The Nervous, Endocrine And Reproductive Systems

Front 1

What are sense organs called and what is their purpose?

Back 1

They are called receptors and detect stimuli both internally and externally

Front 2

How are signals transferred to the CNS?

Back 2

Signal is transmitted along sensory nerves to the Central Nervous System (CNS)

Front 3

How are responses produced?

Back 3

Information is coordinated by CNS. Effect is transmitted along effectors or motor nerves and produces response

Front 4

Neuron parts and functions:

Back 4

Axon: transmitters/conducting fibre
Schwann cell: make myelin
Nodes of Ranvier: Gaps in myelin
Myelin sheath: electrically insulating fatty layer and increases transmission speed
Nucleus
Cell body: Contains cytoplasm, nucleus and organelles
Dendrites: Receivers - connect to other neurons

Front 5

Nerves are made up of:

Back 5

Many neurons

Front 6

Neurons are classified according to the number of processes and the role in the body

Back 6

Multipolar: Many processes - several dendrites, one axon (most common in CNS
Bipolar: 2 processes - embryonic nerves, retina, cochlea and olfactory nerves
Unipolar: 1 process - PNS
Sensory: From sensory receptors to other cells
Motor: From CNS to muscles/glands
Relay: Common in CNS and carry impulse from Sensory to Motor neurons
Glial: Structurally support CNS neurons, myelin sheaths and defence cells

Front 7

Neuron properties

Back 7

Excitable - detect and respond to stimuli
Conductive - transmits signals from one end to the other and between neurons

Front 8

Transmission of nerve impulses:

Back 8

olarization of the neuron's membrane: Sodium is on the outside, and potassium is on the inside.
Resting potential gives the neuron a break. Is polarised
Action potential: Sodium ions move inside the membrane.As this happens, the neuron goes from being polarized to being depolarized. (Negative charge)
Repolarization: Potassium ions move outside, and sodium ions stay inside the membrane.
Hyperpolarization: More potassium ions are on the outside than there are sodium ions on the inside.
Refractory period puts everything back to normal: Potassium returns inside, sodium returns outside.

Front 9

Cns:

Back 9

Brain and spinal cord - integrative and control centre

Front 10

PNS:

Back 10

Cranial nerves and spinal nerves - Communication lines between CNS and the rest of the body

Front 11

The brain:

Back 11

maintains involuntary body functions and initiates semi involuntary and voluntary muscle actions
higher mental functions such as reasoning, emotions and personality.

Front 12

Parts of the brain:

Back 12

Cerebrum
Cerebellum
Pons
Medulla Oblongata

Front 13

Hind brain parts and functions:

Back 13

Medulla Oblongata – controls heart rate, breathing, and blood supply
Cerebellum – controls body movements especially fine movements and maintains balance
Reticular activating system – filters incoming stimuli and controls wakefulness and sleep

Front 14

Forebrain parts and functions:

Back 14

Cerebral Hemispheres – controls and initiates voluntary actions, receives and processes information from the senses and all the body’s receptors, carries out higher mental functions and is regarded as the site of emotions and personality.
Thalamus – directs sensory information from the senses to the particular part of the cerebrum

Hypothalamus – receives huge amounts of internal and external sensory information and acts as a coordinating centre between nerves and hormones. Responsible for hunger and thirst. Regulates body temperature and the balance of water and salts in the blood. Has strong links to the pituitary gland

Front 15

Grey and white matter:

Back 15

Grey matter: contains nerve cell bodies (their nuclei are responsible for the grey colour), glial cells and unmyelinated fibres
White matter: consists mostly of myelinated fibres (the fatty sheaths are creamy white), some unmyelinated fibres and glial cells

Front 16

PNS is made up of 2 sub sections and 2 sub sub sections:

Back 16

Somatic (voluntary, input from sense organs, output to skeletal muscles)

Autonomic (involuntary, input from internal receptors, output to smooth muscles and glands)

Subsections of Autonomic:
Sympathetic MS (fight or flight responses, neurotransmitter is noradrenaline, "Adrenergic system"
Parasympathetic MS (relaxin responses, Neurotransmitter: acyetylcholine, "Cholinergic system"

Front 17

Synapses are:

Back 17

Connections between neurons

Front 18

Structure of a synapse:

Back 18

Axon, Microtubules, Synaptic knob, Mitochondrion, Synaptic vesicle, Neurotransmitter molecules, Synaptic cleft

Front 19

What happens at a synapse:

Back 19

1. action potential arrives at synaptic bulb
2. this opens calcium channels in presynaptic membrane
3. As Ca concentration increases, synaptic vesicles move towards membrane
4. Neurotransmitters are released into synaptic cleftvia vesicles fusing to membrane
5. Neurotransmitter diffuses across cleft ( 1 ms)
6. Neurotransmitter binds to receptors on post synaptic cell membrane
7. These open Na channels which makes the membrane more receptive to another incoming signal
8. with enough Na in the cell the action potential is set up

Front 20

Types of neurotransmitters:

Back 20

Acetylcholine – acts throughout the brain modifying activity of other neurotransmitters. Involved in motivation and memory.

Amino acids – eg gamma aminobutyric acid (GABA), glycine and glutamate.
Monoamines – eg noradrenaline, dopamine and seratonin.
Neuropeptides – eg endorphins

Front 21

Drugs: Nicotine - stimulant

Back 21

Nicotine is taken into the brain very rapidly where it binds to acetylcholine receptors in the synapses. This fools the postsynaptic cells into thinking they are being stimulated. It also binds with dopamine receptors. This causes long lasting changes to cell connections and may explain why it is addictive. Dopamine is responsible for feeling of motivation and pleasure and nicotine reduces the body’s ability to make its own dopamine.

Front 22

Drugs: Cocaine and amphetamines- stimulant

Back 22

Cocaine blocks the dopamine transport sites – the proteins in the presynaptic bulb that reabsorbs dopamine back into the bulb. Dopamine is not removed from the synapse and builds up in increasing amounts. This is the cause of the pleasure associated with cocaine. Synthesis of dopamine is reduced with prolonged use and this causes addiction.
Due to low dopamine, the user suffers fatigue, depression and altered moods between fixes.
Amphetamines work in the same way.

Front 23

Drugs: Ethanol - sedative

Back 23

Ethanol is a fat soluble substance which can enter and change the properties of cell membranes This means that it can alter many neurotransmitters.

Front 24

Drugs: THC - sedative

Back 24

Cannabis mimics neurotransmitters and bind to many receptors called cannabinoid receptors
Affects: Short-term memory, Coordination, Learning, Problem solving

Front 25

Two important aspects of stimuli

Back 25

1. Sensation – general state of awareness of stimuli.
2. Perception – the interpretation of the stimuli by the brain – this allows us to assess the significance of the stimulus.

Front 26

Four types of Sensory receptors

Back 26

Photoreceptors – eyes
Chemoreceptors – taste and smell
Mechanoreceptors – touch, ears
Thermoreceptors – heat

Front 27

Structure of the eye:

Back 27

The iris opens and closes the pupil according to light conditions

The choroid contains the blood vessels and is dark coloured due to melanin (prevent internal reflections)

The ciliary body contains muscles that alter the shape of the lens

The sclera is the tough outer layer and is made mostly of collagen

The cornea is part of the sclera and is the transparent front of the eye

The conjunctiva is a thin layer of tissue that covers the cornea

The blind spot is where blood and nerves enter the eye

Fovea is the focus point of the eye

Front 28

How the eye works:

Back 28

Light enters the eye through the pupil
An image is focused on the retina
Energy in the light is changed into electrical impulses
Nerve impulses carry information to the occipital region of the brain along the optic nerve
The brain decodes the information and constructs the image

Front 29

Rods:

Back 29

Rods contain rhodopsin (vitamin A)
Light is absorbed by rhodopsin -> changes shape and the molecule breaks into two
This results in depolarisation in the cell membrane = action potential
The molecule returns to normal after the stimulus has passed
Rhodopsin = dim light and no colour

Front 30

Cones:

Back 30

Cones contain iodpsin. There are three different types of cone cells (Red, Green, Blue). The colour we perceive depends on which combinations of the three colours are stimulated.
Cones = detailed vision, but function poorly in low light.

Front 31

Structure of retina:

Back 31

Light travels through several layers of nervous tissue before it reaches the rods and cones

Front 32

What is the endocrine system?

Back 32

The endocrine system consists of ductless glands that release chemical messengers that are carried in the blood.
These hormones target only certain cells which then change their activity.
Chemical messengers = close distance, hormones = further away

Front 33

Major endocrine glands:

Back 33

Pineal, hypothalamus, pituitary, thyroid, parathyroids, thymus, adrenals, pancreas, ovaries/testes

Front 34

What does the endocrine system do?

Back 34

To maintain homeostasis (eg balance: blood sugar level, blood pH, and water levels)
Also works with the nervous system to help the body respond to stress eg. adrenal release in the fight or flight response

It controls the body’s rate of growth
It controls sexual development and reproduction.

Front 35

Two types of hormones:

Back 35

water soluble (amino acids, peptides or glycoproteins) include hormones such as adrenaline and insulin
Lipid soluble (fatty acids) include oestrogen and progesterone.

Front 36

Adrenaline:

Back 36

Adrenaline is made in the adrenal medulla and is responsible for raising heart rate and blood pressure under stress. The fight or flight response.

Front 37

Negative feedback:

Back 37

Pathways are turned on and off according to the level of substance. Eg. turning on adrenaline and glucagon

Front 38

How hormones affect target cells:

Back 38

Peptide based hormones attach to receptor molecules in the surface membrane of target cells.
This union creates a series of chemical reactions = effect

Steroid hormones switch on or switch off genes

Front 39

What is homeostatis?

Back 39

Homeostasis is the maintenance of the internal environment within specific limits. Eg. blood pH, carbon dioxide concentration, blood glucose concentration, body temperature and water balance.
Using nerves and hormones via negative feedback.

Front 40

How do we get blood glucose?

Back 40

Digestion of carbohydrates in the diet
Breakdown of glycogen in liver and muscle cells (Glycogen = stored glucose)
Conversion of non carbohydrate material eg protein, fat, pyruvate and lactate.

Front 41

Why is the pancreas important?

Back 41

The pancreas contains special cells that are responsible for the production of blood sugar controlling hormones – Insulin and Glucagon

Front 42

Alpha and beta cells:

Back 42

Alpha cells produce the hormone glucagon
Beta cells produce the hormone insulin

Front 43

How does the body control glucose levels?

Back 43

Negative feedback

Front 44

How is Blood Glucose sensed?

Back 44

Increased glucose = more ATP production
More ATP = potassium channel blocked. Potassium builds up in beta cell
Potassium depolarises membrane and opens calcium channel
Calcium -> stored insulin granules to be released

Front 45

Two types of diabetes

Back 45

Type 1 - early onset (cannot make insulin)
Type 2 - late onset (cells cannot detect insulin)

Front 46

Why do we need to reproduce?

Back 46

Reproduction ensure survival of the species or the DNA contained in it.
Reproduction also and importantly ensures variety (evolution)

Front 47

Asexual reproduction:

Back 47

- produces genetically identical individuals (clones
- Large numbers (survival strategy)
- No variety (bad for evolution)

Front 48

Types of asexual reproduction:

Back 48

Budding
Parthenogenesis - Reproduction without fertilisation (born pregnant)
Regeneration (starfish)

Front 49

Sexual reproduction:

Back 49

Fusion of gametes is called fertalisations -> zygote
- Genetically unique
- brings variety

Front 50

Hormones in reproduction:

Back 50

Hormones control and synchronise reproductive events are produced by three glands – Hypothalamus, pituitary gland and gonads (sex organs)

Front 51

How hormones are used in reproduction:

Back 51

Stimuli are sensed by nervous system
Hypothalamus releases gonadotrophin realising factor (GRF)
Pituitary releases Gonadotrophin
Gonads release steroid sex hormones (eg oestrogen, progesterone or testosterone)
Uses negative feedback to control hormone levels

Front 52

Puberty:

Back 52

Hypothalamus produces gonadotrophin releasing factor. This stimulates the pituitary to produces gonadotrophins follicle stimulating hormone (FSH) in girls and
interstitial cell stimulating hormones (ICSH) in boys
These stimulate gonads to proguce sex hormones and start development of secondary sex characteristics

Front 53

Male reproductive organs:

Back 53

Sperm are made in the testes.
The testes are located in the scrotum and are responsible for spermatogenesis – making sperm.
The epididymis matures the sperm
The vas deferens allows them to move to the seminal vesicle and prostate area.
These produce seminal fluid
The sperm exit the body via the urethra

Front 54

The testes:

Back 54

Each testis is composed of a series of lobules containing seminiferous tubules (coiled tubes)

Front 55

3 stages of Spermatogenesis:

Back 55

Multiplication – cells of the germinal epithelium (on wall of teste tubule) divide by mitosis to produce many spermatogonia
Growth – the spermatogonia grow into primary spermatocytes.
Maturation – the spermatocytes undergo (meiosis) and produce cells with half the number of chromosomes. these are spermatids. Tails are added = spermatozoa. Gets nutrients from sertoli cells

Front 56

Structure of sperm:

Back 56

Acrosome – used in fertilisation
Nucleus – containing half the fathers chromosomes
Mitochondria – to provide energy for motility
Tail – made of microtubules like flagella

Front 57

Ejaculation:

Back 57

Sperm are moved through the vas deferens and are joined by fluids from the seminal vesicles and prostate gland to form semen. The semen is expelled from the body through the urethra inside the penis

Front 58

Female reproductive system:

Back 58

Ovaries produce oestrogen and progesterone as well as ova (singular: ovum) 3-4 cm wide and attached to the pelvis by a ligament.
The fallopian tubes (oviducts) connect the ovaries with the uterus. Fimbiae (fingerlike projections waft the ovum into the funnel of the fallopian tube).
Uterus nourishes protects and expels the foetus
Cervix narrow muscular channel usually blocked by mucous
Vagina - lubricating passage through which the foetus is expelled.

Front 59

Oogenesis:

Back 59

- begins when a foetus
-Multiplication – Primordial germ cells in the epithelium (outer layer of the ovary) undergo mitosis to produce oogonia.
Growth – oogonia move toward the middle of the ovary , undergo further mitosis and become primary oocytes.

Maturation – after puberty a few follicles mature each month. Usually only one completes maturation. The rest degenerate. (mature = secondary oocyte)
Surrounded by graafian follicle

Front 60

Ovulation:

Back 60

The egg cell (secondary oocyte) is released into the body cavity (when the graafian folicle bursts) and the fimbriae waft the egg into the fallopian tube.
The old follicle develops into a secretory body called the corpus luteum
The egg proceeds into the uterus where it usually degenerates

Front 61

Menstrual cycle's 4 phases:

Back 61

Proliferative phase
Ovulation phase
Secretory phase
Menstrual phase

Front 62

Fertilisation:

Back 62

The sperm's acrosome has digestive enzymes these digest a pathway through the corona radiata and the zona pellucida.
Membrane forms, stopping other fertilisation
Nucleus enters and causes egg to split (1/2 becomes polar body) gametes fuse = zygote

Front 63

Early embryonic development:

Back 63

Cell divides rapidly making bundle of cells called morula
-> Hollow ball = blastocyst

Front 64

Implantation:

Back 64

Pregnancy begins with the blastocyst attaching itself to the endometrium (edge of uterus)

Front 65

HCG:

Back 65

HCG forces the corpus luteum to secrete progesterone which maintains the endometrium and inhibits FSH
Pregnancy test

Front 66

Placenta:

Back 66

Sustains foetus

The placenta is also an endocrine organ.
It secretes the hormones that maintain pregnancy (Progesterone) as well as oestrogen which inhibits ovulation, HCG and human placental lactogen which promotes mammary development

Front 67

Birth:

Back 67

Week 38 = drop in progesterone
wk 40 = pituitary starts producing oxytocin and the placenta produces prostoglandins

Front 68

Birth positive feedback

Back 68

The contraction of the uterus and the tension on the cervix stimulates more oxytocin to be produced.