Biology Endocrine System

What is an exocrine gland? [3]

A gland containing a duct or tube [1] that carries secretions [1] out of the body into external environments [1]

Example of an exocrine gland? [4]

Salivary gland. [1] It has a salivary duct [1] and it secretes [1] saliva to the mouth cavity. [1]

What is an endocrine gland? [4]

It is a ductless gland [1] that releases its secretions [1] directly into the bloodstream [1] to be transported to the target organs or cells [1].

What’s the difference between excretion and secretion?

• Excretion refers to the removal of metabolic wastes from the body [1]

• Secretion refers to the release of useful substances for the body [1]

Give an example of pancreas being an endocrine AND exocrine gland

• Pancreatic islet cells are endocrine glands that secrete insulin and glucagon [1] into the blood [1]

• Acinar cells are exocrine glands that secrete pancreatic enzymes [1] into the pancreatic duct [1]

What is a hormone? [8]

• A hormone is a chemical signal molecule [1] produced in minute quantities [1] by an endocrine gland [1].

• It is transported in the bloodstream [1] to target organs [1] where it exerts its effects [1]

• After the hormones have performed their functions, they will be degraded by the liver [1] and excreted by the kidneys [1].

Why are hormones produced in minute quantities?

• Hormones are highly potent [1] and they have to be highly regulated [1].

• It is also to avoid excessive stimulation or suppression of target organs [1].

What’s the significance of hormones? [3]

• They can influence the growth, development and activity of an organism [1]

• They act as chemical messengers that help to control and coordinate body activities [1]

• They also control appearance of characteristics that distinguish a juvenile organism from a s******* mature adult organism [1]

Why do hormones control/coordinate body activities? [3]

• To maintain homeostasis [1]

• To mediate responses to environmental stimuli [1]

• To regulate growth, development and reproduction [1]

Why is production/secretion of hormones carefully regulated? [2]

• Ensure body functions normally [1]

• Inadequate / excessive production may have adverse effects on functioning of the body [1]

What is negative feedback? [2] What’s the importance of it? [1]

A regulatory mechanism where the output of a system counteracts a change [1] to maintain homeostasis. [1]

It ensures stability and prevent over/under secretion of hormones [1]

What’s the process of negative feedback? [3]

1) Change detected (e.g. high blood glucose)

2) Hormone response to counteract change (release insulin)

3) Restoration of equilibrium (blood glucose return to normal)

What is positive feedback? [2] What’s the importance of it? [1]

A regulatory mechanism where the output of a system amplifies the original stimulus [1], leading to a specific outcome [1].

Drives processes that must continue until a specific endpoint is reached. [1]

What’s the process of positive feedback? [3]

1) Initial stimulus (e.g. baby pressing on cervix)

2) Amplified response (oxytocin release, more pushing)

3) Event completion (childbirth)

What parts are responsible for stress response, and what do they each do? [3]

Hypothalamus: Brain’s control center that detects stress and sends signals [1]

Pituitary gland: Receives signals from the hypothalamus and releases hormones [1]

Adrenal gland: Responds to electrical signals (ES) from hypothalamus and chemical signals (CS) from pituitary gland (elaborate on this later) [1]

What is adrenal gland? [1] What does it do? [3]

Small, triangular shaped glands located on top of kidneys [1]

Functions:

• Stress response [1]

• Metabolism, blood sugar, and blood pressure control [1]

• Production of some sex hormones [1]

What triggers short term stress response [1] and what does it do [2]?

Triggered: By stimulation of adrenal medulla (inner region of adrenal gland) [1]
Causes: Release of adrenaline (epinephrine), an amine hormone [1] which helps the body cope with short-term stress situations [1]

List all effects of adrenaline [8]

• Breaks down glycogen into glucose to increase blood glucose level [1]

• Increases blood pressure and heart rate [1]

• Increases metabolic rate [1]

• Increases breathing rate [1]

• Causes changes in blood flow pattern, leading to:

  • Increased alertness [0.5]

  • Decreased digestive, excretory and reproductive system activity [0.5]

• Increases rate of blood coagulation [1]

• Causes pupils of eyes to dilate [1]

• Contracts hair erector muscles, producing ‘goose pimples’ [1]