cries in endocrine 🫥

Endocrine system !

Explain the need for communication systems within organisms

Comm system impt as help maintain constant int. temp. and helps organism survive. 2 comm systems --> nervous and endocrine, they control activities in human body and how it reacts to surroundings

Sensitivity

sensitivity is the ability of living organisms to respond or react to a stimulus (chg in environment). Stimulus caused by external (sound, pressure, light) or internal (temp, water potential).

*The stimulus is detected by a receptor. It is transmitted by means of nerve impulses or hormones and an effector brings about a response.*

glands

A gland is a group of cells that produces and secretes chemicals for release, such as enzymes or hormones. 2 types of glands: exocrine (tubes) and endocrine (str. into bloodstream)

Endocrine glands*** (very impt)

The endocrine system is a collection of endocrine glands (e.g. hypothalamus, adrenal, pancreas) that secrete hormones directly into the bloodstream (ductless) to be carried to target cells or organs. Large no. of blood capillaries surround endocrine glands

PANCREAS AS AN EXOCRINE AND ENDOCRINE GLAND as an example (pancreas too OP)

Pancreas abv small intestine below stomach. Consists of many small lobes and produces enzymes and hormones. Hormone secreting cells are in clusters called ISLETS OF LANGERHANS (capital L) associated with blood cells.

Define hormones (super impt mr han made us star it 5 times)

*defined as a chemical substance, produced by an endocrine gland, carried by the blood, which alters the activity of one or more specific target organs and is then destroyed by the liver*

responsible for growth & dev, metabolism, homeostasis, repro, capable of eeliciting diff responses in diff target cells/tissues

Characteristics of hormones

Small soluble molecules, effective in LOW conc., produced by one organ, secreted into + carries ard body by blood, effect at target site diff from where its synthesised, it is specific!

why secrete adrenaline

Example of coord. between nervous system and endocrine. Stimulus to secrete is detected by hypothalamus, stimuli: feelings of anger fear anxiety stress.

Secreted by adrenal glands, fight or flight response. temporary responses

How is adrenaline secreted?

1. Stimulus detected by hypothalamus.

2. Transmit impulses down spinal cord.

3. Motor impulse to adrenal gland (abv kidneys).

4. Adrenal gland secretes adrenaline into blood stream.

5. Blood transports adrenaline to target organs.

effects of adrenaline secretion

Target Organ	Action of target organ	resulting effect
Stimulates liver and muscles	speed up the breakdown of glycogen into glucose	increase blood glucose levels
stimulate liver	increase in metabolic rate	more energy is released by tissue respiration
Stimulate heart	to increase the rate of heartbeat and cause a rise in heart pressure	oxygen and glucose are carried faster to the muscles
stimulate arterioles in skin	to constrict	cause paleness, channel more blood to muscle
stimulate pupil	to dialate	enhance vision

more effects of adrenaline secretion

• contaction of the hair erector muscle, produces goose pimples

• increase in rate of blood coagulation

Impotance if maintaining a constant level of blood glucose levels

• if blood glucose too high water in cell will leave by osmosis. cell dehydrate and normal metanolic activities cannot be carried out normally

• if blood glucose too low, the brain may not receive sufficient glucose. The person experiences weakness and dizziness cause glucose main energy source of body. Body cell cannot carry out functions properly

when the blood glucose increases beyond norm after meal rich in sugar starch glucose (wow me when eating gummy bears)

more insulin into blood!

blood transport insulin to body cells liver and muscle rahh:

• promotes uptake of glucose by almost all body cells esp liver muscle and adipose tissue (except brain, doesn’t store glycogen)

• stimulate liver and muscle convert excess glucose to glycogen

Blood glucose conc. decrease back to normal. neg feedback sent to pancreas to prevent further corrective action

decreases beyond norm cause vigorous exercise (2.4 moment) or starvation 😢

more glucagon into blood!

blood transport glucagon to body cells liver and muscle rahh:

• glucagon stimulates liver and muscles to convert glycogen to glucose

• increase the release of glucose into blood from liver

Blood glucose conc. increase back to normal. neg feedback sent to pancreas to prevent further corrective action

Diabetes mellitus

best known endocrine disorder. 2 types. marked by high blood glucose concentration

Type 1 diabetes + treatment

early-onset diabetes, deficiency of insulin, where islets of Langerhans in pancreas cannot produced sufficient insulin

treatment: insulin injections

Type 2 diabetes

caused by decreased response to insulin in target tissues. occurs later in life, late-onset diabetes. overweight ppl r more likely to develop type 2 diabetes

Treatment: lifestyle changes, regulate carbs in diet and exercise. if fail, medications + insulin injections

Signs of diabetes mellitus

• persistently high glucose lvl

• slow or difficulty healing of wounds

• presence of glucose in urine, esp aft meal

why presence of glucose in urine is a test of diabetes

elevated blood glucose exceeds reabsorption capacity of kidneys, causeing glucose to remain in filtrate. glucose concentrated in urine, more water excreted with it, excessive volume of urine and persistent thirst. without sufficient glucose available to meet needs, fats become the main substrate for cellular respiration