vitamins

Answer 18

Organic molecules with complex structures that are diverse and clasifed into groups.

Question 19

Types of malnutrition

Answer 19

Stunting
Wasting
Obesity

Question 20

How are fats and cholesterol transported?

Answer 20

Both do not dissolve in the bloodstream and hence are carried by lipoproteins

Question 21

LDL

Answer 21

Low density lipoproteins
saturated trans fats
From liver to rest of the body

Question 22

HDL

Answer 22

High density lipoproteins
cis polyunsaturated fats
From body to liver

Question 23

Phenylketonuria

Answer 23

Genetic condition (autosomal) that results in impaired metabolism of phenylalanine.

Caused due to mutation in gene encoding for enzyme (phenylalanine hydroxylase) that breaks excess phenylalanine into tyrosine.

Normal:
excess phenylalanine –> Tyrosine

With PKU:
Excess phenylalanine –> phenylpyruvate or phenylketone

Question 24

How are release of hormones for hunger triggered?

Answer 24

• Stretch receptors in the stomach and intestine become activated when ingested food distends these organs
• Adipose tissue releases hormones in response to fat storage
• The pancreas will release hormones in response to changes in blood sugar concentrations

Question 25

Which hormone triggers hunger response?

Answer 25

Stomach: ghrelin

Pancreas: glucagon

Question 26

Which hormone triggers satiety response?

Answer 26

Adipose tissue: leptin

Intestine: CCK

Question 27

Hypertension

Answer 27

Abnormally high blood pressure

Question 28

Type II diabetes

Answer 28

Occurs when fat, liver and muscle cells become unresponsive to insulin (insulin insensitivity). Results from a diet rich in sugars causing the progressive overstimulation of these cells by insulin

Question 29

Starvation

Answer 29

Describes the severe restriction of daily energy intake, leading to a significant weight loss.

Question 30

Anorexia nervosa

Answer 30

An eating disorder in which individuals severely limit the amount of food they intake

Question 31

Tight junction

Answer 31

Occluding associations between the plasma membrane of two adjacent cells, creating an impermeable barrier

Question 32

Pinocytosis

Answer 32

is the non-specific uptake of fluids and dissolved solutes (a quick way to translocate in bulk)

Question 33

Fibres

Answer 33

Indigestible portion of food

Question 34

Stomatch ulcers

Answer 34

inflamed and damaged areas in the stomach wall, typically caused by exposure to gastric acids.

Question 35

Vibrio cholerae

Answer 35

A bacterial pathogen that infects the intestines and causes acute diarrhoea and dehydration

Question 36

Bacteria that causes stomach ulcers

Answer 36

Helicobacter pylori

Question 37

Bacteria that causes dehydration and diarrhoea

Answer 37

Vibrio cholerae

Question 38

Function of the liver

Answer 38

• Process nutrients absorbed by gut, hence regulates the body’s metabolic processes.
• Responsible for the storage and controlled release of key nutrients (e.g. glycogen, cholesterol, triglycerides)
• Detoxification of potentially harmful ingested substances (e.g. amino acids, medications, alcohol).
• It produces plasma proteins that function to maintain sustainable osmotic conditions within the bloodstream,
• Responsible for the breakdown of red blood cells and the production of bile salt.

Question 39

Sinusoids

Answer 39

A type of small blood vessel found in the liver that are needed for material exchange. They have increased permeability, allowing larger molecules (e.g. plasma proteins) to enter and leave the bloodstream.

Question 40

How are sinusoids different from capillaries?

Answer 40

• They have an incomplete basement layer
• Their endothelial layer contains large intercellular gaps and less tight junctions allowing larger molecules to pass.

Question 41

How are drugs broken down in the liver?

Answer 41

Toxins are fat soluble but not water soluble hence they are difficult to excrete.
1. Toxins are converted into less harmful chemicals via oxidation, reduction and hydrolysis reactions using cytochrome P450 enzymes.

2. This conversion produces damaging free radicals which are neutralised by antioxidants within the liver.
3. Next conjugation reaction takes place, where the converted chemicals are attached to another substance to make it less harmful and water soluble in order to be carried out of the body via urine.

Question 42

What are the nutrients stored in the liver

Answer 42

glycogen

iron

vitamin a

vitamin d

Question 43

Protein metabolism

Answer 43

amino acids cannot be stored in the body this need to be broken down. They release an amine group which is toxic and the liver is responsible for the removal of this (deamination). The amine is converted to urea and excerpted out.

Question 44

Fat metabolism

Answer 44

Liver converts excess carbohydrates and proteins into fatty acids and triglycerides.

It is responsible for the synthesis of large quantities of phospholipid and cholesterol.