human bio test 1

homeostasis

the process of maintaining a constant internal environment

how does homeostasis maintain the fluid environment of a cell

• keeps at optimum temp of 37

• maintains optimum conc of solutes

• maintains optimum pressure

endocrine system

a communication system that uses chemical messengers rather than nerve impulses to maintain homeostasis

endocrine glands

secretes hormones directly into adjacent tissue

exocrine glands

secretes hormones into a duct that carries the secretion to the body's surface or to a body cavity

hormones

chemicals secreted by endocrine glands to affect functioning of a cell or organ

how do hormones change the functioning of a cell

by changing the type, activities or quantities of proteins produced

enzyme amplification (1 hormone molecule activates thousands of molecules)

a series of chemical reactions in which the produce of 1 step is an enzyme that produces an even greater number of product molecules at the next step

what happens when a hormone is no longer needed

it is broken down by the cell, liver or kidneys and excreted from the body

steroid hormones e.g. oestrogen

hormones that are made from cholesterol and are lipid soluble

what happens to a steroid hormone when they enter a cell

• travel in blood stream via transport proteins

• when reached cell, they diffuse across cell membrane

• combine with a receptor inside nucleus or cytoplasm to form a hormone-receptor complex

• hormone-receptor complex activates gene to produce new proteins - slow to have effect but are long lasting

how does the hormone-receptor complex activate genes

binds to the promoter section of a gene

non-steroid hormones e.g. protein, amine

hormones derived from amino acids that are water soluble

what happens to non-steroid hormones in the cell

• cannot diffuse across the membrane

• attach to receptor molecules on the membrane

• combo of hormone + receptor causes membrane channels to open and a secondary substance can enter the cell to activate enzymes

• fast to cause a response, short lasting

hormone receptors

they are specific. one receptor only binds to 1 specific molecule

how do hormone receptors limit cell activity

when all receptor sites in membrane are full, there can be no increase in cell activity

hypothalamus

responsible for regulating basic bodily functions

what does the hypothalamus secrete

inhibiting factors and releasing factors into the anterior P.G

releasing factors

factors that stimulate the release of a hormone

inhibiting factors

factors that suppress the release of a hormone

how do releasing + inhibiting factors reach the anterior P.G

through blood vessels in the infundibulum

anterior pituitary gland

an endocrine gland that is responsible for secreting follicle stimulating hormone, lutenising hormone, TSH, prolactin, growth hormone + adrenocorticotropic

follicle stimulating hormone

stimulates development of egg + sperm

lutenising hormone

triggers ovulation + release of male sex hormones

adrenocorticotropic hormone

stimulates production + release of hormones from adrenal glands

Thyroid stimulating hormone

stimulates production + release of hormones from thyroid gland

prolactin

stimulates mammary glands + milk production

growth hormone

stimulates growth. increases the rate that amino acids are taken up by cells and built into proteins

posterior P.G

an endocrine gland that is responsible for secreting anti-diuretic hormone + oxytocin

how is hypothalamus joined to posterior P.G

through axons of neurosecretory cells that extend down infundibulum to posterior P.G

where are hormones stored in posterior

at the axon endings of neurosecretory cells

what triggers the release of hormones into posterior

by nerve impulses in the hypothalamus

anti-diuretic hormone

involved in water balance. high levels of ADH increase water absorption of kidneys and reduce amount of water lost in urine

oxytocin

causes contractions of uterine muscles during child-birth + contractions of mammary glands during breast feeding

pineal gland

an endocrine gland that secretes melatonin

melatonin

regulates sleep pattern. stimulated by dark, inhibited by light

thyroid gland

an endocrine gland that secretes T3 + T4

T3

increases rate of metabolism

T4

controls metabolism by regulating catabolic + anabolic reactions. also regulates calcium + phosphate levels via calcitonin cells

calcitonin cells

when calc + phos levels are too high, C cells will be released to reduce reabsorption rate of them into the kidney

parathyroid gland

secretes parathyroid hormone

parathyroid hormone

increase the calc levels in blood and phos excretion in urine

thymus

secretes a group of hormones called thymosins

thymosins

influence maturation of T-lympochytes

adrenal glands

a pair of endocrine glands that secrete adrenaline, noradrenaline, aldosterone + cortisol

adrenal medulla

inner layer of adrenal glands that secretes adrenaline + noradrenaline

adrenaline

prepares body for fight or flight

noradrenaline

increases the rate + force of heart beat

adrenal cortex

outer layer of adrenal glands that secretes aldosterone, cortisol (corticosteroids)

aldosterone

decreases amount of sodium in urine but increases amount of potassium

cortisol

promotes normal metabolism to help body withstand stress + repair damaged tissues

pancrease

an endocrine + exocrine gland that regulates level of glucose in blood by secreting insulin + glucagon through islets of langerhans

islets of langerhans

clusters of cells in the pancreas that produce hormones

insulin

secreted by beta cells in islets of langerhan and decreases the level of glucose in the blood

how does insulin decrease blood glucose levels

promotes the uptake of glucose from blood into somatic cells

what is glucose converted to

• liver: glucose to glycogen

• skeletal muscles: glycogen to glucose

• fat storage: glucose to fat

what is level of insulin secretion determined by

the amount of glucose in blood + controlled by negative feedback

glucagon

secreted by alpha cells of islets of langerhan and increases the glucose levels in blood + stimulates breakdown of fat in liver and storage tissues

how does glucago increase blood glucose levels

promotes breakdown of glycogen to glucose

gonads

reproductive organs that secrete androgens, oestrogens + progesterone

androgens

development + maintenance of male sex characteristics

oestrogen

develops + maintains female reproductive systems + regulates menstrual cycle and pregnancy

progesterone

prepares endometrium for implantation + prepares mammary glands for secretion of milk

placenta

secretes hormones during pregnancy that help maintain the pregnancy, stimulate development of foetus + stimulate mother's mammary glands

stomach + small intestine

secretes hormones that coordinate exocrine glands in digestive system

kidneys

secretes erythropoietin

erythropoietin

stimulates production of red blood cells by bone marrow

heart

secretes a hormone that helps decrease blood pressure

diabetes mellitus

a disease in which there is abnormally high levels of glucose on blood + urine

type 1 diabetes

insulin dependent diabetes, in which there is a fault in the patient's immune system that cause destruction of beta cells in islets of langerhan

causes of type 1 diabetes

• immune system attacking pancreas

• genetics

• insulin just not produced

symptoms of type 1 diabetes

frequent urination, thirst, fatigue, unexplained weight loss

how is type 1 diabetes managed

through regular injections of insulin or recombinant DNA

type 2 diabetes

non-insulin dependent in which our body produces insulin but our cells do not respond to it

causes of type 2

• lack of physical activity

• overweight/obese

• smoking

• high diet in sugar, fat + salt but low in fibres

symptoms of type 2

fatigue, blurred vision, increased hunger

what are risks if type 2 if left untreated

heart disease, stroke, kidney disease or nerve damage

how is type 2 treated

through a management programmed that aims to keep glucose levels high by having a healthy diet, exercising, maintaining healthy weight

how does gene therapy treat type 1

reprogrammes other cells to produce insulin

gene therapy

treatment of a disease by replacing, manipulating or supplementing non-functional genes in cells + tissues

how does gene therapy reprogramme the cells

• gene for insulin introduced into a vector

• vector used to infect desired cells e.g alpha cells

• these cells incorporate new DNA into their nucleus and use p.s to produce insulin

receptors

a structure that is able to detect a change in the body's internal or external environment

sense organ

receptors grouped into a discrete organ

stimuli

any change in the internal or external environment that causes a response

thermoreceptor location

skin + hypothalamus

osmoreceptor location

hypothalamus

osmoreceptors function

• detect osmotic pressure of body fluids

• stimulate the hypothalamus so that body's water content is maintained

chemoreceptor location

nose, mouth, blood vessels

chemoreceptors function

• stimulated by particular chemicals

• in blood they detect the conc of O2, CO2 and pH

• regulates heartbeat + breathing

touch receptors location

skin, external genital organs

touch receptor function

• skin, respond to any touch

• receptors deep in skin are sensitive to pressure + vibration

pain receptor location

skin, mucous membranes, most organs (not brain)

motor neuron

carry messages from CNS to the effector organs known as muscles or glands to create a response

sensory neuron

carry messages from receptor in sense organs or skin to CNS

interneuron

link between sensory and motor neurons

cell body

contains nucleus + other organelles

what are cell bodies outside the CNS called

ganglia

dendrites

extensions of cytoplasm that carry the nerve impulse toward the cell body

nucleus

contains genetic info

myelin sheath

• a white fatty substance that stimulates + protects axon

• speeds up nerve impulses

• formed in PNS by schwann cells or glia cells in CNS