الممرضة تقيس ضغط الدم.

الـ is the Arabic definite article, equivalent to the in English. So الممرضة means the nurse, not just a nurse.

In this sentence, all three nouns are definite:

• الممرضة = the nurse
• ضغط becomes definite because it is linked to الدم
• الدم = the blood

Arabic often uses definiteness a bit differently from English, but here it matches English quite closely.

تقيس is the present-tense form of the verb قاسَ / يَقيسُ meaning to measure.

It is تقيس because the subject الممرضة is:

• third person
• singular
• feminine

In the present tense, a singular feminine subject usually takes a verb beginning with تـ.

Compare:

• هو يقيس = he measures
• هي تقيس = she measures

Since الممرضة is feminine, تقيس is the correct form.

A very common sign of a feminine noun in Arabic is the ending ـة (called taa marbuuTa).

So:

• ممرّض = male nurse / nurse (masculine)
• ممرّضة = female nurse / nurse (feminine)

Because the noun is feminine, the verb also appears in the feminine singular form: تقيس.

Arabic allows more than one word order.

This sentence uses subject–verb–object order:

• الممرضة = subject
• تقيس = verb
• ضغط الدم = object

You could also say:

• تقيس الممرضة ضغط الدم

That is a very normal Arabic pattern too, especially in more formal grammar, where verb–subject–object is common.

Both are correct, but there can be slight differences in style or emphasis:

• الممرضة تقيس ضغط الدم puts the nurse in focus first.
• تقيس الممرضة ضغط الدم starts more neutrally with the action.

ضغط الدم is an iDaafa construction, often called a possessive or genitive construction.

Literally, it is:

• ضغط = pressure
• الدم = the blood

Together: blood pressure

In an iDaafa:

1. the first noun usually does not take الـ
2. the second noun can be definite
3. the whole phrase becomes definite if the second noun is definite

So although ضغط does not have الـ, ضغط الدم as a whole means the blood pressure.

This is one of the most important features of iDaafa.

In Arabic, when two nouns are linked like X of Y, the first noun normally does not take الـ. The definiteness comes from the second noun.

So:

• ضغط دم = blood pressure / a blood pressure in an indefinite sense
• ضغط الدم = the blood pressure

Because الدم is definite, the whole expression becomes definite.

Yes, in fully vowelled formal Arabic, the sentence could be written with case endings:

• الممرضةُ تقيسُ ضغطَ الدمِ

These endings show grammatical role:

• الممرضةُ: subject, so nominative
• تقيسُ: present tense verb ending
• ضغطَ: direct object, so accusative
• الدمِ: genitive because it is the second part of the iDaafa

However, in normal modern writing, short vowels and case endings are usually omitted, so you normally see:

• الممرضة تقيس ضغط الدم

Learners should know the grammar, but also get used to reading unvowelled text.

The ending ـة is taa marbuuTa.

Its pronunciation depends on context:

• When pausing at the end of the word, it is usually pronounced like -a / -ah
• When the word is followed by grammatical endings or in connected speech, it relates to t

So الممرضة is commonly pronounced roughly as al-mumarriDa when said in pause.

But in fully inflected reading, you may hear something like al-mumarriDa-tu.

This is very normal in Arabic: the written ـة often sounds like a in pause, but grammatically it is linked to t.

It can mean either, depending on context.

The Arabic present tense often covers both:

• she measures
• she is measuring

So الممرضة تقيس ضغط الدم could mean:

• The nurse measures blood pressure (general/habitual)
• The nurse is measuring blood pressure (right now)

Context tells you which meaning is intended.

A common way in Modern Standard Arabic is to use لا before the present tense verb:

• الممرضة لا تقيس ضغط الدم
  = The nurse does not measure / is not measuring the blood pressure

For beginners, لا + present tense is the most useful negative pattern to learn for sentences like this.

You would change both the noun and the verb agreement:

• الممرّض يقيس ضغط الدم

Changes:

• الممرضة → الممرّض
• تقيس → يقيس

That is because the subject becomes masculine singular, so the verb changes from the feminine form تقيس to the masculine form يقيس.

Yes, but it means something different.

• الممرضة تقيس ضغط الدم = the nurse measures blood pressure
• الممرضة تقيس الدم = the nurse measures the blood

The second sentence is grammatically possible, but medically it suggests measuring blood itself, not specifically blood pressure. So ضغط الدم is the correct phrase for blood pressure.